A2 Homeostasis and Communication

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  • Created by: Jamie
  • Created on: 29-09-12 17:52

The Need for Communication

What needs to be maintained in all cells? Why is this because? What do enzymes need to work efficiently? Name 4 of these?

What do all living things external enviroments consist of? What does the environment do? What may this change cause? Give example? What must happen for the organism to survive? What is the environmental change called? Whats a response? Give example of slow environemtal change? What will the response be then? Give example? Give an example of quick change in the environment? What must be monitored? What must the organism do?

What do most multicellular organisms have a range of? What are these exposed to? What are they protected by? Such as? What are animals internal cells and tissues bathed in? what is thid? What is used up in metabolic reactions? Whats produced? What are some of these products? What do these substances do? Therefore what does cell activity alter? Whats a waste product? What happens if its allowed to build up? How? Whats the stimulus in the internal environment? Whats the response? However is this response always good?

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The Need for Communication

A certain limitited set of conditions inside their cells, they rely on the actions of enzymes, need a specific set of conditions to work efficently, temp, pH, aqueous eviroment that keeps enviroment that keeps substrates and products in solution, freedrom from toxins and excess inhibitors

air water and soil around them, it will change, it may place stress on the living organism, cooler enviroment will acuse greater heat loss, changes in the enviroment must be monitoired ad the organism must change its behavior or physiology to reduce stress, stimulus, the way in which the organism changes its behaviour or physiology, seasons passing or global warming, gradual response, the arctic fox has a much thicker coat in winter and thinner grey one in summer to help it adapt to the changing conditions, from day to night or walking from bright sunlight into an unliut room, stimulus, must respond to the change

tissues and organs,not exposed to the external enviroment, the epithelial tissues and organs such as ski or bark, tissue fluid, enviroment of the cells, substartes and produce products, unwatnted or toxix, diffuse out of the cells into the tissue fluid, their own enviroment, carbon dioxide, if it builds up in the tissue fluid then it could after the action of enxymes by changing the pH of the neviroment around the cell, acculaamtion of excess waste or toxins, the removal of these wastes so that the cells can survive, may not be good for the whole organism,

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The Need for Communication

Whats more efficient multi or single celled organisms? Why? What does this mean? Whats do these cells form? Whats the result for the distance between cells that monitor the blood and the cells that release a substance? Whats required? To ensure? What will a good communication cover? What will enable? What sort of communication? What speed communication? What two tyoes of responses will it enable?

Whats cell communicaiting with each called? what does one cell release? What happens next? What will the second cell do? What are the two major systsmes that work by cell signalling? What is the neruanl system made up of? What do they signal across? What speed do the neurones conduct a signal? What do they enable to what sort of stimuli? What does the hormonal system use? Cells in what sort of organ release the hormone into the blood? Where is it carried? What is it only recognised by though? What does the hormonal system enable? To be what?

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The Need for Communication

Multi cellular, its cells can be differentiated, its cells can be specialised to perform particualr functions, tissues and organs, cells that monitor the blood may be in a different part of the body and well away from the cells that releasea substance into the blood or well away from the organ that removes that substance from the blood, a good coomunciaton system, that these different parts of the body work  together effectivly, cover the whole body, cells to communicte with each other, specific communication, rapid communication, both short and long term responses

cell signalling, one cell releases a chemical that is detced by another cell, the second cell will respond to the signal released by the first, neuronal ad hormonal systems, interconnected network of neuones, across synapse junctions, neurones can conduct a quick and enable a rapid respose to stumli that may be changing quickly, uses blood to transport signals, endocrine organ release the signal directly into the blood, carried all over the body, only recognised by speicific target cells, longer term responses to be coordinated

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Homeostasis and Negative Feedback

What is homeostasis? What do many living organisms have to maintain? Name 6?

What three process have to occur in order to maintain a constant internal environment? What is negative feedback? What must their be for negative feedback to work effecitvly? Coordinated through? What is produced? What are the four structures required for negative feedback to work? Give an example of a sensory receptor? Where are they? What do they monitor? What if they detect a change? Name the two possible communication systems? How does this act? What is it used to do? What may it pass through? Such as ? give example of effector cells? What will they bring about?

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Homeostasis and Negative Feedback

keeping the internal enviroment constant despite external changes, a great number of conditions constant inside the body, body temp, blood glucose concentration, blood salt concnetration, water potential of the blood, blood pressure, carbon dixoide concentration

any change to the internal enviroment must be detected and the change must be signalled to other cells and there must be a response that reverses the change, the process of reversing a change in the internal enviroment to return to a steady state or optimum position and is essential for homeostasis, there must be a complex arrangemtn of structures that are all cooridated through cell signalling, a standard pathway that is used to produce a suitale response to a stumuls, optimum condition to stimulus to receptor to cell signalling to effector to reposnse, sensory recptoor a communication system and effector, temperature receptors or glucos concentration receptors, internal and monitor confitions iside the body, they will be stimuatled to send a message, the nervous system or hormonal system, signalling betwen cells, used to transmit a message from the receptor cells to the effector cells, cooridnation centre such as the brain,  live or muscle cells, will birng about a response that reverses the cnage detced by the receptor cells

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Homeostasis and Negative Feedback

What can a negative feedback system maintain? What wont they remain? What will their be? Is a little variation ok?Give an example? what does this mean when applied to lving things? warm enough to allow what? and cool enough to?

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Homeostasis and Negative Feedback

Can manintain a reasoiably consstant set of conditions, never remian perfectly constant, variation about the mean or optimum condition, isnt to great then the conditons will remain acceptable, a heatd room will never get to cold or too hot, that the conditons inside a living organuism will remain within a relavtivly narrow range, allow enxzymes to continue functioing effiecnelt and cool eneough to not damage the body many other proteins

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Maintaining body temp- ectotherms

What structure can a dramatic change in temp affect? Including? What sort of proteins are enzymes? What is their structure specific to? What happens if enzymes aren’t kept near or at their optimum temps? What does temp affect then? If enzymes don’t function properly  what also decreases? What temperature is the imoportant factor? Why? What parts may be allowed to increase or decrease without affecting survival?

What are the sort of limits endotherms can maintain temp? what are they indeopendant of?

Whats is an ectotherm? What does an ectotherms temp tend to do? What aren’t they able to do? What do they rely on for warmth? When can ecotherms regulate their body temp? when cant they? Name three advantages to being an ectotherm? Name two disadvantages? Why is warming up a problem in the morning? What do they require in winter?

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Maintaining body temp- ectotherms

Proteins, enzymes, globular proteins, specific to their function, the activity of enzymes, affecst their ability to function inside cells, the level of activity that can be achieved by the organism, core temperature, all the vital organs are found iwthin the main part of the body, peripheral

Strict limtis, largely independanet of the external temperature

Tends to fluctuate with the external temperature, are not able to increase respiration to generate heat internalle, external sources of heat to keep warm, successfully regulate their body temperature under all but the most etrem conditions, use less food in rspiratio, less food and may sruvive long nperiods without eating, snaes can last several weeks betwen meals, proportion of energy obtained from food can be used for growth, less active in cooler temps,warm up in the morning before they can be active, of predation, lizards bask in the sun in the morning,not active in winter as they never warm up, sufficient stores of energy to survive over the winter without eating,


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Maintaining body temp- ectotherms

What does the adapatation exposing body to the sun regulate temp wise? Who does it? What about orientating body to the sun? orientating body away frm un? Hiding in a burrow? Altering body shape? Increasing breathing movements?

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Maintaining body temp- ectotherms

Enables more heat to be absorbed, snakes, exposes larger surface area for more heat absorption, locusts, exposes lower surface area so that less heat is absorbed, locusts, reduces heat absorption by keeping out of the sun, lizards, exposes more or less surface area to sun, horned lizards, evaportes more water, locusts

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Maintaining body temp - endotherms

What is an endotherm? What are exorgernic chemuical reactions in the body? Where can endotherms increase the rate if reaction in the body? To do what? What are they using to produce what? What do they do that ectotherms do? Example? Give a physiological one? Name three advnatges of being an endotherm? Name three disadvtanges?

Name six body components that endotherms use as a physiological mechanism to maintain body temp? Name theyre response if the body core temp is to high or to low?

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Maintaining body temp - endotherms

an organism that can use internal sources of heat such as heat generated from matabloism in the liver to maintain its body temperature, reactions that release energy in the form of heat,, liver, to release heat, using some of their energy intake to stay warm, can use behavioual mechanisms as well to help maintain body temp, basking in the sun, redirecting blood to or away from the skin, fairly cosntant body temp whatever the temp externally and their actie when externa temop is cool such as night or early morning during winter and they have the ability to  inhahbit colder parts of the plant, significant part of the enrgy intake used to maintain body tmep in the cold and they require more food and less of the energy from food is used for growth or more food is needed in order to grow

Sweat glands in the skin, if to high secrete more sweat onto the skin so water in sweat evaportes using heat from blood to supply latent heat of vaporisation, if to low less sweat is secreted less evaportaion of water so less loss of latent heat, Lungs moyth and nose, if to high panting increases evaporation of water from lungs tounge and moist surfaces using latent heat as  previously described, if to low the animal does not pant so less water evaporates, hairs on skin, if to high hairs lie flat providing little insulation and thus more heat can be lost by convection and radiation, if to low hairs are raised to trap a layer of insulating air reducing the loss of heat from the skin, arterioles leading to capillaries in skin, if core temp is to high vasodilation allows more blood into capillaries near the skin surface so more heat can be radiated from the skin which in pale skinned people may look red, if to low vasoconstriction reduces the flow of blood through capillaires near the surface of skin less heat is radiated, liver cells, to high the rate of metabolism is reduced less heat is generated from exergonic reactions such as repsiration, if to low rate of metabolism is increased therefore respiration generates more heat which is transferred to the blood, skelteal muscles, if to high no spontaneous contractions, to low spontaneous contractions (shivering) generate het as muscle cells respire more

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Maintaining body temp - endotherms

Name three behavioiural resoinses if too hot and if to cold?

Where do endotherms monitor the temperature of their blood? What happens if the core drops below optimum temp? what two systemcs carry signals where? what is increased? To do what? Where is more heat released? What is decreased? What if its above the optimum core temp? What is this an example of?

Give the steps for controlling body temperature via negative feedback wether it rises or falls in core temp?

What centre in the hypothalamus montiors the blood temp and core body temp? what would an early warning help? Avoiding? What can the extremtiies effect if they start to cool or warm uop? What monitor the temp in the extremtiies? Where is this information sent? What can the brain then initiate? Such as?

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Maintaining body temp - endotherms

beahvioural if to hot move into the shade or orientate body to decrease surface area exposed to sun or reamin inactive and spread out the limbs to increase surface area, if to cold then move into sunlight or orientate body to increase surafce area exposde to sun or move about to generate heat in muscles (exceot in extreme cold when it is better to kepep still and roll into a ball to reduce surface area)

in thehypothalamus of the brain, the hypothalamus sends signals to reverse the change, increased rate of metabolism in order to release more heat from exergonic reactions, release of heat through extra muscular contractions, decreased loss of heat to the enviroment, the hypothalamus sends signlas that bring about the opposite changes, negative feedback,

Rise in core temp above 37, thermoregulatory centre in hypothalamus detects change, nervous system and hormonal system carry signals to skin live and muscles, less heat generated and more heat lost, temperature falls,  if it falls below core temp 37 then thermoregualtory centre in hypothalmus detects change etc..

Thermoregualtory centre, the hypothalamus to respond more quickly and aoid to much variation in core body temp, affect the core body temp, peripherial temperature receptors in the skin, thermoregulatory centre in the hypothalamus, inititate bahviroual mechanisms for maintaing body temperature such as moving into the shade

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Sensory Receptors

What type of cell are sensory receptors? What can they detect? What are they also? Meaning? What is each type of transducer adapted to detect? Give examples? What is each energy change in the environment called? what do the sensory receptors convert the energy into? Called?

For each one of these name the receptor and where its found in the body- light intensity and range of wavelengths (colours), presence of volatile chemicals, presence of soluble chemicals, pressure on skin, vibrations in air, length of muscle fibres?

What do all cell surface membranes contain? What are some proteins? What do they allow? What are ions? What if the channel is permanatly open? What are nerve cells called? what do they have more of? What are they specific to? What does it also possess? What if its open? When closed? What are the channels usually kept? What do nerve cell membranes also contain? What do they do? What are they called? More of what is actively transported out of the cell than what are actively transported into the cell? What charge is inside the cell with respect to outside? What is the cell membrane said to be? How is a nerve impulse created? What happens as the sodium ion channels open? Is it up or down the gradient? What does the movement of ions across the membrane create? Meaning a what? What does the inside of the cell become compared to the outside? What is this called? what is a polarised membrane? What is depolarisation?

What do receptor cells respond to? What do the gated sodium ion channels do? Allowing what? What is the small chnge in potential caused bu one or two sodium ion channels opening called? what is the stimuls is larger? What initiated if enough sodium ions enter the cell?  What is generator potential? What is action potential?

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Sensory Receptors

Specialised cells, detect changes in our surrounding, energy transducers, they convert one form of energy to another, to detect changes in a particular form of energy, a change in light levels or a chang in pressure on the skin or one of many other energy changes, stimulus, a form of electrical energy called a nerve impluse,

Light sensitive cells in the retina of eyes, olfacotry cells lining the inner surface in the nasal cavity, taste buds in the tounge hard palate epiglottis and the first part of the osephugus, pressure receptors (pacinian corpuscles) in the skin, sound receptors, vinrations in the air, mucles spindles length of muscle fibres,

proteins, channles that allow the movement of ions (charged partivles) across the membrane, the ions can diffuse across the membrane and will do so until conctrations of that particular ion are eaual on both sides, neurones,l, speiclaised channle proteins, either to sodium or pattassium ions, gate that can open or close the channel, permeability of the membrane to that prticular ion is increased, permeability is reduced, kept lcosed,carrier proteins, actively transport sodium ions out of the cell and potassium ions into the cell, sodium/potassium ion pumps, more sodium ions than potassium into the cell, negatively charged with respect to the outside, polarised, altering the permeability of the nerve cell membrane to sodium ions, membrane permeability is incraesed and sodium ions acn move across the membrane down their concentration gradient into the cell, change in potetnial difference (charge) across hte membrane, less negative comapre to the outisde tha usual, depolarisation

changes in the enviroment, open, sodium ions to diffuse across the membrane into the cell, a generator potential, the more gated channels will open, the potential difference changes significantly, impulse of aciton potential

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Sensory Receptors

Once a stimuls has been detected its energy is converted to a? where must it now be transported? What is it transported along? As what? Name the three types of neurons? What does sesory carry from and to? What about motor neurones? What do relay neurones connect? What is the function of a neuron? What do most neurons have? Whats their size? How does this help? What does the cell surface membrane have? How does this help? What pumps do they have? What do they us? To do what? What do they maintain across their membrane? What are they surrounded by? Called? what is it? What does it do? Where are their gaps? Called? Where is the nucleus held? What do they have many of? Where do motor neurons have their cell body? What do they have a long? Whart does it do? What do sensory neurons havea  long? Carrying what? Where is it positioned? Whats their axon length? Carrying what where? What do both have numerous of? Draw a motor and sensory neuron?

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Sensory Receptors

ddepolorisation of the receptor cell membrane, to other parts of the body, neurones as an action potetnial, sensory motor and relay, action potential from  sesory receptor to the central nervous system, cary action potential from the CNS to an effector such as muscle or gland, connect sensory and motor neurones, is to transmit the action potential from one part of the body to antoehr, similiar basic structure, carry out their function, specialised, long, transmit action potetnail over a long distnce, many gated ion channels, the entry or exit of sodium potassium or calcium ions, sodium/potassium ion pumps, ATP, to activly transport sodium ions out of the cell and potassium ions into the cell, a potential difference, fatty sheath, mylein sheath, schwann cells, insulate the neurone from the electrical acitivty in nearby cells, where the schwann cells meet, nodes of ranvier, held in the cell body, mitochondria and ribosomes, in the central nervous system, long axon, that carries the action potential out to the effector, long dendron, carry the action potential from a sensory receptor to the cell body, just outside the central nervous sytem, short axon, carrying action potential into the central nervous system, dendirties, to other neurones

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Resting potentials and action potentials

What is a neuron said to be when it is not transmitting an action potential? In fact what is it doing? What do sodium/potassium ion pumps use? to do what? What pumps out? What pumps in? how many sodium for potassium? What is the plasma membrane more permeable to sodium or potassium? What do many do? What does the cell cytoplasm also contain large? What are they? What is the interior then compared to the outside? What is the membrane said to be? What is the potential difference across the membrane? What is this called? what is the resting potential?

At rest what are the gated channels? What do the sodium/potassium ion pumps use for active transport? How many _____ in and how many ____ out? Into what? What do a few of the potassium ions do? Why? What if some of the sodium ion cahnnels are ioened? From where to where? What dose this cause the membrane to become? In the generator region of receptor cells how are the gated channels opened? Example- what does the pacinian corpuscle detect? How are their gates opened? What are the gates further along the neuron opened by? What are they called? what do these channels respond to?  What are voltage-gated channels?

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Resting potentials and action potentials

at rest, activly transporting ions across its cell surface (plasma) membrane, ATP, to pump three sodium ions out of the cell for every two potassium ions that are pumped in, Potassium ions, many diffuse out again, large organic anions,negtivly charged ions, maintained at a negative potential, polarised, -60mV, resting potential, potential difference or voltage acros the neurone cell membrane while the neurone is at rest and it is about -60mV inside the cell compared to the outisde other cells may aso maintain a resting potnetial that might hcnage under certain circumstances,

kept closed, ATP to actively transport three sodium ions out for every two potassium ions brought into the axon, diffuse back out as some potassium channels are open, sodium ions will quickly diffuse down their concentration gradient into the cell from the surrounding tissue fluid, depolorisation of the membrane, energy changes in the enviroment, pressure changes, deformation, change in the potnetial difference (volatge) across the membrane, volatge-gated channels, depolorisation of the membrane, channels in the cell membrane that allow the passage of charged particles or ions they have mechanisms called a gate which can open and close the chanel in these channels the gates resoond to change in the potnetial difference across the membrane

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Resting potentials and action potentials

What are generator potentials in the sensory receptor of the cell membrane? What effect will a small depolarisation have on the voltage-gated channels? However when may some nearby voltage-gated cahnnels open? What does this cause a large influx of? What does the depolarisation reach? What is that known as? When this value is reached what does the neuron do? Why? What does it mean that the action potential is self-perpetuating? What is threshold potential? What is action potential?

What does an action potential consist of? Whhen do the ions move across the cell membrane? What state does the membrane start in? whats the resting state? What channels open? What diffuse into the cell? What does the membrane do? Meaning? What value? What channels open? What flood in? what happens as more sodium enter? What does the potential difference across the membrane reach? What charge is the inside? What close ad what open? What diffuse out? What does the potential difference become? What is this called? what does the potential difference do slightly? What does this make the cell? What happens last? What state does it return to? Whats in the wrong place after the action potential? what must be restored? By what? For a short time what is impossible after each action potential? what is this known as? What does it allow? What does it also mean? Remember the steps match the diagram!

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Resting potentials and action potentials

depolarisations of the cell membrane, no effect, if the depolarisation is large enough to reach threshold potential, potntial difference across the membrnae of about -50mV if the depolisation of the embrane does not reach the threshold potential then no action potential is created if the depolisation reaches the threshold potential then an action potetial is created, sodium ions and the depolisation reaches +40mV, action potential, the neurone will transmit an action potential because many voltage-gated sodium ion channels open, once it starts at one point in the neurone it will continue along to the end of the neurone, is a depolisation of the cell membrane so that the inside is more positive than the outsie wiht a potential differnfce across the memkbrane of +40mV this can be tranmitted along the acon or dendron plasma membrane

set of ionic movements,  when the correct channels are open, resting state, polarised with the inside of the cell being -60mV compared to the outisde, sodoum ion channels, some sodium ions diffuse into the cell, depolarises, it becomes less negative with respect to the outisde and reaches the threshold value of -50mV, Voltage-gated sodium ion channels, sodium ions flood in, the cell becomes positvily charged inside comapred to outisde, +40mV, positive compared to outisde, sodium ion channels close and potassium channels open, potassium ions, back to negative comapred to the otuside, repolarisation, overshoots, hyperpolarised, the original potential difference is restored so that the cell returns to its resting state, sodium and potassium ions, concentrations of these ions inside and outside the cell, the action of the sodium/potassium ion pumps, stimulate the cell membrane to reach another action potential, refractory period, the cell to recover after an action potential, action pitentials are transmitted in only one direction 

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Transmission of action potentials

What is the role of the neuron? What does the opening of sodium ion channels at one particular point of the nuron upset? What state? Whats that created by? What does this create where? What do these local currents cause? when an action potential occurs what opens? Where? What does this allow? What does this movement of sodium ions cause? what rises at this point? Why? What does this cause sodium ions ro do? Away from what region? What is this movement of charged particles called? what are local currents?

What is their further along the membrane? How are the gates on these channels operated? At rest what is the voltage? What does the movement of sodium ions along the neurone alter? What happens when the potential difference is reduced? What does this allow? What has moved along the neurone?

What is the myelin sheath? What can diffuse through it? What does this mean for the length that the ionic movements that creat an action potential of the neurone? What are the gaps in the myelin sheath? What are the gaps called? where do the ionic exchanges that cause an action potential occur only? In myelinated neurones what are the local currents? What do sodium ions do? What does this mean the action potential does? What is this called? what is salutatory conduction?

What does the myelin sheath mean for action potential? does this speed or slow up the transmission? Are myleinated neurones faster or slower than non-myelinated neurones? What the value?

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Transmission of action potentials

is to transmit information in the form of action potentials to other parts of the body, balance of sodium and potassium ions, resting potential, sodium.potassium ion pumps, local currents in the cytoplasm of the neurone, sodium ion channels further along the membrane to open, sodium ion channels open, at a particular point along the neurone, sodium ions to diffus across the membrane from higher concentration to isnide the neurone, upsets the balance of ionic concentrations created by the sodium/potassium ion pumps, concentration of sodium ions inside the neuron, the sodium ion channels are open, to diffuse sideways away from the region of increased concentration, local current, the movemnt of ions along the neurone the flow of ions is cuased by an increase in concentration at one point which causes diffsuion away from the region of higer concentration

more gated sodium ion channels, changes in the voltage across the membrane, resting potential (-60mV inside the neurone), the potetial difference across the membrane, the gates open, sodium ions to enter the neurone at a point further along the membrane, the action potential,

1) sodium ion channels open allowing sodium ioons to diffuse into the neurone 2) localised increase in concetration of sodium ions inside neurone, the action potential 3) sodium ions diffuse along the axon/dendron away from the region of higher concetration 4) sodium gate which which was initialy closed will opne because of the movement of sodium ions allowing the action potential to move along the neurone as more sodium ions enter and set up another action potnetial

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Transmission of action potentials

What is the myelin sheath? What can diffuse through it? What does this mean for the length that the ionic movements that creat an action potential of the neurone? What are the gaps in the myelin sheath? What are the gaps called? where do the ionic exchanges that cause an action potential occur only? In myelinated neurones what are the local currents? What do sodium ions do? What does this mean the action potential does? What is this called? what is salutatory conduction?

What does the myelin sheath mean for action potential? does this speed or slow up the transmission? Are myleinated neurones faster or slower than non-myelinated neurones? What the value?

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Transmission of action potentials

insulating layer of fatty material, sodium and potassium ions cant, the ionic movement that creat an action potential cannot occur over much of the length, gaps beween the schwann cells that make up the myelin sheath, nodes of ranvier, at the nodes of ranvier, are elongated and sodium ions diffuse along the neurone from one node of ranvier to the next, appears to jump from one node to the next, saltatory conduction,

can only occur at the gaps between the Schwann cell that make up the myelin sheath, speeds up the transmission, more quickly than non-myleinated neurones, 120m s-1

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Nerve Junctions

What is a synapse? What can one neurone do here with another? Whats the gao between them called? approx how wide? How is an action potential produced? What cant the action potential do? What does the presynaptic action potential do instead? Whats the chemical known as? What does it do? What does it generator? What are synapses that use acetylcholine as the neurotransmitter called? what is a neurotransmittier called?

What does the presynaptic neurone end in? called? name its four specialised features? What does many mithcondria indicate?

What does the postsynaptic membrane contin? What can they respond to? What do these channels consist of? What do two of the polypeptides have? Specific to? What do the receptors have? What happens when acetylcholine  binds to the two receptpors?

Whats the first step in the sequence of tranmistting a signal across the synaptic cleft? What opens? What diffuses where? What does the calcium ions cause? what is released via what? What diffuse across what? What binds to what where? What opens? What difusses across what into what? What is created? When is the threshold potential reached? What is the last step? Once a actional potential is achieved where will It pass?

What is acetylcholinesterase? Wheres it found? What does it do? What does this stop? So what can happen? Whats happens to the ethanoic acid and choline? What do they do? Via what? What do they recombine to? Using what from where? What happens to the recycled acetylcholine?

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Nerve Junctions

a junction between two or more neurones, communcaite with or signal to another neurone, synaptic cleft, 20nm wide, by the movements of ions across the neurone membrane, bridge the gap between two neurones, presynatpci action potential causes the release of a chemical,  the transmitter substance, diffuses across the gap, gernates a new action potential in the postsynaptic neurone, cholinergic synapses, transmitter substacne which is a chemucal that diffuses acros the cleft of the synapse to transmit a signal to the postsynaptic neurone

swelling called the synaptic knob, many mitochondria which indicates that an active process needing ATP,  large amount of smooth endoplasmic reticulum, vesciesl of a chemical called acetylcholine, voltage gated calcium ion channels in the membrane

specialised sodium ion channels, transmitter substance, five polypeptide molecules, special receptor site that is specific to acetylcholine, complementary shape to the acetylcholine molecule, sodium ion channel opens

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Nerve Junctions

Whats the first step in the sequence of tranmistting a signal across the synaptic cleft? What opens? What diffuses where? What does the calcium ions cause? what is released via what? What diffuse across what? What binds to what where? What opens? What difusses across what into what? What is created? When is the threshold potential reached? What is the last step? Once a actional potential is achieved where will It pass?

What is acetylcholinesterase? Wheres it found? What does it do? What does this stop? So what can happen? Whats happens to the ethanoic acid and choline? What do they do? Via what? What do they recombine to? Using what from where? What happens to the recycled acetylcholine?

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Nerve Junctions

an action potential arrives at the synaptic knob, the voltage gated calcium ion channels open, calcium ions diffuse into synaptic knob, synaptic vesicles to move to and fuse with the presynapti cmembrane, acetylcholine is relased by excotysis, acetylcholine molecules diffuse across the cleft, acetylcholine molecules bind to the receptor sites on the sodium ion cahnnels in the postsynaptic membrane, sodium ion channels, sodium ions diffuse across the postynaptic membrne into the postynaptic neurone, a generator or excitatory postynaptic potneial is created, if sufficne tgenerator potentials combine,  a new action potential is created in the postynaptic neurone, it will pass down the posytnaptic neurone,

an enzyme found in the synaptic cleft, hydrolyses the acetycholine to ethanoic acid and choline, this stops the transmission of signals so that the synapse does not continue to produce action potentials in the postsynaptic neurone, recycled, re-enter the synaptic knob by diffusion and are recombined to acetylcholine using ATP from respiration in the mitochindria, stored in the synaptic vesicles for future use

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Signals and Messages

What does it mean that an action potential is an all or nothing response? once the action potential starts what will a nerurone do? does the action potential vary in size or intensity? What happens at the end of the neurone? What is the signal sent to the next neurone? Are these processes the same in all neurones and cholinergic synapses?

What is the main role of the synapse? Is that their only function? How many do several presynaptic neurones converge to postsynaptic neurones? What does this allow? Where could this be useful? What may one presynaptic neurone diverge to?what would this allow? What is this useful in? what happens here? What do synapses ensure? How? What can synapses filter? If a low-level stimulus creates an action potential in the presynaptic neurone what is unlikely to happen? Why? What process amplifies low level stimuls? What will happen if a low level stimulus is persistent? Why is an acion potential produced? When can summation also occur? What is acclimatisation? What is the synapse said to be? What does this mean no longer happens? What does this explain? What does it help to avoid? What is the creation of specific pathways within the nervous system thought to be? Overall what do the pathways created by synapses enable? When does the brain perceive light? What about sound? Why is this?

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Signals and Messages

neurone either coducts an action potnetial or it does not, conduct it all along its length, its doenst vary in size or intensity, the presynaptic knob releases the tranmitter substance into the synaptic cleft, molecule of acetylcholine, they are the same

conect two neurones together so that a signal can be passed from one to the other, a number of other important functions, several, signals from different parts of the nervous system to create the same response, where several different stimuli are warning us of danger, several postsynaptic neurones, one signal to be transmitted to several parts of the nervous system, reflex arc, one postsynaptic neurone elcits the response while another informs the brain, that signals are transmitted in the correct direction, only the presynaptic knob contains vesicales of acetylcholine, filter out unwanted low-level signals, to pas across a synapse to the next neurone because several vesicles of acetycholine must be released to create an action potetnial in the postynaptic vesicle, summation, it will generate several successive action potentials in the presynaptic neurone, the release of many vesicles of acetylcholine oer a short period of time will enable the postsynaptic generator potentials to combine together to pduce an action potential, when several presynaptic neuroneseach release small numbers of vesicles into one synapse, after repated stimulation a synapse may run out of vesicles containing the transmitter substance, fatigued, the nervous system no longer responsds to the stimulus, why we soon get used to smell or background noise, overstimulation of an effecctor which could damage it, basis of concious thought and memory, the nervous system to convery a wide range of messages, when it recieves signals from the light receptors in the eyes, when it recieves signals from the ears, it knows where the signals are coming from because the neurones from specific receptors always connect to specific regions of the brain

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Signals and Messages

Are the complex interconnections of the nervous system the only way different messages can be conveyed? What does a signal coming from the light receptors in the eye to the relevant optical centre in the brain inform the brain? What doesn’t it? What happens when a stimulus is higher? What will this cause? What happens when they arrive at a synapse? In turn what does this create? What can our brain determine? What do higher frequency of signals mean?

How many of the peripherial neruones in verterbeas myelinated? What is the sjheath created by? What are the cells called? where are they? So what does the sheath actually consist of? At what intervals along the neurone are there gaps in the myelin sheath? What are these called? how big are the nodes? Value of size? What are non-myelinated neurones also assoiated with? What may several be enshrouded by? What does this mean for the action potential? rather than?

Whats one advantage of myleianted neurones? Whats a typical transmission speed in nmyleianted neurones? What may non only reach? Where do myelinated neurones carry signlas from to where? And from the CNS to where? Do they carry over long or short distances? What can the longest neurone in a human be? The increased speed of transmission means that the signal reaches the end of what quicker? What does this enable? What do non myleianted tend to be in size? And what distance? What are they used in? such as? Whats not important then? Draw and identify non and myelianted neurones?

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Signals and Messages

not the only way, light is falling on the eye, it doesnt say anything about the intensity of the light, the sensory recptor will produce more generator potentials, more frequent action potentials in the sensory neurone, cause more vesicles to be released, creates a higher frequecy of action potentials in the postyanptic neurone, the insentiy of the stimulus from the frequency of signals arrving, higehr frequency of signals means a more intense stimulus

one third, a series of seperate cells called scwann cells, wrapped around the neurone, several layers of membarne and thin cytoplasm from the Schwann cell, 1-3mm along, nodes of ranvier, very short about 2-3 um, schwann cells, one looselly wraped schwann cell, moves along the neurone in a wave rather than jumping from node to node as seen in myleinated neurones,

can transmit an action potential much more quickly than non-myleinated neurones, 100-120 ms-1, 2-20ms-1, sensory recptors to the CNS and from the CNS to effectors, long disatnces, 1m length, end of the neurone,  a more rapid response to a stimulus, shorter and carry signals only over a short distance, coordinating body functions such as breathing, action of digestive system, the increased speed of transmission

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The Endocrine System

What sort of system is the endocrine system? What does it use? to do what? Where does the blood system transport materials? Therefore where will the signals released into the blood go? What are the signals released by the endocrine system? Where are hormones released directly into the blood from? What sort of glands are these? What do they consist of? That produce what? Straight into where? Through? What are hormones? What are endocrine glands?

How many types of glands in the body? What do endocrine glands do? whats the other type? What don’t they release? What do they have? What does it carry? Give example? Whats an exocrine gland?

What must cells receiving a hormone signal have? Where? What does the hormone do? what if all the cells in the body have such a receptor? What is each hormone from the others? What does this assure? What are the cells that possess the specific receptor called? what are they usually grouped together to form? For this reason what can the endocrine system do? what can it also send? What are target cells?

What are the two types of hormones? Give examples for each? What are there also? Give an example?  Do they work the same way? What are proteins not? So what don’t they enter? What can steroids do? what do they have a direct effect on?

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The Endocrine System

another communication system, blood circulation to transport its signals, materials all over the body, throughout the body, are molecules called hormones, glands called endocrine glands, ductless glads, group of cells that produce and release the hormone straight into teh blood capalrries running through the gland, molecules that are released by endocrine glands directly into the blood they act as messengers carrying a signal from the endocrine gland to a specific target organ or tissue, a gland that secretes hormones directly into the blood they have no ducts

two, release or secrete their hormones directly into the blood, exocrine gland, do not release hormones, small tube or duct that carries their secretion to another place, salivary glands secrete saliva into a duct, the salivva flows along the duct into the mouth, gland that secretes moleculese into a duct that carries the molecules to where they are used

possess a specific complementary receptor,  plasma membrane, bids to the receptor, then all the cells can respond to the signal, differnet, a hormone can travel around the blood without affecting cells that dont possess the correct specific receptor, taregt cells, target tissues, used to send signals all over the body at the same time, very specific signals, are those that possess a specific receotr on their plasma membrane the shape of the recepot is complemntary to the shape of the hormone molecule many similiar cells together forma  tissue

protei/ peptide and steroid hormones, insulin and glucagon, sex hormones, derratives of amino acids, adrealine, different ways, soluable in the phospholipid membrane and dont enter the cell, pass through the membrane and enter the cell to have a direcet effect on the DNA in the nuceleus

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The Endocrine System

What type of hormone is adrenaline? What is it unable to do? therefore what must it do? what is on the outside of the cell surface membrane? Whats its shape to what? What is this receptor associated with? Where? What is this enzyme called? what does adrenaline in the blood bind to? What is this adrenaline molecule called? what happens when it binds to the receptor? What does the adenyl cyclase convert? What is the cAMP? What can the cAMP cause? define first and second messenger?

Where are the adrenal glands found? What does anterior mean? How many? What can each be divided into? And a?

Where is the medulla found? What do the cells in the medulla manufacture? In response to? Such as? How big are the effects of adrenaline in the body? Why? What is the effect of adrenaline? What relax? What three things does it increase? What does it cause to raise blood pressure? Whats stimulated? What dilate? Whats inhibited? Whats erected?

What does the adrenal cortex uses to produce what? Name two? What they help to control? And an example?

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The Endocrine System

amino acid derivatie, enter the target cell, cause an effect inside the cell without entering the cell itself, the adrenaline receptor, has a complementary shape to the shape of the adrenaline molecule, with an enzyme on the inner surface of the cell surface membrane, adenyl cyclase, its specific receptor on the cell surface membrane, the first messenger, actiavtes the enzyme adeyl cyclase, ATP to cyclic AMP (cAMP), second messenger inside the cell, an effect inside the cell by activating enzyme action,

lying anterior (just above) the kidneys, one on each side, a medulla region and a cortex region,

centre of the gland, and release the hormone adrenaline in response to stress such as pain or shock, widespread and most cells have adrenaline receptors, prepare the body for activity, smooth muscles in the bronchioles, stroke volume of the heatt and heart rate and mental awareness, general vasocostriction, conversion of glycogen to glucose, the pupils, action of the gut, body hair,

cholestorl to produce certain steroid hormones, mineralocorticoids(aldosterone) and gluccorticoids(cortisol), help to control concentraions off sodium and potassium in the blood and help control the metabolism of carbohydrates and protins in the liver

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The regulation of blood glucose

What is the pancreas? Lying below? Why is it an unusual organ?

What do the majority of cells in the pancreas manufacture? What function is this? How are the cells found? What do they surround? What do they secrete into the tubles? What do the tubles join tomake? What does it carry? Where? What three enzymes does the fluid contain? Whats amylase? Whats trypsinogen? What does the fluid also contain which makes it alkaline? What does this help do?

What are certain areas of the pancreas that contain different types of cells called? what are the two types of cells? What do alpha cells do? what do beta cells do? what are the islets well supplied with? Why? What function is this? Define: pancreatic duct, islets of Langerhans, alpha and beta cells, insulin and glucagon?

What happens to the concentration of blood glucose carefully? What do the cells in the islets of Langerhans monitor? What is the normal concentration of glucose? What can it also be expressed as? What happens if the concentration rises or falls away from the acceptable concentration? How?

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The regulation of blood glucose

Small organ, lying below the stomach, it has both exocrine and endocrine functions

manufacture and relase digetive enzymes, exocrine function, small groups surrounding tiny tubles into which they secret digestive enzymes, the pancreatic duct, the fluid containing the enzymes into the first part of the small intestine, amylase trypsinogen lipase, carbohydrase, inactive protease, sodium hydrogencarbonate, helps neutralise the cotents of the digestive system that have just left the acid enviroment of the stomach,

islets of langerhans, alpha cells and beta cells, manufacture and secrete the hormone glucagon, manufacture and secrete the hormone isulin, well supplied with blood capallries, so the hormones are secredtd directly into the blood, endocrine function of the pancrease, a tube that that collects all the secretions from the exocrine cells in the pancreas and carries the fluid to the small intestine, are small patches of tissue in the pancreas that have an endocrine function, found in the islets of langeherans alpha secreting the hormone glucagona dn beta secreting insulin, insulin being the hormone released from the pancreas that cause blood glucose concetration to go down and glucagon the hormone that cause blood glucose ocnentration to rise

regulated, monitor the concentration of glucose in the blood, 90mg in every 100 cm3 of blood, 4 and 6 mmol dm 03, then alpha and beta cells in th islets of langerhans detect the change and respond by releasing a hormone,

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The regulation of blood glucose

What cell detects a high blood glucose? Whats the B cells response? name the 4 target cells? What do these cells possess? What happens when the blood passes these cells? What do the receptors activate? What does that activate? Where? Name the four effects of insulin on liver cells? What does the increase entry of glucose through the specific channles reduce? Define hepatocytes?

What cell detects a low blood glucose concentration? Whats the response? whats its target cells? Where are the hepatocytes? What do they possess? What three effects do glycagon have? What is the overall effect of these changes?

what detects the rise in blood glucose conetration? what sis sceretd where? what detects isulin? what removes what? covnert it to what? what falls? what detcts a fall in blodo concnetration? what secrets what where? what detects glucagon? what converts what? rleases what where? what rises?

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The regulation of blood glucose

beta cells, secrete insulin into the blood, liver cells or hepatocytes muscle cells and some other body cells including those in the brain, soecific membrane-bound receptors for insulin, insulin binds to the receptors, a second messenger system which activates a series of enzymes-controlled reactions in the cell, more glucose enters cells through glucose cahnnels and glucose in the cell si converted to glycogen for storage (glycogenesis) and more glucse is converted to fat and more glucsoe is used in respiration, the blood glucose concentration, are liver cells they are specilaised to performa  range of metabolic functions

alpha cells, alpha cells secree the hormone glucagon, heptaocytes (liver cells) which posses the specific receptor for glucagon, conversion of glycogen to gluce (glycogenolysis) use of more fatty acids in respiration and the production of glucose by conversion from amino acids and fats (gluconeogenesis), increase the blood glucose cocentration

detecd by beta cells in the islets of langerhans, insulin into the blood, detected by receptors on liveer and muscles cells, remove glucose from blood and convert glucose to glycogen, glucose concentration falls,  detetced by alpha cells, secrete glucagon into the blood, detcted by receptors on lvier cells, convert glycogen to glucose and release glucose into the blood, glucose concentration rise

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The Regulation of Insulin Levels

What does insulin bring about? If the blood glucose concentration is to high what is important is released? From what cell? What has to stop if it drops to low?

What does the cell memkbane of th B cell contain both of? What are thepotassium ion channels normally? What about the calium io cahnnels? What diffuses out of the cell? What does this make the inside of the cell? At rest whats the potential difference? What happens when glucose concnetrations outside the cell aer high? What is glucose quickly used in? to produce? What does the extra ATP cause? what can no longer diffuse out? What does this alter? What does it become less where? What does this change in potential difference open? What enters the cell? What does this cause? how? Releasing what? Via what?

What don’t blood glucose levels remain? What will happen after a meal? What about exercise? What mechanism keep the blood concentration fairly well within certain limits? What is diabetes mellitus? What can this lead to? Whats this called? or it could lead to? After what? Whats this called?

What is type 1 diabetes also known as? Why is it often called juvenile-onset diabetes? What is it thought to be the result of? What may it also be a result of? What is the body no longer able to manufacture? What cant it store?

What is type 2 diabetes also known as? What can a type 2 diabetes people still produce? What happens as people age? What is this probally due to? What may also decline? What is thought for everyone? What age? What may bring on earlier onset type 2 diabtes? Name 4?

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The regulation of insulin levels

effects that reduce the blood glucose concentration, insulin is released, beta cells, insulin secretion stops, both calcium and potassium ion channels, open, closed, potassium ios, making the inside more negative, -70mV, glucose molecules diffuse into the cell, metabolism to produce ATP, potassium channels to close, potassium ions can no longer diffuse out, altering the opitetnial difference across the cell memrane, less negtaive inside, opens the calcium ion channels, calcium ions enter the cell and cause the secretion of insulin by making the veicles containing insulin to move to the surface mmebrane and diffuse with it realising insulin by exocytosis

reain constant, concnetration will rise and during exercise will fall, negative feedback mechanisms the body is able to keep tehj blood concetration fairly controlled within certain limitis, is a disease where the body no longer is able to control its blood glucose conentration, high cocentrations of glucose afer a meal rich in sugars and other carbohydrates (hyperglycaemia), cocnetrations dropping to low (hypoglycaemia) after exercise or after fasting

insulin-depedent diabetes, juvenile-onset diabetes as it starts in chilhood, autoimunne response in which the bodys own immune system attacks beta cells and sdestroys them, viral attack, manufacture sufficent insulin and *** store excess glucose and glycogen, non-insulin-dependent diabettes, still produce insulin, responsivness o insulin declines, specific receptor on the surface of the liver and muscle cells decline and the cells lose their ability to respond to the insulin in the blood, may also decline, become diabetic, 120, obestity a diet high in suagrs particular refined sugars being aisian or afro-caribbean faily hisotry

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Control of heart rate in humans

What system does the heart pump blood around? What does blood supply tissues with? What does it remove? Like? So what doesn’t happen? What does the requirement of the cells depend on? When your physically active what does your muscles need? What does your heart mucsles cells need more? What do they also need to do more of? what is therefore important so that the requirements of the body are met?  What is cell metabolism?

What is the most obvious change in the heart to adapt too supply more oxygen and glucose? What is this known as? What can the heart also increase? What can it also increase? Whats this volume known as?

What is the heart muscle? What does myogenic mean? What does the heart contain? Whats a pacemaker? Whats the pacemaker called? what is the SAN? What can it inititate? How does it travel? Over what? Through what? Down what? To where? What does that cause? what is the heart supplied by? What is the medulla oblongata? Where do these nerves connect? What don’t they initiate? What can they affect? What do action potetntials sent down the accelerator nerve increase? What about action potential down the vagus nerve? What hormone does the heart muscle respond to?

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Control of heart rate in humans

circulatory system, oxygen and nutrients such as glucose fatty acids and amino acids, waste products such as carbon dicoide and urea, from tissues so that they do not accumulate and inhibit cell metabolism, level of actibity, more oxygen and gluvose and your heart muscle cells need more oxygen and fatty acids, more co2, can adapt to meet the requierments of the body, result of all the chemical reacctions taking place in the cytoplasm

increase in the number of beats per minutre, heart rate, the strength of its contractiopns, volume of blood pumped per beat (the stroke volume)

myogenic, muscle tissue can inititate its own contractions, pacemaker,  region of tissue in the right atrium wall that can generate an impulse and initiate the contrtion of the chambers, sinoatrial node (SAN) an action potential which travels as a wave of excitiation over the atria walls through the AVN(atrioventricular node) and down the purkyne fibres to the ventricles causing them to contract, medulla oblongata of the brain, conect to the SAN, dont intiiate contrafction but they can affect the frequency of the contractions, increase the heart rat reduce the heart rate, presence of the gormone adrenaline in teh blood,

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The Need for Communication

Whats the composition of the tissue fluid maintained by? Where does blood flow? Whats its function? What does waste from cells do? How is acculumination in the blood prevented? Whats this called? what does monitoring this ensure? Whats maintained? What does it also ensure?

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The Need for Communication

the blood, throughout the body and transports susbatcnes to and from cells, enter the blood and be carried away, they must be remvoed from the body, excrted, that the body does not excrete to much of any useful substance but removes enough wwaste to maintaing good health, that all the cells of the body are supplied with substrtes they need

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Homeostasis and Negative Feedback

What is less common than negative feedback? What is positive feedback? What does it do the system? What is this usually? Give example? What happes to enzymes below a certain core temp? what happns to what reactions if theyre less active? what does this allow the body to do? What slows? What does the body temp do? What is positive feedback used to stimulate? Wheres an example? Where is it signalled to that the cervix is about to stretch? What does it stimulate it to secrete? What does oxytocin do? What does this do? What does this cause nmore of? What can happen when the cerix is fully dialted?

What can a negative feedback system maintain? What won they remain? What will their be? Is a little variation ok?

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Homeostasis and Negative Feedback

Positive feedback, a proess that increases any change dected by the receptors it tends to be harmful as it destabluses the system and does not lead to homeostasis, when the body gets cold, the enzymes become less active, exergonic reactions which release heat are alower and release less heat, the body to cool furhter and slows dow the enzymecontrolled  reactions even more, the body temp spirals downwards, optimum condition to change away from optimum to receptor to communciaton system to effector, an increase in a change, at the end of pregnancy to bring about dialation of

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Maintaining body temperature- ectotherms

What don’t ectotherms use to maintain body temp? what happens when they are active? from what? What does temperature regulation rely on? What will an ectotherm do when its cold? To do  what? What will an ectotherm do when its hot? To do what? What will they do to warm up? What if theyre to hot? What do locusts do to warm up? When theyre to hot? Why? What do some ecotherms have? Name one? What can it do? How? What may the frilled lizard do? What have locusts been known to do? What will it increase?

What does the adapatation exposing body to the sun regulate temp wise? Who does it? What about orientating body to the sun? orientating body away frm un? Hiding in a burrow? Altering body shape? Increasing breathing movements?

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Maintaining body temperature- ectotherms

intern energy sources to maintain body temp when cold, muscle contractions will generate some heat from increased respirtion., increasing the echange of heat with their enviroment, change its beaviour or physiology to increase absorption of heat from its enviroment, its behaviour or physiology to decrease absorption of heat and increase loss of heat to its enviroment, bask in the sun or lie on a warm surface, stay undergorund or in the sahde, orinatet themselve to be side-on to the sun when they need to warm up, move higher up a plant to get away from the hot ground and also face into the sun, smaller surface area to the sun,. phsyiological or anatomical adaptions to help echanhge heat with their enviroemnt, horned lizard cn alter its surface area by epanding or contracting its rib cage, frilled lizard may use its frills to help asborb heat from the sun, locusts also increase their abdominal breathing movements when hot, increase evaportion of water and aid cooling

expose body to sun, enables more heat to be absorbed snakes, orintates body to sun, exposes larger surface area so that less heat is absorbed locusts, orinated body awa from sun eposes lower surface area so that less heat is absorbed locusts, hide in burrow, reduces heat absorption by keeping out of the sun lizards, alter body shape exposes more or less surface area to sun horned lizards, increase breathing movement, evaportes more water, locusts

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Control of heart rate in humans

How must the various factors act to ensure the heart beats at the most appropriate rate? Under resting conditions what controls the heart rate? What frequency does it have? Is it the same in every person? What does it initiate? What is the frequency of waves typically? What can the frequnency of them waves be controlled by? Wheres that? What detects the movement of limbs? What do these send and where? Informing what? What does this increase? What happens when we exercise? What does some of this react with? Reducing? What detects the change in PH? Where are they? What do they send where? What does this increase? What happens when we stop exercising? What does this reduce? What declies? What is adrenaline secreted in response to? What does the presence of adrenaline increase? What does this help the body do? what is blood pressure monitored by? What is this? Why would blood pressure rise? What does the stretch recptors do if blood pressure rises? How does that respond?

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Control of heart rate in humans

coordinated way, SAN, a set frequency, varying from person to person, at which it intiates waves of excitiation, typically 60-80 per min, be controlledby the carivasular centre in the medualla oblongata, strecth receptors in the muscles, send impulses to the cardiovascular centre informing it that extra oxygen may soon be needed, tends to increase heart rate, muscles produce more carbon dioxide, reacts with water in the blood plasma and reduces its pH, detcted by chemoreceptors in the carotid arteries the aorta and the brain, the chemoreceptors send impulses o the cardiovasular centre which ncreases the heart rate, cocnentration of carbon dixide in the blood alls, the activity of the accelort pathweay, heart rate deceline,s adrenaline is secretd in  response to stress shock anticipation or excitment, presence of adrenaline in the blood increases the heart trate,n body for activiy, by stretch receptors in teh all os the carotid sinus, small swelling in the carotid artery, to high pherhaps during nvigorous exercise the strecth reecptoes send signals to eh cardiovascular centre, this responds by reducing the heart rate

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Comments

Lollypop

Good notes but pictures and diagrams would help

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