Communication and Homeostasis

?
What is a stimulus?
A change in the environment that causes a response.
1 of 103
What is a response?
A change in behaviour or physiology as a result of a change in the environment.
2 of 103
What is the environment of cells in animals?
The tissue fluid which they are bathed/surrounded in.
3 of 103
How does carbon dioxide build up disrupt enzyme action?
It changes the pH of the environment around cells.
4 of 103
What is the composition of the tissue fluid maintained by?
The blood as it removes toxins in the tissue fluid.
5 of 103
How are multicellular organisms more efficient than single-celled organisms?
Because their cells can be differentiated and therefore specialised to perform certain functions.
6 of 103
What 5 things does a good communication system do?
Cover the whole body. Enable cells to communcate. Enable specific communication. Enable rapid communcation. Enable short and long term responses.
7 of 103
What is cell signalling?
The way cells communicate by releasing a chemical that will be detected and form a response.
8 of 103
What 2 major systems use cell signalling?
The neuronal system and the hormonal system.
9 of 103
What is the neuronal system?
An interconnected network of neurones that signal to each other across synapse junctions.
10 of 103
What is the hormonal system?
Uses the blood to transport signals in the form of hormones which will have been released by cells in an endocrine organ.
11 of 103
What is homeostasis?
The maintenance of the internal environment in a constant state despite external changes.
12 of 103
What is negative feedback?
The process that brings about a reversal of any change in conditions of the internal environment so that it is returned to a steady state or optimum position (its original condition).
13 of 103
What pathway is involved in negative feedback?
Stimulus > receptor > cell signalling > effector > response.
14 of 103
What are sensory receptors?
Internal receptors that monitor conditions in the body that detect changes and are stimulated by this to send a message.
15 of 103
What are effector cells?
Cells that bring about a response that reverses changes detected by sensory receptor cells.
16 of 103
What is positive feedback?
A process that increases any change detected by the receptors. It tends to be harmful.
17 of 103
What are 2 examples of positive feedback?
When the body gets too cold. When the cervix is dilated during pregnancy.
18 of 103
What hormone is release to incrase uterine contractions and stretch the cervix?
Oxytocin.
19 of 103
What is an endotherm?
An organism that can control production and loss of heat to maintain their body temperature.
20 of 103
What is an ectotherm?
An organism that relies on external sources of heat and behavioural activities to regulate their body temperature.
21 of 103
What are 3 advantages of being an ectotherm?
Use less food in respiration. Able to survive long periods without food. Energy from food can be used for growth.
22 of 103
What are 2 disadvantages of being an ectotherm?
Less active in cooler temperatures which requires them to warm up so they are at greater risk of predation. May have to store sufficient energy for winter if they are not capable of activity.
23 of 103
What does an ectotherm do in cold or hot weather to absorb/lose heat?
Change its behaviour or physiology.
24 of 103
What are 3 advantages of being an endotherm?
Maintaining a fairly constant body temperature. Can be active in cool temperatures. Can inhabit colder parts of the planet.
25 of 103
What are 3 disadvantages of being an endotherm?
Most energy intake is to maintain body temperature. Require more food than ectotherms. Require more/extra food for growth.
26 of 103
What 6 body components are used in temperature regulation in endotherms?
Sweat glands, lungs/mouth/nose, hairs, arterioles, hepatocytes, skeletal muscles.
27 of 103
What monitors the blood temperature and core body temperature in endotherms?
The thermoregulatory centre in the hypothalamus of the brain.
28 of 103
Why are sensory receptors energy transducers?
Because they convert one form of energy to another.
29 of 103
What does a sensory receptor convert a stimulus into?
A nerve impulse which is a form of electical energy.
30 of 103
What specialised channel proteins to neurones contain?
Those specific to either sodium or potassium ions.
31 of 103
What type of sodium or potassium channels are in neurones?
Gated channel proteins.
32 of 103
How many sodium ions are pumped out and how many potassium ions are pumped in?
3 sodium ions out for every 2 potassium ions in.
33 of 103
What is transported out and in of a sodium/potassium ion pump?
Sodium ions out. Potassium ions in.
34 of 103
What is a polarised membrane?
One that has a potential difference across it. It is at resting potential.
35 of 103
What is depolarisation?
The loss of polarisation across the membrane. Caused by sodiumions entering the cell making it less negative with respect to the outside.
36 of 103
What is a generator potential?
A small depolarisation caused by sodium ions entering thecell.
37 of 103
What is an action potential?
When the threshold level is reached so enough sodium ions enter the cell so that the membrane is depolarised to +40mV.
38 of 103
Where do sensory neurones carry action potentials from/to?
From a sensory receptor to the central nervous system (CNS).
39 of 103
Where do motor neurones carry action potentials from/to?
From the central nervous system (CNS) to an effector.
40 of 103
What do relay neurones connect?
Sensory and motor neurones.
41 of 103
What is the myelin sheath?
A series of Schwann cells (that meet at nodes of Ranvier) that insulates the neurone from electrical activity in nearby cells.
42 of 103
Where is the cell body of a motor neurone located?
In the central nervous system.
43 of 103
Where is the cell body of a sensory neurone located?
Just outside the central nervous system.
44 of 103
What connects both sensory and motor neurones to other neurones?
Dendrites.
45 of 103
What is the resting potential?
The potential difference across the neurone cell membrane while it is at rest. It is at around -60mV inside compared to the outside.
46 of 103
What are voltage-gated channels?
Channels in the cell membrane that allow passage of charged particles or ions. Their gate can open and close in response to changes in the potential difference across the membrane.
47 of 103
Are gated sodium ion channels open or closed at rest?
Closed.
48 of 103
What is the threshold potential?
A potential difference across the membrane of about -50mV which causes an action potential once it is reached.
49 of 103
What is repolarisation?
When potassium ions diffuse out of the cell bringing the potential difference back to being more negative inside.
50 of 103
What happens to the cell when it is hyperpolarised?
When the potential differents overshoots slightly (is even more negative).
51 of 103
What is the refractory period?
A short time after each action potential where the cell membrane cannot reach another action potential.
52 of 103
What are local currents?
The flow of ions along a neurone which is caused by an increase in concentration at one point and causes diffusion away from the region of high concentration.
53 of 103
What is saltatory conduction?
The way that the action potential appears to jump from one node of Ranvier to the next.
54 of 103
Do myelinated or non-myelinated neurone conduct action potentials quicker?
Myelinated neurones.
55 of 103
What is a neurotransmitter?
A chemical that diffuses across the synaptic cleft to transmit a signal to the postsynaptic neurone.
56 of 103
What are cholinergic synapses?
Ones that use acetylcholine as their neurotransmitter.
57 of 103
What is the swelling at the end of the presynaptic neurone called?
The synaptic knob.
58 of 103
What do specialised sodium ion channels in the postsynaptic membrane consist of?
5 polypeptide molecules. 2 with a special receptor site specific to acetylcholine to open the channels.
59 of 103
How is acetylcholine released?
By exocytosis.
60 of 103
What is acetylcholinesterase?
An enzyme in the synaptic cleft used to break down acetylcholine.
61 of 103
How does acetylcholinesterase break down acetylcholine?
By hydrolising it to ethanoic acid and choline.
62 of 103
How are ethanoic acid and choline recycled to acetylcholine?
By using ATP from respiration.
63 of 103
What is summation?
The way that several small potential changes can combine to produce one larger change in potential difference across the membrane.
64 of 103
Does the presynaptic or postsynaptic knob contain vesicles and why?
The presynaptic knob to ensure signals are transmitted in the correct direction.
65 of 103
What is acclimatisation?
Where repeated stimulation causes the synapse to be fatigued so that the nervous system no longer responds to the stimulus.
66 of 103
How does the brain determine the intensity of a stimulus?
By the frequency of the signals arriving. Higher frequency means more intense stimulus.
67 of 103
What is a hormone?
Molecules released by the endocrine glands directly into the blood acting as messengers to carry a message to a target organ or tissue.
68 of 103
What is an exocrine gland?
One that secretes molecules into a duct that carries molecules to where they are used.
69 of 103
What is an example of exocrine glands?
The salivary glands.
70 of 103
What are the 2 types of hormones?
Protein/peptide/derivatives of amino acids. And steroid.
71 of 103
How are steroid hormones different to protein hormones?
They can pass through the membrane of a cell to have a direct effect on the DNA.
72 of 103
What type of protein is adrenaline?
An amino acid derivative.
73 of 103
What is adenyl cyclase?
An enzyme associated with receptors for hormones (such as adrenaline) on the inside of the cell surface membrane.
74 of 103
In the action of adrenaline, what are the first and second messengers?
First is the adrenaline molecule. Second is cyclic AMP (cAMP).
75 of 103
What does cyclic AMP (cAMP) do inside a cell?
Activates enzyme action to cause the desired effect.
76 of 103
Where are the adrenal glands?
Just above the kidneys.
77 of 103
What do the adrenal medulla's cells do?
Manufacture and released adrenaline in response to stress or shock.
78 of 103
What does the adrenal cortex do?
Uses cholesterol to produce steroid hormones.
79 of 103
What are mineralocorticoids and what is an example?
Steroid hormones that help control concentrations of sodium and potassium in the blood. An example is aldosterone.
80 of 103
What are glucocorticoids and what is an example?
Steroid hormones that help control the metabolism of carbohydrates and proteins in the liver. An example is cortisol.
81 of 103
What is the exocrine function of the pancreas?
To manufacture and release digestive enzymes.
82 of 103
What is the pancreatic duct?
A tube that collects all the secretions from the exocrine cells in the pancreas and carries the fluid to the small intestine.
83 of 103
Fluid in the pancreatic duct contains which 3 enzymes?
Amylase, trypsinogen and lipase.
84 of 103
What does sodium hydrogencarbonate in the pancreatic duct fluid do?
Neutralises the contents of the digestive system that have been in the acidic stomach environment.
85 of 103
What type of cells are in the islets of Langerhans?
Alpha (a) cells and beta (b) cells.
86 of 103
What do alpha cells manufacture and secrete?
Hormone glucagon.
87 of 103
What do beta cells manufacture and secrete?
Hormone insulin.
88 of 103
Which cell type detects a high blood glucose concentration?
The beta cells in the islets of Langerhans.
89 of 103
Which cell type detects a low blood glucose concentration?
The alpha cells in the islets of Langerhans.
90 of 103
What is diabetes mellitus?
A disease in which blood glucose concentrations cannot be controlled effectively.
91 of 103
What is hyperglycaemia?
When blood glucose concentration is too high.
92 of 103
How can type I diabetes be treated?
Using insulin injections and monitoring blood glucose concentrations.
93 of 103
How can type II diabetes be treated?
Careful control of diet. May be supplemented by insulin injections.
94 of 103
What does myogenic mean?
Muscle tissue that can initiate its own contractions, like the heart muscle.
95 of 103
What is the sinoatrial node? (SAN)
The pacemaker in the right atrium wall that generates an impulse to initiate the contraction of heart chambers.
96 of 103
What is the medulla oblongata?
A part of the brain that coordinates unconscious functions such as heart rate and breathing.
97 of 103
What is in the medulla oblongata?
The cardiovascular centre.
98 of 103
What does the accelerator nerve between the medulla oblongata and SAN do?
Send signals to the SAN to increase the heart rate.
99 of 103
What does the vagus nerve between the medulla oblongata and SAN do?
Send signals to the SAN to decrease the heart rate.
100 of 103
What receptors detect the movement of the limbs?
Stretch receptors in the muscles.
101 of 103
What is change in pH of blood plasma detected by?
Chemoreceptors in carotid arteries, aorta and brain.
102 of 103
What is blood pressure monitored by?
Stretch receptors in the walls of the carotid sinus in the carotid artery.
103 of 103

Other cards in this set

Card 2

Front

What is a response?

Back

A change in behaviour or physiology as a result of a change in the environment.

Card 3

Front

What is the environment of cells in animals?

Back

Preview of the front of card 3

Card 4

Front

How does carbon dioxide build up disrupt enzyme action?

Back

Preview of the front of card 4

Card 5

Front

What is the composition of the tissue fluid maintained by?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Communication and Homeostasis resources »