F214 complete summary

I found this whilst looking for rescources and it has turned into being my main tool for revision i have changed somethings to better suit the teminology used in the text books, it is the complete syllabus then with a summary of each underneath it, have a look and download its so helpful also have f215

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Communication, Homeostasis & Energy
Communication and homeostasis
(a) Outline the need for communication systems within multicellular organisms, with reference to the need to
respond to changes in the internal and external environment and to coordinate the activities of different
Organisms need to respond to external stimuli, e.g. temperature, oxygen concentration and levels of
sunlight. These may be over time, e.g. winter fur to summer fur, or quickly, e.g. changing size of pupils.
Internal environments change too the build up of carbon dioxide as a result of respiration changes the pH
of the tissue fluid, and therefore inhibits enzyme activity. Multicellular organisms need to coordinate
different organs, so this requires a good communication system which will:
· Cover the whole body
· Enable cells to communicate with each other
· Enable specific communication
· Enable rapid communication
· Enable both short and longterm responses.
(b) State that cells need to communicate with each other by a process called cell signalling.
(c) State that neuronal and hormonal systems are examples of cell signalling.
(d) Define the terms negative feedback, positive feedback and homeostasis.
Negative feedback A process in which any change in a parameter brings about the
reversal of that change so that the parameter is kept fairly constant.
Positive feedback A process in which any change in a parameter brings about an
increase in that change
Homeostasis The maintenance of a constant internal environment despite changes
in the environment
(e) Explain the principles of homeostasis in terms of receptors, effectors and negative feedback.
Any change is detected by receptors, the communication system transmits a message from the
receptor to the effector and, through negative feedback, the effectors reverse the change.
(f) Describe the physiological and behavioural responses that maintain a constant core body temperature in
ectotherms and endotherms, with reference to peripheral temperature receptors, the hypothalamus and
effectors in skin and muscles.
The horned lizard expands its ribcage and the frilled lizard uses its frill to expand its
surface area to absorb more heat from the sun
Locusts increase their abdominal breathing movements to increase water loss when
Snakes expose their body to the sun so more heat is absorbed
Locusts orientate their body towards the sun to expose a larger surface area & so
more heat is absorbed. By orientating their body away from the sun, more heat is
Lizards hide in burrows to prevent heat absorption by staying out of the sun.

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Physiological (temp drops)
Peripheral skin thermoreceptors are stimulated by a decrease in external
impulses are sent to the hypothalamus
vasoconstriction of arterioles to reduce heat loss by radiation / conduction /
increased metabolic rate (respiration) to generate heat energy
release of adrenaline
shivering to generate heat energy
erector pilli muscles raise hair to trap air and therefore heat
sweating or panting is reduced
Move into shade or hide in burrow
Orientate body to decrease surface area exposed to sun
Remain…read more

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(a) Outline the roles of sensory receptors in mammals in converting different forms of energy into nerve
Light sensitive cells in the retina detect light intensity and range of wavelengths (colour).
Olfactory cells in the nasal cavity detect the presence of volatile chemicals.
Tastebuds detect the presence of soluble chemicals.
Pressure receptors in the skin detect pressure on the skin.
Sound receptors in the cochlea detect vibrations in the air.
Muscle spindles detect the length of muscle fibres.…read more

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Voltage gated sodium ion channels open, and sodium ions flood in. As more sodium ions
enter, the membrane becomes positively changed on the inside compared to the outside.
5. The potential difference across the membrane reaches +40mV. The inside is positive
compared to the outside.
6. The sodium ion channels close and the potassium ion channels open.
7. Potassium ions diffuse out of the cell, bring the potential difference back to negative
inside compare to out this is called repolarisation.
8.…read more

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The postsynaptic membrane contains:
· Specialised sodium ion channels that will only open when acetylcholine binds to
(j) Outline the role of neurotransmitters in the transmission of action potentials.
A neurotransmitter is a chemical that diffuses across the cleft of the synapse to transmit a
signal to the postsynaptic neurone. They cause the generation of a new action potential in
the postsynaptic neurone. In cholinergic synapses the neurotransmitter is acetylcholine. It is
stored in vesicles in the synaptic knob.…read more

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Describe, with the aid of diagrams and photographs, the histology of the pancreas, and outline its role as an
endocrine and exocrine gland.
The exocrine cells of the pancreas secrete digestive enzymes into the pancreatic duct,
which transports them to the small intestine. These cells make up the majority of the
The exocrine cells are found in the the Islets of Langerhan and consist of and cells. The
cells manufacture and secrete glucagon, whereas the cells manufacture and secrete
insulin.…read more

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Outline how insulin secretion is controlled, with reference to potassium channels and calcium channels in
beta cells.
1. The cell membranes of the cells contain Ca2+ and K+ ion channels.
2. The K ion channels are normally open, and the Ca ion channels are normally shut. K ions
diffuse out of the cell, making the inside more negative.
3. When glucose concentration outside of the cells is high, more glucose molecules diffuse
into the cell.
4. The glucose is quickly metabolised to ATP.
5.…read more

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Scientists have found stem cells in the pancreas of adult mice.
· Undifferentiated.
(i) Outline the hormonal and nervous mechanisms involved in the control of heart rate in humans.
Action potentials sent down the accelerator nerve to the heart from the cardiovascular
centre of the medulla oblongata to the SAN cause the heart rate to increase. As the SAN
controls the frequency of the waves of depolarisation in the heart these impulses will speed
up the heart rate.…read more

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Nitrogenous wastes must be removed because the amino group is highly toxic, but proteins
and amino acids are very high in energy, so it would be wasteful to excrete them. In the
orthinine cycle, the amine group is removed to form ammonia, which forms urea, water and
a keto acid when added to oxygen and carbon dioxide. The keto acid can be used in
respiration and the urea (which is less toxic) is transported to the kidneys for excretion.…read more


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