OCR Biology F2144 - module 1 Communication and homeostasis

These are my summary notes for OCR Biology F2144 - module 1 Communication and homeostasis from my A2 OCR Boilogy textbook (purple with brain MRI on cover). Words in light blue are definitions and bolded words are either key words or key parts of definitions. Enjoy!

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OCR Biology F2144 - module 1 Communication and homeostasis


Stimulus ­ any change in the environment that causes a response
Respons e ­ a change in behaviour or physiology as a result of a change in the

Conditions needed to maintain life (and keep enzymes working):
Suitable temperature…

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Increase breathing movements Evaporates more water

Endotherms ­ an organism that can use internal sources of heat to maintain its body

Advantages Disadvantages
Body temperature is fairly constant Have to spend a lot of energy on
whatever the temperature is externally keeping themselves warm when it is

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Skeletal muscles No spontaneous Spontaneous contractions
contractions (shivering); generates heat
as muscle cells respire

Peripheral temperature receptors are located on the surface of the skin and
monitor the temperature in extremities. The information is then fed to the
thermoregulatory centre in the brain (hypothalamus), where a mechanism is then…

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1. Stimulus ­ causes sodium ion channels to open, Na+ ions flood in making the
axon more positive
2. Depolarisation ­ the change in potential difference causes voltage-gated
sodium ion channels to open and then trigger more to open along the axon
3. Repolarisation - after 0.5 ms the sodium…

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Spatial = space


1. Action potential reaches pre-synaptic know and causes voltage-gated calcium

ion channels to open, so Ca2+ ions flood in
2. The Caions cause the synaptic vesicles to fuse to the pre-synaptic know
membrane and acetylcholine is released into the synapse by exocytosis
3. Acetylcholine binds…

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Target cells ­ cells that possess a specific receptor on their plasma membrane. The
shape of the receptor is complementary to the shape of the hormone molecule

Two types of hormone:
Protein and peptide hormones and derivitives of amino acids not soluble
in the phospholipid membrane, so cannot enter cells…

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The islets of Langerhans ­ small patches of tissue in the pancreas that have an
endocrine function
-cells ­ cells found in the islets of Langerhans and secrete the hormone glucagon
-cells - cells found in the islets of Langerhans and secrete the hormone insulin
Insulin ­ a hormone that…

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Treatment: careful monitoring and control of diet

Stem cells could be used to cure diabetes, as they are unspecific they can be grown
into -cells and implanted into the pancreas. This treatment would mean that a
person with diabetes could produce their own insulin and wouldn't need regular
insulin injections.…


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