A2 F214 complete revision notes (communication, homeostasis and energy)

Hi there.

So these notes took me forever and I would really appreciate if you didn't pass them off on your own.

Now that's out of the way, hopefully they are effective and helpful in your revision.

If you have any problems or any general feedback then please comment!

Thanks and good luck!

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June 13


F214-Communi
cation,
homeostasis
20
and energy.
14
OCR A2

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OVERVIEW OF THE EXAM
COMMUNICATION AND HOMEOSTASIS

COMMUNICATION

WHAT IS THE NEED FOR COMMUNICATION SYSTEMS WITHIN MULTICELLULAR ORGANISMS?

All living things need to maintain a certain limited set of conditions inside their cells. This is because the cellular activities rely
on the action of enzymes. Enzymes need a specific set…

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Expose body to sun This enables more heat to be absorbed.
Orientate body to sun Exposes a larger surface area for more heat absorption.
Orientate body away from sun Exposes a smaller surface area for less heat absorption.
Hide in burrow/shelter Reduces heat absorption.
Alter body shape Exposes more/less surface…

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Increase in temperature-vasodilation allows more blood into the arterioles near the skin surface and so more heat can be
radiated from the skin.

Decrease in temperature-vasoconstriction reduces the flow of blood through the arterioles near the surface of the skin and so
less heat is radiated.


LIVER

Increase in temperature-the…

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Temperature Skin ---------------------------- Heat
Pressure Skin Pacinian corpuscle Kinetic
Pain Skin ---------------------------- Chemical
Balance Ears ---------------------------- Kinetic
Limb placement Muscles ---------------------------- Kinetic
There are more than 5 senses.

STIMULUS-this is the type of energy in the environment detected by the sensory neuron and may/may not cause a change.


EXAMPLE IS…

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Has a Dendron (like an axon). Doesn't have an axon.

Sensory neuron has a synaptic vesicle. Motor neuron has a motor end plate.

Towards the CNS (Central Nervous System). Away from the CNS (Central Nervous System).



HOW IS RESTING POTENTIAL ESTABLISHED AND MAINTAINED?

WHY IF YOU PUT AN ELECTRODE ON…

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The Sodium Potassium pump moves Sodium outside the membrane of the axon and two Potassium are pumped in.
There is a net outflow of positive charge
Potassium diffuses down the concentration gradient.


MEMBRANE IS DE-POLARISED




Membrane potential becomes less negative on the inside and this is because the sodium ions…

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The voltage gated sodium channel closes and the sodium ions can no longer pass into the membrane.
More voltage gated potassium channels open.
More potassium ions diffuse out.
The Sodium Potassium pump continues to work.


MEMBRANE IS HYPERPOLARISED




For a brief period, the membrane potential can become even more negative…

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COMPARE AND CONTRAST THE STRUCTURE AND FUNCTION OF MYELINATED AND NON-MYELINATED NEURONES

HOW IS MYELIN SHEATH FORMED?



Schwann cells wrap themselves around the axon and this occurs in many
layers of the plasma membrane.
The plasma membrane which includes lipids and this does not allow charged
particles (ions) can pass.…

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WHAT IS THE ROLE OF NEUROTRANSMITTERS IN THE TRANSMISSION OF ACTION POTENTIALS; THE STRUCTURE OF A CHOLINERGIC SYNAPSE




HOW DOES IT WORK?




HOW DO YOU TURN THE SIGNAL OFF?

An enzyme breaks the neurotransmitter (acetylcholine down).

Comments

Bethany Cunningham

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Oxaloacetate* for the Krebs cycle diagram. Sorry for the mistake but I've only just realised I spelt it wrong.

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