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!

HideShow resource information
Preview of A2 F214 complete revision notes (communication, homeostasis and energy)

First 18 words of the document:

June 13
F214-Communi
cation,
homeostasis
20
and energy.
14
OCR A2

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

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 of conditions in which to work effectively and this includes:
temperature, pH, aqueous environment and freedom from toxins and excess inhibitors.…read more

Page 3

Preview of page 3

Here's a taster:

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 area.
Increased breathing Evaporates more water and so cooled down.…read more

Page 4

Preview of page 4

Here's a taster:

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 rate of metabolism is reduced and so less heat is lost through respiration.
Decrease in temperature-the rate of metabolism is increased by the hormones adrenaline and thyroxin therefore respiration
generates more heat.…read more

Page 5

Preview of page 5

Here's a taster:

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 PACINIAN CORPUSCLE
The bigger the receptor potential, the more frequent the action potentials.
Action potentials are the same size.
Receptor potentials are different sizes.…read more

Page 6

Preview of page 6

Here's a taster:

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 THE INSIDE AND OUTSIDE IT IS -70
MILLION VOLTS?
Types of channels on the membrane of the axon:
Open Potassium (K+) channel.
Gated Sodium (Na+) channel.
Sodium Potassium pump.
Gated Potassium (K+) channel.
1.…read more

Page 7

Preview of page 7

Here's a taster:

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 went down the electro
chemical gradient.
The sodium channel has opened because of the change in voltage to +40 volts.…read more

Page 8

Preview of page 8

Here's a taster:

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 than usual.
THRESHOLD
Voltage at which this voltage gated sodium channel opens.
If the membrane potential ever reaches threshold, you get an action potential.…read more

Page 9

Preview of page 9

Here's a taster:

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.
TRANSMISSION OF ACTION POTENTIALS
* Adjacent charges inside the membrane are attracted to each other.
* This is known as a LOCAL FLOW OF CURRENT- a local circuit.…read more

Page 10

Preview of page 10

Here's a taster:

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).…read more

Comments

Bethany Cunningham

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

Similar Biology resources:

See all Biology resources »See all resources »