Electrical + Synapic Signalling

Question 1

what makes up extracellular fluid

Answer 1

dissolved salts, mostly NA, Cl

Question 2

what makes up the cytosol

Answer 2

Pottasium (couter ions= protein/RNA)

Question 3

Vm

Answer 3

-60- -75

Question 4

why is the Vm usually negative

Answer 4

K+ leaks out and their are no channels for - macromolecules so therefore more negative inside

Question 5

3 different types of ion channels

Answer 5

voltage gated

ligand gated- open when a ligand binds

Leak channels- allow resting cells to be permeable to cations

Question 6

steps of action potential

Answer 6

1. resting state at -60Mv
2. Na channels open brings Na into cell. reaches threshold potential at -40 and then reaches +40
3. Na closes, K opens and K flows out of cell- hyper polarizes

Question 7

What is a Gap junction made up of

Answer 7

made up of 6 pro. subunits each called connexin, set of 6 called connexon

Question 8

steps of transmission of a signal across synapse

Answer 8

1. action potential reaches presynaptic bulb
2. depolarization opens calcium channels
3. increased calcium induces secretion of neurosecratory vesicles
4. neurotransmitter diffuses across synaptic cleft
5. Channels open, letting ions flow into postsynaptic cleft and cause depolarization/ hyperpolarization