lecture 2

Question 1

what are the parts to a neuron

Answer 1

cell body, dendrite, axon hillock, pre-synaptic cell, post-synaptic cell, synapse, myelin sheath

Question 2

what is the structure of a nerve

Answer 2

many axons in one package - many packages - nerve

Question 3

what is the white layer around the axon

Answer 3

myelin sheath

Question 4

where are cell bodies bunched at in a nerve

Answer 4

nucleus (CNS) or ganglion (PNS)

Question 5

what is a nerve supplied with and what do they do

Answer 5

nutrients, O2, removing waste

Question 6

what are the three types of glial cells and what do they do

Answer 6

microglia - macrophage - destroy old cells into parts
astrocytes - anchor neurons in place, blood brain barrier
oligodendrocytes (CNS) or schwann cells (PNS) - create myelin sheath (phospholipid bilayer)

Question 7

what are glial cells

Answer 7

cells that helps the neuron function but is not part of the neuron

Question 8

how does a myelin sheath form

Answer 8

schwan cells have nucleus, they engulf the axon and wraps itself around it many times

Question 9

what are the gaps created by myelin sheath called and what type of conduction occurs there

Answer 9

nodes of ranvier, saltatory conduction

Question 10

where does an AP originate

Answer 10

axon hillock

Question 11

what is the resting membrane potential of the axon

Answer 11

-70mV

Question 12

what are axon hillocks and nodes of ranvier rich in

Answer 12

sodium channels

Question 13

what are the types of synaptic transmissions called and how do they work

Answer 13

electrically - junctions directly connect pre and post synaptic - ions and current flow through

neurotransmitters - vesicles in pre-synaptic cell binds with plasma membrane for exocytosis, neurotransmitters released into the synapse,, bind to receptors, cause Na channels to open, create another AP

Question 14

what is in the cytosol compared to the ECF during resting membrane potential

Answer 14

cytosol - large anions, high K, low Na, proteins and AA

ECF - high Na, low K

Question 15

what are the structures used to move ions during an action potential

Answer 15

voltage-gated Na channels, voltage-gated K channels, ATPase pump

Question 16

where do the majority of the body’s ATP go

Answer 16

ATPase pump

Question 17

what is the threshold potential voltage

Answer 17

-50mV

Question 18

what are the parts to an action potential

Answer 18

resting potential, threshold potential, depolarization, repolarization, hyperpolarization

Question 19

what are the components to the voltage-gated Na channel

Answer 19

activation and inactivation gate

Question 20

what are the components to the voltage-gated K channel

Answer 20

activation gate

Question 21

what happens when the membrane approaches the threshold potential

Answer 21

some Na activation gates open, allows for potential to slowly become less negative

Question 22

what happens when membrane reaches threshold potential

Answer 22

all Na activation gates open –> depolarization

Question 23

what happens when you reach the peak of depolarization

Answer 23

Na inactivation gates slowly close, activation gates are still open

K activation gates slowly open, K leaves the cell, making cytosol more negative again

membrane begins to repolarize

Question 24

what happens at the peak of repolarization

Answer 24

K activation gates start to close slowly

Na inactivation and activation gates open slowly

Question 25

what happens when membrane potential starts to fall below threshold after repolarization

Answer 25

Na activation gates begin to close

Question 26

what happens at hyperpolarization

Answer 26

ATPase pump moves 3 Na out and 2 K in

Question 27

how does saltatory conduction work

Answer 27

starts in axon hillock - rich with Na channels

positive charge rushes down axon - node of ranvier, trigger Na channels to open, another Ap generated, positive charge continues to spread

Question 28

what is an internode

Answer 28

myelinated region where the current passes through

Question 29

what is the asbsolute refractory period at depolarization

Answer 29

all Na channels are open, there are no more Na channels that can allow for more Na to come in for another AP

Question 30

what is the absolute refractory period at repolarization

Answer 30

Na activation gates are closed because of high membrane potential - AP increasing potential will further close gates

Question 31

what is the relative refractory period

Answer 31

after mid repolarization, another AP can be generated

Question 32

what are the types of chemical synapses

Answer 32

excitatory - cause Na channels to open for new AP

inhibitory - cause Cl channels to open, makes membrane more negative so more stimulus is needed for a new AP