Nervous System

Question 1

What is the main function of the nervous system?

Answer 1

generates action potentials that aid in cell communication

Question 2

What makes up the CNS?

Answer 2

The brain and the spinal cord

Question 3

What makes up the PNS?

Answer 3

All nervous tissues/nerves outside of CNS

Question 4

What is the difference between sensory and motor neurons?

Answer 4

Sensory - impulses from stimulus to CNS

Motor - impulses from CNS to target tissues

Question 5

What neurons are afferent?

Answer 5

Sensory

Question 6

What neurons are efferent?

Answer 6

Motor

Question 7

Is the somatic nervous system voluntary or involuntary?

Answer 7

Voluntary

Question 8

What occurs in the sympathetic division of the autonomic nervous system?

Answer 8

fight/flight

exercise and emergency action

Question 9

What occurs in the parasympathetic division of the autonomic nervous system?

Answer 9

rest/digest activities

Question 10

What does neuroglia do?

Answer 10

support/nourish/protect neurons

Question 11

What is the role of a dendrite?

Answer 11

input portions of a neuron, housing numerous receptor sites for other cells to bind to

Question 12

What is the role of an axon?

Answer 12

creates nerve impulses towards another neuron, muscle fibre or gland cell

Question 13

What is the role of a myelin sheath?

Answer 13

insulates the axon, “swchan” cell inside

Question 14

What is another name for the cell body?

Answer 14

Soma

a nucleus surrounded by cytoplasm that includes typical cellular organelles (lysosomes, mitochondria, and a Golgi complex)

Question 15

Where is the Node of Ranvier?

Answer 15

exposed areas of the axon, increased number of protein channels

Question 16

What are graded potentials?

Answer 16

small, localized electrical signals that occur along the dendrites and cell bodies of neurons, triggered by a stimulus

Question 17

What type of potential influences voltage-gated channels?

Answer 17

Action potentials

Question 18

What type of potential influences ligand-gated channels

Answer 18

Graded potentials

Question 19

What type of potential influences leak channels?

Answer 19

Resting membrane potentials

Question 20

What is the value of threshold?

Answer 20

-55mV

Question 21

What is RMP?

Answer 21

-70mV

Question 22

What does summation mean?

Answer 22

GP added together to cause an AP

Graded potentials must be summated (added together) to depolarize the membrane to threshold (-55mV) and generate an action potential

Question 23

What is the difference between hyperpolarisation and depolarisation?

Answer 23

Hyperpolarisation - cell becomes more positive

Depolarisation - cell becomes more postitive

Question 24

What is an action potential?

Answer 24

the electrical signal that neurons send along the length of the axon, cell needs to be DEPOLARIZED, do not vary in size (all or nothing)

Question 25

Are AP all or nothing events?

Answer 25

Yes

Question 26

What state are voltage-gated sodium channels in when they are inactive?

Answer 26

Ball and chain

Closed when gate shuts

Question 27

Explain the events of an AP

Answer 27

Cell membrane is at resting state (-70mV)
Graded potentials summate to depolarizes axon hillock to threshold (-55mV)
Depolarization: At threshold, voltage-gated Na + channels open and sodium floods into cell (cell becomes less negative)
Repolarization: inactivation Na+ channels shut (ball and chain) and Na+ stops coming in, voltage-gated channels K+ channels open slowly (cell becomes more negative)
Hyperpolarization: K+ continues to leave cell (more negative)
Cell membrane returns to resting state (leak channels and pumps only –70mV)

Question 28

What are the 2 types of refractory periods?

Answer 28

Absolute and relative

Question 29

Where do AP occur along the neuron?

Answer 29

Axon hillock

Question 30

Where do graded potentials summate?

Answer 30

Dendrites, cell body and axon

Question 31

Do Shwann cells produce myelin?

Answer 31

Yes

Question 32

Are myelinated axons generally faster for AP to move?

Answer 32

Yes, AP able to leap from myelin to myelin, therefore a faster process

Question 33

What is the difference between saltatory conduction and continuous conduction?

Answer 33

saltatory - AP leaping with myelinated axons

continuous - leaky Na+ channels so need to be close together to conduct AP

Question 34

How do you measure the intensity of an AP if it is an all or nothing event?

Answer 34

Stimulus intensity is coded by the frequency of action potentials;
Weak stimulus – lower frequency of AP
Strongest stimulus – higher frequency of AP

Question 35

Where are synapses located?

Answer 35

Axon terminal

Question 36

What molecule is involved in synaptic transmission?

Answer 36

Calcium (triggers vesicles to move)

Question 37

What are EPSP’s and IPSP’s?

Answer 37

Excitatory post-synaptic potential - depolarisation (brings membrane closer to potential)

Inhibitory post-synaptic potential - hyper polarisation (brings membrane further away from potential)

Question 38

What are the two types of summation?

Answer 38

Temporal - repeated from one

Spatial - various from different directions

Question 39

Where are myelinated axons found why?

Answer 39

skeletal cells

where speed is crucial

Question 40

What is the approx value that repolarisation occurs?

Answer 40

+30mV

Question 41

Can a relative refractory period produce a 2nd AP?

Answer 41

Yes (if strong enough)