Nervous System and RMP

Question 1

Two types of nerves (origin wise) and where they come from

Answer 1

Cranial nerves (brain) and spinal nerves (spinal cord)

Question 2

What is in the peripheral NS (anatomically)

Answer 2

Ganglia, cranial and spinal nerves

Question 3

What are the two divisions of the PNS

Answer 3

Afferent (brings sensory information to the CNS)
Efferent (delivers motor commands from the CNS
1. Somatic NS - skeletal muscle (ones you can control)
2. Autonomic NS - smooth muscle, cardiac muscle and glands and adipose tissue (ones you can’t control)

Question 4

Two types of cells in the nervous system

Answer 4

Neurons - send electrical signals through the NS (functional unit of the NS)
Neuroglia - supporting cells, isolate, much more than neurons inn numbers

Question 5

Structure of a neuron

Answer 5

Soma (cell body), dendrites (receive information), axon (sends information) - axon hillock (where an action potential or electrical impulse starts) & axon terminals (release neurotransmitters t communicate with other cells)

Question 6

Three types of neurons

Answer 6

Bipolar (soma in middle with an axon and and synaptic terminals on one end, dendrites on other end) rare and associated with special sensors such as vision (in retina) and smell (in olfactory system)
Unipolar - soma is to the side of axon with a small process. neuron is mostly axon with dendrites at the end. single fused process (dendrites and axon). mostly sensory neurons. axon hillock (where the action potential originates) is right up near the dendrites
Multipolar - stereotypical shape (one axon, more than two dendrites coming from the soma) many motor neurons are multipolar

Question 7

Bundle of axons in the PNS

Answer 7

Nerves

Question 8

Bundle of axons in the CNS

Answer 8

Tract

Question 9

Cluster of neural cell bodies in the PNS and CNS

Answer 9

PNS - ganglia (ganglion singular)

CNS - nuclei

Question 10

What are the two supporting cells (neuroglia) in the PNS

Answer 10

Satellite and Schwann cells

Question 11

Neuroglia in the CNS

Answer 11

Oligodendrocytes
Astrocytes
Ependymal cells
Microglia

Question 12

What supporting cells produce the myelin sheath

Answer 12

Schwann (PNS), Oligodendrocytes (CNS)

Question 13

What does the myelin do

Answer 13

Increase the speed of the electrical conduction

Question 14

Difference between myelination in CNS and PNS

Answer 14

Oligodendrocytes myelinated up to 60 cells, whereas Schwann cells only wrap around one axon

Question 15

What is the RMP and what is its range in mV

Answer 15

A separation of opposite charge across the membrane of a cell, it can vary from -50 to -100 depending on the cell

Question 16

Why is the body cell voltage negative?

Answer 16

the inside of the cell is negative compared to the outside

Question 17

How is the body electrically neutral but there is still a voltage for every cell

Answer 17

There are an equal number of positively charged particles as negative in the body, the voltage occurs just at the membrane

Question 18

When and how is a RMP established, what is it dependent on and how much is it for most neurons

Answer 18

When the concentration and electrical gradient of the ions is “balanced” or reached equilibrium so to speak.
Also dependent on the permeability of the ions through the membrane
-70mV

Question 19

How does the cell maintain a concentration gradient after a while

Answer 19

via the sodium potassium pump which actively transports the ions against their concentration gradients

Question 20

Q for lecturer - don’t the ions still maintain a concentration gradient due to the electrical gradient (eg. they go against their c gradient because they’re attracted to an opposite charge on the other side of the membrane)

Answer 20

…

Question 21

What two cells can harvest (use) the energy provided/created by the RMP
How do they do it?

Answer 21

Neurons and muscle cells do it by changing the permeability of the plasma membrane to Na+ and K+ ions to alter the RMP

Question 22

How do muscle cells and neurons create electrical signals

Answer 22

By craning the membrane potential by:

1. changing membrane permeability to certain ions
2. changing the number of open channels