Nerve Cells and Neuron Potentials 1

Question 1

What is considered afferent sensory information?

Answer 1

• somatic senses
• special senses
• visceral senses

Question 2

Afferent sensory information (input/output) to/from the brain and spinal cord.

Answer 2

input

Question 3

Efferent sensory information (input/output) to/from the brain and spinal cord.

Answer 3

output

Question 4

What are the 2 categories of efferent sensory information?

Answer 4

• somatic

- autonomic

Question 5

Somatic output goes to _____ ______.

Answer 5

skeletal muscles

Question 6

What are the 2 categories of autonomic output?

Answer 6

• sympathetic

- parasympathetic

Question 7

Sympathetic output goes to …

Answer 7

• cardiac muscle
• smooth muscle
• glands

Question 8

Parasympathetic output goes to …

Answer 8

enteric nervous system

Question 9

Enteric nervous system goes to …

Answer 9

gastrointestinal tract

Question 10

Name and describe the 2 cells of the nervous system.

Answer 10

• neurons: excitable cells

- glial cells: support cells

Question 11

What is the synapse?

Answer 11

site of communication between 2 neurons or between a neuron and an effector organ

Question 12

What is the soma?

Answer 12

• cell body

- contains nucleus and most organelles

Question 13

What do the dendrites do?

Answer 13

reception of incoming information

Question 14

What does the axon do?

Answer 14

transmits electrical impulses called action potentials

Question 15

What is the axon hillock?

Answer 15

where the axon originates and action potentials are initiated

Question 16

What happens at the axon terminal?

Answer 16

releases neurotransmitter

Question 17

What is anterograde transport?

Answer 17

from soma to axon terminal

Question 18

What is retrograde transport?

Answer 18

• from axon to soma

- microtubules and neurofilaments

Question 19

What is considered slow retrograde transport?

Answer 19

0.5-40 mm/day

Question 20

What is considered fast retrograde transport?

Answer 20

100-400 mm/day

Question 21

Describe leak ion channels.

Answer 21

• always open
• throughout the neuron
• resting membrane potential

Question 22

Describe gated ion channels.

Answer 22

• open or close in response to binding
• dendrites and cell body
• synaptic potentials

Question 23

Describe voltage-gated ion channels. Give examples.

Answer 23

• open or close in response to changes in membrane potential
• ex. sodium and potassium channels
• ex. calcium channels

Question 24

Where are sodium and potassium channels located? What goes through them?

Answer 24

• throughout, more in the axon (hillock)

- action potentials

Question 25

Where are the calcium channels? What are they responsible for?

Answer 25

- axon terminal | - neurotransmitter release

Question 26

Afferent neurons (input/output).

Answer 26

input

Question 27

Efferent neurons (input/output).

Answer 27

output

Question 28

______ make up 90% of all cells in the nervous system.

Answer 28

glial cells

Question 29

What are the 4 types of glial cells in the CNS?

Answer 29

- astrocytes - microglia - oligodendrocytes - ependymal cells

Question 30

What are the 2 types of glial cells in the PNS?

Answer 30

- satellite cells | - Schwann cells (neurolemmocytes)

Question 31

What are the 2 myelin forming cells?

Answer 31

- oligodendrocytes | - Schwann cells

Question 32

One oligodendrocyte:

Answer 32

- forms several myelin sheaths | - myelinates sections of several axons

Question 33

One Schwann cell:

Answer 33

- forms 1 myelin sheath | - myelinated one section of an axon

Question 34

Describe the resting membrane potential. What is the resting membrane potential for neurons?

Answer 34

- more negative charges inside and positive charges outside the cell - ~-70 mV

Question 35

Name 2 critical factors for resting membrane potential.

Answer 35

- ion concentration gradients (sodium and potassium ions) | - membrane permeability to these ions

Question 36

How is membrane permeability changed?

Answer 36

- ion channels - chemical and electrical forces - concentration and electrical charge

Question 37

What is the permeability for the resting membrane potential of neurons?

Answer 37

25x more permeable to K+ vs Na+

Question 38

Describe ion distribution for the resting membrane potential of neurons.

Answer 38

- outside cell: sodium and chloride | - inside cell: potassium and organic anions

Question 39

What do chemical driving forces do to K+ and Na+?

Answer 39

- K+ out | - Na + in

Question 40

What happens when the cell becomes more permeable to K+?

Answer 40

- more K+ leaves the cell than Na+ enters | - inside of the cell = negative

Question 41

What happens when electrical forces develop?

Answer 41

- Na+ into cell - K+ into cell - K+ outflow slows - Na+ inflow speeds

Question 42

What happens to Na+ and K+ when a steady state develops?

Answer 42

- Na+ and K+ in/outflow is balanced | - -70 mV

Question 43

A small Na+ leak at rest would be ...

Answer 43

- high force | - low permeability

Question 44

A small K+ leak at rest would be ...

Answer 44

- low force | - high permeability

Question 45

What maintains the resting potential?

Answer 45

sodium pump

Question 46

If the membrane potential is not at equilibrium for an ion:

Answer 46

- the electrochemical force is not 0 - force acts to move ions across the membrane in the direction favouring the equilibrium - farther from equilibrium = greater force for movement

Question 47

Describe the forces acting on ions at -70 mV.

Answer 47

- membrane is further away from Na+ equilibrium | - a stronger force to move Na+ to equilibrium is present

Question 48

Each ion has it's own _____.

Answer 48

force

Question 49

The resting membrane potential is closer to the _________ equilibrium potential.

Answer 49

- potassium (-94 mV) | - Na equilibrium potential is (+60 mV)