chapter 11.

Question 1

what structures make up the CNS and PNS?

Answer 1

CNS is made up of brain and spinal cord
PNS is made up of cranial and spinal nerves

Question 2

list the two types of cells that compose nervous tissue? Functions?

Answer 2

neurons - transmit electrical signals
neuroglia - small cell that surrounds and wraps around delicate neurons

Question 3

list the 3 classes of neurons and functions?

Answer 3

multipolar - 3 or more processes, motor function carries impulse from CNS to effector
Bipolar - 2 processes, send signals, recieve information
unipolar - 1 T-like process (two axons), sensory receptors to CNS

Question 4

List the parts of a neuron and describe the function of each

Answer 4

dendrites - branched extensions that receive signals
axon hillock - connects cell body to axon, generates impulse in neuron
nodes of Ranvier - gap in myelin sheath
axon - extension that transmits signals to other cells
nucleus - controls the entire neuron
synapse -portion of the neuron where information is received

Question 5

List the neuroglia found in the CNS and give the function of each

Answer 5

1. astrocytes = highly branched, respond to nerve impulses and neurotransmitters, support and brace nerves
2. microglial cells = migrate toward injured neurons, small ovoid cells with thorny processes that touch and monitor neurons
3. ependymal cells =may be ciliated, cilia beat to circulate CSF, line the central cavities of brain and spinal column
4. oligodendrocytes = branched cells, forming myelin sheaths

Question 6

List the neuroglia found in the PNS and give the function of each

Answer 6

1. satellite cells = surround the neuron cell bodies in PNS, similar to astrocytes
2. Schwann cells = surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers, similar to Oligodendrocytes, vital to regeneration of damaged peripheral nerve fibers

Question 6

what causes multiple sclerosis?

Answer 6

is an autoimmune disease that affects primary young adults, myelin sheaths destroyed by hardening

Question 7

describe gray matter

Answer 7

mostly neuron cell bodies and nonmyelinated fibers

Question 8

describe white matter

Answer 8

regions of brain and spinal cord with myelinated fibers

Question 9

resting membrane potential? RMP of a neuron?

Answer 9

a neuron is approximately -70mV (polarized),depends on differences in K+ and Na+ concentrations

Question 10

List the different types of ion channels

Answer 10

leakage = channels are always open
gated = channels, in which part of the protein changes shape to
open/close to the channel

Question 11

action potential & threshold stimulus?

Answer 11

ap = principal way neurons send signals, only in muscle cells and axons of neurons
Threshold = all or nothing

Question 12

List the characteristics of an action potential

Answer 12

means of long-distance neural communication
occur only in muscle cells and axons of neurons
brief reversal of membrane potential with a change in voltage
don’t decay over distance

Question 13

Describe the events that occur during the depolarization phase of an action potential

Answer 13

Na+ channels open at threshold (-55 to -50mV) , results in large action

Question 14

Describe the events that occur during the repolarization phase of an action potential. RMP restored? what causes hyperpolarization?

Answer 14

Na+ channels are inactivating, K+ channels are open membrane returns to resting membrane potential.
hyperpolarization - some K+ channels remain open, and Na+ channels
rest.

Question 15

refractory period?

Answer 15

time in which neuron cannot trigger another AP

Question 16

graph of an action potential

Answer 16

rest, threshold, ap

Question 17

Describe saltatory conduction vs. continuous conduction.

Answer 17

continuous is slow conduction
saltatory is only in myelinated axons (30x faster)