Chapter 42: Nervous system

Question 1

T/F: All animals even sponges have a nervous system

Answer 1

False - All animals except sponges have a nervous system

Question 2

What 2 structures does the nervous system link together?

Answer 2

It links sensory receptors that detect stimulus with the motor effectors that respond to the stimuli

Question 3

What are the 3 types of neurons in vertebrates? Explain

Answer 3

1) Sensory neurons (afferent) => carry impulses to the central nervous system.
2) Motor neurons (efferent) => Carry impulses from CNS to effectors.
3) Interneurons => provide more complex reflexes and associative functions.

Question 4

What are the 2 parts of CNS ?

Answer 4

1) Brain
2) Spinal cord

Question 5

What is the PNS comprised of?

Answer 5

Sensory and motor neurons

Question 6

Define the somatic nervous system

Answer 6

Motor neurons that stimulate skeletal muscles to contract (Voluntary movement)

Question 7

Define the autonomic nervous system

Answer 7

Regulate the activity of the smooth muscles, cardiac muscle, and glands (Involuntary movement)

Question 8

What are the 2 parts of the autonomic nervous system?

Answer 8

1) Sympathetic (Fight or flight)
2) Parasympathetic (rest and digest)
Counterbalance each other

Question 9

What are the 3 components of a neuron?

Answer 9

1) Cell body => containing nucleus
2) Dendrites => receive stimuli
3) Axon => conduct impulses

Question 10

Name 4 glial cell types:

Answer 10

1) Neuroglia
2) Astrocytes
3) Ependymal
3) Microglia

Question 11

What are the 2 most important kinds of neuroglia? What are their functions?

Answer 11

1) Schwann cells: produce myelin in the PNS
2) Oligodendrocytes: produce myelin in the CNS
They support neurons both structurally and functionally.

Question 12

What is the main function of astrocytes?

Answer 12

Formation of the blood-brain barrier which selectively restricts the movements of compounds from the blood into the CNS

Question 13

What is the main function of ependymal cells?

Answer 13

Ciliated cells, lining the cavities of the brain and the central canal of the spinal cord, PRODUCE THE CEREBROSPINAL

Question 14

Define Cerebrospinal:

Answer 14

Fluid that provides nutrients and the elimination of waste for the CNS.

Question 15

What is the main function of microglia?

Answer 15

Aid with immune responses and serve as macrophages.

Question 16

T/F: A potential difference exists across every cell’s plasma membrane.
Negative pole - Cytoplasmic side
Positive pole - extracellular fluid side

Answer 16

True

Question 17

T/F: When a neuron is not being stimulated, it maintains a resting potential that ranges from -40 to -120 mv, and averages about - 50 mv.

Answer 17

False - from -40 and -90 mV and averages about -70 mV

Question 18

What are the 3 factors for making the inside of the cell more negatively charged?

Answer 18

1) The sodium-potassium pump (2K+ in 3Na+ out)
2) More K+ channels than Na+ (K+ diffuse out of the cell)
3) Negatively charged molecules that accumulates inside the cell

Question 19

What creates the diffusional forces?

Answer 19

The build-up of positive charge up outside the membrane and negative charge inside the membrane results in an electrical potential which is an attractive force pulling K+ ions back inside the cell.

Question 20

What’s the result of the balance between the diffusional forces and electrical force?

Answer 20

Production of the equilibrium potential

Question 21

T/F: The uniqueness of neurons compared with other cells is the production and maintenance of the resting membrane potential.

Answer 21

False - Rather the sudden temporary disruptions to the resting membrane potential that occur in response to stimuli.
(Graded or Action potential)

Question 22

Define: Graded potentials:

Answer 22

The summation of subthreshold potentials produced by the opening of different chemically gated ion channels.

Question 23

Define Action potentials:

Answer 23

o Transient disruptions triggered by a threshold change in potential (voltage-gated channels).
o The actual signals that move along an axon.

Question 24

Define ligands:

Answer 24

Ligands are chemical signals - hormones or neurotransmitters

Question 25

What is the main function of ligand-gated channels

Answer 25

Induce opening and cause changes in cell membrane permeability.

Question 26

Match each number with a letter:
1) Depolarization
2) Hyperpolarization

a) Makes the membrane more negative.
b) Makes the membrane more positive.

Answer 26

1 - b
2 - a

Question 27

T/F: Depolarization and hyperpolarization result in graded potwntials.

Answer 27

True

Question 28

T/F: Size depends on the strength of the stimulus only.

Answer 28

False - Size depends either on the strength of the stimulus or the amount of ligand available to bind with their receptors

Question 29

Define the concept of Summation:

Answer 29

The ability of graded potentials to combine