Ch 11.1 Structures and Processes of the Nervous System

Question 1

What is homeostasis?

Answer 1

A state of relative stability, maintaining the body with a narrow range of conditions

Question 2

Describe the central nervous sytem

Answer 2

The CNS consists of the brain and spinal cord, and integrates and processes information sent by nerves

Question 3

Describe the peripheral nervous system

Answer 3

The PNS includes nerves that carry sensory messages to the CNS and nerves that send information from the CNS to the muscles and glands

Question 4

What type of muscle(s) does the somatic system control?

Answer 4

Voluntary muscles- skeletal muscles

Question 5

What kind of muscle(s) does the autonomic system control?

Answer 5

Involuntary muscles- smooth and cardiac muscles

Question 6

What types of cells is the nervous system composed of?

Answer 6

Neurons and cells that support the Neurons which are called glial cells

Question 7

What are glial cells?

Answer 7

Non conductive cells which nourish the neurons, removes their wastes, and defend against infection

Question 8

What are nerves?

Answer 8

Individual neurons organized into tissues

Question 9

Describe the structure of the neuron

Answer 9

Dendrites, cell body, axon, and branching ends

Question 10

Define a dendrite

Answer 10

Short branching terminals that receive nerve impulses from other neurons or sensory receptors and relay the nerve impulse to the cell body

Question 11

What is a cell body?

Answer 11

Contains the nucleus and is the site of the cell’s metabolic reactions

Question 12

What does the axon do?

Answer 12

It conducts impulses away from the cell body

Question 13

What does the myelin sheath do?

Answer 13

It protects the neurons and speeds the rate of nerve transmission. PROTECTS AGAINST THE LOSS OF IONS

Question 14

What is the function of the neurilemma?

Answer 14

Promotes the repair and regeneration of axons

Question 15

What is a simple reflex?

Answer 15

UNCONDITIONED response to stimuli

Question 16

What is a conditioned reflex?

Answer 16

A learned and practiced reflex

Question 17

What is a ganglion?

Answer 17

A cluster of sensory cell bodies found along the spinal cord

Question 18

What is a nerve impulse and what steps does it involve?

Answer 18

An electrochemical event that uses cellular energy to generate a series of action potentials. It involves resting potential, depolarization, and repolarization

Question 19

Describe the resting membrane potential

Answer 19

An unequal distribution of ions across neural membrane. When not stimulated, it is more positive on the outside

3 factors

• na K pump moves 3 sodiums out and 2 K in using ATP. High Na outside, high k inside
• negative proteins and Cl remain inside
• the membrane is more permeable to K( k diffuses out faster than Na diffuses in)

Question 20

Describe depolarization

Answer 20

Stimulus causes na gates to open and na rapidly diffuses into cell. Membrane has reverse polarity due to excessive + ions inside (40mV). Depol causes na gates to close and K gates to open

Question 21

Define threshold

Answer 21

Min level of stimulus required to produce an action potential

Question 22

Describe repolarization

Answer 22

K leaves cell by diffusion

Restores original polarity (+ outside, -inside)

Question 23

What is hyperpolarization

Answer 23

When the intracellular fluid becomes more negative than before (-90mV)

Question 24

What is a refractory period

Answer 24

Time it takes to repolarize after an action potential

No new impulse can be initiated until after the original resting is re-established

Question 25

What is a saltatory conduction?

Answer 25

When actions potentials are forced to “jump” from one mode of ranvier to the next due to the myelin sheath

Question 26

What is a synapse?

Answer 26

Where the axon of one neuron meets the

dendrite of another neuron/effector

Question 27

Describe the process of synaptic transmission

Answer 27

1. Nerve impulse arrives at the axon terminal
2. Impulse causes synaptic vesicles to move to the membrane and fuse with it releasing neurotransmitter to the synapse (exocytosis) 3.neurotransmitters defuse across to the dendrite
3. Neurotransmitters bind to the receptors and initiate a nerve impulse

Question 28

Describe excitatory and inhibitory

Answer 28

Excitatory- opens na gates (depolarize)

Inhibitory- opens k gates (hyperpolarize)

Question 29

Define neuromuscular junction

Answer 29

Modified synapse where a motor neuron meets a muscle cell

Question 30

What is summation?

Answer 30

When 2+ neurons must both fire in order to depolarize the same postsynaptic neuron

Question 31

What is acetylcholine?

Answer 31

Is a neurotransmitter that crosses a neuromuscular junction. It excites the muscle cell membrane, causing depolarization and contraction of the muscle fibre

Question 32

What enzyme breaks down acetylcholine?

Answer 32

Cholinesterase