Quiz 5 Nervous System pt 1

Question 1

Central Nervous System involves the:

Answer 1

Brain

Spinal Cord

Question 2

Peripheral Nervous System involves the:

Answer 2

Nerves

• Afferent Neurons
• Efferent Neurons
• Sympathetic Autonomic Control
• Parasympathetic Autonomic Control

Question 3

Afferent Neurons

Answer 3

sensory neurons

• sense stimulus and send info about the stimulus to CNS e.g. smell, light

Question 4

Efferent Neurons

Answer 4

motor neurons

• carry signals away from CNS, initiating action

Question 5

Somatic Motor Neurons

(Efferent Neurons)

Answer 5

skeletal muscle

Question 6

Autonomic Motor Neurons

(Efferent Neurons)

Answer 6

cardiac muscle (heart), glands, smooth muscles in the body; “hollow tubes”

Question 7

Sympathetic Nervous System

(Autonomic Motor Neurons)

Answer 7

FIGHT OR FLIGHT

e.g. blood pressure, sweat, digestion stops

Question 8

Parasympathetic Nervous System

(Autonomic Motor Neurons)

Answer 8

REST OR DIGEST

• counteracts effects of sympathetic nervous system (starts digestion again, lowers BP)
• optimal level of functioning exists in the parasympathetic nervous system

Question 9

Enteric Nervous System

Answer 9

bowels, small intestine

Question 10

Neuron

Answer 10

• is a nerve cell, fully differentiated, and capable of transmitting a nervous (electrical) impulse

Question 11

Nervous Tissue

Answer 11

• composed of neurons
• therefore our brain, spinal cord, and nerves are all cariations of neuronal arrangement

Question 12

3 basic structures of a neuron

Answer 12

Cell Body (Soma): interpretation and protein synthesis; also contains nucleus

Dendrites: branched projections acting to propogate electrochemical stimulation received from other neural cells to the cell body (soma).

Axon: conducts/transmits electrical impulses away from the soma to different neurons, glands, or muscles; “nerve fibers”

Question 13

White Matter/Grey Matter

Answer 13

White Matter: myelinated axon

Grey matter: unmyelinated axon, dendrite, or soma

Question 14

Neurons and signal direction

Answer 14

A neuron is only capable of carrying a signal in one direction along its axon, thus the distinction between sensory and motor neurons.

(A bundle of axons w/in CNS is referred to as a tract; a bundle of axons outside the CNS is referred to as a nerve)

Question 15

Synapse

Answer 15

• the junction between the axon terminal and there the axons lead (muscle, other neuron, gland)
• transmission of a signal across the synapse may be electric, but is more commonly chemical (involving a neurotransmitter)

Question 16

Neuronal Membrane

(Channels and Pumps)

Answer 16

the membrane of a neuron is impermeable to most ions such as Na+, K+, Cl-, and Ca+, however, many distint channels and gates exist for their passage, but most notably:

Voltage Gated Channels: “Na+ stay high, K+ stay low”?

Na/K ATPase Pump: re-establish resting membrane (push Na+ out, K+ in)

Slow leak ion channels: K+ leaks out slowly (but faster than Na+)– creates + outside and - inside

Question 17

Resting Membrane Potential

Answer 17

A membrane at rest has a higher concentration of sodium on the outside and potassium on the inside of the cell. Potassium slowly leaks out creating a negative charge on the inside of the resting membrane; measured in millivolts

Question 18

Action Potential

Answer 18

• a rapid change in membrane potential and is the mechanism by which a nerve signal is transmitted
• muscle cells, cardiac cells, and neural cells all support an action potential though slight variations exist among the differing tissue types
• the ability to support an action potential is characterized by the term ‘excitable’ tissue

RESTING STAGE

DEPOLARIZATION STAGE (Na+ channels open, flooding inside the cell)

REPOLARIZATION STAGE (K+ channels open, flood out of the cell) ATP pump kicks in?

Question 19

Saltatory Conduction

Answer 19

• occurs along the myelinated axons allowing for a more rapid and energy conserving signal transmission
• able to “skip” all the gates… jumps from one node to the next

Question 20

Neurotransmitters

Answer 20

• are chemicals released into the synapse once an action potential reaches the end of the axon
• its release is calcium dependent, and its action is determined by the postsynaptic receptor
• the resulting action may last milliseconds or days and include:

– opening or closing of membrane channels

– enzyme activation on the postsynaptic structure

– altered cell metabolism

– altered gene expression

Question 21

Two Major classes of neurotransmitters exist:

Answer 21

Large molecule NT: neuropeptides/neurohormones

- insulin, growth hormone, prolactin, melanocyte stimulating hormone

Small molecule NT: have a more rapid and shorter duration of action

• dopamine, seratonin, histamine, acetylcholine, norepinephrine

Question 22

The obvious variable in a neuron’s ability to carry a signal is:

Alterations in Neuronal Transmission

Answer 22

Ion concentration

• neurotransmitter deficiencies, demyelination, damage to the neuron

Question 23

Alterations in Neuronal Transmission cont…

Answer 23

• neuroregeneration* is possible through axonal regrowth assuming the cell body of that neuron is in tact
• also, extracellular changes of endogenous and exogenous matter must be considered with respect to ingestion, metabolism, and excretion ability
  (e. g. a drop in extracellular pH will result in increased excitability of a neuron while a rise in pH will result in the opposite effect)
• Low oxygen levels may decrease synaptic activity

Question 24

Alterations in Neuronal Transmission Cont

(synaptic fatigue and synaptic facilitation)

Answer 24

Synaptic Fatigue: ​occurs if stimulation is too rapidly repeated

Synaptic Facilitation: occurs if repetitive stimulation is followed by a brief period of rest, then re-stimulation

Question 25

Ganglia

Answer 25

• masses of soma and dendrites in a close proximity; “clusters of cell bodies” (the term plexus is used to describe groupings of various ganglia)

Question 26

Two Ganglia of note:

Answer 26

Dorsal Root Ganglia (spinal ganglia) of the sensory neurons

Autonomic Ganglia of the autonomic motor neurons

• sympathetic ganglia are paraspinal
• parasympathetic ganglia are close to their effector organ
• Somatic motor neuron cell bodies are located within the spinal cord at various levels, thus no ganglia