Nervous System Function

Question 1

Central nervous system consists of which structures?

Answer 1

Brain & spinal cord

Question 2

Peripheral nervous system consist of which structures?

Answer 2

cranial nerves, spinal nerves, ganglia, and also sensory & motor fibers.

Question 3

Name the two divisions of the PNS

Answer 3

Sensory (afferent) & motor (efferent)

Question 4

Sensory division of the PNS consists of which types of fibers:

Answer 4

somatic & visceral sensory nerve fibers which conduct impulses from receptor to CNS

Question 5

Name the two motor divisions of the PNS

Answer 5

Somatic nervous system and ANS

Question 6

Somatic nervous system function:

Answer 6

somatic/voluntary nerve fibers conduct impulses to skeletal muscles

Question 7

What is the function of the Autonomic Nervous System (ANS)?

Answer 7

visceral/involuntary motor nerve fibers conduct impulses to smooth & cardiac muscles and glands

Question 8

Name the main function of the Sympathetic Nervous System and some examples of how the body responds.

Answer 8

mobilizes body systems during activity (fight or flight); increases heart rate, blood flow, increase glucose, brachiodilation, reduced saliva, bladder restriction, dilated pupils, reduced peristalsis & secretion

Question 9

Name the main function of the Parasympathetic nervous system and some examples of how the body responds.

Answer 9

conserves energy and promotes housekeeping during rest (rest & digest); stimulated salivary flow, lower heart rate, bronchiorestriction, stimulated peristalsis & secretion & bile release, bladder contraction, constricted pupils

Question 10

Astrocytes

Answer 10

highly branched, most abundant glial cells, cling to neurons and capillaries, monitor/regulate/modify surrounding environment, regulate blood/brain barrier, can modulate neuron activity & strength of stimulus

Question 11

Microglia

Answer 11

defensive cells of CNS, immune response; monitor health of neurons; are mobile and can change into macrophages if necessary

Question 12

Ependymal cells

Answer 12

form sheets of cells and line CSF filled CNS cavities, contain cilia that beat and move CSF around which helps maintain health of CNS

Question 13

Oligodendrocytes

Answer 13

have processes that form myelin sheaths around CNS fibers, increase velocity of impulses

Question 14

Name the two types of neuroglia in PNS and their function.

Answer 14

Satellite cells- like astrocytes, surround cell body and monitor surrounding environment
Schwann cells- wrap axons with entire cell to form myelin sheath

Question 15

Name the 4 special characteristics of neurons

Answer 15

extreme longevity, amitotic, high metabolic rate, possess a cell body and one or more processes

Question 16

Name the clusters of neuronal cell bodies in the CNS and PNS

Answer 16

CNS- nuclei; PNS- ganglia

Question 17

Name the clusters of axons in the CNS and PNS

Answer 17

CNS- tracts; PNS- nerves

Question 18

Where is AP generated in axon?

Answer 18

Initial segment, after graded potentials converge on axon hillock

Question 19

Myelin sheath function & type of conduction

Answer 19

Increase speed of impulses; saltatory conduction via more VGCs at nodes of Ranvier

Question 20

Multipolar neurons

Answer 20

3+ processes; 1 axon & 2 or more dendrites; most common neuron

Question 21

Bipolar neurons

Answer 21

2 processes; one axon and one dendrite; rare- found in ear, retina

Question 22

Unipolar neurons

Answer 22

cell body offset from T-like axon; peripheral process assoc w/ sensory receptor and central process enters CNS (most sensory neurons are unipolar)

Question 23

Sensory/afferent neurons

Answer 23

mainly unipolar, cell body in ganglia, transmit into CNS from PNS

Question 24

Motor/efferent neurons

Answer 24

multipolar; cell body in nuclei & gray matter of CNS; carry impulses away from the CNS

Question 25

Interneurons

Answer 25

remain in CNS, multipolar; connects sensory neurons to motor neurons

Question 26

What causes hyperpolarization?

Answer 26

K+ leak channels slow closure

Question 27

What are graded potentials?

Answer 27

short distance signals that depolarize a small part of the membrane, spreads via Na+ influx but decays over a distance due to leak channels

Question 28

What is approximate threshold for an action potential?

Answer 28

-55mV

Question 29

What is the extra state in voltage gated sodium channels?

Answer 29

Besides the open & closed state, they also have an inactivated state due to inactivation gate. Must return to closed state before it can reopen (absolute refractory period)

Question 30

How is a strong AP created?

Answer 30

Increased frequency of stimulus.

Question 31

How are action potentials prevented from going the wrong way?

Answer 31

The absolute refractory period, which is caused by the inactivation state of VGSCs.

Question 32

What is the relative refractory period?

Answer 32

A period when most VGSCs are resetting and the threshold for generating an AP is elevated; stronger stimulus needed to overcome hyperpolarization

Question 33

Multiple Sclerosis cause & remission

Answer 33

Auto-immune disease where oligodendrocytes are destroyed which slows impulses; remission is caused by demyelinated axons producing more Na+ channels; treated with immunosuppressants

Question 34

Why are electrical synapses faster than chemical synapses?

Answer 34

the neurons are connected via gap junctions which allows ions to pass quickly between cells

Question 35

What is a metabotropic receptor?

Answer 35

A GPCR in the post-synaptic neuron that binds a neurotransmitter. This binding triggers an intracellular cascade or it can alter the number of ionotropic receptors.

Question 36

Excitatory Postsynaptic Potential

Answer 36

brings neuron closer to AP threshold; neurotransmitter binds chemically gated channel and opens for Na+ to move in

Question 37

Inhibitory Postsynaptic Potential

Answer 37

causes hyperpolarization; neurotransmitter binds chemically gated channel allowing K+ to exit or Cl- to enter cell

Question 38

What is temporal summation?

Answer 38

when impulses are fired more rapidly, EPSPs summate and reach threshold

Question 39

Spatial summation

Answer 39

impulses summate from multiple synapses

Question 40

Serial processing

Answer 40

Input travels along one pathway to a specific destination; all or nothing response (stimulus - receptor-sensory neuron-integration center- motor neuron- effector- response)

Question 41

With this type of processing, input travels along several pathways and different part of circuitry deals simultaneously with the info. It's important in higher level mental function.

Answer 41

Parallel processing

Question 42

Diverging circuit

Answer 42

one input, many outputs (like a motor neuron to skeletal muscle)

Question 43

Converging circuit

Answer 43

many inputs, one output; sensory stimuli elicit same memory

Question 44

Reverberating circuit

Answer 44

signal travels through chain of neurons, each feeding back on previous neurons (important for controlling rhythmic activity)

Question 45

Parallel after-discharge circuit

Answer 45

single input stimulates multiple parallel neurons which converge to a single output