Chapter 11 Test

Question 1

Functions of the nervous system

Answer 1

Sensory input, integration, motor output

Question 2

Divisions of the nervous syste

Answer 2

Central nervous system(CNS), peripheral nervous system (PNS)

Question 3

CNS includes

Answer 3

Brain and spinal cord; integration and command center

Question 4

PNS involves

Answer 4

Paired spinal and cranial nerves carry messages to and from the CNS

Question 5

Sensory PNS functions

Answer 5

Somatic afferent fibers—convey impulses from skin, skeletal muscles, and joints
Visceral afferent fibers—convey impulses from visceral organs

Question 6

Motor PNS functions

Answer 6

Transmits impulses from the CNS to effector organs

Question 7

Neuron functions

Answer 7

Plasma membrane functions in:
Electrical signaling
Cell-to-cell interactions during development

Question 8

Tracts are in

Answer 8

CNS

Question 9

Nerves are in

Answer 9

PNS

Question 10

Neurons structural classification

Answer 10

Multipolar, bipolar, unipolar

Question 11

Multipolar

Answer 11

1 axon and several dendrites
Most abundant
Motor neurons and interneurons

Question 12

Bipolar

Answer 12

Bipolar—1 axon and 1 dendrite

Rare, e.g., retinal neurons

Question 13

Unipolar

Answer 13

single, short process that has two branches:
Peripheral process—more distal branch, often associated with a sensory receptor
Central process—branch entering the CNS

Question 14

Functional classification of neurons

Answer 14

Sensory, motor, interneurons

Question 15

Sensory

Answer 15

Transmit impulses from sensory receptors toward the CNS

Afferent

Question 16

Motor

Answer 16

Carry impulses from the CNS to effectors(efferent)

Question 17

Interneurons

Answer 17

Shuttle signals through CNS pathways; most are entirely within the CNS ( association neurons)

Question 18

Neuroglia supporting cells

Answer 18

Astrocytes (CNS)
Microglia (CNS)
Ependymal cells (CNS)
Oligodendrocytes (CNS)
Satellite cells (PNS)
Schwann cells (PNS)

Question 19

Astrocytes location

Answer 19

Cling to neurons, synaptic endings, and capillaries

Question 20

Astrocytes functions

Answer 20

Support and brace neurons
Help determine capillary permeability
Guide migration of young neurons
Control the chemical environment
Participate in information processing in the brain

Question 21

Microglia location

Answer 21

Migrate toward injured neurons

Question 22

Microglia functions

Answer 22

Defensive cells in the CNS

Question 23

Ependymal location

Answer 23

Line the central cavities of the brain and spinal column

Question 24

Ependymal functions

Answer 24

Separate the CNS interstitial fluid from the cerebrospinal fluid in the cavities

Question 25

Oligodendrocytes location

Answer 25

Processes wrap CNS nerve fibers, forming insulating myelin sheaths

Question 26

Oligodendrocytes functions

Answer 26

Oligodendrocytes have processes that form
myelin sheaths around CNS nerve fibers

Question 27

Satellite cells location

Answer 27

Surround neuron cell bodies in the PNS

Question 28

Schwann cells location

Answer 28

Surround peripheral nerve fibers and form myelin sheaths

Question 29

Schwann cells function

Answer 29

Vital to regeneration of damaged peripheral nerve fibers

Question 30

The synapse

Answer 30

A junction that mediates information transfer from one neuron: To another neuron, or To an effector cell

Question 31

Presynaptic neuron

Answer 31

conducts impulses toward the synapse

Question 32

Postsynaptic neuron

Answer 32

transmits impulses away from the synapse

Question 33

Action potential (AP)

Answer 33

Brief reversal of membrane potential with a total amplitude of ~100 mV

Question 34

Generation of an action potential

Answer 34

Resting state: Only leakage channels for Na+ and K+ are open All gated Na+ and K+ channels are closed

Question 35

Phases of action potential

Answer 35

Resting state->depolarization->depolarization->hyperpolarization->restarts

Question 36

Depolarizing Phase

Answer 36

``` Depolarizing local currents open voltage-gated Na+ channels Na+ influx causes more depolarization At threshold (–55 to –50 mV) positive feedback leads to opening of all Na+ channels, and a reversal of membrane polarity to +30mV (spike of action potential) ```

Question 37

Repolarizing phase

Answer 37

Na+ channel slow inactivation gates close Membrane permeability to Na+ declines to resting levels Slow voltage-sensitive K+ gates open K+ exits the cell and internal negativity is restored

Question 38

Hyperpolarization

Answer 38

Some K+ channels remain open, allowing excessive K+ efflux | This causes after-hyperpolarization of the membrane (undershoot)

Question 39

Absolute refractory period

Answer 39

Time from the opening of the Na+ channels until the resetting of the channels Ensures that each AP is an all-or-none event Enforces one-way transmission of nerve impulses

Question 40

Relative refractory period

Answer 40

Follows the absolute refractory period Most Na+ channels have returned to their resting state Some K+ channels are still open Repolarization is occurring Threshold for AP generation is elevated Exceptionally strong stimulus may generate an AP

Question 41

Neurotransmitters

Answer 41

Biogenic Amines,Ach, purines, amino acids,peptides, gases and lipids

Question 42

Graded potential vs. action potential

Answer 42

Graded potentials: Incoming short-distance signals | Action potentials: Long-distance signals of axons

Question 43

Resting Membrane Potential (Vr)

Answer 43

Potential difference across the membrane of a resting cell Approximately –70 mV in neurons (cytoplasmic side of membrane is negatively charged relative to outside) Generated by: Differences in ionic makeup of ICF and ECF Differential permeability of the plasma membrane

Question 44

Impulse conduction

Answer 44

Larger diameter fibers have less resistance to local current flow and have faster impulse conduction Impulse conduction slows and eventually ceases

Question 45

Weak vs strong stimuli

Answer 45

Strong stimuli can generate action potentials more often than weaker stimuli

Question 46

Nerve fiber classification

Answer 46

Nerve fibers are classified according to: Diameter Degree of myelination Speed of conduction

Question 47

Multiple Sclerosis (MS)

Answer 47

An autoimmune disease that mainly affects young adults Symptoms: visual disturbances, weakness, loss of muscular control, speech disturbances, and urinary incontinence Myelin sheaths in the CNS become nonfunctional scleroses Shunting and short-circuiting of nerve impulses occurs Impulse conduction slows and eventually ceases