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Anatomy & Physiology > Chapter 11: Nervous System > Flashcards

Chapter 11: Nervous System Flashcards

1
Q

central nervous sytem (CNS)

A

brain & spinal cord

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2
Q

peripheral nervous system (PNS)

A

nerves throughout the body

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3
Q

sensory (afferent) division

A

carries signals from nerve endings to CNS

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4
Q

motor (efferent) division

A

transmits information from CNS to rest of body

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5
Q

somatic sensory

A

carries signals from skin, bones, joints, and muscles

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6
Q

visceral sensory

A

carries signals from viscera of heart, lungs, stomach, and bladder

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7
Q

somatic motor

A

allows voluntary movements of skeletal muscles

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8
Q

autonomic motor

A

provides automatic activities (blood pressure, heart rate, etc)

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9
Q

sympathetic division

A

arouses the body for action

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10
Q

parasympathetic division

A

has a calming effect

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11
Q

neuroglia (glial cells)

A
  • about 50 glial cells to every neuron
  • diverse in shape and function
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12
Q

oligodendrocytes

A
  • form myelin sheath in the CNS
  • speed signal conduction
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13
Q

ependymal cells

A
  • line spinal cord and cavities of the brain
  • some secrete cerebrospinal fluid
  • some have cilia that aid fluid circulation
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14
Q

microglia

A
  • perform phagocytosis
  • engulf microorganisms and cellular debris
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15
Q

astrocytes

A
  • extend through brain tissue
  • nourish neurons
  • help form blood-brain barrier
  • attach neurons to blood vessels
  • provide structural support
  • most numerous of all glial cells
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16
Q

Schwann cells

A
  • form myelin sheath around nerves in PNS
  • form neurilemma
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17
Q

blood-brain barrier (BBB)

A
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18
Q

neurons

A
  • handle communication
  • 3 classes
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19
Q

sensory (afferent) neurons

A
  • detect stimuli (pressure, heat, etc)
  • transmit info about stimuli to the CNS
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20
Q

interneurons

A
  • only in the CNS
  • connect incoming sensory pathways with outgoing motor pathways
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21
Q

motor (efferent) neurons

A
  • relay messages from the brain to the muscle or gland cells
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22
Q

types of neurons

A
  • multipolar neurons: one axon, multiple dendrites
  • bipolar neurons: cell body is between axon and dendrite
  • unipolar neurons: branches in a T-shape
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23
Q

cell body (soma)

A
  • control center of the neuron
  • contains the nucleus
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24
Q

dendrites

A
  • resemble tree branches
  • receive signals from other neurons
  • conducts info to the cell body \
  • some neurons have one, some have thousands
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25
Q

axon

A
  • carries nerve signals away from the cell body
  • rope-like, vary in length
  • one in each neuron
  • branches at the end
26
Q

myelin sheath

A
  • encase most axons
  • consists mostly of lipid
  • insulates the axon
  • made up of Schwann cells in PNS and oligodendrocytes in CNS
27
Q

nodes of Ranvier

A
  • gaps in the myelin sheath
  • occur at evenly spaced intervals
28
Q

synaptic knob

A
  • found at the end of each axon branch
  • have vesicles containing a neurotransmitter
29
Q

sciatic nerve

A
  • contains the longest axon in the body
  • extends from the base of the spine to the big toe in each foot
30
Q

unmyelinated nerve fibers

A
  • perform functions where speed isn’t essential
  • ex. secretion of stomach acid
31
Q

myelin sheath in PNS

A
  • Schwann cells wrap around the axon
  • multiple layers of cell membrane
  • nucleus and most of the cytoplasm are located in the outermost later (neurilemma)
  • neurilemma is essential for an injured nerve to regenerate
32
Q

myelin in the CNS

A
  • one oligodendrocyte forms the myelin sheath for several axons
  • nucleus is located away from axons
  • outward projections wrap around the axons of nearby nerves
  • no neurilemma prevents CNS neurons from regenerating
33
Q

fetus

A
  • myelination begins during the 14th week of fetal development
  • not complete until late adolescence
  • children need an adequate amount of fat in their diet for proper myelination
34
Q

repair process in a somatic motor nerve

A
  1. nerve fiber is cut. distal part of axon is separated from nutrition source and begins to deteriorate. macrophages clean up resulting debris
  2. muscle fibers innervated by the nerve are deprives of nervous input and begin to atrophy. severed portion of axon sprouts new growth processes. the neurilemma forms a tunnel near the site of the injury. new Schwann cells grow within the tunnel.
  3. one growth process finds its way into the tunnel. it grows rapidly and the others retract
  4. the new fiber grows until it reconnects with the muscle. the reinnervated muscle fibers regrow
35
Q

synapse

A
  • area where impulses transfer from one neuron to the next
  • some are electrical
    • adjacent neurons touch
    • present in cardiac and some smooth muscle
      cells
  • some are chemical
    • neurons do not touch
    • a neurotransmitter bridges the synaptic cleft
    • first neuron = presynaptic neuron
    • next neuron = postsynaptic neuron
36
Q

chemical synapse process

A
  1. action potential reaches a synaptic knob. membrane depolarizes. ion channel opens, allowing calcium ions to enter the cell
  2. calcium causes vesicles to fuse with the plasma membrane and release their neurotransmitter into the synapse
  3. the neurotransmitter binds to receptors on the postsynaptic membrane. each transmitter has a specific receptor
  4. the specific neurotransmitter determines whether the impulse continues (excitation) or is stopped (inhibition)
  5. the receptor releases the neurotransmitter then is reabsorbed by the synaptic knobs and recycled or destroyed
37
Q

small-molecule neurotransmitters

A

trigger rapid synaptic actions

38
Q

neuropeptides

A

modulate slower, ongoing synaptic functions

39
Q

spinal cord

A
  • relays messages from the brain to the rest of the body
  • 31 pairs of spinal nerves branch out
  • about as wide as your finger and 17 inches long
  • extends from the base of the brain to the first lumbar vertebra
  • cauda equina extends from the end
40
Q

gray matter in the spinal cord

A
  • lacks myelin
  • contains mostly cell bodies of motor neurons and interneurons
  • H-shaped
  • posterior and anterior horns
41
Q

white matter in the spinal cord

A
  • abundance of myelin
  • contains abundance of myelin
  • contains bundles of axons (tracts) that carry impulses
42
Q

epidural space

A
  • lies between the outer covering of the spinal cord and the vertebrae
  • contains cushioning layer of fat, blood vessels, and connective tissue
43
Q

central canal

A
  • tiny canal in the middle of spinal cord
  • carries cerebrospinal fluid
44
Q

dorsal (posterior) nerve root

A
  • carries sensory info into the spinal cord
  • enters the dorsal horn
45
Q

ventral (anterior) nerve root

A
  • exit from the ventral horn
  • carry motor info out of the spinal cord
46
Q

ganglion

A
  • knot-like cluster of dorsal nerve cell bodies
47
Q

spinal nerve

A
  • single nerve resulting from fusion of dorsal and ventral nerve roots
  • contains sensory and motor fibers
  • transmits impulses in two directions
  • “mixed nerve”
48
Q

meninges

A
  • fibrous connective tissue
  • protect spinal cord and brain
    • pia mater
    • arachnoid mater
    • dura mater
49
Q

3 layers of the meninges

A
  1. pia mater: innermost layer, clings to brain and spinal cord, contains blood vessels
    - subarachnoid space lies between pia mater and arachnoid mater. filled with cerebrospinal fluid
  2. arachnoid mater: delicate layer between pia mater and dura mater
  3. dura mater: tough outer layer
50
Q

tracts

A
  • bundles of axons
  • routes of communication
  • nerve fibers in a tract have a similar origination, destination, and function
51
Q

ascending tracts

A

convey sensory signals up the spinal cord to the brain

  • dorsal column relays sensations of deep pressure and vibration
  • spinocerebellar tract is responsible for proprioception
  • spinothalamic tract relays sensations of temp, pain, pressure, and touch
52
Q

descending tracts

A

conduct motor impulses down the spinal cord to skeletal muscles

  • corticospinal (pyramidal) tract is responsible for movement of hands, fingers, feet, and toes on the opposite side of the body
  • extrapyramidal tracts are associated with balance and muscle tone
53
Q

decussation

A
  • most spinal cord tracts cross from one side of the body to the other in the brainstem
54
Q

meningitis

A

infection or inflammation of the meninges

55
Q

cranial nerves

A

(I) olfactory
(II) optic
(III) oculomotor
(IV) trochlear
(V) trigeminal
(VI) abducens
(VII) facial
(VIII) vestibulocochlear
(IX) glossopharyngeal
(X) vagus
(XI) accessory
(XII) hypoglossal

56
Q

olfactory nerve (I, sensory)

A
  • sense of smell
  • damage: impaired sense of smell
57
Q

facial nerve (VII, mixed)

A
  • taste (anterior 2/3 of tongue), facial expression, tear/saliva secretion
  • damage: sagging facial muscles, distorted taste
58
Q

vestibulocochlear nerve (VIII, sensory)

A
  • hearing and balance
  • damage: deafness, dizziness, nausea, loss of balance
59
Q

vagus nerve (X, mixed)

A
  • longest & most widely distributed
  • supplies organs in head, neck, thoracic & abdominal cavities
  • affects heart, lung, digestive, and urinary functions
  • damage: hoarseness/loss of voice, impaired swallowing. damage to both can be fatal
60
Q

optic nerve (II, sensory)

A
  • vision

Anatomy & Physiology (20 decks)

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