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Anatomy and Physiology I > Lesson 18 > Flashcards

Lesson 18 Flashcards

1
Q

reflexes

A

quick, involuntary, stereotyped reaction of glands or muscle to stimulation; controlled by the spinal cord alone

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2
Q

what do reflexes require? (4)

A

require stimulation, quick, involuntary, stereotyped

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3
Q

somatic reflexes

A

reflexes involving the somatic nervous system, innervating skeletal muscle

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4
Q

visceral reflexes

A

reflexes involving organs such as heart and intestines

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5
Q

reflexes generally _____ original stimulus, what is this called?

A

opposes; negative feedback

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6
Q

somatic reflex arc (5)

A
  1. somatic receptors in skin, muscle, or tendons
  2. afferent nerve fibers carry information from receptors to posterior horn of the spinal cord or the brainstem
  3. integrating center: a point of synaptic contact between neurons in gray matter of the spinal cord or brainstem
  4. effect nerve fibers carry motor impulses to muscles
  5. effectors the muscles that carry out the response
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7
Q

four classification of reflexes

A
  1. development
  2. type of motor response
  3. complexity of neural circuit
  4. site of information processing
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8
Q

innate reflexes (3)

A
  • formed before birth
  • basic neural reflexes
  • withdrawal from pain, chewing, sucking, tracking objects with eyes
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9
Q

acquired reflexes (3)

A
  • learned motor patterns
  • rapid, automatic
  • riding a bike, pressing breaks when cut off
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10
Q

motor response

A

nature of resulting motor response

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11
Q

somatic reflexes (3)

A

involuntary control of the nervous system
1. superficial reflexes of the skin and mucous membranes
2. stretch or deep tendon reflexes

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12
Q

visceral reflexes

A

aka autonomic reflexes
- control systems other than muscular system
- smooth/cardiac muscles, glands, adipose tissue

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13
Q

monosynaptic reflex

A

sensory neuron synapses directly onto motor neurons

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14
Q

polysynaptic reflex

A

at least one interneuron between the sensory and motor neurons

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15
Q

spinal reflexes

A

occur in the spinal cord

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16
Q

cranial reflexes

A

occur in the brian

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17
Q

intersegmental reflex arcs

A
  • many spinal segments interact producing highly variable motor responses
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18
Q

monosynaptic reflex arcs (3)

A
  • little synaptic delay
  • very prompt response
  • knee-jerk reflex
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19
Q

reciprocal inhibition

A

reflex phenomenon that prevents muscles from working against each other by inhibiting antagonist when agonist is excited

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20
Q

stretch (myotatic) reflex (3)

A

when a muscle is stretch it “fights back” and contracts
- helps maintain equilibrium and posture
- stabilizes joints

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21
Q

what is the stretch reflex primarily mediated by?

A

the brain, but it’s spinal component can be more pronounced if muscle is suddenly stretched by a tendon tap (like knee jerk)

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22
Q

muscle spindles (4)

A

stretch receptors embedded in skeletal muscles
- serve as proprioceptors
- inform brain of muscle length and body movement
- enable brain to send motor commands back to the muscles and control coordinated movement

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23
Q

intrafusal fibers

A

modified muscles fibers within a muscle spindle

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24
Q

extrafusal fibers

A

muscle fibers outside the muscle spindle that generate force

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25
Q

gamma motor neuron

A

innervates the ends of an intrafusal fiber and keeps it taut, allowing the CNS to adjust sensitivity to the spindle; allows voluntary contraction to NOT trigger the reflex

26
Q

where is the gamma motor neuron located?

A

the anterior gray horn of the spinal cord

27
Q

what do alpha motor neurons innervate?

A

extrafusal fibers (aka normal muscles)

28
Q

the _____ of the intrafusal fiber contains sensory nerve fibers

A

midportion

29
Q

primary afferent fibers in muscles

A

monitor fiber length and speed of length changes

30
Q

secondary afferent fibers

A

monitor length only

31
Q

postural reflex

A

a type of stretch reflex, helps keep you upright when standing on a boat

32
Q

steps of the patellar reflex (7)

A
  1. tap on patellar ligament excites nerve endings of muscle spindle in quadriceps
  2. stretch signals travel to spinal cord vis primary afferent fiber and dorsal root
  3. primary afferent neuron stimulates alpha motor neuron in spinal cord
  4. efferent signals in alpha motor nerve fiber stimulate quads to contract
  5. at the same time, a branch of the afferent nerve fiber stimulates inhibitory motor neuron in the spinal cord
  6. that neuron inhibits alpha motor neurons that supply hamstrings
  7. hamstring contraction is inhibited so hamstrings do not antagonize quads
33
Q

five general characteristics of polysynaptic reflexes

A
  1. involves pools of interneurons
  2. involve reciprocal inhibition
  3. have reverberating circuits
  4. are intersegmental in distribution
  5. several reflexes cooperate
34
Q

polysynaptic reflex arc

A

pathway in which signals travel over many synapses on their way to the muscle

35
Q

flexor reflex

A

the quick contraction of flexor muscle resulting in the withdrawal of a limb from an injurious stimulus

36
Q

reciprocal inhibition

A

relaxation of the extensors in a limb which is undergoing a reflex

37
Q

tendon organs

A

proprioceptors in a tendon near its junction with a muscle; involved in the tendon reflex

38
Q

tendon reflex

A

response to excessive tension on the tendon by inhibiting muscle from contracting strongly

39
Q

crossed extension reflex

A

contraction of extensor muscles in the limb opposite to the one that is withdrawn

40
Q

ipsilateral reflex arc

A

stimulus and response are on the same side of the body

41
Q

contralateral reflex arc

A

input and output are on opposite sides of the body

42
Q

intersegmental reflex

A

one in which the input and output occur at different levels or segments of the spinal cord

43
Q

reinforcement of spinal reflexes (3)

A

higher centers reinforce spinal reflexes by stimulating excitatory neurons in the brain stem or spinal cord
- EPSPs
- facilitating postsynaptic neurons

44
Q

Jendrassick maneuver

A

hooks fingers together to try and pull hands apart, reinforces the knee jerk reflex

45
Q

inhibition of spinal reflexes (3)

A

higher centers inhibit reflexes by:
- stimulating inhibitory neurons
- creating IPSPs
- suppressing postsynaptic neurons

46
Q

Babinski’s sign

A

displayed by infants normally, but may indicate CNS damage in adults

47
Q

neural pools

A

functional grouping of neurons; each pool consists of thousands of interneurons concerned with a particular body function

48
Q

diverging circuit

A

one nerve fiber branches and synapses with several postsynaptic cells

49
Q

converging circuit

A

input from many different nerve fibers can be funneled to one neuron or neural pool

50
Q

reverberating circuit

A

positive feedback; neurons stimulate each other in linear sequence but one or more of the later cells re-stimulates the first cell to start the process all over again

51
Q

parallel after-discharge circuit

A

input neuron diverees to stimulate several chains of neurons

52
Q

what does after-discharge mean?

A

continuation of firing after the stimulus stops; staring at a bright light, then closing your eyes and still seeing it

53
Q

serial processing

A

neurons and neural pools relay information along pathways in relatively simple linear fashion

54
Q

how many flows of info can serial processing, process?

A

just one, you cannot really multitask

55
Q

parallel processing

A

information is transmitted along diverging circuits through different pathways that act on it simultaneously for different purposes; think all the things that go into driving

56
Q

complete transection

A

complete severance of the spinal cord

57
Q

complete transection of the spinal cord above what vertebra poses a threat of respiratory failure?

A

C4

58
Q

what comes from complete transection?

A

intermediate loss of motor control below level of injury

59
Q

paraplegia

A

paralysis of both lower limbs

60
Q

quadriplegia

A

paralysis of all four limbs

61
Q

hemiplegia

A

paralysis on one side of the body

62
Q

paresis

A

partial paralysis or weakness of the limbs

Anatomy and Physiology I (22 decks)

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