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Anatomy And Physiology > Chapter 14 > Flashcards

Chapter 14 Flashcards

1
Q

Sensory receptor structure and function

A

Detect somatic sensory info
Specialized cell or dendrite of sensory neuron
Respond to environmental changes
Responsible for trandsduction: convert stimuli to into AP sent to CNS
1st order neuron: sensory neuron (PNS cell bodies)
2nd order interneuron (in nuclei of SC/brain stem)
3rd order interneurons (thalamus)

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2
Q

Process of sensation

A
  1. transduction: 1st order neuron converts stimulus to graded potential (if threshold reached, AP is formed)
  2. Peripheral sensory receptor “linked” to cortical neuron
  3. Cortical destination depends on stimulus location and nature
  4. Different ascending tracts of axons in SC/brain carry specific stimulus type (filtered through thalamus)
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3
Q

General senses (6)

A

temperature
pain
touch
pressure
vibration
proprioception

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4
Q

special sense (5)

A

olfaction
vision
gustation
equilibrium
hearing

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5
Q

receptor sensitivity

A

receptor detect specific stimuli, insensitive to others
simple: dendrites of sensory neurons (free nerve endings)
complex: eye’s protected visual receptors, hair cells

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6
Q

receptive field

A

area monitored by single receptor cell
larger field = poorer ability to localize stimulus
ex: back surface vs fingertip

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7
Q

how are sensory receptors classified?

A

location: exteroreceptor, interoreceptor, proprioceptor
activation stimulus: nociceptors (pain), thermoreceptors, mechanoreceptors, chemoreceptors
somatic vs. visceral

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8
Q

Nociceptors

A

pain receptor
free nerve ending with large receptive fields
location: superficial skin, joint capsules in periosteum of bone, blood vessel walls
Type A and C fibers

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9
Q

type A fibers

A

fast pain
myelinated fibers
reflex result

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10
Q

type C fibers

A

slow pain
unmyelinated fibers
aware, but general idea of affected area

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11
Q

thermoreceptors

A

temperasture sensor
free nerve endings in dermis, sk. muscle, liver, hypothalamus
cold receptors (superficial) > warm receptors (deep)
same pathway as nociceptors

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12
Q

mechanoreceptors

A

distortion of plasma membrane (mechanically gated ion channels that open/close w/ stretch
Tactile: touch, pressure, vibration
Baroreceptor: pressure changes (blood vessel, digestive sys., urinary tract)
proprioceptors: position of joint/muscles

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13
Q

chemoreceptors

A

chemical concentration changes
no conscious awareness: info sent to brain stem
central: respiratory system, brain (H+, CO2 in CSF)
peripheral: carotid bodies + aortic bodies (H+, CO2, O2 in blood)

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14
Q

1st order neuron

A

unipolar neuron
sensory neuron delivers somatic sensory info to CNS
cell bodies located in DRG (spinal nerve) or cranial nerve ganglion (cranial nerve)

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15
Q

2nd order neuron

A

interneuron
cell bodies in SC (dorsal horn) or brain stem
conduct to opposite side thalamus

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16
Q

3rd order neuron

A

interneuron
cell bodies in thalamus
conduct impulses to same-side primary somatosensory cortex

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17
Q

Somatic sensory ascending pathways

A

carry sensory info from skin and sk. muscles of body wall, head, neck, and limbs
Major pathways: posterior column, spinothalamic, spinocerebellar

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18
Q

Posterior column pathway (medial lemniscus)

A

Carry sensation of localized “fine touch”, pressure, vibration, proprioception
Starts at peripheral receptor
Ends at primary somatosensory pathway

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19
Q

Posterior column pathway neurons

A

1st: axons come into SC through dorsal root ganglia then ascend into posterior column
2nd: decussate in medulla oblongata and go to thalamus, synapses on opp side of 3rd order
3rd: in thalamus nuclei, filter arriving stimuli (nature/region)

20
Q

Spinothalamic pathway (anterolateral system)

A

Nerve impulses for poorly localized touch, pain, pressure, temp
Damage: phantom limb syndrome, interneurons activated when limb isn’t there

21
Q

Spinothalamic pathway neurons

A

1st: connect receptor to 2nd order in SC dorsal gray horn
2nd: cell bodies in posterior gray horn of SC decussate there, axons go to brainstem as spinathalamic tracts
3rd: cell bodies in thalamus, both tracts synapse in thalamus, sorted/sent to primary somatosensory cortex

22
Q

Visceral sensory pathway

A

Visceral sensory info collected by interoceptors
Inaccurate perception of sensory localization
Referred pain: pain is felt in location other than the stimulus
Visceral + somatic info from same segment runs together in same tract

23
Q

Spinocerebellar pathway

A

Posture, balance, coordination of skilled movement
Cerebellum receives proprioception info
Tracts enter cerebellum via cerebellar peduncles
Perjunke cells: last synaps in cerebellum
Doesn’t reach awareness

24
Q

Spinocerebellar pathway

A

1st: neurons synapse on 2nd order interneurons in SC dorsal gray horns
2nd: interneurons axons ascend via spinocerebellar tracts (anterior tracts decussate, posterior don’t)

25
Q

Upper motor neuron

A

Cell body located in cerebral cortex or a brainstem nucleus
Synapses on lower motor neuron (inhibit/activate LMN)
Carry impulses for movement

26
Q

Lower motor neuron

A

Cell body located in anterior horn or a brainstem nucleus
Axons leave CNS through cranial or spinal nerves

27
Q

Motor/descending pathways (efferent)

A

Pyramidal tracts
Extrapyramidal tracts

28
Q

Sensory and ascending pathways (afferent)

A

Dorsal column medial lemniscus system
Spinocerebellar tracts
Anterolateral system

29
Q

Corticospinal pathways (pyramidal system)

A

Control voluntary skeletal muscle movement
Left cerebral cortex controls right side muscles
Upper motor neurons originate in primary motor cortex
Most UMNs decussate in brainstem
2 pyramidal tracts: lateral corticospinal tract, anterior corticospinal tract

30
Q

Lateral corticospinal tract

A

Individual digit movement, distal muscles (limbs)
Tracts descend on opp side of SC + synapses on LMNs in ventral gray horns at correct SC segment
LMN innervates motor unit through ventral root

31
Q

Anterior (ventral) corticospinal tract

A

Axial, Proximal muscle movement
Decussates in anterior white commissure of SC

32
Q

Extrapyramidal system

A

Involuntary movement/reflexes, muscle tone, gross movements of neck, trunk, proximal limbs (posture/coordination)
UMNs originate in brainstem
Indirectly regulated by basal ganglia and cerebellum

33
Q

Basal nuclei

A

Indirectly regulate extrapyramidal system
Innitiation and cessation of muscle activity/control
Damage: Movement disorders (dyskinesia: parkinsons, huntingtons, CP)

34
Q

How does cerebellum influence movement?

A

Posture, Balance, Coordination
Indirectly modulates extrapyramidal system
Learning rapid, coordinated, skilled movement
Compares actual movement to planned movement
Adjust to fit plan
Dysfunction: decreased muscle tone, intentional tremor

35
Q

Reflex inhibition

A

Counter excitation from spindles
Generates normal reflex with certain speed/amplitude

36
Q

Muscle tone

A

Maintained by balance between spindle excitation and inhibition from descending tracts

37
Q

LMN lesion

A

Muscle permanently limp
Less muscle tone
Decreased reaction to thump on muscles
Fasciculations (spontaneous twitches)
Muscle atrophy/degeneration

38
Q

UMN lesion

A

No atrophy of twitch
First increase in tone
Hyper-reactive reflexes (lack of inhibition)
Limbs resist passive stretch
Positive babinski test

39
Q

Memory

A

Declarative: facts, data, events
Procedural: learned motor behaviors, stored in brain stem, involve basal nuclei, cerebral cortex, and cerebellum

40
Q

Storage of memory

A

Working memory: few seconds
Short term memory: info recalled immediately, contain small bits of info, primary memories
Long term memory: secondary memories fade, tertiary last forever
Memory consolidation: requires hippocampus, amygdala links memory to emotion

41
Q

Memory storage sites

A

Cerebral cortex: long term memory
Visual association cortex: visual memory
Premotor cortex: voluntary motor activity
Temporal lobe: voices + words

42
Q

Cellular mechanisms of memory formation

A

Increased neurotrasmitter release: greater effect on postsynaptic neuron
Facilitation at synapse: brings membrane closer to threshold
Formation of additional synaptic connections: repeated communication, axons branch/form additional synapses on postsynaptic neuron

43
Q

Deep sleep

A

Slow wave
Entire body relaxes
Minimal cerebral cortex activity
HR, BP, Respiratory rate, energy use decline 30%

44
Q

REM sleep

A

Dreaming
Changes in BP and respiratory rate
Muscle tone decreases
Intense inhibition of somatic motor neurons

45
Q

Benefits of sleep

A

Increased protein synthesis in neurons
Time for memory consolidation

Anatomy And Physiology (19 decks)

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