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PAS 600 - Anatomy > med phys e3 > Flashcards

med phys e3 Flashcards

1
Q

somesthetic receptor

A
  • aka somatosensory
  • a sensory end organ concerned with reception of stimuli producing one of the generalized sensations such as temp, pressure, position or movement
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2
Q

sensation

A
  • signals transmitted by receptors to brain in form of light, sound, tactile, thermal, pain, etc
  • receptors respond specifically to one form of energy more than any other but may respond to other forms (photoreceptors may respond to pressure; we might see “stars”
  • unconscious processing/at subcortical level
  • ex. nociception is sensation; pain is perception
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3
Q

perception

A
  • refers to how sensory information is organized, interpreted and consciously experienced
  • conscious processing/at cortical level
  • ex. nociception is sensation; pain is perception
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4
Q

Meissner’s corpuscles

A
  • mechanoreceptors present in highly sensitive areas like fingertips, palms, soles, tongue, lips & genital skin
  • have small receptive fields to allow two-point discrimination
  • respond to low frequency stimuli (flutter)
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5
Q

Pacinian corpuscles

A

rapidly adapting mechanoreceptors for pressure and vibration

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6
Q

Merkel’s disks

A

slow adapting mechanoreceptor that respond to pressure and touch

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7
Q

hair follicle receptors

A

rapidly adapting mechanoreceptors that respond to movement across surface of skin

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8
Q

Ruffini’s corpuscles

A

slow adapting mechanoreceptors that respond to stretch found in dermis & joints

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9
Q

thermal receptors

A
  • free nerve endings that respond to temp changes

- divided in cold and warm slow adapting receptors

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10
Q

nociceptors

A
  • free nerve endings found in skin, muscle, joints, periosteum and visceral organs capsules
  • respond to noxious (harmful/unpleasant) chemicals, mechanical stimuli (stretch) and temp
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11
Q

muscle spindles (in muscles) and golgi tendon (in tendons)

A
  • important in proprioception & coordination of motor activity
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12
Q

sensory receptive fields

A
  • region of skin that elicits a response in somatic sensory neuron (2 pt discrimination)
  • vary in diameter (1-2 mm on fingertips [high precision]; 5-10 mm on palms; larger in abd & back [lower precision]) and may overlap
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13
Q

ascending (afferent) tracts - anterior column

A

ventral spinothalamic tract (pressure and crude touch - can’t localize)

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14
Q

ascending (afferent) tracts - lateral column

A

lateral spinothalamic tract (pain and temperature); ventral & dorsal spinocerebellar tracts

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15
Q

ascending (afferent) tracts - posterior column

A

fasciculus cuneatus & gracilis (vibration, proprioception, fine touch - can localize)

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16
Q

descending (efferent) tracts - anterior column

A

ventral corticospinal/pyramidal tract (voluntary mvoements, reflexes)

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17
Q

descending (efferent) tracts - lateral column

A

lateral corticospinal/pyramidal tract (voluntary movements, reflexes)

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18
Q

thalamus

A
  • awareness of nociceptive stimuli (non-discriminative form)
  • subjective response to sensation
  • activation and arousal with reticular formation
  • modification of affective component of behavior with limbic system
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19
Q

reticular formation

A
  • network of neurons located throughout brainstem
  • reticular activating system (RAS)
  • conscious awareness and behavioral responses to stimuli
  • maintain wakefulness
  • muscle tone & posture
  • respiratory centers (rhythm, depth, pattern)
  • BP, CO & blood distribution to organs
20
Q

limbic system

A
  • hippocampus, amygdala, anterior thalamic nuclei, limbic cortex
  • emotion, behavior and long term memory
21
Q

wernicke’s area

A

comprehension of written and spoken language

22
Q

broca’s area

A

production of language

23
Q

somatosensory cortex

A

part of brain in parietal lobe that processes sensation

  • somatic sensory cortex (sensory homunculus, skin sensation, proprioception, stereognosis, integrates info w/ visual & auditory signals)
  • sensory association area (complex sensory information processing, spatial relationships, two-point discrimination, graphesthesia)
24
Q

stereognosis

A

mental perception of depth or 3D by senses, usually in reference to ability to perceive form of solid objects by touch

25
Q

graphesthesia/graphagnosia

A

ability to recognize symbols when they’re traced on skin

26
Q

pain

A

free nerve endings detect damage to tissues

  • group A fibers (bigger) = sharp, shooting, intense pain
  • group C fibers (smaller) = steady, slow, constant pain
  • visceral pain = produced by distension, spasm, contraction, torsion, ischemia, chemical irritation or inflammation of viscera
27
Q

ascending pain pathways

A
  • spino-thalamic-somatosensory cortex = sensation of pain

- spino-thalamic-frontal cortex/anterior cingulate gyrus = subjective psychological and physiological effects of pain

28
Q

descending pain pathways

A
  • inhibitory fibers modulate pain sensation (gate control)
  • modulation by fibers from periaqueductal grey matter, nucleus raphe & RF to dorsal horn
  • neurotransmitters - Serotonin, Adrenaline, GABA, Endorphins (opioids)
29
Q

gate control theory of pain

A
  • explains how non-painful sensation can override & reduce painful sensations
  • substantia gelatinosa at tip of dorsal horn - gate controlling
  • painful, nociceptive sitmulus stimulates primary afferent fibers → to brain via transmission cells → increased perceived pain
30
Q

therapeutic use of gate control theory

A
  • pain is lessened when area is rubbed because activation of non-nociceptive fibers inhibits firing of nociceptive one
  • transcutaneous nerve stimulation (TENS): use of electrodes to selectively stimulate non-nociceptive fibers to lessen pain
  • stimulation of central areas (periaqueductal grey matter) produces analgesia (not total numbness) by activating descending pathways (opioid neurons in spinal cord)
31
Q

referred pain

A
  • brain is unable to distinguish visceral signals from more common signals that arise from somatic receptors
  • theories
  • — nociceptive sensory fibers from different viscera (pericardium) can use same set of 2nd order neurons (neck, arm, jaw muscles)
  • — visceral nociceptors may activate somatic nociceptive 2nd order neurons
32
Q

hyperalgesia

A
  • enhanced sensitivity and responsivity to stimulation of area around damaged tissue that may be caused by sensitization of nociceptors (lower threshold to respond)
  • sensitization to local signals (prostaglandins, leukotrienes from damaged cells, substance P from afferent nerve fibers, etc)
33
Q

taste

A
  • mediated by taste receptor cells (rapidly adapting) which are bundled in clusters called taste buds within tongue papillae
  • food MUST BE DISSOLVED IN SALIVA to reach receptors
  • taste sensation can change according to body’s specific nutritional needs
34
Q

taste modalities and how taste gets in

A
  • taste ligands (molecules) dissolve in saliva → reach taste pores (surrounded by taste hairs) → bind to chemoreceptors on taste buds → receptor-ligand interaction increases intracellular calcium → release of NT → graded potentials → AP in sensory neurons
  • sweet = sugars; G protein, coupled
  • bitter = alkaloids; G protein, coupled
  • sour = H+; ion channel
  • salty = Na+; ion channel
  • umami = glutamate; both
35
Q

anterior 2/3rd of tongue nerve innervation

A
  • trigeminal nerve (CN V) = somatosensation (touch, pain, pressure)
  • facial nerve (CN VII) = taste sensation
36
Q

posterior 1/3rd of tongue nerve innervation

A
  • glossopharyngeal nerve (CN IX) = taste and somatosensation
37
Q

root of tongue nerve innervation

A
  • vagus nerve (CN X)
38
Q

how smell gets in

A
  • odorant molecules bind to G protein coupled receptors on cilia of olfactory neurons → activation triggers graded potential → AP → signal to olfactory cortex
  • molecules MUST BE DISSOLVED IN MUCUS to activate receptors
  • – proteins in mucus help keep it dissolved & transport odorants to olfactory dendrites
  • axons from olfactory bulb project to limbic cortex, amygdala, hippocampus (temporal lobe - long term memory formation)
  • NO THALAMUS - intimate connection w/ brain cortex & reticular formation
  • smell neurons replaced every 60 days
39
Q

structures involved in olfaction

A
  • olfactory bulb contains mitral cells that receive info from olfactory cells
  • olfactory cells found within nasal epithelium & pass their info thru cribriform plate of ethmoid bone
40
Q

how light gets in

A
  • light detected by retina receptors (cones and rods) → retina changes shape → activating photopigment, rhodopsin → if light, present → rods & and cones hyperpolarize → activate neurons → stimulate ganglion cells which sent APs via optic nerve to lateral geniculate nucleus (thalamus) → visual cortex in occipital lobe
  • if light is not present, neurons are inhibited by rods and cones
  • horizontal cells can create lateral inhibition, which enhances light & dark contrast in images
  • tonic activity - when photoreceptors become slightly active even when not stimulated by light
  • rhodopsin - a light-sensitive pigment in rod cells of retina; consists of opsin protein bound to carotenoid retinal
41
Q

visual system

A
  • higher cortical areas process & integrate visual inputs, supporting coherent visual perception what & where (retinal sensation/image converted to our personal view/percept of outside world)
  • optic nerve can be considered part of CNS (axons have oligodendrocytes & surrounded by meninges)
  • macula - part of retina where we process a high-definition visual information (shapes, colors)
42
Q

anatomical structures involved in visual system

A
  • cornea & lens - bend to focus image on retina
  • iris & pupil - regulate amount of light entering eye
  • aqueous humor - maintains convex shape of cornea
  • vitreous humor - supports lens & maintains shape of entire eye
  • presbyopia occurs because image focuses behind retina
  • – hyperopia (farsightedness) = eyeball that is too short
  • – myopia (nearsightedness) = eyeball is elongated
  • rods - rod-shaped cell located in outer retina of eye that is sensitive to light; used for peripheral and nighttime vision
  • retina - thin layer of cells at back of eyeball where light is converted into neural signals sent to brain
  • cone - cell located near center of retina that is weakly photosensitive & is responsible for color vision in relatively bright light; used for daytime and color vision
  • fovea - acute vision because it has high density of cones
43
Q

retinal receptors

A

Rods: high sensitivity to light, and scattered light, specialized in night vision, more sensitivity to movement, low resolution, monochromatic

Cones: low sensitivity to light, more sensitive to direct light rays, high acuity, concentrated in fovea, polychromatic (3 types of cones)

44
Q

types of cones

A
  • trichromatic system
  • color is a result of ratio of activity of three types of cones
  • S cones = respond to short waves
  • M cones = respond to medium waves
  • L cones = respond to light to long waves
45
Q

fovea

A
  • special area where cells are displaced to allow light to be directly absorbed
  • focal point of image & region where most cone cells are concentrated
  • constantly move our eyes to view the foveal image
  • at optic dis, fibers leave the eye - no photoreceptors here (blind spot)

PAS 600 - Anatomy (13 decks)

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