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Pathophysiology > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

Special Senses

A

Vision Hearing Taste Smell Equilibrium *Conscious Stimulus processing

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2
Q

Somatic Senses

A

Touch

Temperature

Pain/ Itch (Nociception)

Proprioception

*Conscious Stimulus processing

  • Pathways go to the cortex and cerebellum.
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3
Q

Somatic Stimuli

A

Muscle length/tension

Proprioception

*Unconscious stimulus processing

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4
Q

Visceral Stimuli

A

Blood pressure Distension of GI Blood glucose concentration internal body temp osmolarity of fluids lung inflation pH of CSF *Unconscious stimulus processing

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5
Q

Simple sensory system

A

single sensory neuron with branched dendrites that function as receptors Pain and itch receptors

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6
Q

Complex sensory system

A

includes multicellular sense organs–> ear and eye

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7
Q

Special Sense Receptors

A

most are very specialized non-neuronal accessory structures (except for nose, which are just plain old neurons) -cornea of the eye -hair on arms

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8
Q

Chemoreceptors

A

sense oxygen, pH, glucose, etc.

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9
Q

Mechanoreceptors

A

sense pressure (baroreceptors), cell stretch (osmoreceptors), vibration, sound, etc.

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10
Q

Photoreceptors

A

Sense light

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11
Q

Thermoreceptors

A

sense temperature

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12
Q

Signal transduction

A

in order to propagate a sense, you need to send the signal. Signal transduction: stimulus energy converted into information that can be processed by CNS. in many cells, there are ion channels or second messenger systems that initiate a membrane potential change.

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13
Q

Adequate stimulus

A

a form of energy to which a receptor is most responsive. (receptors can respond to most other forms of energy as well, if the intensity if high enough–> seeing stars from falling down). sensory receptors can be very sensitive to their preferred form of stimulus (single odorant molecule).

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14
Q

Threshold

A

the minimum stimulus required to activate a receptor

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15
Q

Receptor Potential

A

the change in sensory receptor membrane potential. Is a graded potential. Will initiate an action potential that travels.

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16
Q

Graded potential

A

variable strength signal that travels over short distances and loses strength as it travels through the cell

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17
Q

Receptive field

A

A sensory neuron has a receptive field, which is the region surrounding it that can sense the stimulus. Simplest case is one neuron/receptive field, but they can overlap. more sensitive areas have smaller receptive fields (fingertips vs your leg)

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18
Q

Convergence

A

multiple presynaptic neurons providing input to a smaller number of postsynaptic neurons. Creates a larger overall receptive field.

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19
Q

Sensory system –> the brain

A
  1. can travel up the spinal cord via ascending pathways 2. can get directly to the brain via cranial nerves *Each major area of the brain processes at least one major category of sensation. *Most pathways, once in the brain, go through the thalamus.
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20
Q

Sensory pathway that does NOT pass through the thalamus

A

Olfactory senses. These are one of the oldest senses. They are chemoreceptors

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21
Q

Proust phenomenon

A

the ability of odors spontaneously to cue autobiographical memories which are highly vivid, affectively toned and very old

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22
Q

Perceptual threshold

A

level of stimulus intensity necessary for you to be aware of a particular sensation- most senses get filtered out by the brain, otherwise you would be aware of the noises your organs make, etc.

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23
Q

habituation

A

decreased perception of a stimulus

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24
Q

inhibitory modulation

A

diminishes a suprathreshold stimulus until it is below the perceptual threshold. often occurs in secondary and higher neurons in a sensory pathway

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25
Q

The CNS must distinguish 4 properties of a stimulus:

A
  1. nature, or modality
  2. location
  3. Intensity
  4. duration
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26
Q

Stimulus property: Modality

A
  1. what sensory neurons are activated? 2. where are they synapsing in the brain?
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27
Q

Labeled line coding

A

1:1 association of receptor with sensation ex: stimulation of a cold receptor is always perceived as cold, whether the actual stimulus was cold or an artificial depolarization of the receptor.

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28
Q

Stimulus property: Location

A

Coded according to which receptive fields are activated (auditory coding is an exception to the location property because sensitive to different frequencies and timing). –> the homunculus

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29
Q

Lateral inhibition

A

Increases contrast between activated receptive fields and inactive neighbors

30
Q

Population Coding

A

–Multiple receptors functioning together to send the CNS more information than would be possible from a single receptor

31
Q

Stimulus property: Intensity

A

–Coded by number of receptors activated and frequency of action potentials (frequency coding)

-As a stimulus increases in intensity, additional receptors are activated; the CNS then translates the number of active receptors into a measure of stimulus intensity (the system can react appropriately)

32
Q

Frequency of action potentials

A

is proportional to stimulus intensity

33
Q

Duration of a series of action potentials is proportional to:

A

the stimulus duration

34
Q

Stimulus duration

A

Depends on the duration of the action potentials.

Affected by ADAPTATION

35
Q

Tonic receptors

A

slowly adapt to a sustained stimulus.

  • iritants
  • tactile
  • proprioceptors
  • barorecptors
36
Q

Phasic receptors

A

rapidly adapt to a sustained stimulus, and will shut off if the stimulus doesnt stop.

  • Allows body to ignore information that has been evaluated and found not to threaten homeostasis
  • Lets us focus on what is new, different or essential
  • Sense of smell
37
Q

Somatosensory pathway

A
  1. Pain, temperature and Coarse touch cross the midline in the spinal cord
  2. Fine touch, vibration, and proprioception cross the midline in the medulla
  3. All synapse in the thalamus
  4. Senses all percieved in the primary somatosensory region of the cortex–> recognizes where the sensation originated from (homunculus)
38
Q

Free nerve endings

A

are unmylenated nerve endings, located around hair roots and under surface of the skin. Respond to temperature, noxious movement and hair movement.

39
Q

Meissner’s corpuscles

A

these are in the superficial layers of skin, encapsulated in the connective tissue. Respond to flutter and stroking of skin. Have rapid adaption.

40
Q

Pacinian corpuscles

A

Receptors encapsulated in connective tissue in the deep layers of skin. Respond to vibration and have rapid adaptation.

41
Q

Ruffini corpuscles

A

Enlarged nerve endings in the deep layer of skin. Respond to the stretching of skin, and have a slow adaptation.

42
Q

Merkel receptors

A

Enlarged nerve endings in the superficial layers of skin. Respond to steady pressure and texture and have a slow adaptation.

43
Q

Temparature Receptors

A

Free nerve endings in the subcutaneous layers.

Cold receptors respond to temps below body temp

Hot receptors respond to temps above body temp, 45C.

Above 45C activates PAIN receptors.

44
Q

Noxious Receptors

A

Respond to things that may damage tissue. Are free nerve endings that are modulated by local chemicals- Substance P released in response to inflammatory pain.

Have reflexive properties (pull away reflex) in the brain.

Nociceptors are not found in the CNS.
•Activitation of nociceptor pathways initiates adaptve, protective repsonses

45
Q

Itch

A

From skin nociceptors
–Histamine activates C fibers, causing itch

46
Q

Pain

A

Subjective to perception
–Fast pain
–Sharp and localized—by Ab fibers (mylenated)
–Slow pain
–Duller and more diffuse—by C fibers (unmylenated)

In the absense of a stimulus from C fibers, there is an interneuron that inhibits the pain pathway. When pain is sensed, C fibers activate, and the interneuron is supressed.

pain can then be modulated by input from the Ab fibers

47
Q

inflammatory pain

A

increased sensitivity to pain at sites of tissue damage.

Local Chemicals:
–K+, histamine, prostaglandins released from damaged cells
–Serotonin released from activated platelets
–Substance P is secreted by primary sensory neurons

48
Q

Ischemia

A

•lack of adequate blood flow
Vs. Chronic pain, which is pathological pain.

49
Q

Analgesic drugs

A
  • Aspirin, less potenti
  • Opiods, more potent
    • Act directly on CNS opiod receptors
50
Q

Olfactory System

A

olfactory neurons in the olfacory epithelium of the nose activate CN I, which converges at the olfactory bulb–> olfactory tract–> olfactory cortex–> cerebral cortex and limbic system.

51
Q

Gustatory System

A

•Taste is a combination of five basic sensations: sweet, sour, salty, bitter, umami
•Taste cells are non-neural epithelium
•Each taste cell is sensitive to only one taste
•Taste transduction: gustducin
1.

52
Q

Sound Sensory Pathway

A
  1. sound waves hit TM and beceome vibrations
  2. the 3 bones of the middle ear vibrate
  3. the stapes, the last of the 3 bones, hits the oval window–> fluid waves in cochlea
  4. Hair cells bend and ion channels open in the cochlea, creates an electrical signal.
  5. AP fired at the cochlear nerve to the brain.

*Goes primarily to the cerebellum.

*High pitch percieved at stiffer region closer to the round window.

53
Q

Conductive hearing loss

A

–No transmission through either external or middle ear

54
Q

Central Hearing loss

A

–Damage to neural pathway between ear and cerebral cortex or damage to cortex itself

55
Q

Sensorineural hearing loss

A

–Damage to structures of inner ear

56
Q

Vestibular Apparatus

A

of the inner ear, responds to changes in the body’s position in space.

is a series of connected, fluid-filled chambers.

  • Otolith organs- linear accelleration and head position.
  • Semicircular canals- rotational accelleration.
57
Q

Crista

A

sensory receptors of the ear for rotational acceleration.

Movement of the endolymph pushes on the gelatinous cupula and activates the hair cells.

When the head turns right, endolymph pushes the cupula to the left.

58
Q

maculae

A

sensory receptors in the ear for linear acceleration and head position

59
Q

The Pupil

A
  • Size of the pupil modulates light that reaches photoreceptors
  • Pupillary reflex is a consensual reflex

–Standard part of neurological examination

60
Q

The Lens

A
  • A concave lens scatters light rays.
  • A convex lens causes light rays to converge.
  • The lens is flatter for distant objects, and becomes more round for closer objects.
  • Changes in lense shape controlled by the ciliary muscle, when relaxed, the lense is flat, and when contracted, the lense is round (contraction releases tension on the ligaments, allowing the lense to go loose)
61
Q

Focal length

A

the distance from the center of the lens to the focal point.

62
Q

Accommodation

A

•Process by which the eye adjusts lens shape to keep objects in focus

63
Q

Near point of accommodation

A
64
Q

Presbyopia

A

loss of accommodation

65
Q

Myopia

A

near-sightedness,
occurs when the focal point falls in front of the retina.

Gets corrected with a concave lens.

66
Q

Hyperopia

A

far-sightedness,
occurs when the focal point falls behind the retina

Corrected with a convex lens

67
Q

Astigmatism

A

•Usually caused by a cornea that is not a perfectly shaped dome, resulting in distorted images

68
Q

Phototransduction

A

Converts light energy into electrical signals

Photoreceptors- rods and cones and gaglion cells with melanopsin (changing light cues)

Most acute vision occurs at the fovea and macula
Optic disk has no photoreceptors and is called the blind spot

69
Q

Rods

A

function well in low light

Contain rhodopsin

70
Q

Cones

A

responsible for high-acuity vision and vision during the daytime
Contain three pigments –> Color-blindness

Pathophysiology (8 decks)

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