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Physiology (MPP 3202) > Ch. 10 Sensory Physiology > Flashcards

Ch. 10 Sensory Physiology Flashcards

1
Q

Sensory Receptors

A

Transduce (convert energy into a different form) different forms of energy in the “real world” to nerve impulses.

Different modalities of sensations (sound, light, pressure) arise from differences in neural pathways and synaptic connections
–ex: If the optic nerve delivers an impulse, the brain interprets it as light even though the impulse is the same as for hearing

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2
Q

Functional Sensory Receptors: Chemoreceptors

A

Sense chemicals in the environment (taste, smell) or blood

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3
Q

Functional Sensory Receptors: Photoreceptors

A

Sense light

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4
Q

Functional Sensory Receptors: Thermoreceptors

A

Respond to cold or heat

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5
Q

Functional Sensory Receptors: Mechanoreceptors

A

Stimulated by mechanical deformation of the receptor (touch, hearing)

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6
Q

Information Sensory Receptors: Proprioceptors

A

Found in muscles, tendons, and joints. Provide a sense of body position and allows fine muscle control

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7
Q

Information Sensory Receptors: Cutaneous (skin)

A

Touch, pressure, heat, cold, and pain

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8
Q

Information Sensory Receptors: Special Senses

A

Vision, hearing, taste, smell, equilibrium

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9
Q

What are the 2 origins of sensory receptors?

A

Exteroceptors and Interoceptors

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10
Q

Exteroceptors

A

Respond to stimuli from outside the body; includes cutaneous receptors and special senses

Vision, hearing, taste, smell

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11
Q

Interoceptors

A

Respond to internal stimuli; found in organs; monitor BP, pH, and oxygen concentrations

Cardiovascular system: sense BP

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12
Q

Phasic

A

Respond w/ a burst of activity when stimulus is first applied but quickly adapt to the stimulus by decreasing response
–sense something and fire response/signal

Allow sensory adaptation - cease to pay attention to constant stimuli
–ex: live near airport hearing constant noise –> adaptation and it becomes background activity

Ex: smell, touch, temperature

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13
Q

Tonic

A

Maintain a high firing rate as long as the stimulus is applied

Ex: pain

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14
Q

Phasic Receptor

A

Fast-adapting

Fire less frequently –> consistency of signal

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15
Q

Tonic Receptor

A

Slow-adapting

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16
Q

What is the only special sense that bypasses the Thalamus?

A

Olfaction (smell)

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17
Q

Describe Olfaction’s Sensory Pathway

A

Olfaction goes from nose to Olfactory cortex, not relayed through Thalamus

Directly process smell, all other senses relayed through Thalamus to be processed and sent to where it needs to go

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18
Q

What are the 2 types of Chemoreceptors?

A

Taste (gustation)

Smell (olfaction)

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19
Q

Taste (gustation)

A

Responds to chemicals dissolved in food and drink

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20
Q

Smell (olfaction)

A

Responds to chemical molecules from the air; olfaction influences gustation

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21
Q

Gustation

A

Receptors are called taste buds - consist of 50 to 100 specialized epithelial cells w/ long microvilli that extend out through the pore in the taste bud

  • -each taste bud has taste cell sensitive to each category of 5 tastes: salty, sour, sweet, umami (meaty), bitter
  • -microvilli come into contact w/ chemicals
  • -cells behave like neurons by depolarizing and producing action potentials
  • -cells release neurotransmitters onto sensory neurons
22
Q

Olfactory Receptors

A

Bipolar neurons w/ ciliated dendrites projecting into nasal cavity

Proteins in the cilia bind to odors

~380 genes code for ~380 different olfactory receptors

One odorant molecule stimulates one protein

23
Q

Vestibular Apparatus

A

Provides sense of equilibrium

Located in inner ear

Consists of:

  • Otolith organs
  • ->Utricle and Saccule - linear acceleration (ex: running toward door)
  • Semicircular canals - rotational acceleration (ex: rotating body)
24
Q

Inner Ear

A

Consists of a body labyrinth surrounding a membranous labyrinth

Between the 2 is fluid called Perilymph

W/in the membranous labyrinth is fluid calls Endolymph, which has an unusually high K+ concentration, which will produce depolarization

25
Q

Why is the Perilymph important?

A

The multiple layers of membrane and fluid allow us to detect subtle movements

This wouldn’t be possible if the membrane was against bone w/o fluid

26
Q

Sensory Hair Cells

A

Modified epithelial cells w/ 20-50 hairlike extensions called Stereocilia (not true cilia) and one Kinocilium (true cilium)

When the stereocilia bend toward the kinocilium, K+ channels and K+ rushes into the cell and depolarizes the cell
–K+ concentration high on outside of cell, so when channels open it rushes in and depolarizes cell

Cells release a neurotransmitter that depolarizes sensory dendrites in vestibulocochlear nerve

27
Q

Which has more structural support: stereocilia or microvilli?

A

Stereocilia

28
Q

What causes the stereocilia to move?

A

Fluid moving causes stereocilia to bend (won’t bend w/o fluid movement)

29
Q

What is the tympanic membrane?

A

The eardrum

30
Q

Which part of the ear (outer, middle, or inner) is the fluid filled cavity?

A

The inner ear

31
Q

Middle Ear

A

Air-filled cavity between Tympanic Membrane and Cochlea

Contains 3 bones called Ossicles:
-Malleus, Incus, Stapes

Vibrations are transmitted and amplified along the bones

The stapes is attached to the Oval Window, which transfers the vibrations into the cochlea

32
Q

What is the purpose of the 3 ossicles (malleus, incus, stapes)?

A

Transmit sound waves that passed through tympanic membrane to the cochlea via the oval window

33
Q

Cochlea

A

Hearing part of inner ear

3 chambers:

  • -upper chamber is portion of bony labyrinth called Scala Vestibule (Perilymph)
  • -lower bony chamber called Scala Tympani (Perilymph)
  • -cochlea also contains a membranous labyrinth called Cochlear Duct (Scala Media) filled w/ Endolymph
34
Q

What’s special about Endolymph?

A

There’s a high K+ concentration outside of the cell; contains stereocilia

35
Q

How does the ear prevent echoing?

A

Sound waves are dissipated back into the middle ear from the inner ear at the Round Window

36
Q

Is the Cochlea fluid filled?

A

Yes (part of inner ear)

37
Q

Hearing: Mechanism

A

When sound waves enter the scala media, the tectorial membrane vibrates, bending stereocilia in the hair cells of the Organ of Corti.

  • -opens K+ channels that are facing endolymph
  • -K+ rushes in, depolarizing cell (b/c it’s high concentration on outside)
  • -releases glutamate onto sensory neurons
  • -K+ returns to perilymph at base of stereocilia
38
Q

Hearing: Neural Pathways

A

Sensory neurons in inner ear –> integrated in Thalamus –> auditory cortex

39
Q

Vision

A

Comes from light energy transduced into nerve impulses

Only a limited part of the electromagnetic spectrum can excite photoreceptors

40
Q

Where is the blind spot in the eye?

A

At the optic disc

41
Q

Is the eye highly vascularized?

A

Yes

42
Q

Path of Light (I’m sorry, but you need to know this)

A
  1. Light passes through cornea and into anterior chamber of eye
  2. Passes through pupil, which can change shape (due to pigmented iris muscle) to allow more/less light in
  3. Passes through lens, which can change shape to focus image
  4. Passes through posterior chamber and the vitreous body
  5. Finally, it hits the retina, where photoreceptors are found and then absorbed by the pigmented choroid layer
43
Q

Pupil and Iris

A

Iris can increase or decrease the diameter of the pupil

  • Constriction: contraction of circular muscles via parasympathetic stimulation
  • Dilation: contraction of radial muscles via sympathetic stimulation

Iris also has pigmented epithelium for eye color

44
Q

Lens

A

Composed of layers of living cells that are normally completely clear (must be transparent to do its job)

Avascular

Cell metabolism is anaerobic (lens is a group of cells!)

Attached to muscles called Ciliary Bodies

Suspended from Suspensory Ligaments

45
Q

Visual Fields

A

Part of the external world projected onto the retina

Right side is projected onto the left side of retina

Left side is projected onto right side of retina

(see ch. 10 p. 36 notes for a good picture of how this works)

46
Q

Lens Accommodation

A

Accommodation is the ability of the lens to keep an object focused on the retina as the distance between the eye and the object moves

Contraction of the ciliary muscle causes the lens to thicken and roundup (close vision)

Relaxation of the ciliary muscle causes the lens to thin and flatten (distant vision)

47
Q

Retina

A

Extension of the brain, so the neural layers face outward toward incoming light (have to face outward in order to receive light)

Neuron axons in retina are gathered at a point called the Optic Disc (blind spot) and exit as the Optic Nerve; blood vessels also enter/leave here

Photoreceptors (rods and cones) are in the inner layer (toward vitreous body)

These synapse on a middle layer of bipolar cells, which synapse on the outer layer of ganglion cells

There are also horizontal cells and amacrine cells w/in the layers

48
Q

Rods and Cones: Outer and Inner Segments

A

Outer segment: full of flattened discs with photopigment molecules

Inner segment: contains the cell organelles

49
Q

Rods

A

Black and white vision in low light; contain rhodopsin

50
Q

Cones

A

Color vision and acuity, contain photopsin which vary depending upon cone

51
Q

Vision: Mechanism

A

Stimulation of photoreceptor cells is outlier

Stimulation results in hyperpolarization (instead of depolarization)

Bipolar cells activate ganglion cells that transmit action potentials to brain

Physiology (MPP 3202) (32 decks)

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