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Human Biology, 13th Edition - Sylvia S. Mader > Ch 14 - Senses > Flashcards

Ch 14 - Senses Flashcards

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1
Q

On a high level, how do sensory receptors convert stimuli into nerve impulses?

A

Sensory signals are converted to electrical signals via depolarization of sensory neuron membranes upon stimulus of the receptor, which causes opening of gated ion channels that cause the membrane potential to reach its threshold. This is what we refer to as an action potential.

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2
Q

What is sensory transduction?

A

When a sensory receptor converts some type of event, or stimulus, occurring in the environment into a nerve impulse.

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3
Q

What are exteroceptors?

A

Sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision, hearing and equilibrium.

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4
Q

What are interoceptors?

A

Sensory receptors that detect/receive stimuli from inside of the body, such as baroreceptors that respond to changes in blood pressure or chemoreceptors that monitor the pH of the blood (in the carotid arteries and aorta)

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5
Q

What are the sensory receptors (exteroreceptors), stimuli and receptor categories for the four senses?

  1. Taste
  2. Smell
  3. Vision
  4. Hearing
  5. Touch

What about rotational and gravitational equilibrium?

A
  1. Taste
    - taste cells
    - stimulus: chemicals
    - chemoreceptor
  2. Smell
    - olfactory cells
    - stimulus: chemicals
    - chemoreceptor
  3. Vision
    - rod/cone cells in retina
    - stimulus: light rays
    - photoreceptor
  4. Hearing
    - hair cells in spiral organ of inner ear
    - stimulus: sound waves
    - mechanoreceptor
  5. Touch
    - ?
    - stimulus: strong or slight pressure
    - mechanoreceptor
  6. Rotational equilibrium
    - hair cells in semicircular canals of the inner ear
    - stimulus: motion
    - mechanoreceptor
  7. Gravitational equilibrium
    - hair cells in vestibule of the inner ear
    - stimulus: gravity
    - mechanoreceptor
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6
Q

What are chemoreceptors?

A

Receptors that respond to chemical substances in the immediate vicinity. Taste and smell use these receptors.

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7
Q

What are nocireceptors?

A

Pain receptors (a type of chemoreceptor). Naked dendrites that respond to chemicals released by damaged tissues. They’re protective because they alert us of possible danger (i.e. appendicitis pain makes us aware of issue)

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8
Q

What are photoreceptors?

A

Receptors that respond to light energy and are sensitive to light rays, thus providing us with vision. Rod cells are a type of photoreceptor.

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9
Q

Which cell results in B&W vision and which results in colored vision?

A

Rod cells = black and white

Cone cells = colored

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10
Q

What are mechanoreceptors?

A

Receptors that are stimulated by mechanical forces (pressure). In hearing, sound waves are converted to fluid-borne pressure waves that can be detected by mechanoreceptors in the inner ear. These are found in the lungs, the heart, blood vessels, etc. to detect expansion of these structures.

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11
Q

What are two types of mechanoreceptors, and where are they found/used?

A

Baroreceptors = located in arteries to detect blood pressure changes

Stretch receptors = located in lungs to detect the degree of lung inflation

Proprioceptors = located in muscle fibers, tendons, joints and ligaments to make us aware of the position of our limbs

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12
Q

What are thermoreceptors?

A

Located in the hypothalamus and skin and are stimulated by changes in temperature. Respond to both heat and cold

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13
Q

How does sensation occur?

A

Sensory receptors respond to stimuli in the environment by generating nerve signals. When those signals reach the cerebral cortex, sensation, or the conscious perception of stimuli, occurs

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14
Q

What part of a cell, specifically a chemoreceptor cell, makes “reception” of a stimulus possible?

A

Receptor proteins in the plasma membrane of chemoreceptors bind to certain chemicals. When this happens, ion channels open, and ions flow across the plasma membrane. If the stimulus is significant, nerve signals begin and are carried by a sensory nerve fiber within the PNS to the CNS

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15
Q

Which parts of the brain allow us to perceive sound or sight?

A 
Sound = auditory cortex
Sight = visual cortex
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16
Q

What is integration, and when does this happen in relation to sensory receptors?

A

Integration is the summing up of signals, which happens before sensory receptors initiate nerve signals.

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17
Q

What is sensory adaptation?

A

A type of integration where there’s a decrease in response to a stimulus, as sensory receptors send fewer impulses to the brain. (i.e. when you walk into a room that has a strong odor, after a while you’re not aware of it anymore)

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18
Q

What are the somatic senses, and what are the three types of receptors?

A

Receptors that are associated with the skin, muscles, joints and viscera.

  1. Proprioceptors
  2. Cutaneous receptors
  3. Pain receptors (nociceptors)
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19
Q

What are proprioceptors?

A

Mechanoreceptors involved in reflex actions that maintain muscle tone, and thus the body’s equilibrium and posture.

Example: Muscle spindles (embedded in muscle fibers) are proprioceptors that stretch if a muscle relaxes too much, which generates a nerve impulse that causes the muscle to contract slightly.

If muscles are stretched too much:
Proprioceptors called Golgi tendon organs (buried in tendons) generate nerve impulses that cause the muscle to relax.

Also includes the knee-jerk reflex, which involves muscle spindles

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20
Q

What are cutaneous receptors?

A

Receptors in the dermis of the skin that make skin sensitive to touch, pressure, pain and temperature (warmth and cold). Giver specific information about the touch, such as location, shape, size and texture of what’s touching your skin.

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21
Q

What are some types of cutaneous receptors?

A
  1. Meissner corpuscles and Krause end bulbs
    - concentrated in the fingertips, palms, lips, tongue, nipples, penis, clitoris
    - sensitive to touch
  2. Merkel disks
    - where epidermis meets the dermis
    - sensitive to touch
  3. Root hair plexus
    - free nerve ending, found at base of hair follicle
    - sensitive to hair being touched
  4. Pacinian corpuscles and Ruffini endings
    - sensitive to pressure
  5. Temperature receptors
    - free nerve endings in the epidermis
    - cold receptors more numerous than warmth receptors, but no known structural differences
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22
Q

What is referred pain?

A

When stimulation of internal pain receptors (nociceptors) is felt as pain from the skin, as well as internal organs. For example, pain from the heart is often felt in the left shoulder and arm. This is because nerve impulses from internal organ pain receptors travel to the spinal cord and synapse with with neurons that are also receiving impulses from the skin

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23
Q

What are the “chemical” senses?

A

Taste and smell

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24
Q

What are chemoreceptors?

A

Plasma membrane receptors that bind to particular molecules. There are two types:
1. Those that respond to distant stimuli and
2. Those that respond to direct stimuli
Olfactory (smell) cells act from a distance and taste cells act directly

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25
Q

How many taste buds do adults have?

How many olfactory (smell) cells do we have?

A

4,000 taste buds

between 10 and 20 million olfactory cells

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26
Q

What are papillae?

A

The small elevations on the tongue

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27
Q

How many taste receptors do humans have, and what are they?

A 
Four. 
Sweet
Sour
Bitter
Umami (Jap. "Savory")
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28
Q

What foods have umami flavor?

A 
MSG
foods rich in certain amino acids
certain flavors of cheese
beef broth
some seafood
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29
Q

What is the anatomy of a taste bud?

A
  1. Connective tissue
  2. taste cell/supporting cell
  3. End in microvilli
  4. opens up at a taste pore
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30
Q

What percentage of taste is due to the sense of smell?

A

89-90%

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31
Q

What is the anatomy of an olfactory cell?

A

They’re modified neurons. Each cell ends in a tuft of about five olfactory cilia, which bear receptor proteins for odor molecules.

  1. Sensory nerve fiber starts in olfactory bulb where neurons are located.
  2. Sensory nerve fibers extend down through the skull
  3. Surrounded by supporting cells in the olfactory epithelium
  4. At very end/tip of nerve, olfactory cilia extends out to receive “smells”
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32
Q

Which lobe is the olfactory cortex located? What about the gustatory (taste) cortex?

A

The temporal lobe = Olfactory

The parietal lobe = taste

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33
Q

Why would the smell of a certain food remind you of a favorite vacation?

A

Because the olfactory bulbs have a direct connection with the limbic system and its centers for emotion and memory

34
Q

The number of olfactory cells declines with _____.

A

Age

35
Q

What are the three layers, or membranes, of the eye from outer to inner layer?

A

SCR:

  1. Sclera
  2. Choroid
  3. Retina
36
Q

What does the sclera contain, and what are their defining features or functions?

A
  1. Cornea = the “window” of the eye (transparent collagen fibers…very first outer layer of the eye
  2. Pupil = admits light into the eye
37
Q

What does the choroid contain, and what are their defining features or functions?

A
  1. Iris = our eye color; the donut-shaped iris that sits above the pupil, and regulates the size of the pupil (to moderate the amount of light that comes in)
  2. Ciliary body = extensive blood supply, and holds eye lens in place with tiny ligaments
38
Q

Why is the lens important for the eye?

A

Divides eye into two compartments. Anterior = in front of lens, posterior = behind the lens.

Anterior compartment filled w/ aqueous humor, a clear, watery fluid

39
Q

What is glaucoma?

A

Normally aqueous humor leaves the anterior compartment by way of tiny ducts. With glaucoma, these drainage ducts are blocked and aqueous humor builds up. The resulting pressure compresses the arteries that serve the nerve fibers of the retina, where photoreceptors are located. The nerve fibers begin to die because of lack of nutrients, and the person becomes partially blind. Total blindness can occur

40
Q

What does the retina contain, and what are their defining features or functions?

A

Located in the posterior compartment, which is filled with a clear gelatinous material called the vitreous humor

  1. Rod cells = black & white; very sensitive to light, and therefore, are suited to night vision. Carrots and other yellow veggies are rich in vitamin A, so improves night vision.
  2. Cone cells = color; sensitive to different wavelengths of light, which gives us the ability to distinguish colors
  3. Fovea centralis = cone cells are densely packed (doesn’t contain rod cells), thus the sharpest images are produced by the fovea centralis

Sensory fibers from the retina form the optic nerve, which takes nerve signals to the visual cortex

41
Q

What is vitreous humor and what does it do?

A

A clear gelatinous material located in the posterior compartment. Holds the retina in place and supports the lens.

42
Q

The cornea, assisted by the lens and humors, focuses images on the ____.

A

Retina

43
Q

What happens to the image on the retina? What happens to the image in the brain?

A

It’s inverted (upside down) and reversed from left to right. In the brain, the image is righted so we correctly perceive the visual field.

44
Q

What is visual accommodation?

A

When the lens changes its shape to bring the image into focus on the retina. Occurs for close vision.

45
Q

What part of the eye allows an image to be focused on the retina?

A

Whether ciliary muscles are contracted (focus on near object) or relaxed (focus on distant object)

46
Q

What does the optic nerve do?

A

Transmits impulses to the brain

47
Q

What is rhodopsin? What happens to it when a rod absorbs light?

A

A complex molecule made up of the protein opsin and a light-absorbing molecule called a retinal, a derivative of vitamin A. This is the visual pigment in rods, and is a deep purple pigment. When a rod absorbs light, rhodopsin splits into opsin and retinal, which leads to a cascade of reactions and the closure of ion channels in the rod cells’ plasma membranes.

48
Q

What different types of cones does color vision depend on?

A

BGR
Blue, green, red
Each of these pigments are also made of up retinal and opsin (like with the rod cells), but there’s a difference in the opsin structure of each.

49
Q

How many layers of neurons does the retina have, and what are they?

A

three layers of neurons.

  1. Outermost layer = rods/cones. First light rays penetrate to the back of the retina before the rods and cones are stimulated.
  2. Middle layer = bipolar cells. Integration starts here…
  3. Inner layer = ganglion cells. Integration continues here… The bipolar cells stimulate ganglions, whose axons become the OPTIC NERVE.

Additional integration occurs in the visual cortex

50
Q

How many rod, cone and ganglion cells are there in the retina?

A

rod cells = 150 million (activate many ganglions, as many as 150 rod cells per ganglion –> indistinct, blurred vision)

cone cells = 6.5 million (activate fewer ganglions, as little as one ganglion per cone cell –> sharper, detailed images)

ganglion cells = 1 million

51
Q

What is the blind spot?

A

There are no rods or cones where the optic nerve exits the retina, thus no vision is possible in this area

52
Q

What is the path from the optic nerve to the visual cortex?

A
  1. optic nerve
  2. optic chiasma (where optic nerve fibers cross)
  3. optic tracts
  4. thalamic nucleus (masses of neuron cell bodies)
  5. left/right visual cortex
53
Q

What is the most common visual mutation?

A

Mutation of the cones that causes inability to see the colors red and green. Males are more susceptible because color blindness is on the X chromosome. Affects 5-8% of male population

54
Q

What is nearsightedness?

A

When you can see objects better when they’re closer. When viewing distant objects, the rays focus in front of the retina instead of on the retina.

55
Q

What is farsightedness?

A

When you can see objects better when they’re far away. When viewing close-up objects, the rays focus behind the retina instead of on the retina.

56
Q

How do you correct nearsighted people who can’t see distant objects well?

A

A concave lens (lens caves inward like a crescent moon)

57
Q

How do you correct farsighted people who can’t see close-up objects well?

A

A convex lens (lens protrudes outward)

58
Q

What is astigmatism? How can it be “corrected?”

A

When the cornea is uneven, causing the rays to not focus evenly, creating a fuzzy image. Can be fixed with an uneven lens. LASIK surgery can also help.

59
Q

What is LASIK surgery?

A

Pulses of a laser that remove small amounts of corneal tissue, allowing the surgeon to flatten or increase the steepness of the curve of your cornea

60
Q

What are the two main functions of the ear?

A

Hearing and balance

61
Q

What is the anatomy of the ear?

A

See pg. 324.

There’s three divisions: outer, middle and inner.

62
Q

What does the outer ear consist of?

A

Pinna = external ear flap

Auditory canal = lined w/ fine hairs and sweat glands that produce earwax, which helps guard the ear from foreign invaders

63
Q

What does the middle ear consist of?

A

Contains air

Ear drum (aka tympanic membrane)

Two small openings that lead to different parts of the inner ear

  • oval window
  • round window

3 small bones called the “ossicles”

  • stapes (stirrup)
  • incus (anvil)
  • malleus (hammer)

Auditory tube

  • extends from middle ear to nasopharynx
  • equalizes pressure across ear drum
64
Q

What does the inner ear consist of?

A

Contains fluid.

Semicircular canals = contains mechanoreceptors for equilibrium;

Vestibule = contains mechanoreceptors for equilibrium;

Cochlea = contains mechanoreceptors for hearing; spirals like a snail shell. Oval window is connected to the cochlea

65
Q

How do sound waves travel?

A

By successive vibrations of molecules. A large number of waves strike the ear drum (tympanic membrane), casuing it to vibrate slightly. This causes vibrations of the ossicles (bones in middle ear: malleus, incus, stapes).

Magnitude of original pressure wave increases 20x the pressure. Finally, the stapes strikes the membrane of the oval window, causing it to vibrate. Thus, pressure is passed to fluid within the cochlea.

66
Q

Once pressure waves reach the vestibular canal of the cochlea, what happens next?

A

Pressure waves move across the basilar membrane into the tympanic canal. This vibration in the basilar membrane causes the steriocilia of the hair cells in the tectorial membrane to bend. Nerve signals beginning with the vibration of the hair cells travel through the cochlear nerve to the brain.

67
Q

How is pitch created?

A

Wave frequencies, or pitch depends on which part of the basilar membrane vibrates and which part of the auditory cortex is stimulated. The tip of the spiral organ responds to low pitches. The base responds to high pitches.

68
Q

What creates volume?

A

Volume is a function of amplitude (strength) of sound waves. Loud noises cause fluid within the vestibular canal (in the spiral organ) to exert more pressure on the basilar membrane, which vibrates to a greater extent.

69
Q

Noise levels over ___ decibels may cause permanent hearing loss.

A

85

70
Q

What is rotational equilibrium?

A

Rotational or angular movement of the head

71
Q

What is gravitational equilibrium?

A

Detect movement of the head in the vertical or horizontal planes

72
Q

What is the ampullae?

A

The base of the semicircular canals (there are 3 of them) that contains the cupula, which is a gelatinous material where hair cells reside.

73
Q

How is the ampullae used to detect when we’re out of rotational equilibrium?

A

When fluid within the semicircular canal flows over the cupula and displaces it, the sterocilia of the hair cells bend. This changes the pattern of signals carried by the vestibular nerve to the brain.

74
Q

Why do we get dizzy?

A

If we’re spinning, stereocilia send messages to our brain that we’re spinning.

Once we stop spinning, the slow-moving cupula continues moving in the direction of the spin, but our eyes tell our brain we’ve stopped. The mixed messages to our brains causes us to get dizzy.

75
Q

What are the main structures that help us detect gravitational equilibrium?

A

The utricle and saccule, two sacs located in different areas near the semicircular canals.

In these sacs, the gelatinous material is called “otolithic membrane” (remember in the ampullae this gelatin was called cupula). Hair cells & stereocilia are also located within this gelatinous sac.

Otoliths (particles of CaCO3, or calcium carbonate) float within this gelatinous material.

76
Q

How do we detect gravitational equilibrium?

A

When the otoliths are displaced as the head bends or when the body moves in the horizontal/vertical planes. The otolithic membrane sags to one side as the otoliths are displaced. This causes the hair cells/stereocilia to bend

77
Q

What is kinocilium, and why is it important?

A

Kinocilium is the largest stereocilium in the otolithic (gelatinous) membrane. As stereocilia move toward the kinocilium, nerve impulses increase in the vestibular nerve. The opposite occurs when stereocilia move away from the kinocilium.

78
Q

The frequency of nerve impulses in the vestibular nerve indicates whether you are moving ______.

A

up or down

79
Q

Where does “data” from the vestibular nerve go and why?

A

The cerebellum because that part of the brain is vital in maintaining balance and gravitational equilibrium. Then the cerebellum coordinates skeletal muscle contraction to correct our position in space if necessary.

80
Q

What role does the motor cortex play in equilibrium?

A

The motor cortex in the frontal lobe signals where the limbs should be located at any particular moment.

81
Q

How does motion sickness occur?

A

Continuous stimulation of the stereocilia, especially whe your eyes see that you’re not moving (if indoors on a boat), yet your inner ears are sending messages to your brain that you’re moving.

82
Q

How does Dramamine, an antihistamine, reduce motion sickness?

A

It reduces the excitability of the receptors in the inner ear, thus reducing impulses received by the cerebellum.

Human Biology, 13th Edition - Sylvia S. Mader (16 decks)

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