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human physiology > senses > Flashcards

senses Flashcards

1
Q

what are sensations?

A

Sensations begin as different forms of energy that are detected by sensory receptors. This energy is converted to action potentials that travel to appropriate regions of the brain.

Sensations are action potentials that reach the brain via sensory neurons.

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2
Q

what are the different types of receptors?

A

-Exteroreceptors detect stimuli originating outside the body.

-Interoreceptors detect stimuli originating inside the body.

-Sensory receptors convey the energy of stimuli into membrane potentials and then transmit signals to the nervous system.

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3
Q

what are the steps to an impulse?

A

1) perception

2) amplification: strengthening of stimulus energy that is otherwise too weak to be detected by the nervous system

3) Transmission: conduction of sensory impulses to the CNS

4) Integration: processing of sensory information.

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4
Q
A
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5
Q

what is sensory adaptation?

A

sensory adaptation is a decrease in responsiveness to continued stimulation.

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6
Q

what are the sensory receptors based on the type of energy they transduce?

A

-Mechanoreceptors
-thermoreceptors

-general/specific/internal chemoreceptor

-photoreceptor
-pain receptors

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7
Q

what are mechanoreceptors?

A

respond to mechanical energy. Muscle spindles are an interoreceptor that respond to the stretching of skeletal muscle. Hair cells in the inner ear detect motion.

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8
Q

what are pain receptors?

A

receptors = nociceptors. Different types of pain receptors respond to different types of pain.
Prostaglandins increase pain by decreasing a pain receptor’s threshold.
Anti-inflammatories work by inhibiting prostaglandin synthesis.

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9
Q

what are thermoreceptors?

A

respond to heat or cold.

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10
Q

what are general chemoreceptors?

A

transmit information about total solute concentration ( chem stimuli).

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11
Q

what are the types of chemoreceptors?

A

General chemoreceptors transmit information about total solute concentration ( chem stimuli).
Specific chemoreceptors respond to specific types of molecules.
Internal chemoreceptors respond to glucose, O2, CO2, amino acids, etc.
External chemoreceptors are gustatory receptors and olfactory receptors.

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12
Q

what are photoreceptors?

A

Photoreceptors respond to the radiation we know as visible light.

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13
Q

what type of eyes do vertebrates have?

A

single-lens

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14
Q

where are 70 percent of sensory receptors?

A

70% of body’s sensory receptors are in eye
Half of cerebral cortex is involved in visual processing

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15
Q

what is sclera? what is the functions?

A

a tough white layer of connective tissue that covers all of the eyeball except the cornea.
- protects and shapes eyeball
- anchors extrinsic eye muscles
- posteriorly, where optic nerve exits, sclera is continuous with dura mater of brain

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16
Q

whats the conjunctiva?

A

external cover of the sclera
- transparent mucous membrane that produces a lubricating mucous secretion

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17
Q

what is cornea?

A

transparent covering of the front of the eye, allows for the passage of light into the eye and functions as a fixed lens.

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18
Q

what is the choroid?

A

thin, pigmented layer lining the interior surface of the sclera, prevents light rays from scattering and distorting the image.
- anteriorly it forms the iris.

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19
Q

what is the iris?

A

regulates the size of the pupil.

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20
Q

whats the retina?

A

lines the interior surface of the choroid.

  • contains photoreceptors, except at the optic disk (where the optic nerve attaches). This is also called the blind spot.
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21
Q

whats the ciliary body?

A
  • Anteriorly, choroid becomes ciliary body
  • Thickened ring of tissue surrounding lens
  • Consists of smooth muscle bundles, ciliary muscles, that control shape of lens
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22
Q

whats in the anterior cavity of the eye?

A

Anterior cavity is filled with aqueous humor produced by the ciliary body.

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23
Q

how does a glaucoma happen?

A

Glaucoma results when the duct that drains aqueous humor is blocked.

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24
Q

what is the posterior cavity filled with?

A

Posterior cavity is filled with vitreous humor.

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25
Q

what does the iris do?

A

colored part of eye that lies between cornea and lens, continuous with ciliary body

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26
Q

what does the pupil do?

A

central opening that regulates amount of light entering eye

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27
Q

what plays a role in focusing light onto the retina?

A

The lens, the aqueous humor, and the vitreous humor all play a role in focusing light onto the retina.

28
Q

what is accommodation?

A

Accommodation is the focusing of light in the retina, accomplished by changing the shape of the lens.

29
Q

when is the lens flattened?

A

The lens is flattened for focusing on distant objects

30
Q

when is the lends rounded?

A

The lens is rounded for focusing on near objects.

31
Q

what type of receptors are on the retina?

A

photoreceptors

32
Q

what are the types of photoreceptors on the retina? what do they do?

A

1) About 125 million rod cells.
Rod cells are light sensitive but do not distinguish colors. These enable us to see at night but only in black and white.

2) About 6 million cone cells.
Not as light sensitive as rods but provide color vision. These are most highly concentrated on the fovea – an area of the retina that lacks rods.

33
Q

what is rhodopsin?

A

The light-absorbing pigment rhodopsin triggers a signal-transduction pathway. it is the visual pigment of rods

34
Q

what is the visual pathway?

A

1) light causes the conversion of cis-retinal to trans-retinal, activating rhodopsin

2) the activated rhodopsin activates a G protein called transducin

3) transducin activates a phosphodiesterase

4) the activated phosphodiesterase detaches the cGMP from the Na+ channels in the membrane by hydrolyzing cGMP to GMP

5) this causes the Na+ channels to close. The permeability of the membrane to sodium decreases and the rod hyperpolarizes 

35
Q

what does the rhodopsin mechanism detect? (rod system)

A

light

36
Q

what are the three subclasses of cone cells?

A

three subclasses of cone cells each with its own type of photopsin.

37
Q

what is the color perception based on?

A
  • Color perception is based on the brain’s analysis of the relative responses of each type of cone
38
Q

what is colourblindness due to?

A

colorblindness is due to a deficiency, or absence, of one or more photopsins- Inherited as an X-linked trait

39
Q

what makes the optic tract?

A
  • Ganglion cell axons make up the optic tract.
40
Q

how does visual information get conveyed to the primary visual cortex?

A
  • Ganglion cell axons make up the optic tract.
  • most synapse in the lateral geniculate nuclei of the thalamus
  • neurons then convey information to the primary visual cortex of the optic lobe.
41
Q

where is the mammalian hearing organ?

A

within the ear

42
Q

what does the outer ear include?

A

The outer ear includes the external pinna and the auditory canal

43
Q

what does the outer ear do?

A

Collects sound waves and channels them to the tympanic membrane

44
Q

what happens after the tympanic membrane?

A

transmitted through the middle ear:
Malleus to incus to stapes

45
Q

what happens after the stapes?

A

From the stapes the sound wave is transmitted to the oval window and on to the inner ear.

46
Q

what is the Eustachian tube?

A

Eustachian tube connects the middle ear with the pharynx.

47
Q

what does the inner ear consist of?

A

The inner ear consists of a labyrinth of channels housed within the temporal bone.
The cochlea is the part of the inner ear concerned with hearing.
Structurally it consists of the upper vestibular canal and the lower tympanic canal, which are separated by the cochlear duct.
The vestibular and tympanic canals are filled with perilymph.

48
Q

what are the vestibular and tympanic canals filled with?

A

perilymph

49
Q

what is the chochlear duct filled with?

A

endolymph

50
Q

what does the organ of corti rest on?

A

The organ of Corti rests on the basilar membrane.

51
Q

where is the tectorial membrane?

A

The tectorial membrane rests atop the hair cells of the organ of Corti

52
Q

whats the function of the round window?

A

The round window functions to dissipate the vibrations

53
Q

what happens when there’s a vibration in the cochlear fluid?

A

Vibrations in the cochlear fluid  basilar membrane vibrates  hair cells brush against the tectorial membrane  generation of an action potential in a sensory neuron.

54
Q

how do hair cells in the ear release action potentials?

A

Energy in the sound waves causes the basilar membrane to vibrate, stimulating hair cells. There are changes in the stiffness of the basilar membrane along its length, and so each point on the membrane vibrates maximally in response to waves of a particular frequency.

The hair cells release an excitatory neurotransmitter at a synaplse with a sensory neuron. This conducts and action potential to the CNS. Bending in one direction will depolarize the hair cell, releasing more neurotransmitter and increasing the frequency of action potentials. Bending in the other direction will have the opposite effect.

55
Q

what is the pitch based on?

A

Pitch is based on the location of the hair cells that depolarize.

56
Q

what is volume based on?

A

Volume is determined by the amplitude of the sound wave.

57
Q

true or false, perception of taste and smell are interrelated?

A

true

58
Q

where are taste receptors located?

A

In mammals, taste receptors are located in taste buds most of which are on the surface of the tongue.

59
Q

what determines somethings perceived flavour?

A

It is the pattern of taste receptor response that determines something’s perceived flavor.

60
Q

what are the five basic taste sensations?

A

1) Sweet: sugars, saccharin, alcohol, some amino acids, some lead salts
2) Sour: hydrogen ions in solution
3) Salty: metal ions (inorganic salts); sodium chloride tastes saltiest
4) Bitter: alkaloids such as quinine and nicotine, caffeine, and nonalkaloids such as aspirin
5) Umami: amino acids glutamate and aspartate; example: beef (meat) or cheese taste, and monosodium glutamate
6) Possible sixth taste: Growing evidence humans can taste long-chain fatty acids from lipids

61
Q

how is taste linked the homeostatic value?

A

Guide intake of beneficial and potentially harmful substances
Dislike for sourness and bitterness is a protective way of warning us if something is spoiled or poisonous

62
Q

how do taste receptors get activated?

A
  • Binding of food chemical (tastant) depolarizes cell membrane of gustatory epithelial cell membrane, causing release of neurotransmitter
  • Neurotransmitter binds to dendrite of sensory neuron and initiates a generator potential that lead to action potentials
  • Different gustatory cells have different thresholds for activation
  • Bitter receptors are most sensitive
  • All adapt in 3–5 seconds, with complete adaptation in 1–5 minutes
63
Q

what are the important roles of taste?

A

Triggering reflexes involved in digestion, such as:
Increased secretion of saliva into mouth
Increased secretion of gastric juice into stomach
May initiate protective reactions, such as:
Gagging
Reflexive vomiting

64
Q

where are olfactory receptors?

A

In mammals, olfactory receptors line the upper portion of the nasal cavity

65
Q

what does the binding of odour molecules do?

A

The binding of odor molecules to olfactory receptors initiate signal transduction pathways involving a G-protein-signaling pathway and, often, adenylyl cyclase and cyclic AMP

66
Q

what do odorant molecules do?

A

Odorant molecules bind to specific chemoreceptors in the plasma membrane of the olfactory receptor cells, causing an action potential. Each olfactory receptor has just one type of chemoreceptor. Cells with different chemoreceptors detect different odorants.

human physiology (10 decks)

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