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Anatomy and physiology > Nervous system Part 3 > Flashcards

Nervous system Part 3 Flashcards

1
Q

Outer layer of eye

A

Consists of the sclera and cornea

posterior potion is know as sclera -the “white of the eye”

anterior potion is the cornea and it is the transparent part of the eye where light enters

aqueous humor fills the space between the cornea and lens

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2
Q

Middle layer of the eye

A

Choriod, ciliary muscle, and iris

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3
Q

choroid

A

darkly colored posterior choroid prevents light from dispersing throughout the eye

choroid is highly vascular and supplies blood to the other layers of the eye

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4
Q

ciliary muscle

A

ciliary body changes the shape of the lens allowing it to focus

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5
Q

iris

A

anterior to the ciliary body and contains the circular colored portion of the eye

it controls the amount of light that is let in to the pupil - a hole in the center of the iris

the iris uses its muscle fibers to contract or dilate based on the amount of light in the environment.

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6
Q

retina

A

The inner sensory layers include the retina which has two types of photoreceptors that are sensitive to light.

Rods and cones

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7
Q

rods

A

stimulated by dim light.

Rods are more sensitive to light but do not generate sharp or color images

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8
Q

cones

A

operate in bright light, helping to generate bright, sharp images

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9
Q

lens

A

located posterior to the iris and the pupil

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10
Q

vitreous body

A

the interior of the eye posterior to the lens is called the vitreous body and is filled with vitreous fluid - this helps hold the retina firmly to the choroid.

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11
Q

Vision pathway from environment to the brain

A

cornea
aqueous humor
lens
vitreous humor
posterior surface of retina
photoreceptors detect light
optic nerve
optic chasm
optic tracts
LNG of the thalmus
optic radiations
occipital lobe
interrupted as vision

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12
Q

optic nerve, optic chiasm, optic tracts, LGN, optic radiations,

A

photoreceptors in the retina send a signal through the optic nerve on to the optic chiasm located in the hypothalamus.

the medial fibers of the optic nerve then cross to the other side when they reach the optic chiasm where the optic tracts are formed.

optic tracts terminate in the thalamus in the lateral geniculate nucleus (LNG)

The info continues from the thalamus through the optic radiations to the primary visual area of the occipital lobe

Last it is interpreted as vision in the occipital lobe

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13
Q

nasal visual field

A

the visual field closest to the nose

each eye receives information from the left and right eye

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14
Q

peripheral vision field

A

field of vision on the lateral side of each eye

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15
Q

binocular vision field

A

overlapping information in the nasal fields allows for 3-D vision called binocular visual field

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16
Q

Each eye has a left and right visual field

A

Sensory info from the left side of the body (bilateral left visual fields) will eventually be interpreted by the right side of the brain and is reversed for the right visual fields

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17
Q

what fibers cross at the optic chiasm?

A

only the medial fibers

the information from each retina is carried through the optic nerves to the optic tract

the left side of the brain receives info from the medial side of the left eye and the lateral side of the right eye (bilateral right visual fields)

the situation is reversed for the right side of the brain - with the right side of the brain receiving information for the bilateral left visual fields

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18
Q

six muscles of the eye

A

medial rectus, inferior rectus, superior rectus, inferior oblique, superior oblique, lateral rectus

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19
Q

medial rectus

A

turns the eye medially. CN III

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20
Q

inferior rectus

A

moves the eye medially and depresses it. CN III

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21
Q

superior rectus

A

moves the eye medially and elevates it. CN III

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22
Q

inferior oblique

A

is responsible for eye elevation, lateral movement and external rotation. CN III

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23
Q

superior oblique

A

controlled by the 4th cranial nerve - trochlear nerve

responsible for eye depression, lateral movement, and internal rotation

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24
Q

lateral rectus

A

controlled by the 6th cranial nerve, abducens, and turns the eye laterally

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25
Q

cataracts

A

lens that slowly become hardened and cloudy over time - makes vision appear more blurry because light is unable to enter the lens clearly to be refracted onto the retina.

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26
Q

CVA or brain damage and vision

A

damage from a stroke or brain tumor can also cause vision impairments. For example is the right optic nerve is damaged, the right eye will be unable to see.

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27
Q

cranial nerve damage

A

many cranial nerves supply the muscles to move the eye.

Damage to the abducens nerve causes diplopia, or double vision.

28
Q

how to test for diplopia

A

one way to test for abducen nerve damage is to have a person look left and hold their head still

if the lateral rectus does not receive nervous signals from the abducen nerve, the eye us unable to rotate laterally when looking at the same side

the effected eye deviates medially when looking forward because of the imbalance in muscle tone between the medial and lateral recti.

29
Q

divisions of the ear

A

external, middle, and inner ears

30
Q

external ear

A

consists of the auricle and the external canal (meatus)

auricle- is shaped to funnel sound waves into the acoustic canal so that sounds can be detected. part of the ear that can be seen externally

31
Q

what is the auricle made of?

A

part of the ear that can be seen externally -composed of elastic cartilage covered with thin skin making up the rim (helix) and the lobule (that lacks cartilage)

32
Q

external acoustic meatus

A

the tunnel between the auricle and tympanic membrane

composed of elastic cartilage near the auricle and becomes a cylinder through the temporal bone

canal is lined with skin containing hairs and glands that secrete cerumen (earwax) which traps foreign particles

inner end of canal terminates at tympanic membrane

33
Q

tympanic membrane

A

eardrum

a thin membrane of connective tissue whose vibration transmits sound into the middle ear

34
Q

middle ear

A

or tympanic cavity

air filled chamber containing the three smallest bones in the body- the stapes (stirrup), incus (anvil), and malleous (hammer)

the malleous receives vibrations from the eardrum and transfers them along through the incus and then finally the stapes, which conveys them to the inner ear

35
Q

inner ear

A

composed of the bony and membraneous labyrinths filled with fluid

bony labyrinths divided into three sections. the vestibule, semicircular canals, cochlea

36
Q

vestibule

A

connects to three semicircular canals, which house receptors to provide the body’s vestibular (equilibrium and balance) systems

37
Q

semicircular canals

A

also filled with fluid. each semicircular canal contains equilibrium receptors, which cause action potentials in response to different types of motion (head movements or rotation).

action potentials sent through the vestibular portion of CN VIII (vestibular cochlear nerve)

38
Q

vestibular sense

A

the semicircular canals contribute to the body’s vestibular sense (balance and upright orientation

39
Q

CN VII and the ear

A

CN VII is also located in the inner ear region

the facial innervates a muscle called stapedius, which is attached to the stapes

the stapedius controls the amount of tension on the bone, allowing for increased or decreased vibration to help control the intensity of sound

40
Q

cochlea

A

a spiral, bony chamber containing the membraneous endolymph-filled cochlear duct.

the cochlea houses the organ corti and terminated in the cochlear nerve

41
Q

The organ of corti

A

the sense organ in the auditory system

contains the tectorial membrane and tiny hairs called sterocillia

as fluid within the cochlear ducts receive vibrations, the tectorial membrane moves and bends the stereocillia

this mechanical movement of stereocilla initiates an action potential in neurons that is transmitted through the cochlear nerve portion of CN VIII

42
Q

What happens with the mechanical movement of stereocilla?

A

the mechanical movement of stereocillia initiates an action potential in the neurons that is trnamistted through the cochlear nerve portion of CN VIII

43
Q

What is the process of hearing (events)?

A

First sounds waves are funneled into the external auditory canal causing the eardrum to vibrate

The vibrations transmit to the ossicles which push against the fluid inside the cochlear ear duct

The movement of the fluid causes movement of the stereocillia in the organ of Corti

The movement of the sterocillia then stimulates the neurons to send impulses through the cochlear nerve to the primary audiroty cortex of the temporal lobe

44
Q

How is the auditory pathway unique?

A

the auditory pathway is a unique sensory pathway because the ascending pathways cross in addition to sending signals to the same side of the brain.

the result is the sounds from each ear are equally interpreted on the left and right sides of the brain.

45
Q

deafness

A

damage to the auditory pathways results in hearing loss called deafness

deafness can be partial (if hearing is impaired but not completely lost or total

46
Q

conduction deafness

A

occurs from damage to the outer or middle ear structures.

for example, build up of cerumen (earwax) can partially block sound waves entering the external acoustic meatus.

another cause of conduction deafness is if the ossicle bones fuse, decreasing the amount of vibrations transmitted to the inner ear

**This type of deafness is NOT complete because sound waves can be conducted through the cranial bones to move to the organ of Corti.

47
Q

Nerve deafness

A

occurs when there is damage to the nerve pathway

damage can occur to the receptor cells to the cochlear nerve that transmits the nerve impulses to the brain

Nerve deafness can be complete or partial in one or both ears depending on the amount of damage to the nerve pathway

48
Q

olfaction

A

special sense of smell -chemical

olfactory receptors are activated by airborne chemical substances dissolved in fluid on the surface of the nasal mucus membrane

49
Q

olfactory nerves

A

CN 1 are bipolar receptor cells found in the olfactory epithelium on the roof of the nasal cavity

**The olfactory nerves travel through the ethmoid bone in a location called the CRIBRIFORM PLATE

dendrites extend from the cell body to the surface of epithelium where it terminates in the olfactory bulbs.

50
Q

olfactory bulbs

A

paired masses of gray matter

this is where dendrites extend from the cell body to the surface of epithelium where it terminates in the olfactory bulbs

In the olfactory bulbs, olfactory nerve axons synapse with other cell bodies of the olfactory pathway

The axons then travel together from the olfactory bulbs to form the olfactory tracts.

51
Q

olfactory tracts

A

carry information to the temporal lobes where they get interpreted in the primary olfaction area as smell

52
Q

gustatory system

A

is responsible for special sense of taste.

Taste is a chemical sense because its receptors are activated by chemical substances dissolved in saliva

These receptors are mainly in tastebuds on the tongue, but also throughout the mouth and throat

53
Q

Taste buds

A

contain chemical receptors that are stimulated by the chemical composition of food

primarily found on the tongue, as well as the surface of the mouth and wall of the pharynx.

tastebuds are formed by gustatory cells and supporting cells

54
Q

gustatory cells

A

are the chemoreceptor cells inside the tastebuds

each gustatory cell terminates in a gustatory hair, which projects into saliva to detect dissolved chemicals

55
Q

supporting cells

A

form the bulk of the tastebud and separate the taste receptor cells from one another

56
Q

basal cells

A

these are stem cells that divide and differentiate into new supporting cells that then form new gustatory cells

57
Q

nocireceptors

A

detect pain

58
Q

thermoreceptors

A

detect hot and cold and can contribute to the taste experience of food.

59
Q

Spice and temperature

A

both of these impact how we perceive taste by the brain

60
Q

Taste pathway

A

Starts when food chemicals come into contact with gustatory hairs

This generates an action potential in dendrites that are wrapped around gustatory cells

the nerve impulse is carried by afferent fibers through cranial nerves (the facial and glossopharyngeal nerve)

these transmit the impulse to the thalamus and then the parietal lobe to be interpreted as taste.

61
Q

Facial nerve and glossopharyngeal

A

facial nerve carries info from the anterior 2/3 of tongue and the glossopharyngeal nerve carries info from the posterior 1/3 part of the tongue

62
Q

5 primary tastes

A

sweet- produced by many compounds including sugar and some amino acids

salty-many metal salts like NaCl

sour-acids like acetic acid/vinegar

bitter -produced by many drugs like aspirin

savory (umami)-due to certain amino acids and found in foods like fish, ripe tomatoes, aged cheeses, and soy sauce

63
Q

Anosomia

A

loss of smell

common to have after a traumatic brain injury - can be temporary or permanent depending on the severity of the injury or what part of the pathway was damaged

Can happen gradually such as in the case of a growing brain tumor that blocks the olfactory pathway

64
Q

Ageusia

A

loss of sensation of taste

stimulation to olfactory receptors has a great affect on sense of taste in addition to taste bud stimulation

when olfactory receptors are obstructed by nasal congestion or other factors - the sensation of taste is dulled or completely lost

TBI can also cause ageusia if a taste pathway is damaged.

65
Q

What is smell

A

smell is defined as a combination of a limited number of primary odors that are detectable by the brain

Anatomy and physiology (15 decks)

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