Nervous system 5

Question 1

special senses

Answer 1

smell, taste hearing, equilibrium, sight

Question 2

Smell

Answer 2

• employ chemoreceptors-called olfactory receptor cells.
• bipolar neurons with knows at end of dendrites (detect dissolved chemicals in gases)
• knobs covered with cilia that project into nasal cavity (10-12 cilia per olfactory receptor cell.
• closely related to taste (75% of flavor derived from sense of smell)

**sensory cortex

Question 3

Taste

Answer 3

• employ chemoreceptor
• taste buds special organs: contain taste cells-acts as receptors 50-150 per taste bud.
• detect chemicals dissolved in fluid (usually saliva)
• closely related to smell

Question 4

3 sections of ear

Answer 4

out, middle inner

Question 5

Outer ear (structures)

Answer 5

external structures to tympanic membrane, gathers and transmits sound vibrations to internal structures (pinna, auricle)

Question 6

Middle ear

Answer 6

• air filled cavity within the temporal been of the skull
• contains 3 auditory ossicles-bones articulate by synovial joints
  1. malleus
  2. incus
  3. stapes
• transmit and amplifies sound vibrations to inner ear

Question 7

inner ear

Answer 7

system of intercommunicating chambers

1. cochlea-functions in hearing
2. semicircular canals- functions in equilibrium(dynamic)
3. vestibule- functions in equilibrium(static)

Question 8

process of hearing

Answer 8

1. sound waves enter external ear -different sounds produce different pressure
2. sound pressures cause tympanic membrane to produce vibrations
3. auditory aussicles amplify and transmit vibrations to the cochlea
4. specialized receptor cells (hair cells) in the cochlea respond to different frequencies of vibrations.
5. hair cells respond by releasing neurotransmitters
6. neurotransmitters stimulate sensory neurons in cranial nerve VIII
7. impulses travel along cranial verve VIII to the auditory cortex in the temporal lobe for interpretation

Question 9

static equilibrium

Answer 9

vestibule- senses the position of head when body is not moving. Has specialized receptor cells (hair cells), bending of hairs results in generation of nerve impulses (action potential)
…travels down 8th cranial nerve to temporal lobe

Question 10

dynamic equilibrium

Answer 10

semicircular canals: senses rotation and movement of head and body, three canals at right angles (filled with fluid), has specialized receptor cells (hair cells) rapid turns of body will stimulate hair cells, bending of hairs results in generation of impulse (action potential)

Question 11

sight:

Answer 11

• function of visual receptors (photoreceptors)
• accessory organs- eyelids, lacrimal apparatus, extrinsic ocular muscles
• interpretation of visual stimuli-performed by visual cortex in occipital lobe

Question 12

Outer eye structure

Answer 12

• cornea anterior 1/6th transparent d/t lack of blood vessels, extremely regular pattern of CT fibers, helps focus entering light
• sclera - posterior 5/6ths, white portion of eye, protects eye, attachment site for extrinsic muscles

Question 13

Middle layer of eye:

Answer 13

ciliary body: has ciliary muscles & ciliary processes- suspensory ligaments off ciliary processes hold lens in place- contraction and relaxation of ciliary muscles change shape of lens

Iris: thin diaphragm of CT and smooth muscle

• color portion of eye determined by amnt of melanin
• pupil-center of opening, controls intensity(amnt) of light entering

Question 14

Inner layer of eye:

Answer 14

Retina: contains visual receptors (photoreceptors), continuous with optic nerve, dense capillary network.
Macula lutea- central region of retina, produces the sharpest vision
Optic disc- medial to macula lutea, nerve fibers leave eye and become part of Optic Nerve, does not contain receptor cells (BLIND SPOT)

Question 15

Visual receptors

Answer 15

Photoreceptors and modified neurons

1. rods
2. cones

Question 16

rods:

Answer 16

long thin projections at terminal ends, retina 100million, contain light sensitive visual pigments, much more sensitive to light than cones, produce colorless vision, determines dim vs. bright light. Much more important than cones!

Question 17

cones:

Answer 17

• short blunt projections at ends, retina 3 million, produce sharp images, responsible for color in vision, 3 sets of cones (based on color) Red, green, blue
• color perceived- depends on which set of cones light from image stimulates, overlap between sensitivities to certain colors
  1. orange- simulates red, green-red stim more
  2. white- all 3 stimulated
  3. black- none stimulated

those that lack one or more types of cones- colorblind (genetic), x-linked by mother

Question 18

Color

Answer 18

-when light is separated any single wavelength will produce a specific color impression to eye. What we see is “color effect”
-when an object is hit with light rays-object absorbs some and reflects others=> color effect
-daylight (white light) made up of numerous waves each having different wavelengths
ROYGBIV

Question 19

Visual acuity

20/20 what does each number mean

Answer 19

• snellen eye test, stand 20 ft away

- top: number of feet away, bottom: patient can read line a normal eye can read at 100ft.

Question 20

nearsightedness:
farsightedness:

Answer 20

myopia- can see near objects, not far

Hyperopia- can see far, but not near