3.5 Sensation modalities

Question 1

sensation versus perception

Answer 1

sensation - receiving information

perception - organizing, assimilating, and interpreting sensory input

Question 2

2 types of sensory receptors

Answer 2

exteroceptor - respond to external stimuli

interoceptors - internal stimuli

Question 3

mechanoreceptor

Answer 3

mechanical disturbances

• ex. Pacinian corpuscles - pressure sensors in the skin, 1 of 4 mechanoreceptors in the skin
• send graded potential changes
• ex. Auditory hair cell - detects sound wave vibrations
• autonomic mechanoreceptor -> detection of stretching of intestinal walls

Question 4

chemoreceptor

Answer 4

ex. olfactory, gustatory

- chemoreceptors in the walls of carotid and aortic arteries detect pH, PCO2, PO2

Question 5

nociceptor

Answer 5

pain receptors

• a kind of chemoreceptor, detects chemical signs of damage
• autonomic pain receptors are not clear, but give sensation of dull or aching pain

Question 6

“referred pain”

Answer 6

when nociceptors cross paths with somatic afferents from the skin

Question 7

thermoreceptors

Answer 7

autonomic and somatic

1. cold-sensitive
2. warm-sensitive
3. thermal nociceptors

Question 8

electromagnetic receptors

Answer 8

induced by electromagnetic waves

- rod and cone of the retina of the eye (photoreceptors)

Question 9

sensory stimuli has 4 properties

Answer 9

1. stimulus modality - type of receptor
2. stimulus location - localized by overlapping receptive fields
3. intensity - frequency of APs; dynamic range (or range of intensities) can be expanded by “range fractionation” - multiple groups of receptors with limited ranges to detect a wider range of stimuli
4. duration

Question 10

sensory stimulus — duration

Answer 10

tonic -> fires AP as long as stimulus continues; adaptation -> frequency of APs decreases as stimulus continues at same level; phasic receptors -> fire APs when the stimulus begins, but don’t communicate the duration of the stimulus

Question 11

nerves are trained to respond to

Answer 11

CHANGING stimuli; see adaptation

exception: nociceptors

Question 12

proprioceptors

Answer 12

awareness of the self - body position, the kinesthetic sense

ex. muscle spindle - mechanoreceptor - detects muscle stretch
ex. Golgi tendon organs - tension in tendons

joint capsule receptors - detect pressure, tension and movement in joints

Question 13

five taste buds

Answer 13

1. salty, sweet, bitter (basic), sour (acidic), umami (amino acids)
   taste pore + taste hairs

taste is transmitted through cranial nerve to temporal lobe, not far from olfactory information

Question 14

olfaction

Answer 14

located at roof of nasopharynx, airborne chemical that dissolve in mucus

• olfactory nerves project directly to olfactory bulbs of the brain (near temporal lobes, near limbic system)

Question 15

smell as good and bad

Answer 15

good and bad smells are learned, based on experiences. there is no universally noxious smell – dependent on culture/upbringing

Question 16

pheromones

Answer 16

used by insects to communicate (food, threats, mating). not well studied in humans

Question 17

outer ear

Answer 17

• auricle/pinna (the shape of the ear - the “pinnacle” of the ear)
• external auditory canal

Question 18

middle ear

Answer 18

tympanic membrane

• ossicles
• three bones:
  1. malleus
  2. incus
  3. stapes

Question 19

inner ear

Answer 19

cochlea

• semicircular canals
• utricle
• saccule

Question 20

what controls balance

Answer 20

3 semicircular canals: utricle, saccule, ampullae

filled with endolymph and hair cells that detect motion

detect rotations acceleration of the held

innervated by afferent neurons which send balance information to the pons/cerebellum

detects linear balance and static equilibrium

Question 21

round window

Answer 21

releases excess pressure; membrane-covered hole in the cochlea near the oval window

Question 22

Eustachian tube

Answer 22

passageway to the back of the throat to middle ear, equalizes pressure

Question 23

mechanism of ear

Answer 23

1. sound waves enter external ear
2. pass through auditory canal
3. TM vibrates -> malleus -> incus -> stapes (amplification)
4. stapes -> oval window -> pressure waves sent to perilymph and endolymph (fluids in the cochlea)
5. pressure waves in endolymph cause vibration of the basilar membrane, which is covered with auditory receptor cells called hair cells (cilia from apical structures)
6. hairs contact the tectorial membrane (roof)
7. (movement of basilar membrane bends the hairs on tectorial membrane)
8. the displacement of hair opens ion channels in the hair cells, which result in NT release and stimulation of bipolar auditory neurons
9. dendrites from bipolar auditory afferent neurons are stimulated by NT, thus sound vibrations are converted into nerve impulses

air -> bone -> fluid

Question 24

organ of Corti

Answer 24

1. basilar membrane
2. hair cells
3. tectorial membrane

found in the cochlea

Question 25

pitch

Answer 25

-- different sets of neurons for different pitches frequency -> depends on regions of the basilar membrane thick and sturdy near the oval window; thin and floppy near the apex of cochlea low frequency -> stimulate at farthest away, away from oval window high-pitch -> near the oval window

Question 26

loudness

Answer 26

the amplitude of vibration = more frequency APs

Question 27

auditory cortex

Answer 27

located in temporal lobe, helps with stereophonic hearing

Question 28

hearing is highly adaptive

Answer 28

we hear vocal frequencies, and variations in human voices

Question 29

retina

Answer 29

detects light and sends APs to brain

Question 30

passage of light

Answer 30

enters cornea (clear front of eye), which is refracted,

Question 31

choroid

Answer 31

beneath the sclera (darkly-pigmented cells that absorb excess light), beneath this is retina

Question 32

anatomy of eye (DRAW)

Answer 32

p. 65

Question 33

anterior chamber

Answer 33

contains fluids called aqueous humor. | just behind the cornea, in front of the iris

Question 34

iris

Answer 34

muscles control the diameter of the pupil

Question 35

posterior chamber

Answer 35

behind the iris, in front of the lens, made of aqueous humor

Question 36

lens

Answer 36

fine tunes the angle of incoming light, whose curvature is dictated by the ciliary muscle

Question 37

vitreous chamber

Answer 37

contains vitreous humor

Question 38

part of brain that receives visual input

Answer 38

occipital lobe ("Obama could see the future")

Question 39

Organization of retina (DRAW)

Answer 39

p. 86

Question 40

optic disk

Answer 40

where the axons from ganglion cells converge, contains no photoreceptors

Question 41

fovea centralis

Answer 41

focal point - contains only cones and provides extreme visual acuity

Question 42

rods and cones

Answer 42

rods connect to posterior wall of retina contain special proteins (opsin) that change tertiary structure upon absorbing light synapse on bipolar cells AT DARK: depolarization, they release NT glutamate onto the bipolar cells, which inhibits firing. "GLUTAMINE at NIGHT." AT LIGHT: upon absorption of light, the photoreceptor stops releasing glutamate on the bipolar cells, the bipolar cells can depolarize (removal of inhibition), causing depolarization of ganglion cells, creating AP along the axon of ganglion cell

Question 43

opsin is bound to...

Answer 43

bound to one molecule of retinal, derived from vitamin A

Question 44

at dark...then at light

Answer 44

rods and cones have several trans double bonds and 1 cis double bond retinal and opsin keep a sodium channel open. cell is depolarized. with absorbing a single photon, the retinal is converted to all-trans for, closing the sodium channel and hyperpolarized

Question 45

optic nerve

Answer 45

all axons of ganglion cells form the optic nerve

Question 46

night vision

Answer 46

accomplished by rods, which are sensitive to motion and dim light, found in the periphery of the retina

Question 47

cones

Answer 47

require abundant light, produce color and high-acuity vision, concentrated at the fovea Cones - Color - aCuity each cone makes a particular pigment which changes conformation when light of appropriate frequency strikes it

Question 48

emmetropia

Answer 48

normal vision

Question 49

how to correct myopia

Answer 49

nearsightedness, CONCAVE (diverging) lens can be used

Question 50

how to correct hyperopia

Answer 50

farsightedness, CONVEX lens

Question 51

presbyopia

Answer 51

inability to accommodate focus - occurs with aging

Question 52

visual processing

Answer 52

parallel processing feature-detection theory vision is 30% of the processing

Question 53

depth perception

Answer 53

binocular cues, retinal disparity, convergence

Question 54

monocular cues

Answer 54

depth cues available to either eye alone 1. relative size - sizes of similar objects 2. interposition - subject on top of another 3. relative clarity - fuzziness 4. texture gradient - see poppies 5. relative height - things on top are farther away 6. relative motion - things closer to us move more 7. linear perspective - convergence of lines as distance increases 8. light/shadow - closer object reflect more light

Question 55

retinal disparity

Answer 55

the difference between left and right eyes

Question 56

Sensory modalities table (DRAW)

Answer 56

p. 73