CH 14: Special Senses

sensory receptors

stimulus, transduction of stimulus into receptor potential in sensory receptor, transmission of action potential in sensory neuron, interpretation of stimulus in CNS

3 class of sensory receptor

photoreceptors, mechanoreceptors, and chemoreceptors

photoreceptors

light, heat, electricity, magnetism

mechanoreceptors

pressure, gravity, inertia, sound, touch, vibration

chemoreceptors

taste, smell, humidity

exteroreceptors

sensory receptor

sense stimuli that arise in external env

interoceptors

sensory receptor

sense stimuli that arise within body

touch

thermoreceptors

nociceptors

mechanoreceptors

touch: thermoreceptors

naked dendritic nerve endings

cold: falling temp, inhibited by increase

heat: rising temp, inhibited by decrease

touch: nociceptors

transmit pain to signal to brain

touch: mechanoreceptors

fine touch: face, fingertip

hair follicle receptor

meissner corpuscle: no hair

ruffini endings: duration, extent of touch

merkel cell: duration, extent

pacinian corpuscle: deep subcutaneous, preassure

tastebuds

basal cell, columnar (structural) cell

5 taste sensation

sweet

salty

sour

bitter

umami

smell

olfaction, chemoreceptors in upper nasal passage

ear, hearing

sound waves to external ear and vibrate membrane

eardrum pass vibration through middle ear

ear bones

malleus

incus

stapes

inner ear

cochlea: mechanoreceptors involved in hearing and balance.

organ of corti

the sensory organ located within the cochlea that contains hair cells responsible for converting sound vibrations into nerve impulses

stereocilia

sound makes it rock back and fourth to generate electrical signals that communicate with auditory neurons

deafness

loss hearing of any degree

presbycusis

age related hearing loss

conduction deafness

interferes with conduction of sound vibration

sensorineural deafness

damage receptor to cells in organ of corti, cochlear nerve, auditory cortex

semicircular canals

help keep hearing balance

mechanoreceptors: stereocilia

utricles, saccule

macula tissue

hair cell, support, cell

utricle

sensitive to horizontal acceleration

saccule

sensitive to vertical acceleration

sclera

white portion

connective tissue

iris

color

cornea

light enter eye through transparent cornea

focus on light

pupil

light pass pupil to lens

lens

transparent

complete focusing of light to retina

retina

nervous tissue if eye

phototransduction

sight steps

1. light ray reflect object, enter eye through cornea

2. cornea bends, ray pass through pupil, iris open and closes (makes it bigger or smaller)

3. light ray pass lens, retina is light-sensing nerve cells, rods and cone cells

4. cornea are concentrated in center retina, macula

5. rods outside macula, extend to retuna, rods allow eye to detect motion

6. cells in retina cover light into electrical impulses, send signal to brain

rods, cones

rods: allow eye detect motion, help see in dim light and night

cones: responsible for color vision