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somatic sense
touch, pressure, temperature, pain
special senses
smell, taste, vision, hearing, equilibrium (within ear)
sensory receptors
detect environmental changes and trigger nerve impulses
eyes, ears
large complex organs
taste buds and olfactory epithelium
localized clusters of receptors
chemoreceptors
detect chemical changes
pain receptors
detect pain
thermoreceptors
detect temperature changes
mechanoreceptors
detect touch
photoreceptors
detect light
somatic sense
senses are associated with receptors in the skin, muscles, joints, and viscera (organs of the body)
heat receptors
respond to warmer temperature (29-45C or 82-113F). discharge most vigorously at 45C (113F) above this range, pain receptors are stimulated burning sensation.
cold receptors
respond to colder temperature (5C=40C or 41-104F) discharge most vigorously at 25C(77F). below this, pain receptors stimulate freezing sensation (you feel pain)
visceral pain
occurs in visceral tissues such as the heart, lungs, intestine
referred pain
feels as though it is coming from a different part (heart pain may be felt as pain in the arm or the shoulder)
acute pain
originates from skin, usually stops when stimulus stops (needle prick)
chronic pain
dull aching sensation
phantom limb pain
feels like it’s coming from a body part that’s no longer there. originates in the brain and spinal cord.
regulation of pain impulses
awareness of pain arises when impulses reach the thalamus
cerebral cortex
determine pain intensity, locates pain source , and mediates emotional and motor responses
enkephalins
suppress acute and chronic pain, relieve severe pain
serotonin
stimulates other neurons to release enkephalines
endorphins
extreme pain and natural pain control
sensation
feeling that occur when a brain interprets a sensory impulse
projection
process where the cerebral cortex causes a feeling to stem from a source
sensory adaptation
sensory receptors stop sending signals when they are repeatedly stimulated
adaptation
frequency of the receptor potential decreases over time in response to a continuous stimulus
small elevated projections on the tongue called papillae
where are taste buds located
olfactory receptors
yellowish brown masses- covers upper parts of the naval cavity the superior nasal conchae, and portion of the nasal septum
10,000
how many on tongue
1,000
how many on roof of mouth
sweet, sour, salty, bitter, and umami
what are the five basic tastes
very bitter
PAV-PAV = TT
somewhat bitter
PAV-AVI = Tt
nontaster
AVI-AVI=tt
70% tasters and 30% nontasters
general population of PTC tasting
thiocynate compounds
(bitter taste) found in broccoli, cauliflowers, mustard family
europeans
all 3 alleles (PAV, AVI, AAV)
asians
AAV allele rare
native americans
98% have PAV allele only
auricle (pinna)
flap on the side of the head
external auditory meatus
ear canal, which leads from the auricle, through temporal bone, into the ear canal
tympanic membrane (eardrum)
stretches across the inner end of the auditory canal, separating it from the middle ear
malleus, incus, stapes
3 very small bones named for their shape (hammer, anvil, stirrup); amplify sound
oval window
vibrates as stapes hit against it; passes vibration to fluid in cochlea
round window
acts as a “pressure valve” and allows oval window to continue to transmit vibrations in cochlear fluid
eustachian tube
passage leading from the pharynx to the cavity of the middle ear, permitting the equalization of pressure on each side of the eardrum
inner ear
has structures that help to produce both hearing and balance
static equilibrium
sense the position of the head, maintain stability and posture
dynamic equilibrium
(semicircular canals)- balance the head during sudden movement
cerebellum
interprets impulses from the semicircular canals and maintains overall balance
eye
the ___ is the sense organ for vision and converts light into electrical impulses/action potentials
sclera
white of the eye; protects
choroid
becomes the iris in front
retina
incomplete innermost layer of the eyeball (no anterior portion)
optic disk aka blind spot
where axons of sensory neurons leave the eye as the optic nerve
rods
rhodopsin
cones
erythrolable (red), chlorolable (green), cyanolable (blue)
astigmatism
cornea i
cataracts
protein in the lens clumps together and starts to cloud the lens
colorblindness
inability to distinguish certain colors due to photopigment defect in cone cells
vitamin A deficiency blindness
leading cause of preventable childhood blindness