anatomy exam 5 senses

sensory receptors

detect information in the internal or external environment

neural pathways

convey information from receptors to the CNS

sensory receptors function

allow us to respond to stimuli and keep us safe, can be categorized by structure, location, and type of stimulus

interceptors

respond to visceral stimuli (part of the ANS)

exteroceptors

respond to stimuli outside or on the surface of the body

proprioceptors

respond to stimuli in skeletal muscles and joints

chemoreceptors

respond to changes in chemical concentrations. smell, taste, oxygen concentration

pain receptors

respond to tissue damage. mechanical, electrical, thermal energy

thermorereceptors

respond to moderate changes in temperature

mechanoreceptors

respond to mechanical forces that distort receptor. touch, tension, blood pressure, stretch

photoreceptors

respond to light. eyes

sensation

when sensory neurons reach threshold and achieve an action potential, making the brain aware of a sensory event (conscious and unconscious)

perception

when the brain interprets the sensory impulses

sensory adaptation

the ability to ignore or “tune out” unimportant stimuli

general senses

senses with small, widespread sensory receptors, associated with skin, muscles, joints, and viscera. divided into 3 groups: exteroceptive, interoceptive, and proprioceptive

exteroceptive senses

senses associated with body surface such as touch, pressure, temperature, and pain

interoceptive senses

senses associated with changes in the viscera such as blood pressure stretching blood vessels

proprioceptive senses

senses associated with changes in muscles, tendons, and joints, body position such as stimulated when changing positions or exercising

3 types of mechanoreceptors

free nerve endings, tactile corpuscules, lammellated corpuscles

free nerve endings

common in epithelial tissues, simplest receptors, sense itching and other sensations

tactile corpuscules

abundant in hairless portions of skin and lips, detect fine touch and texture, distinguish between 2 points

lamellated corpuscules

nerve endings encased in large ellipsoidal structures, common in deeper subcutaneous tissues, tendons, and ligaments, detect heavy pressure and vibrations

warm receptors

sensitive to temps greater than 25C, but not above 45C

cold receptors

sensitive to temperatures between 10C and 20C

referred pain

visceral pain may feel as if it is coming from some other part of the body

common nerve pathways

sensory impulses from the visceral organ and a certain area of the skin synapse with the same neuron in the CNS, referred pain results from this

fast pain (A-delta) fibers

myelinated, conduct impulses rapidly, associated with sharp pain in localized skin areas, usually stops as soon as stimulus stops

slow pain (C) fibers

unmyelinated, conduct impulses slowly, associated with dull, aching pain, difficult to localize, pain often continues after stimulus stops

thalamus

begins sensation of pain

cerebral cortex

judges intensity of pain, location of pain, produces emotional and motor responses

gray matter in brainstem

regulates flow of impulses from spinal cord

pain inhibiting substances produced in the body

enkephalins, serotonin, endorphins

muscle spindles

stretch receptors in skeletal muscles, initiate stretch reflexes in which spindle stretch causes muscle contraction

golgi tension organs

stretch receptors in tendons, stimulate reflexes that oppose stretch reflexes, help maintain posture, and protect muscle attachments from being pulled loose

visceral senses

have receptors in internal organs such as lamellated corpuscles and free nerve endings

the eye

spherical organ that is hollow and filled with a gelatinous substance called the vitreous humor

cornea

clear, transparent anterior portion that allows light to enter the eye

sclera

white opaque portion of the eye that attaches to muscles

choroid coat

provides blood supply and contains melanocytes to absorb extra light

cilliary body

forms ring to hold lens and changes lens shape for focusing

iris

pigmented, controls light entering the eye

pupil

opening in the center of the iris, dim light causes this to dilate, whereas bright causes it to constrict

aqueous humor

fluid in anterior cavity of the eye, fills both anterior and posterior chambers of anterior cavity and circulates through the pupil

vitreous humor

thick gel that hold retina flat against choroid coat and helps maintain the shape of the eye

vitreous body

vitreous body and collagen fibers

retina

contains photoreceptors, continuous with optic nerve

fovea centralis

center of macula lutea, produces the sharpest vision

optic disc

blind spot where optic nerve comes into the retina

accommodation

a change in the shape of the lens to focus on close objects

refraction

the bending of light rays by the cornea and lens to focus light on the retina

rods

sense colorless vision

cones

sense color

erythrolabe

red

chlorable

green

cyanolabe

blue

farsightedness of age

greater than 45 years, accommodation impossible, due to loss of elasticity of lens

nearsightedness

eyeball is too long, light focuses in front of retina, blurry image for distant objects

farsightedness

eyeball is too short, light focuses in back of retina, blurry images for closer objects

astigmatism

defect in curvature of cornea or lens

auricle

collects sound

external acoustic meatus

carries sound to tympanic membrane

tympanic membrane

vibrates in response to sound waves

tympanic cavity

air filled space in the temporal bone

auditory ossicles

small bones that vibrate in response to tympanic membrane vibrations

auditory tube

canal that connects the ear to the throat

otitis media

occurs because of mucous membranes of auditory tube and middle ear being continuous, bacteria travels from throat

tympanostomy tube

allows drainage through small opening in tympanic membrane

cochlea

produces nerve impulses in response to vibration

semicircular canals

function in dynamic equilibrium

vestibule

functions in static equilibrium

spiral organ

contains hair cells that function as hearing receptors with steriovilli

tectorial membrane

contracts over steriovilli and creates nerve impulses

pathway for nerve impulses

cholera branch of vestibulocohlear nerve

conductive deafness

interference with conduction of sound vibrations to inner ear

sensorineural deafness

damage to cochlea, auditory nerve, or nerve pathways

static equilibrium

senses position of head when body is not moving, receptors are found in vestibule of inner ear

dynamic equilibrium

senses rotation and movement of head and body, receptors are found in semicircular canals

olfaction

sense of smell

olfactory receptors

located in superior portion of nasal cavity and make up olfactory organs

taste buds

organs of taste and located on papillae of tongue, roof of the mouth, and cheeks of mouth and pharynx

5 primary taste sensations

sweet, sour, salty, bitter, umami

sweet

stimulated by carbohydrates

sour

stimulated by acids (H+)

salty

stimulated by salts (NA+ or K+)

bitter

stimulated by many organic compounds, Mg and Ca salts

Umami

stimulated by some amino acids, MSG