Anatomy chapter 18 (general and special senses)

sensory receptor

receptors distributed through body and grouped based on sensitivity to change

tonic receptor

always sending signales to CNS

phasic receptor

becomes active only with changes in the condition it monitors

chemoreceptors

stimulated by changes in concentration of chemicals (taste and smell)

pain receptors

respond to tissue damage, stimulated by excess mechanical, electrical, thermal, or chemical energy

Thermoreceptor

sensitive to temperature change (heat receptors and cold receptors)

mechanoreceptor

responds to changes in pressure or movement of fluid

proprioceptors

mechanoreceptor that responds to changes in muscles and tendons

pressoreceptors

mechanoreceptor that detects changes to blood pressure

stretch receptor

mechanoreceptor that responds to inflation of the lungs

photoreceptor

only in eye and responds to light

Receptor specificity

each receptor responds to a specific stimulus

Receptive field

area monitored by a single receptor cell

Sensation

sensory info arriving at CNS

Perception

feeling that occurs when sensory impulses are interpreted by brain, result of cerebral cortex

Sensory adaptation

occurs when sensory receptors are subjected to continuous stimulation and they adjust and impulses leave at a decreased rate

Peripheral adaptation

when sensory receptors alter level of activity

fast-adapting receptors

phasic receptors

slow-adapting receptors

tonic receptors

central adaptation

adaptation inside CNS along sensory pathway

Sensory limitations

sensory info from receptors is incomplete due to not having receptors for every stimulus, limited ranges of sensitivity, and stimulation requires a neural event that requires interpretation

General sense

do not have specialized receptor cells or sensory organs, tend to be located through whole body

Special senses

can have specialized receptor cells separate from the sensory neuron, structurally most complex, receptors located in sense organs

Exteroceptor

general sense that senses changes at body surface, relay info about external environment

Proprioceptor

general sense that senses depict body position in space

Visceroceptor (interoceptor)

general sense that senses changes in visceral organs or internal environment

Nocioceptor

general sense with free nerve endings and large receptive field, found everywhere except brain

Function of nociceptors

protective function, do not adapt well

Fast (prickling) pain

quick; inducing a reflex usually; ends when stimulus ends

Slow (burning) pain

begin later; last longer; ache

referred pain

visceral pain that feels like it is coming from another part of the body due to superficial structures being innervated by same spinal nerves as damaged viscera

thermoreceptor

general sense that involves heat and cold with free nerve endings in skin, conduct sensations over same path as nociceptors

do thermoreceptors adapt quickly or slowly?

quickly

When is temperature felt as pain

temperature goes above 45 or below 10

mechanoreceptor

general sense that is sensitive to mechanical forces that cause tissues to be deformed

Tactile receptors

mechanoreceptor that senses touch, pressure, and vibration

baroreceptor

mechanoreceptor that senses pressure changes in walls of vessels, etc

Unencapsulated tactile receptor

free nerve endings, root hair, tactile disc

Free nerve endings

in papillary of dermis

root hair

monitor distortions and movements across body surface

tactile disc

expanded nerve terminal that synapses with Merkel cell

Encapsulated tactile receptor

tactile corpuscles, lamellated corpuscle, ruffni corpuscle

tactile corpuscle

Meissener’s; found where tactile sensitivities are very well developed

lamellated corpuscle

Pacinian; respond to deep pressure

ruffni corpuscle

in skin; detect pressure with little adaptation

baroreceptor

stretch receptor that monitor changes in pressure, responds immediately but adapts rapidly, provides info essential to regulating autonomic activities

Where are baroreceptors found?

mwalls of major arteries and along digestive tract, bladder, carotid sinus, lung, colon

Muscle spindles

proprioceptor that monitors length of muscle

golgi tendon organ

propioceptor that monitors tension during contraction

How quick do proprioceptors adapt?

do not adapt

chemoreceptor

respond to water and lipid soluble materials DISSOLVED in surrounding fluids, monitor chemical composition of body fluids

Where are chemoreceptors found?

inside CNS (medulla sensitive to pH, pCO2 changes), aortic bodies (sensitive to pH, pCO2 and PO2), carotid bodies (sensitive to pH, pCo2 and pO2)

Olfactory organ

located within nasal cavity on either side of nasal septum, covers ciribriform plate of ethmoid

Olfactory receptors

chemoreceptors closely associated with taste, sensitive to chemicals dissolved in mucous

Olfaction

sense of smell

Composition of olfactory organ

olfactory epithelium, supporting cells, basal cells

Olfactory receptor composition

bipolar neurons with cilia (sensitive) on distal end, surrpunded by mucus secreted by olfactory glands

Olfactory pathways

once stimulated, impulses travel along axons of resptor cells, fibers pass through opening in criibroform plate and go to olfactory bulb, impuses analyzed in olfactory bulb, impulses continue along tracts to limbic system, senses interpreted as smell in temporal lobe and part of frontal

What is the only impulse that doesbn’t go through the thalamus?

olfactory pathway

Olfactory discrimination

subtle distinctions between thousands of stimuli, no structural difference between receptor cells

Does olfactory population turn over?

yes but total number decreases with age

Camphorous

1/7 primary odor

Musky

1/7 primary odor

Floral

1/7 primary odor

Pepperminty

1/7 primary odor

Etheral

1/7 primary odor

Pungent

1/7 primary odor

Putrid

1/7 primary odor

Do olfactory receptors adapt quickly or slowly?

quickly

Gustation

taste- chemical but requires chemical to be dissolved to make contact with tongue

Where are taste buds incorporated

papillae

Papillae

epithelial projections along tongue

Firiform

thread-like papillae

fungiform

mushroom shape papillae

Circumvallate

large target papillae near back of tongue

gustatory cell clusters

receptors- about 40/bud, also have basal cells and microvilli

Microvilli

taste hair into taste por

gustatory pathway

monitored by caranial nerves VII, IX, and X, afferent fibers synapse with nucleus solitarious in medulla, proceed to thalamus and cerebral cortx

Sour

taste sensation

sweet

taste sensation

salt

tast sensation

bitter

taste sensation

bitter

taste sensation

water

taste sensation

umami

taste sensation

Can taste buds turnover?

yes but number of taste buds and sensitivity decrease with age

External ear

equilibrium and hearing

Auricle

outer funnell shaped part of ear with supportive elastic fibers

External auditory meatus

s-shaped tube, ends at tympanic membrane

Outer half of external auditory meatus

supported by cartilage, thin skin with dermal papilal, ceruminous glands

Coiled tubular

modified sweat gland

cerumem

waxy secretion

Inner half of external auditory meatus

supported by bone, small hair and glands on upper wall, ends at tympanic membrane

Function of external auditory meaatus

protection, limit microorganism growth, funnel vibrations

Middle ear

auditory tube, tympanic membrane, eutsachian tibe, ossicles, muscles

eustachial

auditory tube

Auditory tube

air filled space in temporal bone

Tympanic membrane

cone-shaped membrane, covered by thin layer of skin, shape amintained due to muscle attachment to ossicles

Tympanic cavity

air filled space between external and internal ear

Eustachian tube

connects middle ear to upper throat