What do specialized cells react to?

stimuli (external or internal)

What are the general senses?

touch, pain, heat, cold, pressure, proprioception, itch, internal environment

What are the special senses?

sight, smell, taste, hearing, balance

5 types of sensory receptors

mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors, nociceptors

mechanoreceptors

sense change in pressure or tension around receptor; detect touch, pressure, proprioception, hearing and balance

chemoreceptors

proteins on cell membrane detect specific molecules/chemicals; internal environment, smell, taste

photoreceptors

senses changes in light-color, intensity, movement; used in vision, therefore located in eye

thermoreceptors

sense changes in temperature above or below a baseline

nociceptors

pain receptors to external or internal stimuli

 2 types (Touch and Pressure)

unencapsulated and encapsulated

unencapsulated receptors

exposed dendrites; simple structure

3 types of unencapsulated receptors

root hair plexus; free nerve endings; tactile discs

root hair plexus

around hair follicles

free nerve endings

upper dermis and lower epidermis; sense touch

tactile discs

flattened nerve endings that function as tonic receptors for fine touch

encapsulated endings

dendrties covered with connective tissue or glial cells

4 types of encapsulated

tactile corpuscles; lamellated corpuscles; Ruffini corpuscles; Krause bulbs

tactile corpuscles (meissner's)

in dermal papillae; detects light touch

lamellated (Pacinian) corpuscles

deep dermis; detect deep pressure and vibration

Ruffini corpuscles

dermis and hypodermis; detects deep pressure and distortion

Krause bulbs

mucous membranes of cavities; detect light touch

Proprioception

mechanoreceptors sense tension in muscles, tendons, and joint capsules; send continous signals to cerebellum

Pain

nociceptors; free nevere endings found mainly in skin, some organs, none in brain; respond to strong stimuil- intense heat/cold, strong pressure, chemicals

Taste (Gustation)

taste buds on surface of tongue

4 types of papillae on surface of tongue

vallate, fungiform, filiform, foliate

vallate

least numerous but are the largest; form a V shape

filiform

short, spiked and on anterior 2/3

fungiform

block like projections on side of the tongue

foliate

ridges on lateral sides of tongue and are only in infants/children

taste buds on sides of tongue are....

vallate and fungiform papillae

How many specialized epithelial cells do taste buds contain?

50-100 cells

Taste buds

long microvilli stick out through taste pore, receptors on microvilli bind one type of chemical; binding of chemicals stimulates the sensory neuron

5 types of taste

salty, sweet, bitter, sour, umami

Where is the pair of olfactory bulbs located at?

on the ethmoid bone

Smell

receptor proteins on the cell detect specific types of odor molecules; 50-60 major types of primary odors; odors stimulate neurons to send signals

Wha does cillia on dendrites do?

increase surface area

Vision

respond to 1 billion stimuli per second; 7 million shades of color

3 parts of the eye

eye muscles, lacrimal apparatus and lacrimal gland

eye muscles

superior, medial, inferior, lateral rectus; superior & inferior oblique

3 layers that form the wall of the eye

Fibrous (outer); vascular (middle); nerual (inner)

What consists of the fibrous layer?

sclera, cornea, conjunctiva

sclera

dense irregular connective tissue; "white" of the eye

Cornea

continuous w/ sclera; collagen fibers arranged parallel to light rays-clear

Conjunctiva

accessory structure; stratified squamous tissue; covers anterior surface and inside of eyelid

What consists of the vascular layer?

choroid; ciliary body; lens; iris

choroid

posterior under sclera; pigmented to absorb light

ciliary body

anterior under cornea/sclera; ciliary muscles with suspensory ligaments which help bind to lens to help control shape

lens

onion like structure of transparent cells; focuses light rays on retina

iris

smooth msucles covered with pigments cells;

pupil

hole in center to allow light in

What consists in the neural layer?

retina (photoreceptors, bipolar cells, ganglion cells)

photoreceptor

most external layer; under choroid; cones & rods

cones

senses color (blue, green, red); vital for bright light; centrally located

Rods

sense black/white and motion; vital for dim light; peripheral

bipolar cells

middle layer; neurons that synapse w/ photoreceptors

ganglion cells

innermost layer; form optic nerve that leaves the eye

External ear

consits of the auricle; protects the entry to the external auditory canal

auricle

skin covered , elastic cartilage supported structure

Middle Ear

located inside temporal bone; includes tympanic membrane; auditory ossicles (malleus, incus, stapes); auditory tube

Auditory tube

equalizes presure on tympanic membrane

Auditory ossicles

amplify sound waves

Inner Ear

located inside temporal bone; tunnel in the bone creates the bony labyrinth; membranous labyrinth; contains cochlea, semicircular canals, vestibule

Semicircular canals

sense rotation acceleration; 3 semicircular canals; like in different planes

semicircular ducts

detect rotation movements of the head

ampulla

enlarged area

crista ampullaris

hair/ supporting cells region

cupula

gel dome over cilia

Vestibule

sense gravity and linear accleration

2 membranous sacs at right angles

utricle and saccule

stereocilia

long, stiff microvilla that are covered w/ gel like membrane

kinicilium

a long cilium on each hair cell

otoliths

tiny rocks on the membrane that move with gravity of linear accelaration