Special Senses

repond to stimuli such as sound or touch

Mechanoreceptors

respond to temperature

Thermoreceptor

Detect tissue damage, extreme heat and cold chemicals released from damaged cells

Pain receptors

respond to light

photoreceptor

detech chemicals

chemoreceptors

detect position of body parts

proprioceptors

Is a phenomenon in which sensations become less noticeable with prolonged exposure to the stimulus

sensory adaptation

Is the process by which a sensory receptor converts energy from a stimulus into electrical signals

transduction

It detects touch, temperature or pain with any part of the skin and in the internal organs.

General senses

It has specialized structures for vision, olfaction, gustation, hearing and equilibrium

Special Senses

Eye accessory structures: 6

Eyelids

Eylashes

Eyebrows

Lacrimal apparatus

Conjunctiva

Extra ocular muscle

Elastic movable folds of skin over the eyes, protects the eyes from debris and trauma

eyelids

Hair that grows at the edge of the eyelids for protection and aesthetic

eyelashes

Hairy area of coarse skin above the eye

eyebrows

Consists of the lacrimal gland and ducts that drain lacrimal secretions

lacrimal apparatus

Mucous membrane lines the eyelids and covers part of the outer surface of the eye

conjunctiva

Innervated by the cranial nerves controlling the movement of the eyes

extra-ocular muscle

CN III Oculomotor, elevation (upward)

(ocular muscle)

Superior rectus

CN III Oculomotor, depression (downward)

(ocular muscle)

inferior rectus

CN III Oculomotor, adduction (inward)

(ocular muscle)

medial rectus

CN VI Abducens, abduction (outward)

(ocular muscle)

lateral rectus

CN IV Trochlear, depresses abducts (donward and outward)

superior oblique

CN III Oculomotor, elevates abducts (upward and outward)

inferior oblique

Eye tunics: 3

Fibrous layer

Vascular tunic

Nervous tunic

Fibrous tunic, outer layer superficial coat of the eyeball

(eye tunics)

fibrous layer

The white coating of the eye, it helps maintain the shape of the eyeball

(eye tunic)

sclera

A modified part of the sclera toward the front of the eye

(eye tunic)

cornea

Middle layer of the eyeball, also known as Uvea

vascular tunic

the vascular layer of the eye

choroid

the optic disk where blood vessels enter the retina

produces aqueous humor

ciliary body

a colored part of the eye, and regulates the size of the pupil

iris

the hole in the middle of the iris tht regulates light entering the eye

pupil

layer that transmit nerve impulses

nervous tunic

a sheet of photoreceptors that forms the innermost layer of the eye

retina

it provides the sharpest vision allowing us to read and recognize faces, located near the center of the retina

macula

slight depression within the macula, has the highest number of cones and provides clearest vision and color perception

Fovea Centralis

a well-defined round or oval area within the retina

optic disk

is a light colord depression within the temporal side of the optic disk where blood vessels enter the retina

Physiologic cup

are photoreceptors, these cells provide black and white vision in dim light and enable us to see at night

Rod cells

are photoreceptors, they require more light and they detect color (photopic or day vision)

cone cells

transparent, flexible tissue located directly behind the iris and the pupil which further bends the incoming light to focus light and images

Lens

fluid found between the cornea, this fluid cleanses and nourishes the cornea and the lens and maintains the shape of the eyeball

aqaueos humor

located right in front of the lens, filled with the aqueous humor

posterior chamber

the amount of aqueous humor in the anterior chamber varies to maintain the pressure in the eye

anterior chamber

is a circular lymphatic-like vessel in the eye that collects aqueous humor from the anterior chamber.

schlemm’s canal

The optic nerve leaves the eye and then meets the optic nerve from the other eye at the optic chiasm

VISUAL PATHWAY

shell shaped projecting structure of the external ear that collects and directs sound waves

(outer ear)

auricle

short and narrow sound passageway that leads from the outer to the inner ear

auditory canal

lines the wall of the auditory canal and secretes a waxy yellow substance called ear wax or cerumen

ceruminous gland

the bony ridge located over the temporal bone and behind the auricle

mastoid process

a membrane that vibrates in response to sound waves

(middle ear)

ear drum

1 mm wide and 35mm long canal that connects the ear to the nasopharynx, it controls the pressure within the ear

auditory tube

3 smallest bones of the body which amplify the sound and transmit the vibratory motion of the eardurm to the fluids of the inner ear

ossicles

the first bony ossicle where the eardrum is attaached

malleus

attched to the malleus and stapes

incus

attached to the oval window

stapes

two covered openings at the end of the ossicles. It seperates the midde ear from the inner ear

windows

where the vibration enters

oval window

exit point of vibration

round window

the hearing part of the inner ear filled with fluid that moves with vibrations from the oval window, stimulating hair cells to produce sound signals

(inner area)

cochlea

found in the space between the membranous and bony labryinth (tunnels & chambers)

perilymph

found in the membranous labryinth

endolymph

sensorineural organ of the cochlea which is composed of hearing receptors called hair cells

organ of corti

specialized sensory cells that change the vibrations into electrical signals that are sent to the brain through the cochlear nerve

hair cells

the sensory organ for static equilibrium that detects head position and gravity changes to help maintain balance, sending signals to the brain through the vestibular nerve

vestibule

the sensory organs for dynamic equilibrium that detect rotational movements of the head and help maintain posture and balance, sending signals to the brain through the vestibular nerve

semicircular nerve

sound travels over the air filled external and middle ear through vibration of the tympanic membrane and ossicles

air conduction

sound travels directly through bone to the inner ear bypassing the tympanic membrande and ossicles

bone conduction

Body balance is maintained by:

muscles/joints,ear,eyes,cerebellum

located at the extreme superior region of the nasal cavity, it has specialized epithelium called the olfactory epithelium which contains approximately 10 million olfactory receptor cells

olfactory region

olfactory receptor neurons that are responsible for the detection of odorants which give rise to the sense of smell

olfactory receptor cells

long cilia on the olfactory receptors in the nasal epithelium, kept moist by mucus. When chemicals dissolve in the mucus and stimulate them, they send signals through the olfactory nerve

olfactory hairs

a neural structure that transmits smell information from the nose to the brain through the olfactory nerve tract

olfacory bulb

are small peglike projection on the dorsal tounge surface that houses the taste buds

papilae

contain chemoreceptors that detect the flavor of food. Their receptor cells connect to sensory neurons that send taste information to the brain.

taste buds

are the specific epithelial receptor cells in the taste buds that respond to chemicals dissolved in the saliva

gustatory cells

it transmit taste impulses to the brain

gustatory hairs