Anatomy unit 4

Sensation

conscious awareness of the stimuli

Transduction

Conversion of stimuli to impulses

perception

brain assigning meaning

General senses

temperature, pain, touch, stretch, and pressure

Special senses

gustation, olfaction, vision, equilibrium and hearing

Chemoreceptors

Detect specific molecules dissolved in fluid

Thermoreceptors

detect changes in temperature

Photoreceptors

detect changes In intensity, color, and position of light (ex: rods and cones)

Mechanoreceptors

detect touch, pressure, vibration and stretch

baroreceptors

detect pressure changes within body structures

Nociceptors

detect painful stimuli

Phantom pain

sensation associated with a part of the body that has been removed

referred pain

impulses from certain viscera are perceived as originating not from the organ but from the skin

Tactile Receptors

Mechanoreceptors thar react to touch, pressure and vibration, located in the dermis and subcutaneous layer

Gustation

sense of taste

Gustatory cells

taste receptors housed in specialized organs termed taste buds

papille

bumps

Olfaction

Sense of smell

Odorants

are dissolved in mucus of nasal cavity and detected

olfactory epithelium

lines superior nasal cavity

olfactory nerves

formed by bundles of axons of olfactory receptor cells

extrinsic muscles

moves the eyeballs

Eyelids

folds of skin that protect the eye

Medial canthus

towards the nose

Lateral Canthus

away from the nose

Lacrimal caruncle

pink fleshy structure

Conjunctiva

pin eye/redness of eyes due to bacteria or infection

Cataracts

lease becomes cloudy, occurs with age, usually results in surgery

Glaucoma

increased pressure within eye due to aqueous humor

Lacrimal fluid

tears (lubricates the anterior surface of the eye)

Lacrimal gland

produces and secretes tears

Lacrimal canaliculi

little canals drain tears to outside of eyes

Cornea

clear anterior portion of eye

sclera

Anterior of eye

Choroid

contains vast network of capillaries supplying nutrients and oxygen to the retina

Ciliary body

changes lens shape

Iris

pigmented part of the anterior eyeupilp

pupil

controls amount of light entering the eye

Retina

internal layer of the eye

neural layer

houses photoreceptors and associated neurons, receives light; converts energy into nerve impulses

photoreceptor cells

outermost layer composed of rods and cones

Rods

Important in dim light (lots of them)

Cones

important for precise vision and color (not that many)

bipolar cells

synapse with photoreceptors and ganglion cells

Ganglion cells

innermost layer of the retina; axons of these cells leave the retina and form the optic nerve

Optic disc

is a “blind spot” on the retina lacking photoreceptors

Fovea centralis

depression in the retina containing the highest proportion of cones and almost no rods

Accommodation

ability of the lens to change shape, to focus and image

myopia

Nearsightedness, inability to focus far away because eyeball is elongated

Hyperopia

inability to focus on objects that are close because eyeball is short

presbyopia

age related farsightedness, sense loosing ability to accommodate

Astigmatism

irregularity on cornea or lens

diabetic Retinopathy

unstable blood vessels that develop in eyes, rupture and cause blindspots

Strabismus

misalignment of eyes, due to one set of extrinsic muscle being stronger than the other

The ear divided into 3 distinct anatomic regions

External ear, middle ear, and inner ear

Structures of the external ear

Auricle, external acoustic meatus, tympanic membrane (eardrum)

Structures of the middle ear

Auditory tube, auditory ossicles (small bones)

What structures increase sound waves?

Malleus, incus and stapes

structures of the inner ear

Cochlea (hearing)

Equilibrium

awareness of head position

Static equilibrium

Maculae within utricle and saccule, contains hair cells

Dynamic equilibrium

3 semicircular canals( anterior, posterior, and lateral canals) Receptors within semicircular ducts detect rotational movement of the head.

Crista ampullaris

elevated region of ampulla covered by an epithelium of hair cells

Cochlea

curled up tube, inner ear organ of hearing

Tinnitus

ringing in the ears, usually resolves itself

Otitis

Infection that can happen in either the Externa (outer ear), Media (middle ear) Interna (inner ear)