Chapter 8 and 9 A and P 2

Sclera

white connective tissue layer

“white part of the eye”

Cornea

transparent

allows light to pass through

transduction

convert physical/ chemical signals into electrical signals (action potential) to the brain and interpreted

choroid

blood rich layer that contains pigment

(prevents light from scattering)

2 Smooth muscle structues

Ciliary Body

Attached to lens by suspensory ligaments called ciliary zonules

changes shape of lens

Iris

amount of light entering the eye

Pupil

opening in the iris which is what controls pupil opening

Bipolar cell

recieves signal from rods and cones

Ganglion cells

recieve signal from bipolar cells

Retina

1. Outer layer- absorbs light and prevents scattering

   1. Inner layer- has receptor cells which are photoreceptors (rods and cones)

Bipolar and Ganglion cells

they are signals that leave the retina toward the brain through the optic nerve

Optic disc (blind spot)

where the optic nerve leaves the eyeball because no photoreceptors are there

Rods

helps vision in dim light and peripheral vision

see in grey tones (no color) night vision

Cones

Helps with detailed color vision

has fovea centralis

Fovea Centralis

where your sharpest vision comes from

Lateral blind spot

it only has cones in the retina

cone sensitivity

3 types of cones

each are sensitive to different wave lengths of visible light

lens

Flexible, biconvex crystal look (clear)

Held by suspensory ligament which is attached to the ciliary body

Anterior (aqueous) segment

(back) to the lens

has (clear, watery fluid)

Posterior (vitreous) segment

(front) to the lens

has (gel-like substance)

pathway of light through the eye and light refraction is:

The light is bent or refracted by the cornea, aqueous humor, lens, and vitreous humor

The eye is naturally set for a distance of?

over 20 feet away

Accomadation

lens has to change shape to focus on closer objects (Less than 20 ft away)

emmetropia

Eye focus images correctly "normal” on the retina

Myopia

when eye ball is too long (nearsightedness)

hyperopia

gets blurry if too close (faraightedness)

Astigmatism

Unequal curvature of the lens or cornea usually causes cylinders so consistent

Presbyopia

“reading glasses” decreased lens due to age

ear houses:

hearing and equilibrium (balance)

External ( outer) ear Auricle (pinna)

is a funnel, also known as the external acoustic meatus (auditory canal)

have glands that secrete cerumen (earwax)

Cerumen traps foreign objects and repels insects

eardrum ends at the tympanic membrane

Oval window

entry to inner ear

round window

pressure release valve

Auditory tube (pharyngotympanic)

Equalizes pressure in middle ear

links middle ear cavity to throat

1.Malleus 2. Incus 3. Stapes

hammer, Anvil, stirrup

Function: transmit and amplify vibrations (sound waves)

Vibration travel

hammer to anvil to stirrup to oval window of inner ear to be now fluid filled

Bony labyrinth has:

cochlea (hearing), vestibule (equilibrium), semicircular canals (equilibrium)q

Spinal organ of corti

located: cochlear duct

Receptors= basilar membrane (below)

Gel-like tectorial membrane (above)

High-pitched sounds have

short hairs ( stiff fibers)

Low pitched sounds have

long hairs (floppy fibers)

Equilibrium

its your balance

receptors are called vestibular apparatus

Static euilibrium

stationary

Oynamic equilibrium

is moving

conduction deafness

transmission of the external and middle ear is hindered

sensorineural deafness

Damage to the nervous system structure (inner ear path)

Maculae (static equilibrium)

Location: receptors in the vestibule

Helps keep our head up

Sends info from the vestibular nerve to the cerebellum of the brain

Anatomy of maculae:

Hair cells

have gel around the hair cells (otoliths) (tiny stones)

movement cause otoliths to roll and bend hair cells

Crista ampullaris (dynamic equilibrium)

responds to movements of the head

Located: ampulla (semicircular canal) (3-dimensional)

Head moves; cupula drags against endolymph

hair cells bend and goes to the cerebellum

chemoreceptors

chemicals in solution

smell

Olfactory receptors in the roof of the nasal cavity

Olfactory hairs detect chemicals

has mucus for detection

olfactory cortex

goes to the olfactory nerve (interprets smell)

Taste buds

house receptor organs

located in the tongue

papillae

The tongue is covered with these projections (increase surface area)

Gustatory cells

the taste receptors

have long hairs

hairs stimulated by chemicals dissolved in saliva

basal cells

This is what taste buds get replaced with when they might get damaged

sweet receptors

sugar

sour receptors

h+ ions

bitter receptors

nitrogen

salty receptors

metal ions na+ and k+

umani receptors

beefy taste of meat

Endocrine system

slower control system

horomones are chemically classified as:

protiens, steriods, postaglandins

horome action

horomes affect only target cells

target cells have specific receptors

horomone turns cells activity up or down (homeostatis)

Direction Gene activation (steriod)

1. Steroid hormone diffuse through cell membrane

2. enters the nucleus

3. binds to specific protien in nucleus

4. binds to DNA cells

5. genes get activated by RNA

6. new protiens are synthesized

second messenger system (protien horomones)

(this horomone cannot move throught membrane)

1. (1st messenger) hormone binds to protien cell membrane

2. causes a series of reactions that activate an enzyme

3. (second messenger) then it activates cyclic AMP

4. responds- tells cell to do something

negative reaction

maintain homeostasis (normal)

The stimulus

Activated by an endocrine gland

1. Hormonal (chemical)

2. humoral (blood)

3. neural (connect and stimulate gland)

Pituitary gland

pea-sized gland with the hypothalamus in the brain

2 functions: anterior and posterior pitutitary (hypothalamus controls these)

hypothalamus is the “boss”of endocrine glands

posterior pituitary

are neurotransmitters released by hypothalamus

which is released by the blood (oxytocin and antidiuretic hormone)

Oxytocin

Only released in childbirth and nursing

stimulates contractions during labor

causes milk ejection in nursing woman (let-down reflex)

Antidiuretic hormone (ADH)

urine production by kidneys

ADH tells kidneys to make H20 channels (to save h20)