Anatomy Chapter 13

In near vision the pupil is _____.

Constricted -Lens is round and loose

Round lens

Constricted pupil contraction of the ciliary body muscles loosens suspensory ligaments resulting in

Inner ear

Contain actual receptors -contains hearing receptors -contains equilibrium receptors

Middle ear

Conveys vibrations inward Middle ear bones: incus, malleus and stapes

Olfaction: physiology

Has a low threshold and high adaptation -low amounts of particles trigger the signal that allows us to sense smaller/ less strong things

What does damage to the optic nerve result in?

Loss of vision and severity depends on where damage occurs

Eyebrows

Overlie supraorbital margins Function Shade eye from sunlight Prevent perspiration from reaching eye

Muscles used to look straight up

Superior rectus and inferior oblique

Cornea

The clear tissue that covers the front of the eye

Refraction

The cornea and the lens refract light rays to focus them on the retina

Fibrous layer of eye

consists of sclera and cornea -structure/protein -very tough -outermost layer

sphincter pupillae muscle

constricts pupil, parasympathetic (radial)

External acoustic meatus

ear canal

External ear

everything up to tympanic membrane (eardrum)

Auricle

external ear

Presbyopia

farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.

Flat lens

focuses light from a distant object dilated pupil

Lacrimal gland

gland located in the upper outer region above the eyeball that secretes tears

presbyopia

impairment of vision as a result of old age

Eyelashes

project from the border of each eyelid

Dilator pupillae muscle

radially organized smooth muscle dilates pupil with sympathetic nervous system activity (circular)

Rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond -dim light -gray scale less visual acuity

Papillae

rough, bumpy elevations on dorsal surface of tongue which contain tastebuds

How do photoreceptors work?

specialized neurons found in the retina that convert light into electrical signals that stimulate physiological processes

optic disc (blind spot)

where the optic nerve exits the eye

Sclera

white of the eye; maintains the shape of the eye and protects the delicate inner layers of tissue -made up of collagen

Acid threshold (sour)

H+

Muscles used to look right

-Medial rectus in left eye -Later rectus in right eye

Muscles used to look left

-Medial rectus in the right eye -Lateral rectus in left eye

Optic discs (blind spot)

-No photoreceptors

Tympanic membrane

-aka the eardrum. -separates the outer and middle ear -transfers vibration signals to the inner ear

Distance vision

-ciliary muscles relax, and border of choroid moves away from lens -suspensory ligaments pull against lens -lens becomes flatter, focusing on distant objects -dilated

Olfactory receptors

-generate action potential -bind to odorants

The process of image formation

1. Refraction (bending) of light 2. Change in lens shape 3. Change in pupil size -adjusts in accordance with lens

Image formation

1. Refraction of light rays by the cornea and lens 2. Accommodation of the lens 3. Constriction of the pupil

During near vision, light rays enter the eye divergently so....

Accommodation must occur and the lens "rounds out", increasing refractory (bending) power

Macula

Center of field of vision -contains photoreceptors

In distant vision the pupil is ______.

Dilated -lens is stretched and flat

Basal cells

Divide and replace gustatory receptors contains stem cells

Photoreceptors

Generate signal in response to light

Bipolar cells

In the retina, the specialized neurons that connect the rods and cones with the ganglion cells.

Ciliary muscle contracts to reduce tension in the lens....

More convex means, more refractory power

Inferior rectus

Moves eye inferiorly -controlled by oculomotor nerve

Lateral rectus

Moves eye laterally -controlled by abducens nerve and hooks around the trochlea

Medial rectus

Moves eye medially -controlled by oculomotor

superior rectus

Moves eye superiorly - controlled by oculomotor nerve

Basal cells (olfactory)

Produce new receptors

Inner layer of eye

Retina -where actual vision is produced

Visual pathway

Retina -> optic nerve -> optic chiasma -> primary visual area (occipital) -Everything in the right field of vision ends up on the left side of the occipital lobe and vice versa.

Salty threshold

Salts, metals

Gustation

Sense of taste -prevents us from eating poisonous things -receptors are spread out throughout tongue

Iris

Shaped like flat donut -controls pupil size -dilates pupillae

What are the primary tastes?

Sour, salty, sweet, butter, and umami (savory)

Ciliary body

Structure surrounding the lens that connects the choroid and iris. It contains ciliary muscles, which control the shape of the lens, and it secretes aqueous humor.

Sweet threshold

Sugars/alcohols

Significance of the fovea centralis within the macula lutea is...

There is no wiring in the way (has only cones)

What is the significance of the fovea centralis within the macula lutea is....

There is no wiring in the way; only cones

Vitreous humor

Thick, gel-like substance found in posterior segment -holds things in place

Aqueous humor

Watery fluid found in anterior segment

Superior oblique

Works with superior rectus to stabilize downward eye movements -controlled by oculomotor

Inferior oblique

Works with superior rectus to stabilize superior movements (looking up) -controlled by oculomotor

Retinal

a chemical synthesized from vitamin A; joins with an opsin to form a photopigment

Ganglion cell

a neuron located in the retina that receives visual information from bipolar cells; its axons give rise to the optic nerve

Cerumen

a waxy substance secreted by glands located throughout the external canal

Macula lutea

a yellowish central area of the retina that is rich in cones and that mediates clear detailed vision

Umami

amino acids glutamate and aspartate

What determines eye color

amount and distribution of melanin

What is clouding of the lens?

cataracts

Supporting cells

cells that insulate, support and protect neurons

Chemoreceptors

chemical sensors in the brain and blood vessels that identify changing levels of oxygen and carbon dioxide

Capsaicin

chemical that stimulates receptors that respond to painful heat like spicy foods

photopigments

chemicals in photoreceptors that respond to light and assist in converting light into neural activity

Photopigments

chemicals that release energy when struck by light

Gustatory receptors

chemoreceptors on the tongue that respond to chemicals in food 1 week lifespan

Vascular layer of eye

choroid, ciliary body, iris, pupil -provides lots of the blood supply -middle layer

Cones

color vision, has higher resolution, red/green/yellow lights -bright light -higher acuity

Near vision

lens rounds out to increase refractory bending power -ciliary muscles contract -constricted

Choroid

middle, vascular layer of the eye, between the retina and the sclera -blood supply -melanin pigment- absorbs light -prevents excess light scattering -oculomotor nerve

Accomodation in the eye

the eye's ability to focus and maintain an image on the retina

lacrimal duct (nasolacrimal duct)

the passageway that drains excess tears into the nose

Olfaction

the sense of smell, which is the response to chemicals that contact the membranes inside the nose

Lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

Fovea Centralis

tiny pit or depression in the retina that is the region of clearest vision