biol114- ch.15

Olfaction

Olfaction

Smell.

Olfaction Process

Receptor → Cribriform Plate → Olfactory Bulb → Olfactory Tract → Olfactory Cortex (Temporal Lobe).

Gustation

Taste.

Main Tastes

Sour, Bitter, Salty, Sweet, Umami.

Which two tastes are most sensitive and a survival advantage.

Sour and Bitter.

Gustation Process

Tongue → Taste Bud → Gustatory Cells → Cranial Nerves → Gustatory Cortex.

Eyelid

Lubricates, keeps foreign objects out, and protects from the sun.

Eyelashes

Helps to keep foreign objects out of the eye.

Superficial epithelium (conjunctiva)

A thin layer of skin membrane that covers the front surface of the eye and lines the inside of the eyelids.

Lacrimal glands

Glands on eyelashes that produce tears, which help to give oxygen and nutrients to the conjunctiva.

Fibrous layer

The outermost layer of the eye, consisting of the sclera (white of the eye) and the cornea (transparent front part of the eye).

Vascular layer

The middle layer of the eye, consisting of the iris, choroid, and ciliary body.

Inner layer

The innermost layer of the eye, consisting of the retina, which contains the photoreceptor cells.

Anterior Cavity

Aqueous humor (watery).

Posterior Cavity

Vitreous humor (gel-like, ball shape)

Cornea

The transparent front part of the eye that refracts light.

Pupil

The opening in the center of the iris that allows light to enter the eye by changing the diameter of the opening.

Melanocytes in iris

Controls Pigments.

Lens

A transparent structure behind the iris that helps to focus light onto the retina and is accommodated by the ciliary body.

Fovea centralis

The central focus, provides the clearest image when the light bends and hits just above the optic nerve.

Dilation

The process of enlarging or widening the pupil.

Expansion

The process of increasing in size or extending the pupil.

Accommodation

The ability of the lens to change shape in order to focus on objects at different distances from a clearer vision.

When an object is ______ the lens are rounded by muscle contraction of the ciliary body.

Close.

When an object is ______ the lens are flattened by muscle relaxation of the ciliary body.

Distant.

Presbyopia

The higher the age, the less lens elasticity.

Photoreceptors in the retina include ______.

Rods, cones, and a blind spot.

Rods

Photoreceptor cells in the retina that are responsible for vision in dim light and dull images in black and white vision.

Cones

Photoreceptor cells in the retina that are responsible for color vision and clear images in intense light.

Blind Spot

The area on the retina where the optic nerve exits the eye, which lacks photoreceptor cells in the optic disc.

Cones primary colors are ____.

Blue, green, red.

Vitamin A

A nutrient that is important for night vision, particularly for the function of the rods in the retina.

Retinol

A form of vitamin A that is found in the rods of the retina.

Visual cortex

The region of the brain, located in the occipital lobe, where visual information is processed.

Emmetropia

The normal condition of clear vision.

Myopia

Nearsightedness, where objects close to the viewer appear clear, but objects farther away appear blurry.

Hyperopia

Farsightedness, where objects farther away appear clear, but objects close to the viewer appear blurry.

Auricle (pinna)

The external part of the ear that funnels sound into the ear canal.

External Acoustic Meatus

The ear canal, which leads from the auricle to the eardrum.

Tympanic Membrane

The eardrum, a thin membrane that vibrates in response to sound waves.

Auditory Ossicles

The three small bones in the middle ear (malleus, incus, and stapes) that transmit sound vibrations from the eardrum to the inner ear.

Auditory Tube

A tube that connects the middle ear to the back of the throat, helping to equalize pressure on both sides of the eardrum.

Semicircular canals

Structures in the inner ear that are responsible for detecting rotational movements of the head and maintaining balance.

Vestibule

A structure in the inner ear that is responsible for detecting changes in linear acceleration and gravity.

Cochlea

A spiral-shaped structure in the inner ear that is responsible for hearing.

Functions of hearing in the cochlea

Captures and funnels sound → Vibrates → Senses sound & sends to brain via CNVIII (vestibulocochlear nerve).

In the cochlea there are ____.

Hair cells.

Function of equilibrium in the vestibule & semicircular ducts

It can sense gravity, acceleration, and rotation by not having stabilized fluid, which sends signals to your cerebellum.

Decibel

A unit used to measure the intensity of sound.

Conductive hearing loss

Hearing loss that occurs due to problems in the external or middle ear, which can often be temporary.

Sensorineural hearing loss

Hearing loss that occurs due to problems in the internal ear or central nervous system, which is often permanent; can use hearing aids.

Sensorineural hearing loss can be caused with damage to ____.

The Internal ear, CN VIII, or hair cells.

Which of the following statements accurately identifies disorders of the special senses?

Hearing: conductive and sensorineural hearing loss.

Which of the following is not a structure of the bony labyrinth?

Semicircular ducts.

What portion of the ear can sense gravity, acceleration, rotation, and sound?

Internal Ear.

Which cranial nerve does NOT carry gustatory information?

Hypoglossal.

Which of the following is NOT an accessory structure of the eye?

Aqueous humor.

What portion of the brain perceives visual images?

Visual cortex of the occipital lobe.

What is the term for the densely packed calcium carbonate crystals found in the macula?

Otoliths.

What is a characteristic of the middle layer of the eye?

Vascular.

Which of the following best compares olfaction and gustation?

Olfaction and Gustation are special senses. Olfaction is smelling and gustation is taste.

A blind spot occurs in the retina where ____.

Axons of ganglion cells converge at the optic nerve forming the optic disc.