Test 1 Flashcards
Why does fat surround the eyeball?
to keep it from bumping against the bone and getting bruised
What is on the opposite side of he cornea and is a white cord on the back of the eye about 3 mm thick?
optic nerve
Describe the auricle?
Major part of the outer ear, also called pinna. Made of elastic cartilage surrounding the opening of the external auditory canal.
Describe the auditory canal?
Part of outer ear, ~2.5 cm long connecting to tympanic membrane of middle ear.
Describe the tympanic membrane or eardrum?
Separates outer from middle ear. Sound waves entering through external auditory canal hit this membrane causing it to vibrate.
Describe the Auditory ossicles?
Smallest bones in human body, viz., malleus (looks like hammer), incus, stapes. Located in middle ear. This portion of ear is filled with air and located within the temporal bone.
Describe the Pharyngotympanic or Eustachian tube?
Part of middle ear, connecting it to the nasopharynx.
Describe the Bony Labyrinth?
Part of inner ear, enclosing membranous labyrinth. Filled with perilymph (watery fluid, outside of membranous labyrinth) and endolymph, a viscous fluid inside of membranous labyrinth. Bony labyrinth consists of,
Describe the Cochlea?
a spiral bone canal that contains organ of Corti, whose specialized hair cells transmits sound impulses to the vestibulocochlear nerve.
Describe the Vestibule?
An egg shaped bony cavity.
Describe the Semicircular Canals?
Situated at right angles to one another. Their swollen base is called ampulla. Orientation of these canals allows them to sense rotational movements of the head and body.
Describe the Basilar Membrane?
Hair cells(auditory receptors) rest on the basilar membrane
Describe the Tectorial Membrane?
Cilia of hair cells (called stereocilia) projects into the gel-like tectorial membrane
Describe the Otoliths?
Small grains of calcium carbonate overriding hair cells.
Oto means?
ear
Lithos means?
stones
Describe the Conjunctiva?
A transparent mucous membrane lining the interior of the eyelids and outer white surface of eye. Infection of conjunctiva results in conjunctivitis or red eye.
Describe the Sclera?
The thick, tough, white outer covering of the eyeball. Fibrous layer made up of collagen and elastic fibers.
Describe the Cornea?
Transparent part of the outer fibrous layer of the eye. Covers iris and the pupil that helps protect the eye. Light bends as it passes through the cornea. The cornea begins bending light to make an image; the lens finishes the job.
Describe the Lacrimal Gland?
Located in the superior-lateral orbit, produces tear that drains into nasal cavity via ducts and lacrimal canal.
Describe the Iris?
Pigmented part of eye. Consists of muscle fibers arranged around an opening called pupil. A cow’s iris is brown. Human irises come in many colors, including brown, blue, green, and gray. Blue colored iris has the fewest number of melanocytes
Describe the pupil?
The pupil is the dark circle in the center of iris. Through this opening light into the inner eye. Human pupil is round, whereas cow’s pupil is oval.
Describe the Lens?
Biconvex structure that is opaque in preserved specimens. Lens makes an image on the eye’s retina. The lens is flexible so that it can change shape, focusing on close and far away objects.
Describe the Retina?
The layer of light-sensitive cells at the back of the eye. The retina detects images focused by the cornea and the lens. The retina is composed of receptor cells (rods and cones), and connected to the brain by the optic nerve.
Describe the choroid?
Thin dark sheet of tissue between the retina and sclera.
Describe Myelin?
The fatty layer that surrounds each nerve fiber.
Describe the Rods?
receptor cells of the retina responsible for perceiving difference in light intensity. Rods respond in dim light.
Describe the Cones?
receptor cells of the retina that are responsible for perceiving color in bright light.
Describe the Vitreous body/chamber?
The thick, clear jelly that fills the posterior cavity and helps give the eyeball its shape.