Chapter 24

Sense of Smell

• The olfactory tract sends impulses related to smell.

Middle Ear

• There are four openings into the middle ear.
• The auditory ossicles include the malleus, incus, and stapes.
• The sequence of auditory ossicles in the middle ear starting at the tympanic membrane and ending at the oval window is: malleus, incus, and stapes.

Sense of Smell and Taste

• Both olfactory receptors and taste buds are chemoreceptors.

Taste Buds

• The number of pure, or primary, tastes is about 5.
• Spicy is not considered a primary taste sensation.
• Taste buds are found in all locations: the lining of the mouth, on the soft palate, and on the tongue
• Filiform papillae do not contain taste buds but allow sensing food texture and "feel".
• Circumvallate papillae contain the most taste buds.
• Key tongue papillae facts:
  • Tongue papillae are classified by structure.
  • Circumvallate papillae are large, dome-shaped bumps in a transverse row at the back of the tongue.
  • Fungiform papillae are large, mushroom-shaped bumps in the anterior two-thirds of the tongue surface.

Inner Ear

• The malleus is not a part of the bony labyrinth.
• The organ of Corti is located in the cochlear duct.
• The cochlea means shell.
• The cochlear duct is not inside the vestibule of the inner ear.

The Process of Hearing

• The tectorial membrane moves against hair cells in the organ of Corti to initiate impulses.
• Impulses are transmitted from the inner ear to the brainstem by way of the cochlear.
• The cochlear duct is concerned with hearing.

External Ear

• The Eustachian tube is not a component of the external ear.
• The tympanic membrane is continuous with the external auditory meatus.
• The external auditory meatus is the passageway leading to the tympanic membrane.

Balance

• The sense organs for static equilibrium are in the utricle and saccule.
• There are three semicircular canals.
• Detecting the position of the head is the main function of the utricle and saccule in the vestibule.

Layers of the Eyeball

• Blood vessels are found in the choroid.
• The sclera refers to the white of the eye.
• The retina is the part of the eye containing nervous tissue.
• Cones are most densely concentrated in the fovea centralis.

Structure of the Eye

• Secreting tears is the main function of the lacrimal apparatus.
• The conjunctiva lines the eyelids and anterior surface of the eye.
• All of the following are accessory structures of the eye: Eyebrows, Eyelashes, and The palpebrae

Formation of Retinal Image

• The aqueous humor is involved in refraction to produce a clear image.
• Loss of lens elasticity results in presbyopia.
• Increased curvature of the lens must happen for near vision to occur.
• Strabismus is a problem related to convergence.

The Role of Photopigments

• Green is a primary photopigment.
• There are three types of cones in the retina.
• Cones that are sensitive to light in the blue wavelength wave are referred to as S cones.
• When looking at a large green field, the M cones would be sending the green wavelength to the brain.
• The photopigment melanopsin is found in ganglion cells.

Mechanisms of Disease

• Convex glasses are used for correction of nearsightedness
• Irregular curvature of the cornea can produce astigmatism.

Middle Ear Cont.

• The vestibule is not a structure of the middle ear.

Visual Acuity

• Clearness, or sharpness, of visual perception is known as visual acuity.

Structure of the Eye Cont.

• The anterior cavity of the eyeball has two subdivisions.

Nearsightedness

• One untrue fact about nearsightedness is that Convex glasses are used for correction.

Olfactory Receptors

• One untrue fact about the olfactory receptors is that The sense of smell in humans is less keen than in many other animals.

Sense of Hearing

• One untrue fact about the sense of hearing is that All of the above statements are true.

Cavities and Humors

• The anterior cavity is filled with vitreous fluid is not true of the eye.