Kaplan Prep - Senses

Question 1

What are the five special senses?

Answer 1

The five special senses are vision, smell, taste, hearing and equilibrium (balance).

Question 2

Why is touch not listed as a special sense?

Answer 2

Touch, is a somatic sense which does not have a specialized organ and uses general receptors composed of modified dendrites of sensory neurons.

Question 3

Describe the sclera and the cornea of the eye.

Answer 3

The sclera is the “white of the eye” and the cornea is the transparent part of the eye where light enters.

Question 4

Describe the choroid, and the pupil of the eye.

Answer 4

The choroid prevents light from dispersing throughout the eye and supplies blood to the other layers of the eye. The pupil controls the amount of light entering the eye by using its muscle fibers to contract or dilate based on the amount of light in the environment.

Question 5

Describe the functioning of the rod and cone cells of the eye.

Answer 5

The rods are dim light and peripheral vision receptors which are more sensitive to light but do not generate sharp or color images. The cones operate in bright light generating sharp color images.

Question 6

Trace the passage of light through the eye.

Answer 6

Light passes into eye moving progressively through the cornea, aqueous humor, lens and vitreous humor to the surface of the retina which sends a signal through the optic nerve.

Question 7

List the parts and functions of the external ear.

Answer 7

The external ear consists of the auricle, the external acoustic canal (meatus) and the tympanic membrane (eardrum). The auricle directs sound waves into the external acoustic canal so that they can be detected. The external acoustic canal is the tunnel between the auricle and the eardrum which is lined with skin containing hairs and glands that secrete earwax which traps foreign materials. The inner end of the acoustic canal terminates at the tympanic membrane, a thin membrane of connective tissue whose vibration transmits sound energy to the middle ear.

Question 8

List the bones of the middle ear.

Answer 8

The middle ear contains the three smallest bones in the body the malleus (hammer), the incus (anvil), and the stapes (stirrup).

Question 9

List the parts and functions of the membranous labyrinth of the inner ear.

Answer 9

The membranous labyrinth is divided into three sections the vestibule, the semicircular canals and the cochlea. The vestibule houses receptors which provide the body’s balance system. The semicircular canals contribute to the body’s balance and orientation. The cochlea is a spiral bony chamber houses the organ of Corti whichs initiate an action potential that is transmitted through the cochlear nerve to the brain for processing.

Question 10

Explain the steps in the hearing process.

Answer 10

Hearing is caused by (1) sound waves passing into the external auditory canal and (2) causing the ear drum to vibrate which (3) transmits the vibrations to the ossicles which (4) push against fluid in the cochlear duct which (5) causes the hairs in the organ of Corti to move which (6) stimulates nearby neurons to (7) send impulses through the cochlear nerve to the brain.

Question 11

Identify the parts of the ear on the diagram

Answer 11

3 = Aurical
4= Eardrum
6 = Malleus
7 = Incus
8 = Stapes
9 = Semicircular canals
10 = Cochlea
11 = Cochlear nerve

Question 12

Why is smell classified as one of the chemical senses?

Answer 12

Smell is one of the chemical senses because its receptors are activated by airborne chemical substances dissolved in fluid on the nasal mucous membranes.

Question 13

Describe in detail the olfactory system.

Answer 13

The olfactory epithelium contains millions of bipolar neuron receptor cells whose dendrite extends from the cell body to the surface of the epithelium where it terminates in a bulb from which arise many cilia called olfactory hairs. The olfactory hairs extend into a thin layer of mucus covering the surface of the epithelium in which airborne chemical substances dissolve in order to be detected. Several unmyelinated axons of olfactory neurons collect to form olfactory nerve fiber bundles which pass through the ethmoid bone in the roof of the nasal cavity and synapse with the olfactory nerve tract in the olfactory bulb.

Question 14

List the 7 primary odors and give an example of each.

Answer 14

The seven primary odors are floral (roses), ethereal dry cleaning fluid), camphoraceous (mothballs), musky (perfumes), pepperminty (mint gum), pungent (vinegar) and putrid (rotten eggs).

Question 15

Why is taste classified as one of the chemical senses?

Answer 15

Taste is one of the chemical senses because its receptors are activated by chemical substances dissolved in saliva.

Question 16

Describe the cells that make up taste buds and their functions.

Answer 16

Taste buds are composed of three types of epithelial cells: gustatory cells which are the chemoreceptors, supporting cells which form the bulk of the taste bud and separate the taste receptors cells from one another and the tongue epithelial cells and basal cells which serve as stem cells dividing and differentiating into supporting cells which then form new gustatory cells.

Question 17

Explain in detail the taste process

Answer 17

Each taste bud sits in a taste pore from which long microvilli called gustatory hairs attached to the gustatory cells project into the saliva. Food chemicals contact the gustatory hairs which serve as the gustatory cell membranes generating an action potential in dendrites which are wrapped around the gustatory cells. The impulse is carried by afferent fibers to two cranial nerve pairs, the facial nerve and the glossopharyngeal nerve which transmit the impulse to the thalamus and ultimately to the parietal lobe.

Question 18

List the 5 primary tastes and give an example of each

Answer 18

There are five primary tastes: sweet (sugar), salty (NaCl), sour (vinegar), bitter (aspirin) and savory (aged cheese).