A&P Special Senses

Q: How often do olfactory neurons regenerate?

A: Every 30–60 days.

Q: What part of the olfactory neuron detects odorants?

A: Nonmotile cilia on the dendritic knob, covered in mucus.

Q: What do bundles of olfactory neuron axons form?

A: The olfactory nerve (Cranial Nerve I).

Q: What is a glomerulus in the olfactory bulb?

A: A structure where axons from the same receptor type converge and synapse with mitral cells.

Q: What is the function of mitral cells?

A: They refine, amplify, and relay olfactory signals.

Q: What role do amacrine granule cells play in smell?

A: They release GABA to inhibit weak mitral cell signals.

Q: Where does the olfactory tract send signals?

A: To the piriform cortex, frontal lobe, and limbic system (hypothalamus, amygdala).

Q: Each odorant molecule can bind to how many receptor types?

A: Multiple; each receptor also responds to multiple odorants.

Q: What additional receptors are found in the nasal cavity?

A: Pain and temperature receptors (e.g., for ammonia, chili, menthol).

Q: What are the five basic taste sensations?

A: Sweet, sour, salty, bitter, umami.

Fungiform papillae:

Scattered across the tongue, most taste buds are here.

Foliate papillae:

On the side walls of the tongue.

Vallate papillae:

Largest taste buds, 8–12 form a “V” at the back of the tongue

Gustatory epithelial cells

Receptor cells with microvilli (gustatory hairs) that extend into taste pores and are bathed in saliva.

Basal epithelial cells

Stem cells that regenerate taste cells every 7–10 days.

Facial nerve (VII)

carry taste signals

Anterior 2/3 of the tongue.

Glossopharyngeal nerve (IX)

carry taste signals

Posterior 1/3 and pharynx

Vagus nerve (X)

Epiglottis and lower pharynx.

carry taste signals

hypothalamus and libic system

contribute to emotional responses of taste

What neurotransmitters are released by gustatory cells

Serotonin and ATP.

red light

visible light

longest wavelength and lowest energy

violet light

visible light

shortest wavelength and highest energy

myopia

nearsightedness

eyeball too long; corrected with concave lenses

hyperopia

farsightedness

eyeball too short; corrected with convex lens

astigmatism

unequal curvature of cornea/lens

corrected with cylindrical lens or laser surgery

rods

non color vision; numerous

high sensitivity and low acuity

in peripheral retina

cones

color vision

low sensitivity and high acuity

in central retina

photorecpetors and bipolar cells

generate graded potentials