Special Senses

Question 1

What are the four types of tongue papillae?

Answer 1

Filiform
Fungiform
Foliate
Circumvallate

Question 2

Which papillae has no taste buds?

Answer 2

Filiform

Question 3

Structure of taste bud

Answer 3

Approx 50 microns in diameter
Contain about 50 specialised cells in a barrel shaped structure
Small apical taste pore at surface

Question 4

What are the 3 cell types present in a taste bud?

Answer 4

Sensory cells
Support cells
Basal cells

Question 5

Structure of sensory cells in taste bud

Answer 5

Apical microvilli with chemical receptors at the apical pore

Question 6

Role of basal cells in taste bud

Answer 6

Act as stem cells for sensory and supporting cells which have a lifespan of 10-14 days

Question 7

How do taste buds work?

Answer 7

An appropriate chemical enters the taste pore and binds its receptor
Neurotransmitter is released from the sensory cell
Sensory nerve endings stimulated within taste bud

Question 8

What are the 5 principal tastes?

Answer 8

Sweet
Sour
Bitter
Salty
Umami

Question 9

What is olfactory epithelium?

Answer 9

Pseudostratified columnar with receptor cells, support cells and basal cells

Question 10

Role of support cells in olfactory epithelium?

Answer 10

Provide mechanical and metabolic support to the neurons

Question 11

Role of basal cells in olfactory epithelium?

Answer 11

Stem cells

Question 12

Structure and role of receptor cells in olfactory epithelium?

Answer 12

Have an olfactory vesicle that extends above epithelium with 10-20 motile cilia attached
Receptors located on cilia respond to odorants that we can detect and depolarise the cell, producing action potentials

Question 13

Structure of support cells in olfactory epithelium?

Answer 13

Numerous apical microvilli

Secrete odorant binding proteins

Question 14

What does the olfactory mucosa consist of?

Answer 14

Olfactory epithelium and underlying lamina propria

Question 15

What does the olfactory mucosa lamina propria contain?

Answer 15

Connective tissue
Blood vessels for warming the air
Bowman’s glands which produce secretion that dissolves odorants
Bundles of axons from receptor cells

Question 16

What covers the ear canal?

Answer 16

Hairy skin with sebaceous glands and modified apocrine sweat glands (ceruminous glands) which produce cerumin, a yellowish waxy substance

Question 17

What are the three layers of the tympanic membrane?

Answer 17

Outer - thin epidermis
Middle - collagenous connective tissue
Inner - simple cuboidal

Question 18

Properties of the cochlea

Answer 18

2.5 turn spiral
Central core - modiolus
Ganglion of bipolar nerve cell bodies - spiral ganglion
3 compartments - scala vestibuli, cochlear duct, scala tympani
Helicotrema - where SV and ST communicate with eachother at very tip of cochlea
Sounds tranduced by hair cells in organ of corti

Question 19

Where is the organ of corti?

Answer 19

Sits on basilar membrane which gets longer and more flexible as you move toward the tip of the cochlea

Question 20

Why do different areas of cochlea respond to different sounds?

Answer 20

The lengthing of the organ of corti
Organ of corti near tip of cochlea - reponds to lower frequencies
Organ of corti near base of cochlea - higher frequencies

Question 21

Structure of the organ of corti

Answer 21

Two sets of hair cells:
- row of 3-5 outer hair cells
- single row of inner hair cells
each with phalangeal support cells

Question 22

How is sound transferred through the organ of corti?

Answer 22

Vibrations in basement membrane cause stereocilia on apical ends of hair cells to move against tectorial membrane
Deformation of stereocilia opens ion channels that depolarise hair cell
Cells then release neurotransmitters that cause action potentials in the terminals of the spiral ganglion neurons

Question 23

What do hair cells in the utricle and saccule detect?

Answer 23

Head position

Question 24

What do hair cells in the semicircular canals detect?

Answer 24

Movement

Question 25

Structure of semicircular ducts?

Answer 25

Each duct contains a swelling called the ampulla within which is a sensory organ called the crista ampullaris

Question 26

How does the cupola detect movement?

Answer 26

When the head turns the fluid bows the cupola which bends the stereocilia
This changes the amount of transmitter released by these cells
They have a resting output, so bending one way increases and the other decreases

Question 27

What are the utricle and saccule?

Answer 27

Two swellings in the vestibule
Fluid filled spaces lined by simple cuboidal epithelium everywhere except a small patch of sensory epithelium (the macula)

Question 28

What is otoconia?

Answer 28

Crystals of calcium carbonate and protein embedded in a gelatinous layer in the utricle and saccule