Lec 13

Question 1

Hair cells

Answer 1

Mechanoreceptors that respond to gravity, movement, vibration and pressure

Question 2

Stotocyst

Answer 2

A small organ of balance and orientation in some aquatic invertebrates, consisting of a sensory vesicle or cell containing statoliths

Question 3

Statocyst purpose

Answer 3

Detect direction of gravity and direction of movement

Question 4

Lateral line system

Answer 4

Present in fish and aquatic amphibians

Detects movement of water, water pressure changes, vibrations

Schooling behavior, prey capture

Question 5

Evolution of anterior end of lateral line

Answer 5

Evolved into the “inner ear” which contains the vestibular apparatus and cochlear-balance and audition

Question 6

What do hair bundles consist of

Answer 6

Cilia or microvilli

Question 7

Stereocillia

Answer 7

Contains actin to make hair bundles rigid, but allows them to bend

Question 8

Do hair bundles have axons

Answer 8

No but they release glutamate to the sensory afferent and receive inhibitory efferent inputs (acetylcholine)

Question 9

What causes depolarization in a hair cell

Answer 9

Movement toward the kinocilium

Question 10

What causes hyperpolarization in a hair cell

Answer 10

Movement away from the kinocilium

Question 11

Hair cell channels

Answer 11

Channels near tip-links open as hair cells stretch

Only a few channels per cilia

Channels open and K+ and Ca2+ cations flow into the hair cell, depolarizing the cell

Question 12

Semicircular canals purpose

Answer 12

Angular accelerations of the head (rotations)

Question 13

Otolith organs

Answer 13

Utricle and saccule

Linear accelerations of the head (including gravity)

Question 14

Otoconia

Answer 14

Gelatinous mass of protein plus calcium carbonate crystals

Otoconia has inertia, meaning hair cells in the utricle and saccule can be activated by linear accelerations, including gravity