Sensory physiology- mechano and thermo sensation

Question 1

What is a TRP channel?

Answer 1

A transient receptor protein

Question 2

What are Pacinian corpuscles?

Answer 2

Phasic receptors that are sensitive to vibrations

Question 3

What are Merkel’s disks?

Answer 3

Sensitive and important for sensing light touch

Question 4

What are hair follicle receptors?

Answer 4

Detect when a hair is stretched and are rapidly adapting phasic receptors so can detect a moving insect but not a still one

Question 5

What are Ruffini’s endings?

Answer 5

Sensitive to skin stretching and help to determine the location of the body

Question 6

Describe the external structures of the outer ear

Answer 6

The pinna and the auditory canal

Question 7

What are the small bones called in the middle ear?

Answer 7

Malleus
Incus
Stapes

Question 8

What is the malleus also known as?

Answer 8

Hammer

Question 9

What is the incus also known as?

Answer 9

Anvil

Question 10

What is the stapes also known as?

Answer 10

Stirrup

Question 11

What do the malleus, incus and stapes do?

Answer 11

Transfer sound waves to the inner ear

Question 12

Describe what the stapes do?

Answer 12

Presses the oval window membrane and transmits pressure to the inner ear

Question 13

What is the second membrane in the middle ear called?

Answer 13

The round window

Question 14

Where is the inner ear?

Answer 14

Embedded within the skull and consists of a series of fluid-filled membraneous sacs and canals

Question 15

Where are the mechanoreceptors (hair cells) in the ear?

Answer 15

Located between two membranes- the basilar and tectorial membranes

Question 16

What is the organ of Corti?

Answer 16

A structure in the cochlea of the inner ear which produces nerve impulses in response to sound vibrations

Question 17

What does the organ of Corti consist of?

Answer 17

Hair cells and supporting cells lying between the tectorial and basilar membranes

Question 18

What happens when the basilar membrane is flexed?

Answer 18

When the basilar membrane is flexed it bends the stereocilia embedded in the overlying tectorial membrane

Question 19

How does the movements of the stereocilia affect sound movement?

Answer 19

The movements of the stereocilia are transduced in action potentials in the cochlear nerve

Question 20

How are hair cell’s stereocilia connected?

Answer 20

By tip links

Question 21

Where are the mechanosensitive ion channels located in the stereocilia?

Answer 21

Near the tips and are involved in sound transduction

Question 22

Describe signal transduction in the vertebrate hair cell

Answer 22

Deformation of the stereocilia leads to the opening or closing of the mechanosensitive ion channels
When the ion channels open, K+ will enter the cells
Ca2+ enters then neurotransmitter is released

Question 23

How are frequencies detected in the cochlea?

Answer 23

Pressure waves of different frequencies flex the basilar membrane at different locations

Question 24

Do low or high frequencies travel further?

Answer 24

Low

Question 25

How does the ear know abound sound frequency?

Answer 25

Depending on what hair cells are activated

Question 26

Describe the structure of the inner ear

Answer 26

3 semi-circular canals arranged in planes

The base contains a swelling (ampulla) and a series of sacs including the utricle and saccule

Question 27

What class of animals are the only ones with a cochlear?

Answer 27

Mammals

Question 28

Where are the mechanoreceptors of the utricle and saccule found?

Answer 28

In the maculae

Question 29

Where are the hair cells of each macula?

Answer 29

Embedded in a gelatinous matrix that is overlain with a series mineralised otoliths

Question 30

What are the otoliths made of?

Answer 30

Calcium carbonate

Question 31

What do the utricle and saccule do?

Answer 31

Detect gravity and are important for determining the position of the body

Question 32

What do the semi-circular canals consist of?

Answer 32

A fluid-filled tube a swelling (ampulla) at the bottom

Question 33

What is the fluid in the semi-circular canals?

Answer 33

Endolymph (high conc. K+)

Question 34

What does ampulla contain?

Answer 34

A neuromast that senses pressure

Question 35

Where are the hair cells in the semi-circular canals?

Answer 35

Embedded in a cup-shaped gelatinous mass called the cupula

Question 36

What is the state of the hair cells of the neuromast at rest?

Answer 36

Partially depolarised

Question 37

What is the state of the hair cells in the neuromast when the head is tilted?

Answer 37

The fluid exerts pressure in the opposite direction causing the stereocilia of the hair cells to pivot thus either depolarising or hyperpolarising depending on the orientation

Question 38

Describe insect ears?

Answer 38

Some have tympanal membranes (eardrums) in their legs
Sound waves are transmitted through the trachea within the legs
Mechanoreceptors in the legs can discriminate sound frequencies

Question 39

Describe how TRP proteins work?

Answer 39

They span the membrane and when open allow Na+ and Ca2+ to enter

Question 40

What specialized part do thermo-TRP have?

Answer 40

A C-terminal domain that is responsible for thermosensation

Question 41

Describe TRPA1 in snakes

Answer 41

Important for the infrared sense in snakes

Located in the trigeminal nerve fibres of the pit organs

Question 42

What part of the brain regulated body temperature in mammals?

Answer 42

Hypothalamus