14.4: Receptors

Question 1

Pacinian corpuscle

Answer 1

A sensory receptor that responds to changes in mechanical pressure

Question 2

Two features of sensory reception as illustrated by the Pacinian corpuscle

Answer 2

• specific to a single type of stimulus

- produces a generator potential by acting as a transducer

Question 3

Transducer

Answer 3

Converts the change in a form of energy by a stimulus into a form that the body can understand eg: into nerve impulses.

Question 4

The stimulus always involves…

Answer 4

… a change in some form of energy

For example: heat, light, sound, mechanical

Question 5

Receptors (therefore) convert…

Answer 5

Receptors convert/ transduce one form of energy into another.

Question 6

Generator potential

Answer 6

Depolarisation of the membrane of a receptor cell as a result of the stimulus.

Question 7

How does the pacinian corpuscle act as a transducer

Answer 7

Transduces the mechanical energy of the stimulus into a generator potential.

Question 8

Stretch-mediated sodium channel

Answer 8

A sodium channel in the plasma membrane of the sensory neurone in the pacinian corpuscle that changes its permeability to sodium when its deformed by stretching.

Question 9

Where is the stretch-mediated sodium channel

Answer 9

In the membrane of the sensory neurone ending at the centre of the pacinian corpuscle

Question 10

Transducer cells

Answer 10

Cells that convert a non-electrical signal

such as light or sound into an electrical (nervous) signal and vice versa.

Question 11

Two main types of light receptor cells in the retina

Answer 11

Rod cells

Cone cells

Question 12

Both rod and cone cells act as…

Answer 12

…transducers by conserving light energy into the electrical energy of a nerve impulse.

Question 13

Rod cells

Answer 13

Can’t distinguish between different wavelengths of light and therefore lead to images being seen only in black and white , more numerous than cone cells.

Question 14

Many rod cells are connected to…

Answer 14

A single sensory neurone in the optic nerve

Question 15

Rod cells use

Answer 15

To detect light of very low intensity.

Question 16

Which cells are rod cells connected to where a generator potential can be created

Answer 16

Bipolar cells

Question 17

Retinal convergence
And means that
Why?

Answer 17

A number of rod cells are connected to a single bipolar cell.
There is a much greater chance of the threshold value being exceeded.
Due to summation

Question 18

What must happen in order to create a generator potential

Answer 18

Break down of the pigment in rod cells (rhodopsin)

Question 19

Consequence of many rod cells linking to the same bipolar cell

Answer 19

Light received by rod cells sharing a neurone will only generate a single impulse regardless of how many of the neurones are stimulated. Therefore the brain can’t distinguish between separate source of light that stimulated them so rod cells have low visual acuity .

Question 20

Cone cells respond to

Answer 20

High light intensity

Question 21

The pigment in cone cells requires…

Answer 21

High light intensity to be broken down

Iodopsin

Question 22

Each cone cell is sensitive to…

Answer 22

…a different specific range of wavelengths

Question 23

Each cone cell has its own…

Therefore

Answer 23

…connection to a single bipolar cell.

Therefore cone cells have good visual acuity .

Question 24

Distribution of rod and cone cell is

Answer 24

Uneven

Question 25

Fovea

Answer 25

Point on the retina that the lens focuses light on opposite the pupil.

Question 26

The fovea receives the…

Answer 26

High intensity of light

Question 27

Which rod/ cone cells are found at the fovea and why

Answer 27

Cone cells

As the fovea receives the highest intensity of light

Question 28

The concentration of cone cells diminishes away from…

Answer 28

…the fovea

Question 29

Where are rod cells found

Answer 29

At the peripheries of the retina where light intensity is the lowest