receptors 2

Question 1

each receptor

Answer 1

responds to specific stimuli

causes a generator potential - lead to response

Question 2

what are the three receptors

Answer 2

1- Pacinian corpuscle

2- Rods

3- Cones

Question 3

Pacinian corpuscle responds to

Answer 3

pressure changes

Question 4

What is a stimulus?

Answer 4

A detectable change in an organism’s environment.

Question 5

How does an increase in pressure affect the pacinian corpusle

Answer 5

1- More stretch-mediated sodium ion channels are deformed

2- More sodium ion channels open

3- More sodium ion channels diffuse in

4- More depolarisation, so more generator potentials

Question 6

What does the pacinian corpuscle consist of?

Answer 6

Single sensory neurone wrapped with layers of tissue separated by gel.

Question 7

Answer 7

Myelin Sheath

Question 8

Answer 8

Sensory neurone’s axon

Question 9

Answer 9

Lamallae of connective tissue

Question 10

Describe how the pacinian corpusle triggers an action potential

Answer 10

1- Stretch-mediated sodium ion channels are deformed by increased pressure

2- So sodium ion channels open, and sodium ions diffuse in

3- Depolarisation occurs, leading to a generator potential

4- Greater pressure causes more sodium ion channels to open, and so more sodium ions to diffuse in

Question 11

What is the pacinian corpusle are deformed by pressure

Answer 11

stretch-mediated sodium ion channels

Question 12

retina contains

Answer 12

two types of photoreceptors

Question 13

what are the two types of photoreceptors

Answer 13

rods and cones

Question 14

What cells are not found in the fovea

Answer 14

Rod cells

Question 15

What cells are found in the fovea

Answer 15

Cone cells

Question 16

When talking about rod and cone cells, what should be reffered to for each

Answer 16

Colour
Visual acuity
Visual sensitivity
Impulses

Question 17

rods

Answer 17

1- cannot distinguish between different wavelengths of light

2- black and white

3- Detect light at very low intensity

Question 18

Visual acuity of rod cell and why

Answer 18

Low as many rods are connected to one sensory neurone

–> cannot distinguish between different wavelengths of light

Question 19

Colour of rod cell

Answer 19

Cannot distinguish colour

Question 20

Visual sensitivity of rod cell

Answer 20

High, as pigment in rods very sensitive to light

Question 21

why can rod cells detect light at very low intensity

Answer 21

MANY rod cells connect to ONE sensory neurone

(retinal convergence)

Question 22

How do rod cells trigger impulse

Answer 22

1- Rhodopsin (pigement in rod cells) broken down

2- by light energy

3- threshold met in bipolar cells

4- spatial summation

Question 23

bipolar cells

Answer 23

link rod cells to sensory neurone

Question 24

why can a threshold can be reached even in low light in rod cells

Answer 24

many rod cells are connected to a single bipolar cell

Question 25

Colour of cone cell

Answer 25

three types, each sensitive to different wavelengths of light, so detect the colours red, green or blue

Question 26

Visual acuity of cone cell

Answer 26

High as each cone is connected to a seperate neurone

Question 27

Visual sensitivity of cone cell

Answer 27

Low, as pigment is not very sensitive to light

Question 28

How do cone cells trigger impulse

Answer 28

1- Iodopsin broken down 2- only in high light intensity 3- action potentials can only be generated with enough light. 4- Only one cone cell connects to a bipolar cell. 5- no spatial summation occurs 6 -Each cone cell sends seperate impulse to the brain

Question 29

Explain how the fovea enables an eagle to see its prey in detail.

Answer 29

1- High visual acuity. 2- Each cone is connected to a single neurone. 3- Cones send separate impulses to brain.

Question 30

Explain how the high density of rod cells in an owl’s retina enables it to hunt at night.

Answer 30

1- High visual sensitivity. 2- Several rods connected to a single neurone. 3- Spatial summation to overcome threshold.

Question 31

Why can the threshold be reached even in low light energy?

Answer 31

many rod cells are connected to a single bipolar cell - summation.

Question 32

What is retinal convergence?

Answer 32

Many rod cells connect to one sensory neuron.