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Biology-14-Response To The Stimuli > Receptors > Flashcards

Flashcards in Receptors Deck (21):
1

What is a pacinian corpuscle specific to

A single type of stimulus, in this case it responds only to mechanical pressure. It will not respond to other stimuli such as heat light or sound

2

What does a pacinian corpuscle produce

A generator potential by acting as a transducer

3

What’s the role of the transducer in the pacinian corpuscle

Convert the change in form of energy by the stimulus into a form, namely nerve impulses, that can be understood by the body

4

Receptors in the nervous system convert the energy of the stimulus into a nervous impulse; what’s this known as

Generator potential

5

What do pacinian corpuscle respond to

Mechanical stimuli

6

How does the pacinian corpuscle function with a stretch mediated sodium channel

The stretch mediated sodium channels of the membrane around the neurone of a pacinian corpuscle are too narrow to allow sodium ions to pass along them. The neurone of the pacinian corpuscle has a resting potential

When pressure is applied to the pacinian corpuscle, it is deformed and the membrane around its neurone becomes stretched

This stretching widens the sodium channels in the membrane and sodium ions diffuse into the neurone

The influx of sodium ions changes the potential of the membrane (becomes depolarised) thereby producing a generator potential

The generator potential in turn creates an action potential(nerve impulse) that passes along the neurone and then, via other neurones , to the central nervous system

7

Where are the light receptors of the eye found

The retina

8

What are the two types of receptors in the retina

Rod cells and cone cells

Both act as transducers by conserving light energy into the electrical energy of a nerve impulse

9

why are rod cells images only seen in black n white

As they can’t distinguish different wavelengths of light

10

What’s the difference in sensitivity to light in rod and cone cells

Rod - sensitive to low intensity light

Cone- not sensitive to low intensity light

11

What would increase the chance that the threshold value will be exceeded in the bipolar cell

If only w single rod were connected to each bipolar cell

12

How do we create a generator potential in the rod cell

The pigment in the rod cell must be broken down, there is enough energy from low intensity light to cause this breakdown

13

Why doe rod cells give low visual acuity

As many rod cells link to a single bipolar cell, light received by rod cells sharing the same neurone will only generate a single impulse travelling to the brain. The brain cannot distinguish between the separate sources of light that stimulated them.


Two dots close together cannot be resolved and so will appear as a single blob

14

What do the three types of cone cells do

Each respond to a different range of wavelength


Depending upon proportion of each type that is stimulated, we can perceive images in full colour

15

Why do cone cells only respond to high light intensity

Often have their own separate bipolar cell connected to a sensory neurone in the optic nerve. Meaning that the stimulation of a number of cone cells can not be combined to help exceed the threshold value and so create a generator potential.

16

What does it take to create a generator potential in the cone cells

The pigment in the cone cells requires a higher intensity for its breakdown

17

How are each cone cells different to specific range of wavelengths

They each contain a specific type of iodopsin

18

Why do cone cells give good accurate vision

Each cone cells has its own bipolar cell, meaning that if 2 adjacent cone cells are stimulated the brain receives two different impulses. The brain can therefore distinguish between the two spectate sources of light that stimulated the two cone cells.

This means that two dots close together can be resolved and will appear as two dots

19

Why are cone cells found at the fovea

As this receives the highest intensity of light.

Concentration of cone cells diminishes further away from fovea

20

Where are rod cells found? Why

At the peripheries of the retina

As this is where light intensity is at its lowest

21

Compare the differences between rod and cone cells

R-rod shapes
C- cone shaped

R- greater numbers than cone cells
C- fewer numbers than rod cells

R- distribution-more at the periphery of the retina, absent at the fovea
C- fewer at the periphery of the retina, concentrated at the fovea

R-give poor visual acuity
C- give good visual acuity

R-sensitive fo low intensity light
C-not sensitive to low intensity light

R-one type only
C- three types each responding to different wavelengths of light