3.6.1.2 receptors Flashcards

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1
Q

Give the location of osmoreceptors in the body of a mammal

A

hypothalamus

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2
Q

When a person is dehydrated the water volume of an osmoreceptor falls - why?

A
  1. Water potential of blood will decrease;
  2. Water moves from osmoreceptor into blood by osmosis;
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3
Q

What is the function of a receptor cell?

A

To detect stimuli

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4
Q

The pressure receptors found in the skin are called…

A

Pacinian Corpuscles

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5
Q

Pacinian corpuscles respond to which type of stimuli?

A

Mechanical pressure.

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6
Q

Receptors cells are transducers. What is a transducer?

A

Something that converts one form of energy (e.g. light) into a form that can be understood by the body (e.g. an electrical impulse).

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7
Q

In order to create an electrical impulse a receptor cell creates a…

A

generator potential.

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8
Q

Where are pacinian corpuscles abundantly found?

A

In the skin of the fingers, genitals, hands, feet, ligaments and tendons.

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9
Q

The cell membrane at the end of the sensory neurone found inside a pacinian corpuscle contains…

A

Stretch-mediated sodium channels

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10
Q

What is a stretch-mediated sodium channel?

A

A sodium channel protein whose permeability to sodium ions increases when they are deformed.

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11
Q

Describe how a generator potential is created by a pacinian corpuscle.

A
  1. In the absence of pressure, stretch-mediated sodium channels in the membrane of the sensory nerve endings found the corpuscle are closed.
  2. This maintains a resting potential difference in Na+ across the membrane (more outside than inside).
  3. Pressure deforms the channel proteins, increasing permeability to Na+.
  4. Na+ influx into cell causes a depolarisation to occur (more Na+ now inside than outside).
  5. The depolarisation creates a generator potential which leads to a wave of depolarisations (action potentials) along the neurone.
  6. This is called an electrical impulse.
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12
Q

In which part of the eye are light receptor cells found?

A

The retina

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13
Q

The 2 types of light receptor cells are called…

A

rod cells
cone cells

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14
Q

Rod and cone cells are transducers. Explain.

A

They convert light energy into an electrical impulse.

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15
Q

Rod cells are responsible for ____________ vision

A

black and white

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16
Q

Why can rod cells only lead to images seen in black and white?

A

They cannot distinguish between different wavelengths of light.

17
Q

Does the eye contain more rod cells or cone cells?

A

Rod cells

18
Q

Rod cells are sensitive to _____ intensity light, cone cells are sensitive to _________ intensity light.

A

Rod cells are sensitive to LOW intensity light, cone cells are sensitive to HIGH intensity light.

19
Q

Why are many rod cells connected to a single sensory neurone?

A
  1. To allow retinal convergence to occur.
  2. The is a greater chance of the threshold value being exceeded to allow an action potential to occur along the sensory neurone. (note: you will need to study next topic to fully understand this).
20
Q

Which pigment, that breaks down in low intensity light, is found inside rod cells?

A

Rhodopsin

21
Q

Because each rod cell connects to multiple single sensory neurones the light from each neurone is not individually distinguishable. This means that rod cells can only produce…

A

LOW VISUAL ACUITY (low resolution)

22
Q

How many types of cone cell are there?

A

3

23
Q

Each of the three types of cone cell contain a specific group of pigments called…

A

iodopsins

24
Q

Does iodopsin break down in the presence of low or high intensity light?

A

high intensity

25
Q

Cone cells are connected to their own individual sensory neurone. True or False?

A

TRUE

26
Q

Because each cone cell connects to a single sensory neuron the light from each neurone is individually distinguishable. This means that cone cells can produce…

A

HIGH VISUAL ACUITY (high resolution)

27
Q

The lens of the eye focuses light at a central point in the retina called the…

A

fovea

28
Q

The outer periphery of the retina (not the fovea) contains _________ cells

A

Rod cells

29
Q

The fovea is where ________ cells are found because it receives the highest intensity of light.

A

Cone cells