3.4.2 Receptors Flashcards Preview

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Flashcards in 3.4.2 Receptors Deck (38)
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1

Receptors only detect ...

one particular stimulus

2

Describe a receptor in its resting state (not being stimulated)

There's a difference in charge between inside and outside of cell

3

What is the difference in charge between inside and outside of receptor cell generated by and what does this mean?

  • Difference is generated by ion pumps and ion channels
  • Means there's a potential difference (voltage) across the membrane

4

What is meant by resting potential?

Potential difference when cell is at rest 

5

Describe how a generator potential is created

  1. When stimulus is detected, cell membrane is excited and becomes more permeable
  2. Allows more ions to move in & out = alerting potential difference
  3. Change in p.d. due stimulus = generator potential

6

Explain how a bigger stimulus results in a bigger generator potential being produced

Bigger stimulus excites membrane more = bigger movement of ions and bigger change in p.d.

7

State when an action potential is generated

 If generator potential is big enough i.e. reaches threshold level, it'll trigger an action potential

8

Describe the size of action potentials

Action potentials are all same size

9

How is the strength of a stimulus measured?

By frequency of action potentials

10

State what SOPI stands for

Sodium Out Potassium In

11

What type of receptors are Pacinian corpuscles?

Mechanoreceptors

(Detect mechanical stimuli e.g. pressure, vibrations)

12

Pacinian corpuscles the contain end of a _____ ____

Pacinian corpuscles contain the end of a sensory neurone 

(Called sensory nerve ending)

13

What is the sensory nerve ending wrapped in?

Lamellae

14

Describe what happens when a Pacinian corpuscle is stimulated

  1. When the Pacinian corpuscle is stimulated the lamellae are deformed and press on the sensory nerve ending
    • = the sensory neurone's cell membrane to stretch
  2. This deforms (stretch-mediated) sodium ion channels
  3. This opens the channels = greater pressure & allows for Na+ to diffuse into the cell creating a generator potential

15

Where are photoreceptors found?

Retina

16

What is the fovea?

An area of retina where there's loads of photoreceptors

17

Nerve impulses from photoreceptor cells are carried from retina to brain by ___ ___ (bundle of neurones)

Optic nerve

18

Where is the blind spot located?

Where optic nerve leaves eye

(aren't any photoreceptor cells)

19

What do photoreceptors do?

Convert light into electrical impulse

20

What happens when light enters the eye?

It hits photoreceptors and is absorbed by light-sensitive pigments

21

Light _____ pigments

bleaches

22

What happens when light bleaches pigments?

  1. Causes chemical change and alters membrane permeability to sodium ions
  2. Generator potential is created & if it reaches threshold = nerve impulse is sent along bipolar neurone

23

What do bipolar neurones do?

Connect photoreceptors to optic nerve, which takes impulses to brain

24

Name the 2 types of photoreceptor the human eye has

  • Rods
  • Cones

25

Where are rods found?

Found in peripheral parts of retina

26

Where are cones found?

Cones packed together in fovea

27

Why do rods and cones give information in different colours?

Rods and cones contain different optical pigments making them sensitive to different wavelengths of light

28

Rods give information in ____

B&W (monochromatic vision)

29

Cones give information in ____

Colour (trichromatic vision)

30

Name the 3 types of cones (each containing a different pigment)

  1. Red-sensitive
  2. Green-sensitive
  3. Blue-sensitive

When stimulated in different proportions = see different colours

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