Sensory Receptors

Question 1

What are sensory receptors?

Answer 1

Sensory receptors are nerve endings which are often specialised with some non-neural structures. They transduce and convert energy into action potentials.

Question 2

What do sensory receptors do?

Answer 2

Convert sensory information / energy into action potentials.

Question 3

What are the 3 types of sensory receptor?

Answer 3

Mechanoreceptors
Proprioceptors
Nociceptors

Question 4

What do mechanoreceptors do?

Answer 4

Stimulated by mechanical stimuli (pressure/stretch/deformation/touch/pressure).

Question 5

What do proprioceptors do?

Answer 5

Mechanoreceptors in the joints and muscle (signal info about body and limb position).

Question 6

What do nociceptors do?

Answer 6

Respond to painful stimuli, tissue damage and heat.

Question 7

What sensory receptors are stimulated by mechanical stimuli?

Answer 7

Mechanoreceptors.

Question 8

Where do proprioceptors exist?

Answer 8

Joints and muscles.

Question 9

What type of sensory receptor responds to pain?

Answer 9

Nociceptor.

Question 10

What are cutaneous mechanoreceptors and proprioceptors a good example of?

Answer 10

Peripheral sensory processing and ion channel transduction.

Question 11

What does an adequate stimulus cause?

Answer 11

Graded potential membrane change.

Question 12

What is the graded potential membrane change called in sensory receptors?

Answer 12

Receptor potential or generator potential.

Question 13

What does membrane deformation lead to?

Answer 13

Activates stretch-sensitive ion channels so ions flow across the membrane and change the membrane potential locally.

Question 14

What is generator potential graded to?

Answer 14

Stimulus intensity.

Question 15

What does generator potential trigger?

Answer 15

Triggers ions to flow through the membrane locally and when depolarisation reaches the VG-ion channel area, action potentials start firing.

Question 16

When do action potentials start firing?

Answer 16

When depolarisation reaches the VG-ion channel area.

Question 17

What is frequency coding?

Answer 17

In a sensory nerve, a larger stimulus causes a larger receptor potential and a larger frequency of action potentials.

Question 18

What is the link between larger generator potential and larger frequency of action potentials called?

Answer 18

Frequency coding.

Question 19

What is the skin packed with?

Answer 19

Sensory receptors for touch.

Question 20

What does the information of skin touch receptors depend on?

Answer 20

Properties of nerve endings and of accessory, non-neural structures.

Question 21

What is adaptation?

Answer 21

Adaptation occurs when mechanoreceptors only respond to a change or novel event.

Question 22

Do different receptors show the same level fo adaptation?

Answer 22

No- they all show different levels.

Question 23

How are adapting receptors characterised?

Answer 23

Rapid/moderately adapting receptors

Slow adapting receptors

Question 24

Do nociceptors adapt?

Answer 24

No.

Question 25

Why do nociceptors not adapt?

Answer 25

To prevent painful stimuli from being ignored.

Question 26

What is the best understood mechanoreceptor?

Answer 26

Pacinian corpsicule.

Question 27

What is the Pacinian corpsicule?

Answer 27

Best understood mechanoreceptor.

Question 28

How is the Pacinian corpsicule structured?

Answer 28

It comprises a myelinated nerve with a naked nerve ending enclosed by a connective tissue capsule of layered membrane lamellae with each layer separated by fluid.

Question 29

What is each layer of membrane lamellae separated by in the Pacinian corpsicule?

Answer 29

Fluid.

Question 30

What happens in the Pacinian corpsicule after a stimulus is detected?

Answer 30

A mechanical stimulus deforms the capsule and nerve ending. This stretches the nerve ending and opens ion channels. Na+ influx causes local depolarisation (generator potential)- APs are generated and fire where myelination begins.

Question 31

What causes the opening of ion channels in the Pacinian corpsicule?

Answer 31

Stretching of nerve ending.

Question 32

What causes the local depolarisation in the Pacinian corpsicule.

Answer 32

Na+ influx causes local depolarisation resulting in a generator potential.

Question 33

Does the Pacinian corpsicule show adaptation?

Answer 33

Shows rapid adaptation through fluid distribution.

Question 34

What does rapid fluid distribution cause in the Pacinican corpsicule?

Answer 34

Rapid adaptation.

Question 35

What happens to Pacinian corpsicule adaptation of lamellae are lost?

Answer 35

Adaptation is lost.

Question 36

What happens do Pacinian corpsicule if the capsule is intact?

Answer 36

On/off function remains intact.

Question 37

What happens to Pacinian corpsicule if the capsule is damaged?

Answer 37

Bare nerve ending loses adaptation because a continuous generator potential is upheld.

Question 38

What is the function of the Pacinian corpsicule dependent on?

Answer 38

Accessory non-neural capsule structure.

Question 39

What does the capsule non-neural accessory structure do in the Pacinian corpsicule?

Answer 39

Enhances sensory function.

Question 40

What are receptive fields?

Answer 40

Specific areas where somatic sensory nerves are stimulated.

Question 41

In what areas are somatic sensory nerves stimulated?

Answer 41

Receptive fields.

Question 42

What is the name of a test that measures our ability to determine 2 points on the skin?

Answer 42

2 point discrimination test.

Question 43

What is our ability to determine 2 points dependent on?

Answer 43

Receptive field size | Neuronal convergence

Question 44

What is neuronal convergence?

Answer 44

When multiple presynaptic neurons input on a smaller number of post-synaptic neurons.

Question 45

What neurones exhibit neuronal convergence?

Answer 45

Neurones with neighbouring receptive fields.

Question 46

What might neurones with neighbouring receptive fields exhibit?

Answer 46

Neuronal convergence.

Question 47

What does convergence allow?

Answer 47

Summation of sub-threshold stimuli.

Question 48

What do lots of convergence and a large receptive field indicate?

Answer 48

Low sensitivity.

Question 49

What areas of the body are sensitive?

Answer 49

Fingers/lips are more sensitive than limbs/back.

Question 50

What is acuity?

Answer 50

Acuity is the ability to locate a stimulus on the skin and differentiate it from another close by.

Question 51

What is low acuity caused by?

Answer 51

Low acuity = high levels of convergence.

Question 52

What is lateral inhibition?

Answer 52

Lateral inhibition is when the surrounding lateral areas around a sensory area are inhibited in order to sharpen the contrast between relevant and irrelevant information.