2: Physiology - Primary sensory neurons and their modalities Flashcards Preview

Neurology Week 2 2018/19 > 2: Physiology - Primary sensory neurons and their modalities > Flashcards

Flashcards in 2: Physiology - Primary sensory neurons and their modalities Deck (42)
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1

Which senses is the somatosensory system concerned with?

Touch (inc. fine, firm, pressure, vibration)

Pain

Temperature

Itch

Proprioception

2

Which structures are classed as the

a) CNS

b) PNS?

a) Brain and spinal cord

b) Nerves outside the brain and spinal cord

3

In which nervous system are the bodies of first-order neurons of the somatosensory system found?

PNS

4

Where in the PNS are most first-order neurons found?

Dorsal root ganglion

5

Most first-order neurons are found at the dorsal root ganglion. Where are they found in the head and neck?

Cervical ganglia

6

Which cranial nerve supplies sensory fibres to the anterior head?

CN V

Trigeminal nerve

7

Where do pre-ganglionic sensory fibres from the trigeminal nerve synapse?

Cervical ganglia

8

Second-order neurons of the somatosensory system can be found in either the dorsal horn or the medulla.

Which sensory pathways have second order neurons in the

a) dorsal horn

b) medulla?

a) Dorsal column - medial lemniscus system

b) Spinothalamic tract

9

What sensations are picked up by the

a) DC/ML system

b) spinothalamic tract?

a) Fine touch, proprioception, vibration

b) Firm touch, pressure, temperature, pain

10

Where are third-order neurons of the somatosensory system found?

Thalamus

No matter which pathway

11

In the

a) DC/ML pathway

b) spinothalamic tract

which structures are connected by the first-order neurons?

a) Dorsal root ganglia TO medulla

b) Dorsal root ganglia TO spinal cord

12

As the intensity of a sensory stimulus increases, what happens to the amplitude of the receptor's potential?

As intensity increases, receptor potential amplitude increases

13

A somatic receptor will generate an action potential once a ___ potential has been reached.

threshold

14

To generate a sensory signal, a stimulus must have enough ___ to overcome the threshold potential of the receptor.

intensity

15

In relation to sensory receptors, what is meant by the term adequate stimulus?

Receptors are only activated by the stimulus they are programmed for

e.g a mechanoreceptor won't generate an action potential in response to heat

16

Which type of receptors sense touch, pressure and vibration?

Where are they found?

Mechanoreceptors

Skin

17

Which type of receptors are responsible for proprioception?

Where are they found?

Mechanoreceptors

Joints and muscles

18

Which type of receptors are responsible for detecting temperature?

Thermoreceptors

19

Which type of receptors are responsible for the sensation of pain?

Nociceptors

20

What is an adequate stimulus?

A stimulus matching the type of receptor which senses it

21

Different receptors respond to increasing ___ of stimulus.

intensities

22

What happens to the frequency of action potentials generated by a receptor as the intensity of a stimulus increases?

APs become more frequent

23

Which receptors respond to

a) low intensity stimuli

b) high intensity, damaging stimuli?

a) Thermoreceptors, mechanoreceptors, etc.

b) Nociceptors

24

What is the difference between low intensity receptors and high intensity nociceptors?

Different threshold potentials

i.e each is activated by different intensities of stimulus

25

In slowly adapting receptors, what is the relationship between stimulus intensity and firing rate?

Directly proportional

The greater the stimulus intensity, the greater the firing rate

26

In fast adapting receptors, what increases the firing rate?

Greater RATE of change in stimulus

i.e a sharp increase will increase the firing rate more than a slow one

27

Which two factors affect the conduction velocity of an axon?

1. Diameter of axon (which is difficult to change in real time)

2. Degree of myelination

28

Which type of receptors tend to have the

a) fastest

b) slowest conduction velocities?

a) Proprioceptors (body needs constant feedback on where its bits are)

b) Pain fibres (why there's a delayed response between burning your hand on something and feeling it)

29

Sensory axons are arranged in groups from to C.

What happens to the axon diameter and degree of myelination as you go from A to C?

Axon diameter decreases

Degree of myelination decreases

So conduction velocity decreases

30

What is the term for a sensory nerve's territory on the skin?

Receptive field