4. Sensory Receptors and Pathways

Question 1

What type of neurons are pain receptors?

Answer 1

Simple
Free nerve endings
Unmyelinated

Question 2

What type of neurons are mechanoreceptors?

Answer 2

Complex
Enclosed nerve ending
Myelinated axon

Question 3

What type of neuron is a hair cell?

Answer 3

Specialised receptor cell

Myelinated

Question 4

What receptors are found within the dermis?

Answer 4

Hair receptor
Merkel's disc
Pacinian corpuscle
Ruffini endings
Meissner's Corpuscles

Question 5

What does Merkel’s disc react to?

Answer 5

Indentation

Question 6

What do Pacinian corpuscles react to?

Answer 6

Vibration

Question 7

What do Ruffini endings react to?

Answer 7

Stretch

Question 8

What do Meissner’s corpuscles react to?

Answer 8

Fine touch

Question 9

What is transduction?

Answer 9

Converting a stimulus to an electrical impulse

Question 10

What is a receptive field?

Answer 10

Area of the body that, when stimulated, results in a change in the firing rate of a sensory neuron

Question 11

How are stimuli coded?

Answer 11

Modality
Location (receptive field)
Threshold
Intensity (no. of receptors, firing rates, type of receptor)

Question 12

What is a tonic receptor?

Answer 12

Fire as long as the stimulus is present at threshold levels

Stops adaptation and desensitisation

Question 13

Name 3 types of tonic receptors

Answer 13

Baroreceptors
Merkel’s disc
Nociceptors

Question 14

What is a phasic receptor?

Answer 14

Fire at onset but not continuously

Filters out unnecessary stimuli

Question 15

What 3 types of stimuli are phasic?

Answer 15

Smell
Pressure
Vibration

Question 16

What types of fibre transmit proprioception, vibration and fine touch?

Answer 16

Aa

Ab

Question 17

What types of fibre transmit pain and temperature?

Answer 17

A

C

Question 18

What 2 stimuli don’t pass through the thalamus sorting centre?

Answer 18

Smell goes directly to cortex

Balance goes directly to cerebellum with a branch to the thalamus

Question 19

What stimuli travel in the spinothalamic/anterolateral tract?

Answer 19

Pain and temperature

Question 20

Describe the spinothalamic tract?

Answer 20

1. Receptor to spinal cord via dorsal root
   Synapse in the dorsal horn
2. Cross spinal cord in anterior commissure
   Ascend in contralateral spinothalamic tract
   Synapse in the thalamus
3. Thalamus to sensory cortex

Question 21

What stimuli travel in the dorsal column/ medial lemniscal tract?

Answer 21

Proprioception
Vibration
Fine touch

Question 22

Describe the dorsal column medial lemniscal tract?

Answer 22

1. Receptor to spinal cord via dorsal root
   Ascend in dorsal column
   Synapse in gracile (LL) or cuneate (UL) nucleus of medulla
2. Decussate in lower medulla to enter medial lemniscus
   Synapse in thalamus
3. Thalamus to sensory cortex

Question 23

What stimulus travels in the spinocerebellar tract?

Answer 23

Unconscious proprioception

Question 24

Describe the spinocerebellar tract for the upper limb?

Answer 24

1. Receptor to spinal cord via dorsal root
   Enters into fasciculus cuneatus
   Ascend in cuneocerebellar tract
   Synapses in accessory cuneate nucleus in medulla
2. Carries impulse to ipsilateral cerebellum through inferior cerebellar peduncle

Question 25

Describe the spinocerebellar tract for the lower limb?

Answer 25

1. Spinal cord through dorsal root
   Ascent in fasciculus gracilis to Clarke’s column
   Synapses
2. Enter ipsilateral dorsal spinocerebellar tract
   Ascends through spinocerebellar tract to medulla
   Enters ipsilateral cerebellum via inferior cerebellar peduncle

Question 26

What is convergence?

Answer 26

Neuron can receive input from many neurons

Question 27

What is divergence?

Answer 27

One neuron communicates with many other neurons