Lecture 13

Question 1

Where is the primary afferent neuron located?

Answer 1

It has its cell body in the dorsal root ganglion, axon passes from the periphery past the basal ganglia.

Question 2

What are the sensory endings of the primary afferent neuron called?

Answer 2

Sensory receptors

Question 3

What is the anterolateral pathway?

Answer 3

It responds to sensory input regarding pain, temperature and touch.
the primary afferent neuron synapses at the spinal cord and crosses over. The secondary neuron axon synapses at the thalamus. The tertiary axon ends in the somatosensory cortex.

Question 4

What is the dorsal column pathway?

Answer 4

It responds to fine touch and position of the limbs.
The primary afferent neuron goes up the dorsal column and into the spinal cord. It synapses at the dorsal column nucleus. The secondary axon synapses in the thalamus, and the tertiary in the sensory cortex.

Question 5

TRUE or FALSE - all receptive fields are the same size

Answer 5

FALSE - receptive fields vary in size and density on different parts of the body

Question 6

Where is the Reticular activating system located?

Answer 6

In the brainstem

Question 7

Where do we detect (in the brain) proprioception and touch?

Answer 7

The cerebellum

Question 8

What is the role of sensory receptors in the skin?

Answer 8

to convert physical stimulus to action potentials in primary sensory neuron (transduction).

Question 9

What are the four types of sensory skin receptors?

Answer 9

1. temperature (thermoreceptors)
2. position of limbs (proprioceptors)
3. touch receptors
4. pain (nociceptors)

Question 10

What do temperature receptors respond to?

Answer 10

changing temperature. different types of receptors are more active at warm or cold temperature ranges

Question 11

Where are proprioceptors located?

Answer 11

muscle spindles, Golgi tendon organs, join capsule

Question 12

What do nociceptors respond to?

Answer 12

Extreme mechanical, temperature and chemical stimuli. they are polymodal

Question 13

What are the characteristics of touch receptors?

Answer 13

• sensitive to mehcanical deformation

- there are various types with different sensitivities and locations

Question 14

What is the function of hair receptors?

Answer 14

Inform the brain about air flow - touch without touch even occurring `

Question 15

What is the pacinian corpuscle?

Answer 15

It is part of touch receptors. It increases the surface area for sensory information. the pecinian corpuscle can be found on myelinated axons in the PNS. It allows for precise, real-time sensation

Question 16

What are the four characteristics of sensory coding?

Answer 16

1. modality - specificity of receptors
2. intensity - frequency of action potentials in each axon
3. location - mapping of receptive fields of individual primary afferents to specific cortical location
4. duration

Question 17

What are the two types of duration sensory coding receptors?

Answer 17

1. rapidly adapting receptors - respond briefly, even if the stimulus is sustained.
2. slowly adapting receptors - signal true duration of the stimulus

Question 18

TRUE or FALSE - information from different sensory receptors can have overlapping receptor fields.

Answer 18

TRUE

Question 19

How is the overlapping of receptive fields useful?

Answer 19

The overlapping of receptive fields allows them to interact, resulting in additional precision and information.

Question 20

What is lateral inhibition?

Answer 20

It is a mechanism which increases accuracy of sensory information.
it is mediate by inhibitory neurons. Lateral inhibition localises sensation to a restricted area of the skin, for reveal the accurate location of a stimulus. It results in centre-surround inhibition.