Sensory Systems

Question 1

What two divisions are the afferent division split into?

Answer 1

• sensory stimuli

- visceral stimuli

Question 2

What is single transduction?

Answer 2

Signal transduction is the conversion of environmental factors into neural information (i.e. action potentials).

Question 3

What are some signal modalities?

Answer 3

• mechanoreception
• thermoreception
• photoreception
• chemoreception
• nociception

Question 4

What is mechanoreception?

Answer 4

Mechanoreception: pressure, body position, sound, acceleration, and gravity (e.g. Pacinian corpuscles, muscle spindles, hair cells in: the organ of Corti, semicircular canals, the utricle and saccule)

Question 5

What is thermoreception?

Answer 5

Thermoreception: temperature (e.g. free nerve endings in skin and core temp sensors in hypothalamus)

Question 6

What is photoreception?

Answer 6

Electromagnetic waves (e.g. rod and cone cells)

Question 7

What is chemoreception?

Answer 7

specific materials / molecules (e.g. olfactory receptors in your nose, and gustatory receptors such as taste buds)

Question 8

What is nociception?

Answer 8

cellular damage (e.g. NK1 receptor for Substance P)

Question 9

What types of receptors are there?

Answer 9

• a sensory neuron (afferent) is directly stimulated

- a sensory cell is stimulated which then indirectly acts by affecting one or more afferent neurons

Question 10

State an example of a mechanoreceptor

Answer 10

The lamellar corpuscles (a.k.a. Pacinian corpuscles) in your skin. Your skin has lots of different mechanoreceptors, along with some thermoreceptors and nociceptors (for damage).

Question 11

How does the Pacinian corpuscle work?

Answer 11

Lamellar corpuscles (a.k.a. Pacinian corpuscles) are dendrites that are surrounded by layers (lamellae) of connective tissue. When these are distorted by a physical pressure gradient, the dendrite membrane stretches, which opens special sodium ion channels. Once sodium rushes in, it opens voltage-gated ion channels and the signal travels down the myelinated part of the dendrite to the soma and axon hillock. It may then trigger an action potential down the axon.

Question 12

State an example of proprioception

Answer 12

stretching the muscles activates the muscle spindle, there is an increased rate of action potential in Ia fibres.
the spindles respond (and inform the brain of) two things:
1) muscle length
2) rate of change of length