Neurophysiology 5

Question 1

What is the difference between somatic and special senses?

Answer 1

Somatic senses refer to receptors distributed throughout the body.

Special senses refer to specialised organs in specific locations that have a structure associated with reception

Question 2

This pathway has 3 neurons between sensory receptor (in body) and somatosensory neuron in postcentral gyrus

Remember: Postcentral gyrus = Primary Somatosensory Cortex

Answer 2

Dorsal Column Pathway

Question 3

What information does the Dorsal Column Pathway usually carry?

Answer 3

Afferent information

Remember: afferent information goes through the dorsal side of the spinal cord

Question 4

What is mechanism is found in the postcentral gyrus?

Answer 4

Primary Somatosensory Cortex

Question 5

These receptors are stimulated by mechanical forces that DISTORT the plasma membrane

Answer 5

Mechanoreceptors

Question 6

What channel gates do mechanoreceptors have?

Answer 6

Mechanically gated ion channels

Question 7

These receptors trigger the perception of pain.

• usually have free nerve endings
• respond to 3 types of painful/noxious stimuli: thermal/chemical/mechanical
• these receptors are ABSENT from the brain

Answer 7

Nosiceptors

Question 8

This is produced when the presentation of stimulus opens ion channels which leads to a chance in membrane potential in a receptor.

Answer 8

Receptor potential

Question 9

This is a mechanism whereby a stimulus from external environment is converted into a change in membrane potential (so converted from one form into another) so that the presence of stimulus can be detected by the brain.

Answer 9

Signal transduction.

The conversion of stimulus into an action potential.

Question 10

This is the area of the body that if stimulated, will result in the firing of an action potential in that axon.

Answer 10

Receptive field (aka where receptors are found)

Question 11

How does the density affect the accuracy of receptor fields?

Answer 11

• higher density = two distinct stimuli can be discriminated more accurately because receptive fields are closer together
• lower density = two distinct stimuli can appear as one because only one receptive field is touched due to distance between the fields.

Question 12

This is made up of a sensory neuron and its associated sensory receptors

Answer 12

Sensory unit

Question 13

This is a motor neuron, its axon and the muscle fibres it controls.

Answer 13

Motor unit

Question 14

This kind of receptor is constantly active to reflect background level of stimulation. It is slowly adapting.

Answer 14

Tonic receptors

Question 15

This kind of receptor is normally silent, responds briefly to change. It is fast adapting.

Answer 15

Phasic receptor (like how something will phase; like how quick a phase can be)