6. Chapter 10- Sensory Physiology

Question 1

What is the general properties of sensory systems?

Answer 1

A sensory neuron with a transducer (receptor) that converts a physical stimulus into an intracellular signal (change in membrane potential)
Usually through the opening or closing of gated channels
Picture on slide 15 oct 5

Question 2

What are the sensory receptors chemoreceptors, mechanoreceptors, photoreceptors, thermoreceptors,

Answer 2

Chemoreceptors- stimulate oxygen, pH, glucose
( taste smell)
Mechanoreceptors- pressure, cell stretch, vibration, acceleration, sound
(Touch balance auditory)
Photoreceptors- photons of light
(Vision rods and cones)
Thermoreceptors- varying degrees of heat

Question 3

What are mechanically gated channels?

Answer 3

Convert mechanical stimulus to electrical signal

Diagram on slide 17 oct 5

Question 4

What are receptive fields?

Answer 4

Sensory neurons are activated by stimuli that fall within a specific physical area
Convergence creates large receptive fields
Small receptive fields are found in more sensitive areas
Picture on slide 18 oct 5

Question 5

What do somatosensory neurons do?

Answer 5

Bring info to the central nervous system

Question 6

What is visceral sensory information?
What about special senses?
What about somatic senses?

Answer 6

visceral senses are integrated into the brainstem and spinal cord
Special senses have dedicated cortical regions
Somatic senses integrated in the primary somatosensory cortex

Question 7

How does the central nervous system distinguish one sensation from another in all stimuli are converted to action potentials and all action potentials are similar?

Answer 7

Central nervous system distinguishes four properties of a stimulus:

1. Modality (physical stimuli being sensed determined by sensory receptor being activated)
2. Location
3. Intensity
4. Duration

Question 8

How can the location of a stimulus help the central nervous system distinguish it?

Answer 8

They are coded according to which receptive fields are being activated
Most sensory stimuli for specific regions of the body are projected to particular areas of the somatosensory cortex
Picture on slide 22 oct 5

Question 9

What can increase the accuracy of localization?

Answer 9

Lateral inhibition

Picture on slide 23 oct 5

Question 10

What are intensity and duration of a stimulus determined by?

Answer 10

Intensity is determined by the number of receptors being activated (population coding) and frequency of action potentials coming from those receptors (frequency coding)
Duration is determined by how long action potentials are being activated
Picture on slide 7-8 oct 10

Question 11

What are the 5 points of sensory pathway specificity?

Answer 11

1. Each receptor is most sensitive to s type of stimulus
2. Stimulus above threshold initiates APs in a sensory neuron that projects to CNS
3. Stimulus intensity and duration are coded in the pattern of APs reaching the CNS
4. Stimulus location and modality are coded with which receptors are activated
5. Sensory pathways project a specific region of cerebral cortex dedicated to a particular receptive field

Question 12

What is sensory nerve convergence?

Answer 12

Multiple primary sensory neurons synapse on a single secondary neuron
Is the reason why receptive fields can be large