General Senses

Question 1

What does receptive field mean?

Answer 1

Area monitored by single sensory neuron

Question 2

What does receptor specificity mean?

Answer 2

Each receptor prefers a specific type of stimulus (mechanical, chemical, temperature).

Question 3

How does a receptor respond to a stimulus?

Answer 3

• Stimulus opens chemically or mechanically gated channels and causes a graded potential at the trigger zone.
• Undergoes transduction
• Reaches a threshold, then produces an action potential.

Question 4

What is a threshold?

Answer 4

Minimum stimulus intensity require to activate a receptor.

Question 5

What is transduction?

Answer 5

Conversion of stimulus into information that can be transformed by nervous system.

Question 6

What are examples of action potential patterns?

Answer 6

• Tonic: continuous action potential that increase/decrease in response to strength of stimulus
• Phasic: silent, AP occurs in presence of stimulus
• Tonic phasic

Question 7

What are the four classes of receptors?

Answer 7

• Thermoreceptors: Temperature.
• Chemoreceptors: Chemical or chemical concentration.
• Mechanoreceptors: Physcial disortion of plasma membrane
• Nociceptors: Actual or potential tissue damage.

Question 8

Describe thermo receptors

Answer 8

• Monitors non-painful temperature and helps to maintain stable body temperature.
• Located in the skin and CNS (hypothalamus and spinal cord).

Question 9

Describe chemo receptors

Answer 9

• Detect small changes in the concentration of specific chemical or pH.
• Respond to stimuli that physically distort plasma membrane.

Question 10

Describe nociceptors

Answer 10

• Detect actual or potential tissue damage.
• Has a large receptive field, why it is difficult to determine exact source of painful sensation
• Discharge action potential in response to: extreme temperature, mechanical damage, dissolved chemicals.

Question 11

What is stimulus location?

Answer 11

Destination of sensory information in central nervous system provides information about where sensory information originated from the body.

Question 12

What is stimulus intensity?

Answer 12

Number of receptors activated and frequency of discharge of action potentials.

Question 13

What is stimulus duration?

Answer 13

How long does the sensory neuron discharge action potentials?

Question 14

What does adaptation refer to and what are the 2 types?

Answer 14

• Change in response to constant stimulus.

- Peripheral and central

Question 15

What is peripheral adaptation?

Answer 15

• Involves change in activity of receptor.

- Decreases amount of information in central nervous system

Question 16

What is central adaptation?

Answer 16

• Involves change in within central nervous system

- Decreases amount of information in cerebral cortex

Question 17

What are the 3 classes of mechanoreceptors?

Answer 17

• Tactile receptors: touch, pressure, vibration.
• Baroreceptor: minor changes in pressure.
• Proprioceptor: position, stretch and tendon.

Question 18

Can you name one specific example of a mechanoreceptor found in skin

Answer 18

Muscle spindles (increases skeletal muscle stretch).

Question 19

Where are muscle spindles and Golgi receptors found.

Answer 19

Muscles spindles: skeletal muscle tissues, they run parallel to muscle fibers.
Golgi tendon organs: collagen fibers of tendons and joint capsules.

Question 20

What type of stimulus do muscle spindles and Golgi tendon organs detect?

Answer 20

The type of stimulus they detect is change in muscle stretch/length.

Question 21

What shape are sensory neurons and where is the receptor, axon and cell body located?

Answer 21

Receptors are located on dendrites of sensory neurons. Cell body is located in the dorsal root ganglion.
Axon enters spinal cord via dorsal root.

Question 22

What is the first order neuron?

Answer 22

Is the receptor on dendrites of sensory neuron.

Question 23

What is the second order neuron?

Answer 23

Relays sensory information from spinal cord to thalamus.

Question 24

What is the third order neuron?

Answer 24

Relays sensory information from thalamus to

primary somatosensory cortex.

Question 25

What happens when action potentials reach the spinal cord?

Answer 25

Trigger reflex and may also be relayed to the cerebral cortex.

Question 26

What is the spinothalamic pathways?

Answer 26

-Anterior and lateral spinothalaic pathways
-Dorsal column medial meniscal pathways
1) Peripheral tissues
Receptors on dendrites of sensory neurons
First order neurons
2) Spinal Cord
Second order neurons
3) Thalamus
Third order neurons

Question 27

What is the role of primary somatosensory cortex in spinothalamic pathways?

Answer 27

-Sends information to primary somatosensory cortex.
Posterior Parietal Cortex
-Integrates somatosensory information with particularly visual system.
-Perception & interpretation of spatial relationships.
-Accurate body image.
-Learning tasks that involve accurate coordination of body in space.

Question 28

What is the difference with spinocerebellar pathways?

Answer 28

• Only first and second order neurons.
• Second order neurons may or may not cross the midline.
• No thalamus.
• Terminates in cerebellum instead of somatosensory cortex.

Question 29

What does somatic sensation below neck involve?

Answer 29

• Anterior and lateral spinothalamic pathways.
• Dorsal column medial lemniscal pathway
• Spinocerebellar pathway.

Question 30

What does somatic sensation above the neck involve?

Answer 30

Trigeminal nerve (cranial nerve V).