Afferent

Question 1

What are the anatomical components of the peripheral nervous system (PNS)?

Answer 1

The components of the PNS are the cranial and spinal nerves.

Question 2

What is the functional organization of the PNS? In other words, can you schematically explain the organization of the efferent division and the afferent division of the PNS?

Answer 2

There are two divisions of the PNS. The afferent division consists of sensory innervation which include somatosensory, special sensory, and visceral innervation. The efferent division consists of somatic and autonomic innervation. Autonomic innervation includes cardiac, smooth muscle, glandular, and adipose innervation. The autonomic system also breaks down into the sympathetic, parasympathetic, and enteric nervous systems.

Question 3

Sensory information enters the afferent division of the PNS. What are exteroceptors?

Answer 3

Exteroceptors are sensory receptors that receive external stimuli for both special and somatic senses, and send the sensory information to the CNS.

Question 4

What are proprioceptors and what type of information do they send to the CNS?

Answer 4

Proprioceptors are sensors that provide information about joint angle, muscle length, and muscle tension, which is integrated to give information about the position of the limb in space.

Question 5

What are interoceptors and what type of information do they send to the CNS?

Answer 5

Interoceptors are receptors that receive stimuli of internal organs (i.e., visceral senses).

Question 6

Interoceptors are receptors that receive stimuli of internal organs (i.e., visceral senses).

Answer 6

There are 12 pairs of cranial nerves. Some, but not all, are mixed.

Question 7

How many pairs of spinal nerves are there?

Answer 7

There are 31 pairs of spinal nerves

Question 8

What are the different types of intervertebral disc abnormalities that can occur and how can these issues relate to spinal stenosis?

Answer 8

Intervertebral disc deterioration and herniation are intervertebral disc abnormalities that can occur. These can lead to spinal stenosis, causing a narrowing of the open spaces within your spine. This can put pressure on your spinal cord and spinal nerves.

Question 9

What is a ventral root composed of?

Answer 9

A ventral root is composed of motor neurons.

Question 10

What is a dorsal root composed of?

Answer 10

A dorsal root is composed of sensory neurons.

Question 11

What is a dorsal root ganglion composed of? I

Answer 11

A dorsal root ganglion contains the cell bodies of unipolar neurons.

Question 12

What is a ventral ramus?

Answer 12

A ventral ramus is the anterior division of a spinal nerve.

Question 13

What is a dorsal ramus?

Answer 13

A dorsal ramus is the posterior division of a spinal nerve.

Question 14

What are the sympathetic chain ganglia?

Answer 14

Sympathetic chain ganglia are paired bundles of nerve fibers, and aggregations of nerve cell bodies, that run from the base of the skull to the coccyx. They are part of the autonomic nervous system.

Question 15

What two components of the PNS combine to form a spinal nerve?

Answer 15

Ventral and dorsal roots combine to form a spinal nerve.

Question 16

What are the three neurons involved and how do they communicate with one another?

Answer 16

The three neurons involved include: afferent neurons, interneurons and motor neurons. These neurons communicate through the neurotransmitters that are released in the synaptic clefts between them.

Question 17

• If you touched a hot stove with your hand, you would reflexively remove your hand from the stove. Does the brain regulate this muscle activity required to remove your hand? Do you sense the pain before or after your hand is withdrawn?

Answer 17

No, the brain does not regulate this muscle activity required to remove your hand. The pain is perceived in the brain after the hand is withdrawn.

Question 18

What are mechanoreceptors and what are some general examples?

Answer 18

Mechanoreceptors respond to mechanical stimuli. Some examples of mechanoreceptors include tactile receptors, baroreceptors and proprioceptors.

Question 19

What are the three examples of tactile receptors in the skin and what do they detect?

Answer 19

Pacinian corpuscles sense deep touch, while Meissner’s corpuscles and Merkel cells sense light touch.

Question 20

What do ipsilateral and contralateral mean?

Answer 20

Senses that are processed ipsilaterally converge at the level of the brain stem. Senses that are processed contralaterally converge at the level of the spinal cord.

Question 21

Which receptors would inform you of an ice cube that was just placed on your arm?

Answer 21

Thermoreceptors

Question 22

Which receptors would inform you of the taste of a cup of coffee?

Answer 22

Chemoreceptors.

Question 23

Which receptors would inform you of the pain of stepping on a nail?

Answer 23

Nociceptors and mechanoreceptors.

Question 24

Are nociceptors tonic or phasic receptors?

Answer 24

Nociceptors are tonic (slowly adapting).

Question 25

When you put on your shirt/top/blouse in the morning, you can feel it on your skin; however, several hours later the feeling is “gone.” Based on this fact, are tactile receptors tonic or phasic?

Answer 25

Tactile receptors are phasic (quickly adapting).

Question 26

Are odorant receptors phasic or tonic?

Answer 26

Odorant receptors are phasic.

Question 27

The receptor portion of tactile receptors (e.g., Meissner’s and Pacinian corpuscles) is literally a modification of what portion of the neuron?

Answer 27

The receptor portion of one of these sensory neurons is a modification of a dendrite.

Question 28

What happens to the membrane of the receptor as a result of receiving a stimulus?

Answer 28

As a result of receiving a stimulus, ion channels open, allowing sodium to enter, leading to the generation of the first action potential at the initial segment of the neuron.

Question 29

If you had a lesion on your arm, what medications could you take to reduce the activity of prostaglandins, histamine and substance P?

Answer 29

To reduce the activity of prostaglandins, you would take an NSAID (e.g., ibuprofen, aspirin); to reduce the activity of histamine, you would take an antihistamine (e.g., Benadryl); to reduce the activity of substance P, you would take capsaicin.

Question 30

What do opiates mimic?

Answer 30

Heroin and prescription opioids chemically resemble the brain’s natural opioids (i.e., endorphins).

Question 31

Does nociceptive information travel to the brain contralaterally or ipsilaterally?

Answer 31

Nociceptive information travels to the brain contralaterally.

Question 32

The phenomenon of referred pain is thought to exist as the result of “cross-talk” between neurons. Where is it believed that this cross-talk occurs?

Answer 32

Cross-talk occurs in the spinal cord gray matter or dorsal root ganglia.

Question 33

Can you use this information to explain how an individual can experience pain in the arm when they are having chest pain due to a heart attack?

Answer 33

When a person is having a heart attack, the pain fibers in the heart and hand go to the spinal cord and they converge (cross-talk). The pain fibers from the heart can induce action potentials in the pain fiber coming from the arm.

Question 34

What are the five different types of special senses?

Answer 34

Taste (gustation), smell (olfaction), sight (vision), hearing (audition) and balance/equilibrium (equilibrioception).

Question 35

Based on your list, would you expect these senses to enter the nervous system at the level of the spinal cord or brain?

Answer 35

These senses enter the nervous system at the level of the brain.

Question 36

How many cells are involved in the peripheral processing of olfactory information?

Answer 36

There are 2 cells involved in the peripheral processing of olfactory information.

Question 37

In what cell are action potentials generated?

Answer 37

An action potential is generated in the primary bipolar sensory neuron and the secondary sensory neuron.

Question 38

Thinking anatomically, can you explain why smell is the only special sense that does not enter the brain by relaying through the thalamus?

Answer 38

The primary neurons enter the brain through tiny holes in the floor of the cranium and synapse with the secondary neurons in the olfactory bulbs at the base of the brain.

Question 39

What are the five different tastes we can perceive and what is/are the tastant(s) for each of these different tastes?

Answer 39

For bitter, the tastants are coffee, beer, unsweetened cocoa, earwax, etc.; for sweet, the tastants are monosaccharides; for umami, the tastant is glutamate; for sour, the tastant is proton; for salty, the tastant is sodium.

Question 40

Is “spicy” one of the basic tastes? Why or why not?

Answer 40

Our bodies detect spice using a completely different system than the one for taste. The nerve that sends touch, pain, and temperature feelings from your face to your brain, interprets it.

Question 41

Many individuals who have experienced COVID-19 symptoms have been said to have “lost their sense of taste”. Is this a true statement?

Answer 41

Technically, no. Many patients notice a loss of their sense of smell. However, because smell is necessary to taste flavor, these individuals are no longer able to discern flavors.

Question 42

How many cells are involved in the peripheral processing of gustatory information?

Answer 42

2 cells are involved in the peripheral processing of gustatory information. These are the taste receptor cell and the bipolar sensory neuron.

Question 43

In what cell are action potentials generated?

Answer 43

Action potentials are generated in the bipolar sensory neuron.