Nervous System

Question 1

How many neurons are in the brain?

Answer 1

85 billion

Question 2

How many neurons are in the spinal cord?

Answer 2

100 million

Question 3

How many neurons are in the walls of the GI tract?

Answer 3

100 million

Question 4

How many pairs of spinal nerves are there?

Answer 4

31

Question 5

What are the two other names for a neuron cell body?

Answer 5

1. Soma
2. Perikaryon

Question 6

What is the name for the pigment that takes the form of clumps of yellowish-brown granules in the cytoplasm?

Answer 6

Lipofuscin

Question 7

What are the four basic senses?

Answer 7

Touch, temperature, pressure, pain

Question 8

Where are multipolar neurons often found and what neuron type (motor, sensory, interneuron) is always multipolar?

Answer 8

CNS; all motor neurons are multipolar

Question 9

What three areas contain bipolar neurons?

Answer 9

Retina, inner ear, olfactory area of brain

Question 10

Where are the cell bodies of unipolar neurons found?

Answer 10

The ganglia of spinal and cranial nerves

Question 11

What is a ganglion?

Answer 11

A cluster of neuronal cell bodies in the PNS

Question 12

With respect to neurology, and not cell biology, what is a nucleus?

Answer 12

A cluster of neuronal cell bodies in the CNS

Question 13

What is the neurology definition of a nerve?

Answer 13

A bundle of axons in the PNS

Question 14

What is a tract?

Answer 14

A bundle of axons in the CNS

Question 15

What is an electrochemical gradient?

Answer 15

When a concentration gradient also has an electrical gradient

Question 16

What is the conus medullaris?

Answer 16

The conical end of the spinal cord between vertebrae L1 and L2

Question 17

Where are the cell bodies of sensory interneurons located?

Answer 17

Posterior horn

Question 18

Where are the cell bodies of sensory neurons located?

Answer 18

Posterior root ganglion

Question 19

Where are the cell bodies of autonomic neurons located?

Answer 19

Lateral horn

Question 20

Where are the cell bodies of somatic motor neurons located?

Answer 20

Anterior horn

Question 21

What is the average mass of the brain?

Answer 21

1300g

Question 22

What are the four types of reflexes?

Answer 22

Stretch, tendon, flexor (aka withdrawal), crossed extensor

Question 23

Which cranial nerve is the smallest?

Answer 23

CN IV Trochlear

Question 24

Which nerve (cranial or spinal) innervates the most muscles?

Answer 24

CN VII Facial

Question 25

What are chromaffin cells?

Answer 25

Cells within the adrenal glands that secrete epinephrine and norepinephrine

Question 26

What are the two neurons usually involved in an ANS motor system?

Answer 26

Preganglionic neuron and autonomic ganglion (aka postganglionic neuron)

Question 27

What is a Type-A nerve fiber?

Answer 27

Largest-diameter nerve fibers with the fastest impulse transmission and shortest relay speed. They're myelinated and are used for skeletal motor neurons and most of the basic sensory neurons

Question 28

What is a Type-B fiber?

Answer 28

Myelinated fibers with a middling diameter. their impulse speed is slower than A-fibers but faster than C-fibers. They typically compose the ANS sensory and preganglionic motor neurons

Question 29

What is a Type-C fiber?

Answer 29

An unmyelinated neuron fiber with the smallest diameter and the slowest impulse speed. They typically compose some SNS and ANS sensory neurons and the ANS postganglionic motor neurons

Question 30

What is the major difference between SNS and PNS motor neurons

Answer 30

SNS motor neurons synapse near the spine while PNS motor neurons synapse near the organ

Question 31

Which four cranial nerves make up the cranial portion of the PNS?

Answer 31

CN 3, CN 7, CN 9, CN 10

Question 32

What are the two tracts of the posterior column in the spinal cord?

Answer 32

1. Gracile fasciculus 2. Cuneate fasciculus

Question 33

Which nucleus of the hypothalamus is involved in arousal (waking?)

Answer 33

Suprachiasmatic nucleus

Question 34

Which sensory modality does not trigger the RAS?

Answer 34

Olfaction