Histology-World!

 

 

 

Histology Testbank: Nervous System 2a

 

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
Which of the following forms myelin in the peripheral nervous system?
a. Schwann cells
b. Basket cells
c. Ganglion
d. Neuroglia
e. Satellite cells

Answer: a

Schwann cells are responsible for the myelination of neurons in the peripheral nervous system. Basket cells are a type of neuron seen in the cerebellum. A ganglion is a collection of nerve cell bodies outside of the CNS. Neuroglia are the supporting cells in the central nervous system Sometimes, neuroglia called glial cells or glia. Satellite cells are found in the ganglia of the peripheral nervous system.

2.
Which of the following is an element of the central nervous system?
a. Receptors
b. Brachial plexus
c. Sciatic nerve
d. Ganglia
e. Spinal cord

Answer: e

The central nervous system consists of the brain and spinal cord. All other nervous system elements are considered to be in the peripheral nervous system. Thus the peripheral nervous system includes receptors, the brachial plexus, the sciatic nerve, and ganglia.

3.
What are motor neurons?
a. Unipolar
b. Pseudounipolar
c. Bipolar
d. Multipolar
e. Both a and b

Answer: d

Motor neurons are multipolar.

Neurons can be classified based on the number of axons and dendrites stemming off of the cell body. A unipolar neuron has one process which branches off of it This process then immediately divides into two. Thus, a unipolar neuron is sometimes also called a pseudounipolar neuron. Sensory neurons are unipolar.

A bipolar neuron has two process that branch from it: an axon and a dendrite. Bipolar neurons are not very common and are found in some of the organs for special senses. Bipolar neurons are found in the retina, inner ear, and the region of the nose involved with smell.

Multipolar neurons have one axon and many (at least two) dendrites that branch off of it. Most neurons are multipolar. Motor neurons and interneurons are multipolar.

4.
What is a collection of cell bodies outside the CNS called?
a. Ganglion
b. Perikaryon
c. Astrocyte
d. Nissl
e. Terminal bouton

Answer: a

A ganglion is a collection of neuron cell bodies outside of the central nervous system. The cell body of a neuron is called a perikaryon or soma. An astrocyte is a supporting cell seen in the central nervous system. The basophilic clusters of ribosomes and rough endoplasmic seen in neuron cell bodies is called Nissl, Nissl bodies or Nissl substance. The terminal bouton is the end portion of an axon. It is also called an axon terminal or end bulb. The terminal bouton will be associated with another neuron in a synapse.

5.
What is tissue which surrounds a nerve fascicle?
a. Perimysium
b. Periosteum
c. Perichondrium
d. Perineurium
e. Endosteum

Answer: d

The perimysium is the connective tissue sheath around fascicles of muscle.

The periosteum is the connective tissue covering of a bone.

The perichondrium is the connective tissue which surrounds cartilage.

The perineurium is the covering of nerve fascicles.

The endosteum is the lining of the inner bone (the side which abuts the medullary cavity).

Note from Sarah Bellham: The prefix "peri" means around, such as in the word "perimeter". The prefix "endo" means within or inner, such as in "endosteum", "endocrine", "endoscope".

6.
The colloquialism "gray matter" refers to somebody using his intellect or reasoning ability. In reality, what is gray matter?
a. Meninges
b. Myelinated nerve fibers
c. Cell bodies
d. Nodes of Ranvier
e. Neurofilaments

Answer: c

A ganglion is a collection of nerve cell bodies outside of the central nervous system. White matter is myelinated nerve fibers. Gray matter is essentially neuron cell bodies. Nodes of Ranvier are the gaps that occur in the myelin sheath. Neurofilaments are a type of intermediate filaments seen in neurons.

7.
Where is the cerebrospinal fluid?
a. Between the dura mater and bone
b. Subdural space
c. Subarachnoid space
d. Between the pia mater and brain
e. None of the above

Answer: c

The cerebrospinal fluid is found in the subarachnoid space. The subarachnoid space is the space between the arachnoid and the pia mater.

8.
Which of the following are considered to be part of the meninges?
a. Dura mater
b. Arachnoid
c. Pia mater
d. Both a and c
e. All of the above

Answer: e

The meninges cover the brain and spinal cord. There are three: dura mater, arachnoid, and pia mater.

The dura mater is the outer meninx. The dura mater is composed of dense irregular connective tissue.

The arachnoid is made of a delicate spider web like connective tissue.

The pia mater is the innermost meninx. It covers the brain intimately.

Note from Sarah Bellham: Arachnoid is derived from the Greek word for spider. It is used in the words arachnophobia, arachnids and arachnoid.

9.
What is the outer gray matter of the brain called?
a. Tracts
b. Islets
c. Soma
d. Cortex
e. Nuclei

Answer: d

A group of fibers traveling together to a destination is a tract. Islets of Langerhans are seen in the pancreas. Soma is another term for a neuron cell body. The outer part of the brain is gray matter called the cortex. The conglomerations of gray matter deep within the cerebrum and cerebellum are called nuclei.

10.
Which of the following is the most abundant neuroglia cell?
a. Astrocytes
b. Ependymal cells
c. Oligodendrocytes
d. Microglia
e. Schwann cells

Answer: a

Neuroglia are the supporting cells of the central nervous system. Sometimes, neuroglia called glial cells or glia. Astrocytes, ependymal cells, oligodendrocytes, and microglia are all neuroglia.

Of the neuroglia cells, astrocytes are the most abundant and the largest. These are star shaped cells involved in the blood brain barrier.

Ependymal cells line the ventricles and spinal canal.

Oligodendrocytes form myelin in the central nervous system.

Microglia are the central nervous system macrophages.

Schwann cells are seen in the peripheral nervous system and are not considered neuroglia. Schwann cells are responsible for the myelination of neurons in the peripheral nervous system.