Nervous system

Question 1

The anterior neuropore closure occurs at …….

Answer 1

lamina terminalis

Question 2

Sulcus limitans is …….

Answer 2

a groove that separates the alar plate (dorsal, sensory) from the basal plate (ventral, motor)
* Extends from the spinal cord into the brain stem

Question 3

Schwann cells surround ……

Answer 3

all axons in the PNS (neurilemma)

• Myelination is formed when Schwann cells wraps many times around an axon
• Myelination begins in the fourth month

Question 4

What is the difference in myelination between the PNS & CNS?

Answer 4

• In the PNS, many Schwann cells wrap around a single axon, separated by Ranvier nodes
• In the CNS, one oligodendrocyte myelinate more the 50 axons

Question 5

Nissl bodies are ……

Answer 5

deeply stain RER in neurons

* Can’t be found in axons

Question 6

Synaptic boutons are ……

Answer 6

the ending of the axons, containing synaptic vesicles full of neurotransmitter

Question 7

Define:

1. Unipolar neurons
2. Pseudounipolar neurons
3. Bipolar neurons
4. Multipolar neurons

Answer 7

1. One axon, no dendrite. Early in life
2. One process, divides into peripheral & central (i.e DRG)
3. One axon, one dendrite (retina, olfactory, cochlear, vestibular)
4. One axon, many dendrites (ventral horn neurons in spinal cord. Most abundant)

Question 8

Satellite cells are …….

Answer 8

similar to Schwann cells. Found in ganglia

• Ganglia are covered by dense C.T (Epi., peri., endoneurium)
• Endoneurium is made of reticular fibers

Question 9

Nuclei are ……

Answer 9

collection of neurons in CNS of the same function

Question 10

Neurotransmitter is released from the axon via ….

Answer 10

Ca dependent process of exocytosis

Question 11

Nerve fibers in the CNS is called ……, while in the peripheral system they are called ……

Answer 11

tracts

peripheral nerves

Question 12

Efferents conduct ………, while the afferents ……

Answer 12

away from CNS

towards the CNS

Question 13

Astrocytes function is ……..

Answer 13

maintenance of BBB, metabolic & structural support

* It is a part of the neuroglia

Question 14

Microglia are ……

Answer 14

phagocytic cells, have short processes covered with spines

* Origin is the mesoderm, unlike the neuroectoderm

Question 15

What are the layers of the eye?

Answer 15

1. outer Corneoscleral coat
2. middle uvea (to which the lens is attached, separating the aqueous humor from the viterous body)
3. retina
   * Viterous body is 99% water

Question 16

The cornea is continuous with the sclera at ….

Answer 16

the limbus

Question 17

What are the layers of the cornea?

Answer 17

1. epithelium
2. Bowman’s layer
3. stroma
4. decemet membrane
5. endothelium

Question 18

At the limbus, the decemet membrane becomes …..

Answer 18

trabecular meshwork (canal of Schlemm, which drain into the venous system)
* Obstruction of this canal causes increase intra ocular pressure (glaucoma)

Question 19

The uvea consists of ……

Answer 19

the choroid, the ciliary body and the iris

• all pigmented. The choroid is highly vascular
• Choroid is black. Non pigmented iris is blue

Question 20

Aqueous humor is formed by ….

Answer 20

the ciliary body

Question 21

The iris has two muscles, …… & ……

Answer 21

sphincter pupillae & radial dilator

Question 22

Cataracts are formed by …….

Answer 22

accumulation of pigments in the clear lens

* caused by DM or UV radiation

Question 23

The fovea is ……

Answer 23

the area of the greatest visual acuity

Question 24

The external ear includes ……..

Answer 24

the pinna, external auditory meatus, and the tympanic membrane

Question 25

The malleus, incus & stapes are attached to the ........

Answer 25

oval window

Question 26

Inner ear is two parts, .... & ......

Answer 26

osseous labyrinth (inside the petrous of the temporal bone) & membranous labyrinth (enclosed within the osseous part, and surrounded by perilymph)

Question 27

The osseous labyrinth of the ear is three parts, ......

Answer 27

cochlea, vestibule, and semicircular canals | * It is filled with perilymph (similar to CSF)

Question 28

The membranous labyrinth is filled with ...... | It is three parts, .....

Answer 28

endolymph (high K, low Na, similar to intracellular fluid) 1. semicircular ducts 2. saccule & utricle (vestibule) 3. cochlear duct (scala media) in cochlear portion)

Question 29

The semicircular canals open at .......

Answer 29

the utericle

Question 30

The center of the cochlea is called .......

Answer 30

``` the modiolus (nerves, spiral ganglion & BV leave through here) * Note: the cochlea is about 35 mm long ```

Question 31

The spiral ganglion is formed by ........

Answer 31

bipolar neurons

Question 32

The utricle is located at ......., while the saccule is at .......

Answer 32

superior posterior portion, near the opening of the semicircular canals * at the opening of the scala vestibuli * The utricle is bigger than the saccule

Question 33

The spiral limbus is .........

Answer 33

an area of loose C.T, covered by epi. * Tectorial membrane extends from the limbus, and touches the hair cells * There is a layer of inner hair cells, & three rows of outer hair cells

Question 34

CN I & II are considered part of .......

Answer 34

CNS

Question 35

The somatic nervous system is part of ......

Answer 35

the PNS