Lecture 18: Nervous System

Question 1

Describe each of the 3 subdivisions of the vertebrate nervous system and list components of each

Answer 1

1. CNS: Brain, spinal cord
2. PNS: cranial and spinal nerves
3. ANS: sympathetic/para-sympathetic

Question 2

List the parts of a typical neuron and give characteristics of each

Answer 2

Cell body: trophic unit and perikaryon-nucleated and organelles for repair and maintenance

Dendrites: receptive unit

Axon: conductive unit

Question 3

Define each of the 7 general terms used in describing the NS anatomy

Answer 3

Nerve: bundle of fibers in the PNS

Tract: bundle of fibers in CNS

Commissure: tract that crosses one side to another

Nucleus: aggregation of dendrites and nerve cell bodies in CNS

Ganglion: aggregation of dendrites and nerve cell bodies in PNS

White matter: areas of myelinated axons.

Gray matter: areas of unmyelinated axons, somas, and dendrites.

Question 4

Be familiar w/ the terminology used to describe nerve pathways and reflex arcs

Answer 4

Synapses: presynaptic, synaptic, postsynaptic-mono-/polysynaptic

Reflex arc: Afferent (sensory), Efferent (motor), and asso. Neurons (interneurons)

Somatic or visceral

Question 5

List each category of glial cell and give characteristics and functions.

Answer 5

Schwann cells: myelinate axons- PNS

Astrocytes: Physically support neurons. Channel materials btw capillaries and neurons. (Blood-brain barrier) guide neurons developing

Microglial cells: transform to phagocyte w/in CNS

Oligodendrocytes: myelinate axons w/in CNS

Ependymal cells: line ventricles of the brain

Question 6

Describe the development of the neural tube from the neural plate to neural fold to the neural tube stage.

Answer 6

Neural plate->neural fold->neural tube

Thin layer epithelium (plate)-undergoes polymerization and thickens, the thickening then creates a fold, then the folds fuse together along midline forming a tube.

Question 7

List the adult derivatives of each of the 5 subdivisions of the pentapartite brain.

Answer 7

Telencephalon: Lumina(ventricle 1/2), floor (basal nuclei/ganglia),roof (cerebral hemisphere)

Diencephalon: lumen(3rd ventricle), roof, walls(thalamus), floor,

Mesencephalon: lumen, roof(tectum-superior/inferior colliculi ), floor

Metencephalon: Lumen (4th ventricle), roof (cerebellum), floor (pons)

Myelencephalon: lumen (4th ventricle), main part (medulla), roof (choroid plexus)

Question 8

List the stages in the histogenesis of the central NS:

Answer 8

Initial tube wall: pseudostratified epithelium.
Outermost membrane: external limiting membrane.

Some of the cells (initial tube wall) remain attached to basement membrane form single layer of ependymal cells. Line the entire ventricular system and neural canal.

Other cells lose contact w/ basement. Migrate past ependymal cells to form a new outer layer =mantle (nerve cell bodies)

Neuroblasts in the mantle layer begin to grow processes(axons) that form new outer layer= marginal layer.

Marginal layer=forms white matter
Mantle layer=forms gray matter