L3: Nervous Tissue 2

Question 1

What is a ganglia

Answer 1

a collection of cell bodies outside of CNS

Question 2

Spinal ganglia

Answer 2

aka DRG

collection of cell bodies of sensory neurons entering the spinal cord; contain pseudounipolar neurons; cell bodies grouped into fascicles

Question 3

Describe the groupings of the cell bodies in spinal ganglia

Answer 3

Grouped into fascicles

cell bodies surrounded by delicate collagen fibrils, fibroblasts and satellite cells= flattened cells continuous with neurilemma of axons.

Function in support and may regulate metabolite exchange between cells and blood

Spinal ganglion covered with dense irregular CT capsule with septa extending into interior

Question 4

Name the 3 types of autonomic ganglion.

Answer 4

lateral chain ganglion
collateral ganglia
terminal ganglia

Question 5

What are lateral chain ganglions?

Answer 5

a type of autonomic ganglia

sympathetic

near and parallel to spinal cord; segmented and connected into chain (except in primitive vertebrates)

Question 6

What are collateral ganglia?

Answer 6

autonomic ganglia

sympathetic

distal to vertebral column (compared to lateral chain ganglia)

Question 7

What are terminal ganglia?

Answer 7

type of autonomic ganglia

parasympathetic

in or near wall of innervated organ (not near spinal cord, therefore different cell body structures)

sympathetic division: short preganglionic, long postganglionic fibers.
parasympathetic division: long preganglionic, short postganglionic fibers (TERMINAL GANGLIA)

Question 8

Describe autonomic ganglia

Answer 8

cell bodies of visceral motor neurons are in lateral chain ganglia, collateral ganglia, or terminal ganglia.

Multipolar neurons, stellate appearance of cell body

Satellite cells present but incompletely surround cell body due to multipolarity

No fascicles present, but possess dense irregular CT capsule with septa (not nec divided into fascicles though)

Question 9

Central canal

Answer 9

filled with CSF (derived from plasma); functions in CNS metabolism and in protection from trauma (shock absorption)

Question 10

ependymal cells

Answer 10

line central canal; non-neural cells composing simple cuboidal epithelium (ciliated)

secrete CSF and monitor CSF composition

Question 11

Meninges

Answer 11

CT membrane covering the CNS

Question 12

Pia mater

Answer 12

innermost, vascular CT

adheres to surface of CNS

lined by simple squamous epithelium on outside

Question 13

Arachnoid meninge

Answer 13

thin, delicate non-vascular membrane with trabeculae extending inwardly, contains collagen and elastic fibers

covered on outside by simple squamous epithelium

Question 14

dura mater

Answer 14

outermost, dense CT protective covering of collagen fibers and some elastic fibers.

Question 15

Subarachnoid space

Answer 15

separates pia and arachnoid mater, filled with CSF

Question 16

subdural space

Answer 16

separates arachnoid and dura mater, filled with lymph-like fluid.

Question 17

What are the six layers of the ceberum gray matter? describe them

Answer 17

1. molecular layer
2. granular layer: relatively small assocation neurons, intracortical communication.
3. pyramidal cell layer: neurons with pyramid shaped cell body, function as assocation and projection neurons
4. inner granular layer: relatively small assocation neurons, myelinated fibers
5. inner pyramidal cell layer: contains large pyramidal cells and small neurons
6. polymorphic cell layer: polymorphous neurons- small neurons with spindle-shaped cell body and branching dendrites; function as assocation and projection neurons (communicate outside cortex)

Question 18

What is the cerebellum for?

Answer 18

coordination of motor movements

Question 19

What is the cerebrum for?

Answer 19

responsible or consciousness, intelligence, thought, interpretation of sensations

Question 20

What is the cerebellum composed of? What does it look like?

Answer 20

superficial cortex of gray matter covering deeper body of white matter.

Cortex is folded into many transverse ridges (folia cerebelli)

each ridge has a core of white matter (stains pink in H&E) and cortex of gray matter (blue-staining) with 3 layers.

Question 21

Name the 3 layers of the cerebellum (don’t describe yet)

Answer 21

1. Molecular layer
2. Purkinje layer
3. granular layer

Question 22

What is the molecular layer of the cerebellum made of?

Answer 22

outermost layer

contains glial cells, dendrites and many unmyelinated axons

also contains stellate cells and basket cells.

both are considered to be inhibitory interneurons that modify actions of cortical neurons

Question 23

What is the purkinje layer of the cerebellum?

Answer 23

Middle layer

composed of single layer of large flask-shaped purkinje neurons with a few major branched dendrites extending into molecular layer

purkinje axons leave cortex and project to nuclei (collection of cell bodies within CNS) in medullary regions.

purkinje cells convey motor impulses from cortex which inhibit function of medullary nuclei

Question 24

What is the granular layer of the cerebellum?

Answer 24

Inner layer.

contains cell bodies of small neurons, granule cells (multipolar neurons with small dark round nuclei, little cytoplasm and no nissl bodies; relay impulses from body to purkinje cells)

also contains golgi cells (large multipolar neurons with prominent nucleus and nissl bodies; function as inhibitory neurons modifying impulses passing to purkinje cells.

Question 25

Fibrous astrocytes

Answer 25

occurs in white matter of brain, have smaller number of cell processes so take on starlike appearance, processes are generally straight; some are attached to blood vessels.

Question 26

Protoplasmic astrocytes

Answer 26

occur in gray matter, have large number of highly branched processes so take on mossy appearance; processes often terminate in expanded foot in blood vessels, or bind pia mater to CNS

Question 27

What do astrocytes do?

Answer 27

may regulate movement of metabolites, ions, fluids, and gases between blood, CSF, and CNS

Question 28

Oligodendroglia

Answer 28

present in both gray and white matter; boxlike cell body with short processes that warp around nearby axons, responsible for myelination in CNS

Question 29

Microglia

Answer 29

tiny cells, may be rod shaped, oval and indented or bent

Mainly found in gray matter near blood vessels and nerve cell bodies

upon CNS damage, become motile and phagocytic; believed to be derived from monocytes (therefore from mesoderm rather than neural crest)

Question 30

What does the blood-brain barrier do?

Answer 30

functions to keep harmful compounds that may gain access to blood out of the brain

Components:

capillaries within brain lined by endothelium with entire perimeter of ecah cell bounded by tight junctions, which restricts passage of dissolved molecules from capillary to brain tissue

Pinocytic transfer of fluid across endothelium is restricted

Capillaries also surrounded by extra thick basement membrane

outer surface of capillaries covered with astrocyte feet which may further regulate passage of molecules