Nervous Tissue Flashcards

Question

Which type of axon conducts impulses faster? what is the action of an impulse "jumping" form node to node called? The speed of transmition is directly related to...

Answer 1

MYELINATED = FASTER - "Saltatory Conduction" - speed directly related to myelin thickness + axon thickness

Answer 2

- Surround ganglionic neuronal cell bodies - Cuboidal: complete layer around cell body (only nuclei visible) - Originate from neural crest cells - Analogous to Schwann cell \*insulation \*nutrition

Answer 3

- "GLIAL" cells in CNS - More numerous than neurons - Most brain tumors = glial in origin

Answer 4

**oligodendrocytes** - form myeline in CNS - 1 cell can myelinate multiple neurons **astrocytes** - physical + metabolic support for CNS neurons - found attached to blood vessels **microglia** - phagocytic cells of CNS

Answer 5

- Largest of glial cells - 2 kinds: * *PROTOPLASMIC** = prevalent in gray matter * *FIBROUS =** more common in white matter - have elaborate processes - extend b/t vessels and neurons

Answer 6

ASTROCYTES | (fibrous connective tissue)

Answer 7

ASTROCYTES

Answer 8

- functional barrier w. tight/occluding junctions sealing capilary endothelium - controls passage of substances fr blood into CNS tissue **=** **protects neuronal microenvironment** - perivascular feet of astrocytes on basal lamina capillaries helps regulate **= stable composition and constant balance of ions in the interstitial fluid** **= Protects neurons + glial cells from potential toxins + infectious agents** NOT in Choroid plexus and posterior pituitary, etc.

Answer 9

- CNS myelin formed by: \*concentric layers of oligocyte plasma membrane - Aligned in rows between axons - gives off several tongue-like processes --\> wraps around an axon **= internodal segment** **- oligodendrocyte forms myelin sheaths for several (3—50) nerve fibers**

Answer 10

- Part of mononuclear phagocytic system - Present in small numbers ** (proliferate during injury/disease)** - Secrete immunoregulatory cytokines = dispose of unwanted cellular debris

Answer 11

- Lines fluid-filled cavities of CNS - Cuboidal to columnar (fluid-transporting characteristics) - several locations = specialized to: **produce cerebrospinal fluid**

Answer 12

**- Modified ependyma** (simple cuboidal - produces CSF) **- dialated fenestrated capillaries** **- invaginated fold of pia mater (villi)** - lateral, 3rd, 4th ventricles in brain - removes water from blood + release it as CSF

Answer 13

endoneurium perineurium epineurium

Answer 14

- thin layer of reticular fibers produced by the Schwann cells - surrounds individual nerve fibers

Answer 15

- Surrounds bundles of nerve fibers - sheath of unique connective tissue cells - Cells joined by tight junctions - Form a barrier to passage of most macromolecules - Protects nerve from aggression - numerous actin microfilaments = contractile cells

Answer 16

- outermost tissue of peripheral nerve - typical dense connective tissue: (binds fascicles together) - adipose tissue often seen in larger nerve sheaths - carry blood vessels supplying nerves: (vessels branch + penetrate perineurium)

Answer 17

- Craniospinal (DRG, cochlear) - Pseudounipolar neurons: \*larger \*close together - Thick fascicles

Answer 18

- Sympathetic and Parasympathetic - Multipolar neurons \*smaller \*far apart - Diffuse nerve fibers

Answer 19

- smooth muscle - cardiac muscle - glandular epithelium

Answer 20

**Sympathetic** - norepinepherine - postganglionic fibers

Answer 21

**Parasympathetic** - acetylcholine - preganglionic + postganglionic fibers

Answer 22

- Confined w/i wall of gut - 2 sets of Plexus * *Myenteric (Auerbach)** * *Submucous(Meissner)** - unmyelinated nerve fibers intermingled w neuronal cell bodies - maintain *peristaltic movements* + *secretory function* of the gut

Answer 23

- Directly continuous with brain - 31 segments: **8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal** - Each segment = pair of spinal nerves - Each spinal nerve is joined to its segment of cord by *roots or rootlets* (grouped as **posterior** (dorsal) or **anterior** (ventral) roots)

Answer 24

- Anterior Grey Horn - Posterior Grey Horn - Lateral Grey Horn - Grey commissure - surrounds the central canal ## Footnote **has neuron cell bodies, dendrites, axons & glia**

Answer 25

**pheripheral** - contains mainly myelinated fibers - Arranged in three pairs of funiculus = **Anterior, Lateral &Posterior** - Functionally related bundles of axons called TRACTS

Answer 26

**gray matter ** - contains cell bodies, axons, dendrites, and glial cells, synapses

Answer 27

**Islands of gray matter** - found in deep portions of cerebrum and cerebellum

Answer 28

contains mainly: - myelinated axons of nerve cells - glial cells - vessels

Answer 29

Cerebral cortex + white matter - Cerebral cortex = 6 layers - PYRAMIDAL CELLS of cerebral cortex: * *found in layers III, V** * *small, medium, large pyramidal cells**

Answer 30

IN CEREBELLAR CORTEX - located between outer molecular layer + inner granular layer **apical numerous dendrites (arborize in molecular layer)** - have a single axon (not visible in H&E) * *extends into granular layer** * *beginning of outflow from cerebellum**

Answer 31

COVER BRAIN & SPINAL CORD **Dura Mater:** - outermost **Arachnoid:** - beneath dura **Pia Mater:** - innermost layer; rests directly on brain/spinal cord - delicate layer

Answer 32

- Neurohypophysis - Substantia nigra - Locus ceruleus

Answer 33

_anterograde_ - degeneration of axon distal to site of injury * *PNS degeneration takes a few days** * *CNS degeneration takes several weeks** \**Some retrograde degeneration also occurs (only extends for several internodal segments)*

Answer 34

- loss of Nissl substance from cell body: * *1-2 days after injury** - Changes in cell body are proportionate to: **amount of axoplasm lost from injury** (large amount =CELL DEATH)

Answer 35

muscles atrophy

Nervous Tissue Flashcards

(59 cards)