First Aid Neurology Part 1

Front 1

What are the CNS/PNS origins in neurology?

Back 1

Neuroectoderm -CNS neurons, ependymal cells (inner lining of ventricles, make CSF), oligodendroglias, astrocytes

Neural crest - Schwann cells, PNS neurons

Mesoderm - Microglia, like Macrophages, originate from Mesoderm

Front 2

Describe neurons

Back 2

Comprise nervous system.

Permanent cells - do not divide in adulthood.

Large cells with prominent nucleoli. Nissl substance (RER) in cell body, dendrites, not axon

Front 3

Describe astrocytes

Back 3

Physical support, repair, K+ metabolism, removal of excess neruotransmitter, maintenance of BBB.

Reactive gliosis in response to injury. Astrocyte marker GFAP

Front 4

Describe microglia

Back 4

CNS phagocytes. Mesodermal origins. Not readily discernible in Nissle stains. Have small irregular nuclei and relatively little cytoplasm

As a response to tissue damage, microglia become large ameboid phagocytes cells

Front 5

Describe HIV-infected microglia

Back 5

They fuse to form multinucleated giant cells in the CNS

Front 6

Describe oligodendroglia

Back 6

Each oligodendrocyte myelinates multiple CNS axons (up to 30). In Nissl stains, they appear as small nuclei with dark chromatin and little cytoplasm. Predominant type of glial cell in white matter.

Front 7

What cells do multiple sclerosis affect?

Back 7

MS destroys oligodendroglia

Front 8

How do oligodendroglia appear on H&E?

Back 8

Like fried eggs

Front 9

Describe Schwann cells

Back 9

Each Schwann cell myelinates only 1 PNS axon. Also promotes axonal regeneration. Derived from neural crest.

Front 10

What cells does Guillain-Barre syndrome affect?

Back 10

GBS destroys Schwann cells

Front 11

Describe acoustic neuromas

Back 11

Type of schwannoma. Typically located in the internal acoustic meatus (CN VIII)

Front 12

Describe free nerve endings

Back 12

-C, Adelta fibers
-Located in the skin, epidermis, some viscera
-Sense pain and temperature

Front 13

Describe Meissner's corpuscles

Back 13

-Located in glabrous (hairless) skin
-Sense dynamic fine touch (e.g. manipulation), adapt quickly

Front 14

Describe Pacinian corpuscles

Back 14

-Located in deep skin layers, ligaments, and joints
-Sense vibration, pressure

Front 15

Describe Merkel's disks

Back 15

-Cup-shaped, unencapsulated
-Located in hair follicles
-Senses static touch (e.g., shapes, edges, textures), adapt slowly

Front 16

Describe the layers of peripheral nerve

Back 16

Endoneurium - invests single nerve fiber

Perineurium (Permeability barrier) - surrounds a fascicle of nerve fibers. Must be rejoined in microsurgery for limb reattachment.

Epineurium - dense connective tissue that surrounds entire nerve (fascicles and blood vessels).

Endo=inner
Peri=around
Epi=outer

Front 17

What are the important neurotransmitters?

Back 17

NE, Dopamine, 5-HT, and ACh

Front 18

Where is NE synthesized? How is it changed in disease?

Back 18

-Synthesized in the locus ceruleus
-Increased in anxiety, decreased in depression

Front 19

Where is dopamine synthesized? How is it changed in disease?

Back 19

-Synthesized in the ventral tegmentum and SNc
-Increased in schizophrenia, diseased in Parkinson's

Front 20

Where is 5-HT synthesized? How is it changed in disease?

Back 20

-Synthesized in the Raphe nucleus
-Decreased in anxiety, depression

Front 21

Where is ACh synthesized? How is it changed in disease?

Back 21

-Synthesized in the Basal nucleus of Meynert
-Decreased in Alzheimer's, Huntington's

Front 22

What structures form the blood-brain barrier?

Back 22

1. Tight junctions between nonfenestrated capillary endothelial cells
2. Basement membrane
3. Astrocyte processes

Front 23

Describe crossing the blood-brain barrier

Back 23

-Glucose and amino acids cross slowly by carrier-mediated transport mechanisms
-Nonpolar/lipid-soluble substances cross rapidly via diffusion

Front 24

What occurs when infection destroys endothelial cell tight junctions?

Back 24

Vasogenic edema

Front 25

Describe the importance of the few specialized brain regions with fenestrated capillaries and no BBB

Back 25

These allow molecules in the blood to affect brain function
(e.g. area postrema - vomiting after chemo, OVLT - osmotic sensing) or neurosecretory products to enter circulation (e.g. neurohypophysis - ADH release)

Front 26

Describe the hypothalamus

Back 26

The hypothalamus wears TAN HATS
-Thirst and water balance
-Adenohypophysis control
-Neurohypophysis releases hormones from hypothalamus
-Hunger
-Autonomic regulation
-Temperature regulation
-Sexual urges

Inputs: OVLT (senses changes in omolarity), area postrema (responds to emetics)

Front 27

Describe the function of the supraoptic nucleus of the hypothalamus

Back 27

Makes ADH

Front 28

Describe the function of the paraventricular nucleus of the hypothalamus

Back 28

Makes oxytocin

Front 29

Describe the function of the lateral area of the hypothalamus

Back 29

It is for hunger. Its destruction leads to anorexia. It is inhibited by leptin.

If you zap your lateral nucleus, you shrink laterally

Front 30

Describe the function of the ventromedial area of the hypothalamus

Back 30

It is for satiety. Its destruction leads to hyperphagia. It is stimulated by leptin

If you zap your ventromedial nucleus, you grow ventrally and medially

Front 31

Describe the function of the anterior hypothalamus

Back 31

Cooling, parasympathetic

Anterior nucleus = cool off (cooling, parasympathetic).
A/C = anterior cooling

Front 32

Describe the function of the posterior hypothalamus

Back 32

Heating, sympathetic

Posterior nucleus = get fired up (heating, sympathetic). If you zap your posterior hypothalamus, you become Poikilotherm (cold-blooded, like a snake)

Front 33

Describe the function of the septal nucleus of the hypothalamus

Back 33

Sexual urges

Front 34

Describe the function of the suprachiasmatic nucleus of the hypothalamus

Back 34

Circadian rhythm

You need sleep to be charismatic (chiasmatic)

Front 35

Describe the posterior pituitary

Back 35

-Also called the neurohypophysis
-Received hypothalamic axonal projections from supraoptic (ADH) and paraventricular (oxytocin) nuclei

Oxytocin: oxys=quick, tocos=birth
Adenohypophysis=Anterior pituitary