Neuro1 Neurology Anatomy and Physiology

Question 1

CNS/PNS origins

Answer 1

Neuroectoclerm-CNS neurons, ependymal cells (inner lining of ventricles, make CSF),
oligoclenclroglia, astrocytes.
Neural crest-Schwann cells, PNS neurons.
Mesoderm-Microglia, like Macrophages, originate from Mesoderm

Question 2

Neurons

Answer 2

Compose nervous system. Permanent cells-do not divide in adulthood.
Large cells with prominent nucleoli. Nissl substance ( RER) in cell body, clenclrites, not axon.
Wallerian degeneration-axon injury

Question 3

Astrocytes

Answer 3

Physical support, repair, K+ metabolism, removal of excess neurotransmitter, maintenance of bloodbrain
barrier. Reactive gliosis in response to injury. Astrocyte marker-GFAP.

Question 4

Microglia

Answer 4

CNS phagocytes. Mesodermal origin. Not readily discernible in Nissl stains. Have small irregular nuclei and relatively little cytoplasm. Scavenger cells of the CNS. Respond to tissue damage by differentiating into large phagocytic cells.

HIV-infectecl microglia fuse to form
multinucleated giant cells in the CNS.

Question 5

Myelin

Answer 5

CNS -oligoclendrocytes; PNS - Schwann cells.

Insulates axons: Increases space constant, conduction
velocity.

Question 6

Oligodendroglia

Answer 6

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

These cells are destroyed in multiple sclerosis.
Look like fried eggs on H&E staining.

Question 7

Schwann cells

Answer 7

Each S chwann cell myelinates only 1 PNS axon . Also promote axonal regeneration. Derived from neural crest.
Increased conduction velocity via saltatory conduction between nodes of Ranvier, where there are high concentrations of Na channels.

These cells are destroyed in Guillain-Barre
syndrome.
Acoustic neuroma-type of schwannoma.
Typically located in internal acoustic meatus
(CN VIII).

Question 8

Free nerve endings

Answer 8

C-slow, unmyelinated fibers; Ao -fast, myelinated
fibers
Location: All skin, epidermis, some viscera
Senses: Pain and temperature

Question 9

Meissner’s corpuscles

Answer 9

Large, myelinated fibers
Location: Glabrous (hairless) skin
Senses: Position sense, dynamic fine
touch (e.g., manipulation),
adapt quickly

Question 10

Pacinian corpuscles

Answer 10

Large, myelinated fibers
Location: Deep skin layers, ligaments, and joints
Senses: Vibration, pressure

Question 11

Merkel’s disks

Answer 11

Large, myelinated fibers
Location: Hair follicles
Senses: Position sense, static touch
(e.g. , shapes, edges,
textures), adapt slowly

Question 12

Peripheral nerve

Answer 12

Endoneurium-invests single nerve fiber layers
(inflammatory infiltrate in Guillain-Barre).
Perineu rium ( 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) .

Question 13

N E (Norepinephrine)

Answer 13

Increase in anxiety, Decrease in depression

Location of synthesis: Locus ceruleus

Question 14

Dopamine

Answer 14

Increase in schizophrenia, Decrease in Parkinson’s and depression

Location of synthesis: Ventral tegmentum and SNc

Question 15

5-HT

Answer 15

Decrease in anxiety, depression

Raphe nucleus

Question 16

ACh

Answer 16

Decrease in Alzheimer’s, Huntington’s, Increase REM sleep

Basal nucleus of Meynert

Question 17

GABA

Answer 17

Decrease in anxiety, Huntington’s

Nucleus accumbens

Question 18

Locus ceruleus

Answer 18

stress and panic

Question 19

Nucleus accumbens and septal nucleus

Answer 19

reward center, pleasure, addiction, fear

Question 20

Blood-brain barrier

Answer 20

Formed by 3 structures:
l . Tight junctions between nonfenestrated
capillary endothelial cells
2. Basement membrane
3. Astrocyte processes
Glucose and amino acids cross slowly by carrier mediated transport mechanism.
Nonpolar/lipid-soluble substances cross rapidly via diffusion. A few specialized brain regions with fenestrated capillaries and no blood-brain barrier 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).

Other barriers include:
l. Blood-testis barrier
2. Maternal-fetal blood barrier of placenta
Infarction and/or neoplasm destroys endothelial cell tight junctions —7 vasogenic edema.
Hypothalamic inputs and outputs permeate the BBB.

Question 21

Hypothalamus

Answer 21

The hypothalamus wears TAN HATS-Thirst and water balance, Adenohypophysis control, Neurohypophysis releases hormones from hypothalamus, Hunger, Autonomic regulation, Temperature regulation, Sexual urges.
Inputs: OVL:T (senses change in osmolarity), area postrema
(responds to emetics).
Supraoptic nucleus makes ADH.
Paraventricular nucleus makes oxytocin.

Question 22

Hypothalamus Leptin Lateral area

Answer 22

hunger. Destruction —7 anorexia, failure to thrive (infants). Inhibited by leptin.

If you zap your lateral nucleus, you shrink laterally.

Question 23

Hypothalamus Leptin Ventromedial area

Answer 23

satiety. Destruction
(e.g., craniopharyngioma) —7 hyperphagia.
Stimulated by leptin.

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

Question 24

Anterior hypothalamus

Answer 24

cooling, pArasympathetic.

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

Question 25

Posterior hypothalamus

Answer 25

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

Question 26

Suprachiasmatic nucleus

Answer 26

circadian rhythm. You need sleep to be charismatic (chiasmatic).

Question 27

Posterior pituitary | neurohypophysis

Answer 27

Receives hypothalamic axonal projections from supraoptic (ADH) and paraventricular (oxytocin) nuclei. Oxytocin: oxys = quick; tacos = birth. Adenohypophysis = Anterior pituitary.

Question 28

Thalamus

Answer 28

Major relay for all ascending sensory information except olfaction.

Question 29

Thalamus VPL

Answer 29

Input: Spinothalamic and dorsal columns/medial lemniscus. Info: Pain and temperature ; pressure, touch, vibration, and proprioception. Destination: Primary somatosensory cortex.

Question 30

Thalamus VPM

Answer 30

Trigeminal and gustatory pathway. Face sensation and taste. Primary somatosensory cortex.

Question 31

Thalamus LGN

Answer 31

CN II. Vision. Calcarine sulcus.

Question 32

Thalamus MGN

Answer 32

Superior olive and inferior colliculus of tectum. Hearing. Auditory cortex of temporal lobe.

Question 33

Limbic system

Answer 33

Includes cingulate gyrus, hippocampus, fornix, mammillary bodies, and septal nucleus. Responsible for Feeding, Fleeing, Fighting, Feeling, and sex.

Question 34

Cerebellum

Answer 34

Receives contralateral cortical input via middle cerebellar peduncle and ipsilateral proprioceptive information via inferior cerebellar peduncle. Input nerves = climbing and mossy fibers. Provides stimulatory feedback to contralateral cortex to modulate movement. Output nerves = Purkinje fibers output to deep nuclei of cerebellum, which in turn output to cortex via superior cerebellar peduncle. Deep nuclei (L --t M) - Dentate, Emboliform, Globose, Fastigial ("Don't Eat Greasy Foods"). Lateral-voluntary movement of extremities. Medial-balance, truncal coordination, ataxia; when injured, propensity to fall toward injured (ipsilateral) side.

Question 35

Basal ganglia

Answer 35

Important in voluntary movements and making postural adjustments. Receives cortical input, provides negative feedback to cortex to modulate movement. Striatum = putamen (motor) + caudate (cognitive). Lentiform = putamen + globus pallidus.

Question 36

Parkinson's disease

Answer 36

``` Degenerative disorder of CNS associated with Lewy bodies (composed of a-synuclein intracellular inclusion) and loss of dopaminergic neurons (i.e., depigmentation) of the substantia nigra pars compacta. ``` ``` TRAP = Tremor (at rest-e.g., pill-rolling tremor), cogwheel Rigidity, Akinesia, and Postural instability (you are TRAPped in your body). ```

Question 37

Hemiballismus

Answer 37

Sudden, wild flailing of l arm +/- leg. Characteristic of contralateral subthalamic nucleus lesion (e.g., lacunar stroke in a patient with a history of hypertension). Loss of inhibition of thalamus through globus pallidus. Half ballistic (as in throwing a baseball).

Question 38

Huntington's disease

Answer 38

Autosomal-dominant trinucleotide repeat disorder. Characterized by chorea, aggression, depression,and dementia (sometimes initially mistaken for substance abuse). Neuronal death via NMDA-R binding and glutamate toxicity. Atrophy of striatal nuclei (main inhibitors of movement) can be seen on imaging. Expansion of CAG repeats (anticipation). Caudate loses ACh and GABA.

Question 39

Chorea

Answer 39

Sudden, jerky, purposeless movements. Characteristic of basal ganglia lesion (e.g., Huntington's disease). Chorea = dancing (Greek). Think choral dancing or choreography.

Question 40

Athetosis

Answer 40

Slow, writhing movements, especially of fingers. Characteristic of basal ganglia lesion (e.g., Huntington's disease). Athetos = not fixed (Greek) . Think snakelike.

Question 41

Myoclonus

Answer 41

Sudden, brief muscle contraction. | Jerks, hiccups.

Question 42

Dystonia

Answer 42

Sustained, involuntary muscle contractions. Writer's cramp, blepharospasm.

Question 43

Tremor

Answer 43

Essential/postural tremor-action tremor (worsens when holding posture), autosomal dominant (often with positive family history) . Essential tremor patients often self-medicate with alcohol, which decreases tremor. Treatment: Beta blockers. Resting tremor-most noticeable distally. Seen in Parkinson's (pill-rolling tremor). Intention tremor-slow, zigzag motion when pointing toward a target; associated with cerebellar dysfunction.