FA Neurology - Anatomy and Physiology Flashcards
What are ependymal cells?
Inner lining of ventricles, make CSF
What parts of the nervous system come from neuroectoderm?
CNS neurons, ependymal cells, oligodendroglia, astrocytes
What parts of the nervous system come from the neural crest?
Schwann cells, PNS neurons
What parts of the nervous system come from the mesoderm?
Microglia, like Macrophages, original from Mesoderm.
What is Nissl substance and where is it?
Nissl substance (RER) in cell body and dendrites but NOT the axon.
What is Wallerian degeneration?
Axon injury –> neuron degeneration distally, axonal reaction (cellular swelling, dispersal of Nissl substance) proximally.
What do astrocytes do/?
Physical support, repair, potassium metabolism, removal of excess neurotransmitter, maintenance of blood-brain barrier. Reactive gliosis in response to injury. Astrocyte marker - GFAP.
What are microglia? What happens to microglia in HIV?
CNS phagocytes. Mesodermal origin. Not readily discernible in Nissl stains. Have small irregular nuclei and relatively little cytoplasm. They are the scavenger cells of the CNS. Respond to tissue damage by differentiating into large phagocytic cells.
HIV-infected microglia fuse to form multi-nucleated giant cells in the CNS.
What is myelin?
CNS - oligodendrocytes; PNS - Schwann cells.
Insulates axons: increase space constant and conduction velocity.
How many CNS axons are myelinated by one oligodendocyte?
Up to 30!
What do oligodendrocytes look like on H&E and Nissl stains?
On H&E, like fried eggs. In Nissl stains, they appear as small nuclei with dark chromatin and little cytoplasm. They are the predominant type of glial cell in white matter.
What types of cells are destroyed in MS?
Oligodendrocytes
How many PNS axons are myelinated by Schwann cells?
1:1.
What do Schwann cells do?
Promote axonal regeneration and increase conduction velocity via saltatory conduction between nodes of Ranvier, where there are a high concentration of Na channels.
What diseases are associated with Schwann cells?
Destroyed in Guillain-Barré; Acoustic neuroma is a type of schwannoma that is typically located in the internal acoustic meatis (CNVIII).
Type of fibers in free nerve endings
C - slow, unmyelinated fibers; a-delta - fast, myelinated fibers.
Location of free nerve endings
All skin, epidermis, and some viscera
What do free nerve endings sense?
Pain and temperature
What fibers are in Meissner’s corpuscles?
Large, myelinated fibers
Where are Meissner’s corpuscles located?
Glabrous (hairless) skin
What do Meissner’s corpuscles sense?
Position, dynamic fine touch (e.g. manipulation), adapt quickly.
What type of fibers in Pacinian corpuscles?
Large, myelinated
Where are Pacinian corpuscles located?
Deep skin layers, ligaments, and joints
What do Pacinian corpuscles sense?
Vibration and pressure
What type of fibers in Merkel’s disks?
Large, myelinated
Where are Merkel’s disks located?
Hair follicles
What do Merkel’s disks sense?
Position sense, static touch (e.g., shapes, edges, textures), adapt slowly
What are the layers of the peripheral nerve? What does each layer do?
Endoneurium: invests single nerve fiber layers (inflammatory infiltrate in Guilliain Barré
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).
Where is norepinephrine synthesized?
Locus ceruleus (pons)
Where is dopamine synthesized?
Ventral tegmentum and SNc (midbrain)
Where is 5-HT synthesized?
Raphe nucleus (pons)
Where is acetylcholine synthesized?
Basal nucleus of Meynert
Where is GABA synthesized?
Nucleus accumbens (where the caudate and putamen come together)
What is associated with the locus ceruleus?
Stress and panic
What is associated with the nucleus accumbens and septal nucleus?
Reward center, pleasure, addiction, fear.
How does NE change in disease?
increased in anxiety, decreased in depression
How does dopamine change with disease?
Increased in schizophrenia, decreased in Parkinson’s and depression
How does 5-HT change with disease?
Decreased in both anxiety and depression
How does ACh change with disease?
Decreased in Alzheimer’s and Huntington’s. (Increased with REM sleep).
How does GABA change with disease?
Decreased in anxiety and Huntington’s
Of what three structures is the blood-brain barrier formed?
- Tight junctions between non-fenestrated capillary endothelial cells
- Basement membrane
- Astrocyte processes
What can cross the blood-brain barrier?
Non-polar/Lipid soluble substances cross rapidly via diffusion.
Hypothalamic inputs and outputs permeate.
Glucose and amino acids cross slowly by carrier-mediated transport mechanism.
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., posterior pituitary - ADH release)
Name three barriers in the body
- Blood-brain
- Blood-testis
- Maternal-feltal blood barrier of placenta
What happens if infarction and.or neoplasm destroys the endothelial tight junctions of the BBB?
Vasogenic edema
What does the hypothalamus do?
The hypothalamus wears TAN HATS!
Thirst and water balance (produces ADH)
Adenohypophysis control
Neurohypophysis releases hormones from H
Hunger
Autonomic regulation
Temperature regulation
Sexual urges
Makes ADH (supraoptic) & oxytocin (paraventricular)
Name two inputs to the hypothalamus (areas not protected by BBB)
OVLT (senses change in osmolarity) area postrema (responds to emetics)
What part of the hypothalamus makes ADH?
The supraoptic nucleus!
What part of the hypothalamus makes oxytocin?
Paraventricular nucleus
With what is the lateral nucleus of the hypothalamus associated?
Hunger!
Destruction –> anorexia, failure to thrive (infants). Inhibited by leptin.
If you zap your lateral nucleus, you shrink laterally.
With what is the ventromedial nucleus of the hypothalamus associated?
Satiety!
Destruction (e.g. craniophayngioma) –> hyperphagia. Stimulated by leptin.
If you zap your ventromedial nucleus, you grow ventrally and medially.
With what is the anterior hypothalamus associated?
Cooling (parasympathetic)
Anterior nucleus = cool off. A/C = anterior cooling
With what is the posterior hypothalamus associated?
Heating (sympathetic)
Posterios nucleus = get fired up (heating, sympathetic). If you zap your posterior hypothalamus, you become a Poikilotherm (cold-blooded, like a snake).
With what is the suprachiasmatic nucleus of the hypothalamus associated?
Circadian rhythm.
You need sleep to be charismatic (chiasmatic).
What does the posterior pituitary (neurohypophysis) do?
Receives hypothalamic axonal projections from supraoptic (ADH) and paraventricular (oxytocin) nuclei.
What is the thalamus?
It is the major relay for all ascending sensory information except olfaction.
VPL Input, info, and destination
Spinothalamic and dorsal columns/medial leminiscus
Pain and temperature; pressure, touch, vibration, and propioception;
primary somatosensory cortex
VPM input, info, and destination
Trigeminal and gustatory pathway
Face sensation and taste
(Makeup goes on the face!)
Primary somatosensory cortex
LGN input, info, and destination
CN II
Vision
Calcarine sulcus
Lateral = Light! (LGN for vision)
MGN input, info, and destination
Superior olive and inferior colliculus of tectum
Hearing
Auditory cortex of temporal lobe
Medial = Music! (MGN for hearing)
To what part of the thalamus does AL and DC information go?
VPL
To what part of the thalamus does Trigeminal and gustatory pathway (face sensation and taste) go?
VPM
To what part of the thalamus does vision go?
LGN (Lateral geniculate nucleus)
To what part of the thalamus does hearing go?
MGN (medial geniculate nucleus)
To what part of the thalamus does the spinothalamic tract go?
VPL (Ventral posterolateral nucleus)
To what part of the thalamus does the trigeminal nerve go?
VPM (Ventral posteromedial nucleus)
To what part of the thalamus does the dorsal column go?
VPL
To what part of the thalamus does the gustatory pathway go?
VPM
Where is the auditory cortex?
Temporal lobe
Where is the primary visual cortex concentrated?
Calcarine sulcus of the occipital lobe
Trace the route of the spinothalamic through the thalamus and cerebrum
VPL –> primary somatosensory cortex (postcentral gyrus of the parietal lobe)
Trace the route of the trigeminal through the thalamus and cerebrum
VPM –> primary somatosensory cortex
What is the limbic system?
Includes cingulate gyrus, hippocampus, fornix, mammillary bodies, and septal nucleus
Responsible for the 5Fs: feeding, fleeing, fighting, feeling, and sex
What does the lateral cerebellum do?
Voluntary movement of extremities
What does the medial cerebellum do?
Balance, truncal coordination, ataxia; when injured, propensity to fall toward injured (ipsalateral) side.
If someone starts falling to his left, what might you suspect?
Injury in the LEFT medial cerebellum
If someone starts falling to her right, what might you suspect?
Injury to the RIGHT medial cerebellum
What are the deep nuclei of the cerebellum?
From lateral to medial, Don’t Eat Greasy Foods.
Dentate,
Emboliform,
Globose,
Fastigial
The cerebellum receives contralateral cortical input via WHAT?
The middle cerebellar peduncle
The cerebellum receives ipsilateral proprioceptive information via WHAT?
The inferior cerebellar peduncle
What are the input nerves to the cerebellum?
Climbing and mossy fibers (WHAT?)
What kind of input does the cerebellum receive from the MIDDLE cerebellar peduncle?
Contralateral cortical input
What kind of input does the cerebellum receive from the INFERIOR cerebellar peduncle?
Ipsilateral proprioceptive input
Name the two types of input that the cerebellum receives
Contralateral cortical and ipsilateral proprioceptive
To modulate movement, the cerebellum provides stimulatory feedback to the XXXX cortex.
CONTRAlateral
What does the cerebellum do?
Provides stimulatory feedback to contralateral cortex to modulate movement
If you injure your medial cerebellum, you fall towards the XXXXX (same or opposite) side of the body as the injury.
Same
What are the output nerves of the cerebellum?
Purkinje fibers output to deep nuclei of cerebellum, which in turn output to cortex via SUPERIOR cerebellar peduncle.