Neuro - Anatomy & Physiology Part 1 Flashcards
An alcoholic gets rapid IV fluids for electrolyte disturbance. MRI is taken after he develops acute paralysis. What disease does he have?
Central pontine myelinolysis with paralysis, dysarthria, diplopia, and loss of consciousness; caused by rapid correction of hyponatremia
Microglia originate from what embryologic layer?
The mesoderm
Except for microglia, all central and peripheral nervous system supportive cells originate from what layer?
The ectoderm
What is the function of ependymal cells?
Ependymal cells make cerebrospinal fluid
Which two types of cells of the nervous system are derived from neural crest cells?
Schwann cells and peripheral nervous system neurons
Central nervous system neurons are derived from ________ (neuroectoderm/neural crest cells) whereas peripheral nervous system neurons are derived from _________(neuroectoderm/neural crest cells).
Neuroectoderm; neural crest cells
Which four types of cells are derived from neuroectoderm?
Central nervous system neurons, ependymal cells, astrocytes, oligodendroglia
What is Nissl substance, and where is it found?
It is the rough endoplasmic reticulum in the cell body and dendrites (not axon) of a neuron
Neurons are _____ (permanent/labile) cells that _____ (do/do not) divide in adulthood.
Permanent; do not
On histopathology, what is the response of astrocytes to injury known as?
Reactive gliosis
What are the five functions of astrocytes?
Physical support, repair, potassium metabolism, removal of excess neurotransmitter, maintenance of the blood-brain barrier
Which cells comprise the blood-brain barrier?
Astrocytes
What is the molecular marker for astrocytes?
Glial fibrillary acidic protein (GFAP)
In HIV-infected patients, what cell type fuses to form multinucleated giant cells?
Microglia
In response to tissue damage, what do microglia transform into?
Large ameboid phagocytic cells
What is the histologic appearance of microglia?
They have small, irregular nuclei and relatively little cytoplasm and are not readily discernable in Nissl stains
What is the main function of microglia?
Phagocytosis (in the setting of tissue damage) in the central nervous system
Which cells in the central nervous system are destroyed in multiple sclerosis?
Oligodendrocytes are attacked in an autoimmune process leading to demyelination
What type of cell myelinates multiple (up to 30 each) central nervous system axons?
Oligodendrocyte
In Nissl stains, what types of cells appear as small nuclei with dark chromatin and little cytoplasm (like a fried egg)?
Oligodendrocytes
Oligodendrocytes are the predominant type of glial cell in _____ (gray/white) matter.
White; the white appearance is due to myelin
_____ (Oligodendrocytes/Schwann cells) are found in the central nervous system and myelinate _____ (one/up to 30) axon(s), whereas _____ (oligodendrocytes/Schwann cells) are found in the peripheral nervous system and myelinate _____ (one/up to 30) axon(s)
Oligodendrocytes; up to 30; Schwann cells; one
What type of cells promote axonal regeneration in the peripheral nervous system?
Schwann cells
An acoustic neuroma is a tumor derived from which cell type?
Schwann cells; it is a Schwannoma
Schwannomas often affect which cranial nerve?
Cranial nerve VIII
Schwann cells are derived from what embryonic cell population?
Neural crest cells
Which syndrome is characterized by destruction of Schwann cells?
Guillain-Barr syndrome, which involves the acute, self-limited destruction of myelin in the peripheral nervous system
What are the four sensory corpuscles?
Meissner;s corpuscles, Pacinian corpuscles, Merkel;s discs, and free nerve endings
What kind of corpuscles are involved in dynamic fine touch (eg, manipulation)?
Meissner;s corpuscles; these are quickly-adapting receptors
What kinds of corpuscles are located in glabrous (hairless) skin?
Meissner;s corpuscles; glabrous skin includes the lips and fingertips
What kind of corpuscles are located in deep skin layers?
Pacinian corpuscles
Ligaments and joint capsules contain what type of sensory corpuscles?
Pacinian corpuscles
What kind of corpuscles are responsible for sensations of vibration and pressure?
Pacinian corpuscles
What kind of sensory receptors are located in hair follicles?
Merkel’s discs
What type of touch do Merkel;s discs sense?
Static touch (eg, shapes, edges, textures); these are slowly adapting receptors
What type of sensory corpuscles can be found throughout the skin as well as some viscera?
Free nerve endings
Free nerve endings are made up of what two types of fibers? How do they differ?
C and Aδ fibers; C are slow and unmyelinated, Aδ are fast and myelinated
Pain and temperature are sensed by what type of sensory corpuscles?
Free nerve endings
In peripheral nerves, single nerve fibers are immediately contained within the _____.
Endoneurium; the prefix endo- means inner
Each fascicle of peripheral nerve fibers is surrounded by a permeability barrier called the _____.
Perineurium (remember: Perineurium and Permeability barrier)
What dense connective tissue surrounds the entire nerve, including the fascicles and the blood vessels?
The epineurium; the prefix epi- means ‘outer’
During a limb reattachment, what nerve layer must be rejoined for the surgery to be successful?
The perineurium; the prefix peri- means around; some axons will regrow if there is an intact perineurium
Where in the brain is norepinephrine synthesized?
The locus ceruleus
Where in the brain is dopamine synthesized?
The ventral tegmentum and the substantia nigra pars compacta
Where in the brain is serotonin synthesized?
The raphe nucleus
Where in the brain is acetylcholine synthesized?
The basal nucleus of Meynert
How do neurotransmitter levels change with anxiety?
Anxiety increases norepinephrine, decreases serotonin and γ-aminobutyric acid, and does not affect dopamine or acetylcholine
How do neurotransmitter levels change with depression?
Norepinephrine, dopamine, and serotonin all decrease
In which psychiatric condition are central nervous system dopamine levels increased?
Schizophrenia
In Alzheimer;s and Huntington;s diseases, central nervous system levels of which neurotransmitter is decreased?
Acetylcholine
Which neurotransmitter is involved in the pathogenesis of Parkinson;s disease?
Dopamine activity is decreased
The locus ceruleus is a nucleus in the brain stem involved with physiologic responses to which two emotions?
Stress and panic
Which brain region, found in the striatum, plays an important role in laughter, fear, reward, and addiction
The nucleus accumbens
The blood-brain barrier is formed by what three structures?
Capillary endothelial tight junctions, basement membranes, and astrocyte foot processes
What two substances cross the blood-brain barrier slowly by a carrier-mediated transport mechanism?
Glucose and amino acids
What properties of a molecule allow it to diffuse across the blood-brain barrier?
Nonpolar and lipid-soluble substances
Name the three blood-tissue barriers found in the body.
The blood-brain barrier, the blood-testis barrier, and the maternal-fetal blood barrier of the placenta
Name three specialized brain regions with fenestrated capillaries and no blood-brain barrier.
The area postrema (responsible for vomiting with chemotherapy), the organum vasculosum of the lamina terminalis (osmotic sensing), and the neurohypophysis (responsible for antidiuretic hormone release)
Infarction destroys endothelial cell tight junctions in the blood-brain barrier, leading to leakage of fluid into the brain from damaged blood vessels, causing _____ _____.
Vasogenic edema
Central control for thirst and water balance is found in what part of the brain?
The hypothalamus (the supraoptic nucleus)
Destruction of the lateral nucleus of the hypothalamus would produce what disorder?
Anorexia (remember: if you zap your lateralnucleus, you shrink laterally)
A patient presents with hyperphagia and obesity after a localized injury to the hypothalamus. What part of the hypothalamus has been injured?
The ventromedial nucleus (remember: if you zap your ventromedialnucleus, you grow ventrallyand medially)
Parasympathetic activity is regulated by the _____ (anterior/posterior) hypothalamus.
Anterior (remember: pArasympathetic, Anterior; A/C = anterior cooling)
Sympathetic activity is regulated by the _____ (anterior/posterior) hypothalamus.
Posterior
Circadian rhythms are predominantly regulated by which part of the hypothalamus?
The suprachiasmatic nucleus (remember: you need sleep to be charismatic [chiasmatic])
A patient presents with the inability to regulate heat conservation and production. What part of the brain is injured?
The posterior hypothalamus (remember: if you zap your Posterior hypothalamus, you become a Poikilotherm [cool, like a snake])
What area of the brain coordinates the cooling of the body in hot temperatures?
The anterior hypothalamus
What region of the brain regulates sexual urges and emotions?
The septal nucleus
How does the mnemonic TAN HATS describe the functions of the hypothalamus?
TAN HATS: Thirst and water balance, Adenohypophysis control, Neurohypophysis releases hormones from hypothalamus, Hunger, Autonomic regulation, Temperature regulation, Sexual urges
Which area of the hypothalamus responds to emetics?
The area postrema (responsible for vomiting with chemotherapy)
Leptin stimulates the _____ (ventromedial/lateral) area, leading to _____ (hunger/satiety) and inhibits the _____ (ventromedial/lateral) area, leading to _____ (hunger/satiety).
Ventromedial; satiety; lateral; satiety
The posterior pituitary receives axonal projections from the _____ and _____ nuclei.
Supraoptic and paraventricular
The posterior pituitary secretes which two hormones?
Antidiuretic hormone and oxytocin
The supraoptic nucleus produces which hormone?
Antidiuretic hormone
Oxytocin is produced in the _____ nucleus of the posterior pituitary.
Paraventricular
What structure is the major relay for sensory information ascending to the cortex?
The thalamus
The ablation of the lateral geniculate nucleus would produce what kind of deficits?
Visual
The medial geniculate nucleus is responsible for the relay of what type of stimuli to the cortex?
Auditory
A patient with a thalamic defect presents with a lack of proprioception. What part of the thalamus has the defect?
The lateral part of the ventral posterior nucleus
Sensory stimuli from the spinothalamic tract are relayed to the cortex via what part of the thalamus?
The lateral part of the ventral posterior nucleus