nerves June 7 Flashcards
What do Platelets do?
Platelets are stem cell fragments made in your bone marrow. These cells bind together to help repair damaged blood vessels and stop bleeding. If you have a cut or a scrape, for example, platelets will stick together causing the blood to clot and stop the bleeding.
Is ACH always excitatory? Is this the same as stimulatory?
The neurotransmitter acetylcholine is excitatory at the neuromuscular junction in skeletal muscle, causing the muscle to contract. In contrast, it is inhibitory in the heart, where it slows heart rate.
My notes say parasympathetic is always stimulatory. Even though it is “stimulatory”, that stimulation may mean calming down. Does this mean ACH always stiumulates? or ? only in the Parasympathetic, and why? is it about the receptors?
Cells of cajal - where do they come from? and where do they live?
Interstitial cells of Cajal (ICC) are mesenchymal cells located within the muscle layers of the alimentary tract that mediate communication between the autonomic nervous system and smooth muscle and may underlie dysrhythmias, gastroparesis, and slow intestinal transit comprising diabetic gastroenteropathy
How does arachnoid villi work?
The arachnoid granulations act as one-way valves. Normally the pressure of the CSF is higher than that of the venous system, so CSF flows through the villi and granulations into the blood. If the pressure is reversed for some reason, fluid will not pass back into the subarachnoid space.
Are ependymal cells special?
Ependymal cells are a specialized type of epithelial cells that line the ventricular system of the brain and play a key role in the production of cerebrospinal fluid.
They line the internal cavities of the CNS - part of the blood-brain barrier and they can absorb and secrete cerebrospinal fluid.
What is the purpose of the nodes of ranvier?
The myelin sheath is regularly interrupted along the length of the axon by specialized regions called the nodes of Ranvier, which are necessary for the propagation of an action potential along the axon.[1] The nodes of Ranvier are essential in the speed and timing of delivery of impulses from one neuron to another,
Slow vs fast anterograde flow down axons?
Neurofilaments and other cytoskeletal polymers are transported down the axon at a rate of 0.2–8 mm day−1, in a process known as ‘slow’ axonal transport. This transport is orders of magnitude slower than the transport of vesicular cargos in ‘fast’ axonal transport
What is the speed of retrograde flow re axons and what is the danger?
Speed is about 200 (half between fast and slow antero - and danger is toxins - tetanus, herpes, rabies - toxins and viruses.
DYNEin powers retrograde flow
What are the two types of synapses?
Chemical and electrical. neurotransmitters vs. gap junctions, CAN BE EXCITATORY OR Iinhibitory
How many synapses can occur in one nuero
10 or a zillion. Purkinje in cerebellum 100,000
What are NSF and how does it relate to vesicles?
NSF is on the membrane of synaptic vesicles and is required for formation, targeting and fusion w/ membrane
synapses are morpholically classified how?
type 1 - asymmetrical, type ROUNDED / excitatory suggestion 2, symectrical FLATTENED - suggested to be INHIBITORY
Does release of nerotrasnmitter create excitation or inhibition?
Both - depending upon… Parasympathetic only excitation.
ACH bindings
M1, M2, M3 (muscarinic - G protein linked) - NICOtinic is Gated ION channel
What are catecholamines?
Norepinephrise, epinephrine, dopanmine - all G protein linked - NE and E bind with alpha 1,2 and beta 1,2,3
Dopamine binds w/ D1,2
NE - roles in anxiety, panic attacks, depression, mania
E - secreted by chromaffin cells in adrenal medulla
DOPA - role in parkinsons
What is required to restore the vesicle fro the membrane edge back into the bulb?
Clathrin, dynamine and syapsin are used to effect this, protein kinase is also involved -
four types of neuerglia?
astrocytes (BBB, etc), oligodendrocytes (made and wrap myelin), ependyma (line w/ cuboidal, / link w/ desmosomes - and CSF) and microglia - police (mesodremal v. neuroectodermal)
CNS has no CT - it’s mushy - so these help support. Pathologically, create 40% of tumors.
What protein do astorcytes have?
GFAP - glial fibrillary acidic protein. = these are prominent bundes of intermediate filament
What do astrocyte feet line?
external limiting membrane (pia) and internal limiting membrane (epedympa - lining ventricles)
they COVER the vare areas of nodes of ranvier in myelinated fibers - they lie on cell body or axolemma
They form gap junctions w/ each other -
have adrenergic receptors, GABA and peptide receptors
Can astrocytes remove excess neurotransmitters at synapses?
yes. They can also form scar tissue called gliosis. Huge roll in BBB
What are Tanycytes?
specialized Ependymal glial-like cells that line the third ventricle, are emerging as components of the hypothalamic networks that control body weight and energy balance. They contact the cerebrospinal fluid (CSF) and send processes that come into close contact with neurons in the arcuate and ventromedial hypothalamic nuclei.
Where do microglia come from?
Bone marrow.
What disease injures Schwann cells?
Guillian barre
A rare disorder in which your body’s immune system attacks your nerves. Weakness and tingling in your extremities are usually the first symptoms. These sensations can quickly spread, eventually paralyzing your whole body
What disease injures oligodendrocytes?
MS.
What causes Wallerian degeneration?
Any lesion of the axons that leads to an interruption and any lesion of the nerve cell bodies that leads to the cell death is followed by Wallerian degeneration. In the CNS common causes are infarction, hemorrhage, tumors, and head injury with shearing of nerve fibers.
four parts of cerebrum
frontal (reasoning)
parietal (movement, (TOP) perception of stiumli)
Occiptal (behind - visual)
temporral ( memory speech, auditory stimuli - on the SIDE)
Cerebellum is called the ?
Little brain - associated with regulation and coordination of movement, posture and balance, fine motor skills (ice skating
Brain stem
basic vital life functions - breathing, heartbeat BP
Midbrain (vision, hearing, eye and body movement);
Pons (motor control) consciouness, sleep
Medulla oblongata - breathing, heart rate
Alcohol effect?
forebrain - motor coord
midbrain - lose control of emotion and chance of blackout
brainstem - heart rate, body empt, appetite, consciousness
White matter in brain - not on the edge - and what’s it consists of?
myelinated axons and oligodendrocytes and microglia - no neural cell bodies
Where do synapses occur, grey or white area?
GREY. on the edges - with nucli (islands of grey) in the white
Where is the cortex of the brain?
On the outside - with GREY matter. White matter organizes in tracts
How many layers does the cerebral cortex have?
six - lots of pyramidal BETZ cells on 5th level.
What’s the function of the cerebral cortex?
integration of sensory info and initiation of voluntary motor responses.
First layer of cerebral cortex?
Lots of fibers, microglial and few cells - a few horizontal cells of cajal -
Cerebellum, how many layers
3 - purkenji with lots of dendrites in center layer. -
What are the granule layers made of in both cerebral and cerebellum?
small neruons
In the spinal cord, where does the lumen develop from ?
neural tube
Grey matter in spinal cord - anterior and posterior horns do what?
Posterior - receive sensory fibers info - anterior contain motor neurons that are the axon roots of motor neurons. spinal cord neurons are large and multipolar, especially in motor neurons..
what are the neuroglial processes in the brain?
Thin layer between pia mater and the nerve layer - BBB
Dilated ventricles in brain might signify?
Hydrocephalus. Failure of absorption of obstruction of CFS. Main absorption is by… archnoid villi - there is no lymph to absorb fluid in brain.
In PNS - do schwann cell wrap unmylienated axons?
YES - and schwann can wrap many - not just one (which is the case when mylinated)
What are neurilemma cells?
Schwann cells
What is the signal protein re how thick myelin should be?
Nrg1 - neuregulin - in axoleema
Spaces between nodes of Ranvier?
Each space, an internode, is covered by one Schwann -
deep cleft on where tight schwann wrapping has loosened are called?
Schmidt-Lantermann clefts or incisures - thought perhaps have to do with nutrition.
What proteins do Schwann cells make?
zero (MPZ) and PMP22. In the CNS is PLP - proteolipid protein
What types of axons are the thickest and have the most mylination - which will cause faster speed?
Motor and Skeletal muscles. Fiber type A alpha.
What are the different types of neural diseases?
Ones that affect mylination (MS, Guillian Barre - Schwann) and neural degeneration (Alz, huntington, Parkinson, ALS?)
Are there various demylination disease beyond the two mentioned above - that are IMMUNE Mediated?
Yes - In MS and Guillain Barre - the immune system attacks mylination - but mylination can also be attacked by:
Inherited - adrenoleukodystrophy (peroxisomal fatty acid beta oxidation disorder)
Metabolic - adverse effect from medical treatment - too quick rise in body sodium, vitamin B deficienty
Virus inducted - JC virus - almost exclusive where have severe immune deficiency
What characterizes these mylinating attacking diseases?
they leave the axons alone - and go after the fatty mylenations - clinical defects come from loss of transmission of electrical impulses.
Lose sensory (often eye sight), limbs fall asleep, muscles weakened, shake -
Autonomic system breaks down with incontinence, impotence
What are some nuerodegenerative diseases - Dementias? and what characterizes them?
Loss of grey matter (neurons) - progressive loss - typically affects groups of neurons located near one another - often associated with accumulation of abnormal proteins resistant to degrdation and which manifest inclusions (ALZ)
What is the sulcus of the brian
The furrows - the GYRI is the other part.
What are tangles caused by?
Tau protein - correlates w/ degree of dementia
IS ALZ missing ACH?
Yes - and narrowing of Gyri and widening of sulci - and cortical atrophy, especially hippocampus
What is parkinson’s disease about?
gene mutations - loss of dopaminergic neuron and lewy bodies causes Pallor of substantia nigra.
What does Parkinson’s do to your body?
TRAPS it - tremor, rigidity, akinesia )or bradykinesia), postural instability and shuffling gait.
What are lewy bodies?
Lewy body dementia (LBD) is a disease associated with abnormal deposits of a protein called alpha-synuclein in the brain. These deposits, called Lewy bodies, affect chemicals in the brain whose changes, in turn, can lead to problems with thinking, movement, behavior, and mood.
What causes parkinson’s?
Unknown - heroin production methods, possible envionmental
What causes huntington disease?
autosomal dominant - appears when 30 - 50 years old. Can be confused with substance abuse re aggressive, depressed, dementia -
Caudate loses Ach and GABA`
can cause ventricular enlargement
sensitive to glutamate
What is ALS?
Lou Gehrig - mostly autosomal dominant, various genetic mutations -
degenerative upper and lower motor neurons, weak hands, arms and legs - and respiratory muscles - deaht in 2 - 3 years for most.
degenerates anterior horn cells and in the brain
Tell me about the perineurium??
It is made of actin filaments and attaches to other cells by tight junctions -
Two functions:
Elastic (so nerves can stretch) and forms a Blood nerve barrier.
What are functions of epineurium (EPIC)
protective when nerves cross joints - acts as a cushion. disppears as nerve branches out - dense fibrous irreg CT, merging with loose CT and adipose surrounding nerve contains mast cells and fibroblasts and collagen bundles
What is chromatolysis?
nerve degeneration when Nissi substances disappear - during degeneration - whole cell size increases due to water entering cell, nucleus moves to edge, golgi shrinks, etc
What is Wallerian degeneration?
myelin sheath breaks down into fat droplets, axoplams disintegrates with 24 hours, endo tube collapes (if can stay together - better regeneration chances) Macrophages move in
how do schwann cells aid in regeneration?
They proliferate at both ends of axon and form bridge from which axon can start to sprout and crawl along.
What does sympathetic nervous system INHIBIT, Stimulate and Dilate?
saliva, GI actions are inhibited, bladder relaxed, pupils, bronchia are dilated, excites - heart rate, adrenal medulla (to release adenaline and NE, and orgasm
What does parasympathetic excite vs. inhibit?
It only excites, except that excitement for PSNS means reducing heart rate and constricting pupils and urinary bladder - stimulates also erection
Autonomic vs somatic receptors?
Somatic - only nicotinic - Autonomic - Nicotinic, alpha 1,2, beta 1,2 M 1 - 5, D 1,2
what post ganglionic axons are mylinated?
NONE. The most heavily mylinated axons are ?? skeletal muscles that have no postganglionic feature.
Where does ganglia come from?
Neural crest cells. ?? all?
What are the collateral ganglia of the Sympathetic nervous system?
Greater, Lesser and Least Splanchnic, and Lumbar - maybe more other places.
What are the two types of sympathetic ganglia?
Chain and collateral - (celiac, aorticorenal, superior and inferior mesenteric)
What do sympathetic and parasympathetic ganglia syntheize?
Symp: catecholamines - PARA - ACH.
What is each ganglion surrounded by?
A layer of small cuboidal cells - satellite cells
Explain the organization of the Ganglionic neurons in the Sympathetic NS?
Lateral grey horns T1 - L2,
chain ganglia (paired), collateral (unpaired) Adrenal medulla (paired)
Chain ganglia effects most of body - including pila, blood vessels, sweat glands -
Collateral in abdominopelvic area
Adrenal by the use of hormones affects throughout body.
Does parasympathetic have a chain ganglia?
No - long preganglionic flow from Cranial 3, 7, 9, 10 (vagus - intramural ganglia), and S2 - 4 -intramural) - named intramural because they are near the organs they innervate
Does sympathetic relax or contract smooth muscles and inhibit glandular secretions?
Relaxes smooth, inhibits glandular secretion - while contracting cardia and vascular.
What does prevertebral and paravertebral mean?
Pre - (in the spinal cord), Para adjaced to spinal cord - hence the sympathetic nervous system and chain ganglia
in the parasympathetic, are there organs not controlled by the vagus in the abdominal cavity?
only the hindgut organs - supplies up to the splenic flexure.
What does peristalsis mean?
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward.
What are the exceptions to the rule that post ganglionic receptors receive NE/E in the SNS?
sweat glands receive ACH,
renal vasculature receive dopamine
chomaffin cells of adrenal medulla - they release epinephrine
Adrenergic receptors - what a1 about?
located on vascular smooth muscle of skin and GI, bladder sphincters - generally produce excitation (constriction) -
GQ protein, Phopholipade C, and IP3, Ca2) intracellular
IN GI - produce RELAXATION
a2 receptors?
Often produce inhibition (relax or dilation) ,
LOCATION - platelets, fast cells, walls of GI tract
Pancreas - less insulin released, Platelets less aggregation,
via GI protein, inhibition of ACH and decrease in cyclic adenosine monophosphate (Camp)
B1 receptor?
produce excitation - located SA and AV node - and ventricular muscle of heart -
Kidney - renin release
Adipose - lipolysis
GS protein, stim of adenylate cyclas and increase in camp
B2 receptors?
blood vessels supplying skeletal, liver, heart; smooth muscles - eye, bronchial and walls of GI and bladder, and blood vessels
RELAXATION - dilation
methods same as B1
ACH and muscarinic - all excitory?? however… some inhibit
M2 and M3 - in heart inhibits Gi protein)
In smooth muscle and glans (excites) (Gq protein, stim phospholipase C, and increase in IP3 and intracellular ca2+.
Are nerves only sensory or motor, or can they be mixed and contain both?
Mixed - most common.
Neural crest cells give rise to which of the following?
dorsal horn,
adrenal cortex,
sympathetic ganglia, preganglion autonomic nerves,
somatic motor neurons?
Sympathetic ganglia
Does NE increase or decrease cardiac output?
Increase.
Are dopamin and GABA inhibitors or excitors?
inhibitors
What’s the most excitatory neurotrasnmitter of the CNS?
Glutamate.
Does seritonin help deal with pain?
Yes, it inhibits pain in mood control and sleep.
What roll does potassium K+ play in cell polarization?
Repolarization of the membrane, which follows membrane depolarization by sodium, and in some cases calcium, channels during the action potential; this is necessary for returning the membrane to a negative resting potential to terminate the action potential signal.
What do Nissi bodies contain?
polysomes and RER
What structure do axon hillocks contain?
microtubules
Rapid onset of fever, stiff neck headache and altered state of consciousness are associated with what neural disease?
meningitis
A patient has a lesion affecting the intermediate lateral horn of the spinal cord. What is the function of this region?
The intermediate horn carries sympathetic cell bodies from the brain and preganglionic neurons
Which form of dementia results from depigmentation of the substantia nigra pars compacta?
Parkinson’s
Patients with Parkinson disease have a loss of which neurons?
Dopaminergic. Dopaminergic neuron loss and excess cholinergic activity
What is the sodium potassium pump?
mechanism where Na+ is pumped out of the membrane and K+ is pumped back in to restore the original configuration within the membrane
What protects cell bodies of neurons?
Satellite cells
What connects sensory and motor neurons?
Interneurons
long axon and short process leaving cell body
unipolar
one axon and one dendrite
bipolar
where about would you find a unipolar neuron?
in the peripheral autonomic regions
Unipolar neurons are typically sensory neurons with receptors located within the skin, joints, muscles, and internal organs. The axons of such neurons are usually long, terminating in the spinal cord.
where would you find a pseudounipolar neurone
dorsal route ganglia
What symptoms of amyotrophic lateral sclerosis (ALS) result from lower motor neuron (LMN) deficits due to anterior horn cell involvement?
Dysarthria, dysphagia, fasciculation, asymmetric limb weakness, atrophy of muscles
Which brain cells respond to infection, such as in bacterial meningitis?
microglia
Which areas of the brain are most commonly affected in a patient with secondary reactivation of latent JC virus?
Parietal and occipital areas; visual symptoms are common
What are the 3 histologic hallmarks of chromatolysis in a peripheral nerve?
Swelling of the cell body, peripheral nuclear displacement, and Nissl substance dispersion throughout the cytoplasm
What parts of a neuron are seen with Nissl staining and why?
Cell bodies and dendrites are stained because they contain rough endoplasmic reticulum (Nissl substance) unlike axons, which do not appear on staining
Which cranial nerve (CN) innervates the muscles of mastication?
3, receptor musc?
What is the difference between Lewy body dementia and dementia secondary to Parkinson disease?
If cognitive and motor symptom onset are <1 year apart, it is called Lewy body dementia; otherwise, it is considered dementia secondary to Parkinson disease
Acute inflammatory demyelinating polyradiculopathy results in destruction of what cell type?
Schwann
How do oligodendrocytes appear histologically?
fried eggs - small nuclei, dark chromatin, and scant cytoplasm)
Which nerve roots are needed for the cremaster reflex?
L1 and l2 (“tesicle move”
What are the embryologic derivatives of each of the 3 meningeal layers?
Dura mater is derived from mesoderm; pia mater and arachnoid mater (leptomeninges) are derived from the neural crest
What is the name of the cranial nerve (CN) that carries parasympathetic efferent fibers from the Edinger-Westphal nucleus?
CN3
What pathology usually results in cauda equina syndrome?
Intervertebral disc herniation or tumor
What brain stem and cerebellar syndromes does multiple sclerosis present with?
Diplopia, ataxia, intention tremor, scanning speech, nystagmus/internuclear ophthalmoplegia (bilateral > unilateral)
Which sinus is the primary site of CSF return?
The superior sagittal sinus
What protein makes up ALZ Disease?
Amyloid-β (cleaved from APP), which forms neuritic plaques in gray matter (diagnosis: Alzheimer disease)
A patient from a nursing home presents with altered mental status after several falls. Likely cause of altered mental status?
Subdural hematoma (or several) as a result of shearing injury from the falls
Which nerve roots cause referred shoulder pain in patients with peritoneal injuries?
C3-C5 (phrenic nerve, which allows for pain referral from the diaphragm and gallbladder)
A patient has a lesion affecting the intermediate lateral horn of the spinal cord. What is the function of this region?
The intermediate horn carries sympathetic cell bodies from the brain and preganglionic neurons
What see in person with Alzheimer’s
Widespread cortical atrophy, especially in the hippocampus with narrowing of gyri and widening of sulci
What phenomenon causes successive generations to manifest features of Huntington disease earlier in their lives?
Anticipation - !!!!
Dopamine from which area binds D1 receptors? Does this stimulate or inhibit movement?
Stimulates
Substantia nigra pars compacta (SNc); this stimulates movement (via the direct pathway)
What markers are associated with neurons?
Synaptophysin and neurofilament protein
Which 2 cranial nerves (CNs) innervate the salivary glands?
CN VII (submandibular and sublingual glands) and CN IX (parotid gland)
Through which layers of the meninges does the venous system of the brain run?
Through the periosteal and meningeal layers of the dura mater
Which neurotransmitter decreases in a patient with Alzheimer disease?
ACH
What organellar activity is increased in this neuron?
Increased activity of the Nissl substance, which allows for increased protein synthesis necessary for axonal repair (this is chromatolysis, image: round cellular swelling)
What is the only type of cutaneous sensory receptor associated with unmyelinated nerve fibers?
free nerve endings
A patient cannot feel pressure, vibration, or touch, and proprioceptive sensation is absent. Which pathway in the spinal cord is impaired?
The dorsal column pathway
What is the purpose of chromatolysis in neuronal cells?
Axonal repair
A biopsy specimen of a brain tumor stains positive for glial fibrillary acid protein (GFAP). From what germinal layer did it arise?
Neuroectoderm (GFAP is an astrocyte marker)
man has an infection. What 3 structures of the blood-brain barrier prevent the infection from spreading into the brain?
Astrocyte foot processes, basement membrane, and tight junctions of nonfenestrated capillary endothelial cells
What brain changes result in a patient with Huntington disease?
Atrophy of caudate and putamen with ex vacuo ventriculomegaly
Which 2 meningeal layers form the subarachnoid space?
Pia mater and arachnoid mater
What 2 structures are present on the apical surfaces of ependymal cells, and what are each of their core functions?
Cilia (circulate cerebrospinal fluid [CSF]) and microvilli (help with CSF absorption)
In which space is cerebral spinal fluid (CSF) collected?
Subarachnoid space
how does a hot bath affect someone with MS?
Symptoms worsen as a result of increased body temperature
Which neural functions are not affected by amyotrophic lateral sclerosis (Lou Gehrig disease)?
Sensory and bladder/bowel functions
What features does Huntington disease usually present with?
Chorea, athetosis, depression, aggression, dementia (sometimes mistaken for substance abuse)
What disease would present in a patient with AIDS experiencing rapidly progressive memory loss and aphasia and who tests positive for active JC virus infection?
Progressive multifocal leukoencephalopathy (reactivation of latent JC virus infection)
What is the usual disease course of amyotrophic lateral sclerosis?
fatal
Describe the pathogenesis of multiple sclerosis.
Autoimmune inflammation and demyelination in the CNS (ie, the brain and spinal cord) with subsequent axonal damage
What demographic group (race, sex, and age) is most likely to be affected by multiple sclerosis?
White women in their 20s and 30s; risk of MS increases with distance from the equator and with low serum vitamin D levels
What does the epineurium surround?
An entire nerve, including both the fascicles and blood supply
What other axonal process is likely occurring at the same time as chromatolysis?
Wallerian degeneration (distal axonal degeneration and proximal retraction) occurs concurrently in response to axonal injury
What symptoms are commonly seen in a patient with Charcot-Marie-Tooth disease?
Foot deformities (eg, pes cavus, hammer toe), sensory deficits, and lower extremity weakness (eg, foot drop)
Charcot-Marie-Tooth disease (CMT) is a group of inherited conditions that damage the peripheral nerves. It’s also known as hereditary motor and sensory neuropathy (HMSN) or peroneal muscular atrophy (PMA). The peripheral nerves are found outside the main central nervous system (brain and spinal cord).
What are Lewy bodies?
Intracellular eosinophilic inclusions composed of α-synuclein; seen in Parkinson disease and Lewy body dementia
What does the epidural space contain?
Fat and blood vessels
receptors that inhibit and excite?
the M’s (1-3) excite, M’s (2,4) inhibit. A1,B1 excite, A2,B2 inhibit. Thats what I remember off the top of my head
In Parkinson disease, due to less dopamine binding D1 receptors in the striatum, what happens within the direct pathway to decrease movement?
Striatum releases less γ-amino butyric acid (GABA); this disinhibits the globus pallidus interna (GPi), leading to inhibition of the thalamus and cortex to decrease movement
What 2 anatomic structures surround the epidural space?
The dura mater and skull
What are the steps in smooth muscle contraction that follow calmodulin binding to Ca2+?
Myosin–light-chain kinase (MLCK) is activated, phosphorylating myosin and leading to contraction
Patients with myasthenia gravis and Lambert-Eaton syndrome develop muscle weakness. Would patients with Lambert-Eaton syndrome display autonomic symptoms?
Yes; autoantibodies to presynaptic Ca2+ channel are produced, so the autonomic system (eg, dry mouth, constipation, impotence) and muscular junctions are affected
Describe the sequence of skin color changes that occur in Raynaud phenomenon.
White (ischemia), then blue (hypoxia), then red (reperfusion)
A weight trainer benches on a daily basis. He is inducing hypertrophy of which type of muscle fiber?
white fast - this is what sprinting and weight lifting build
A patient who had abdominal surgery reports burning at the incision site that radiates to the inguinal region. Which nerve is affected?
Iliohypogastric nerve (T12–L1)
How does estrogen exert its effects on bone?
Stops bone growth in puberty, promotes oclast activity throughout life - so when older women don’t have it - their bones may get weak.
It inhibits apoptosis in osteoblasts and induces apoptosis in osteoclasts
Osteoblasts keep living, and osteoclasts die
What is the function of the Golgi tendon organ, a muscle proprioceptor?
It senses tension via the dorsal root ganglion and facilitates inhibition of muscle activation, which reduces tension in the muscle and tendon
Name the 2 ophthalmic manifestations that can present in a patient diagnosed with myasthenia gravis.
eye droop Ptosis and double vision. Diplopia,
What is the fundamental mechanism of osteoarthritis?
Mechanical; wear and tear causes destruction of articular cartilage, leading to inflammation with inadequate repair (chondrocyte mediated)
Where is the Golgi tendon organ located and what type of sensory axons does it innervate?
It is located in the tendons; it innervates type Ib sensory axons
Patients can reduce their risk of osteoporosis by taking what 2 supplements?
Calcium and vitamin D (should be taken throughout adulthood)
Osteopetrosis leads to thickened, dense bones. How likely are these bones to fracture?
Brittle bone disease,
Very likely, because the normal process of remodeling and resorption is disrupted
A patient has an L3–L4 disc herniation. Which nerve roots are impaired by this lesion?
The L4 nerve roots (in the lumbar spine, the nerve roots are found inferior to the associated vertebral body)
Lambert-Eaton myasthenic syndrome predominantly leads to weakness in which muscle groups?
Proximal muscle groups
In membranous ossification, what is the role of cartilage in the formation of woven bone?
Woven bone is formed directly without cartilage (ie, there is no role for cartilage); woven bone is later remodeled to lamellar bone
A patient is told that an x-ray image shows diffuse symmetric sclerosis. What other phrase is used to describe this observation?
Bone-in-bone or “stone bone” seen in osteopetrosis
Are osteoclastomas (giant cell tumors) benign?
Yes, but they are locally aggressive
A patient with osteitis deformans has increased osteoblastic and osteoclastic activity with normal Ca2+, PO43-, and PTH levels. What disease stage is this?
The mixed stage of osteitis deformans (also known as Paget disease of bone) in which increases in both osteoblast and osteoclast activity occur
Which muscles are innervated by the obturator nerve?
Obturator externus, gracilis, pectineus, adductor longus, adductor brevis, adductor magnus
Rheumatoid arthritis is more prevalent in what population?
females
During the power stroke, what happens to myosin?
Myosin releases ADP and Pi and becomes displaced on the actin filament
Osteitis deformans has high-yield oncologic and non-oncologic complications. What cancerous outcome can you see in a patient with osteitis deformans?
Osteogenic sarcoma; increased activity of osteoblasts can create mutations, resulting in osteosarcoma
Achondroplasia is inherited in what fashion?
Autosomal dominant (with full penetrance); associated with increased paternal age
In achondroplasia, what type of bone ossification is impaired?
long bone growth - due to impaired endochondral ossification (due to a mutation in FGFR3)
What is the term for chronic joint degeneration caused by calcium pyrophosphate deposition disease?
Pseudo-osteoarthritis
Achondroplasia is inherited in an autosomal dominant manner. Are most cases of achondroplasia inherited?
No; most cases result from sporadic mutation
An osteoma affects what age group?
Middle-aged adults
Surface of facial bones
Associated with Gardner syndrome
How does estrogen deficiency (eg, due to surgery or menopause) lead to osteoporosis?
Excess remodeling cycles and bone resorption occur without the protective effects of estrogen
From which metabolic process do type II muscle fibers derive their energy?
Anaerobic glycolysis
Osteochondromas rarely transform into which type of malignancy?
Chondrasarcoma
A 2-year-old boy has bowing of the legs. His labs show elevated parathyroid hormone levels but decreased Ca2+ levels. What is the primary deficiency?
Rickets - Vitamin D - C is scurvy
What are the common extraarticular manifestations of rheumatoid arthritis?
Rheumatoid nodules; interstitial lung disease; pleuritis; pericarditis; anemia of chronic disease; Felty, carpal tunnel, and Sjögren syndromes; AA amyloidosis; scleritis
Inflammation and exuberant proliferation of the synovium leads to formation of pannus and destruction of cartilage, bone, tendons, ligaments, and blood vessels. Basically, the hypertrophied synovium is called pannus.
What secretions of osteoclasts effectively dissolve bone?
H+ and collagenases
Osteoporosis is most often diagnosed because of what finding in which procedure?
T-score of ≤ -2.5 on DEXA scan (at the lumbar spine, total hip, and femoral neck)
A new drug inhibits the ryanodine receptor. What ion will not be released from the sarcoplasmic reticulum as a result?
Calcium
What part of bone will be affected by osteosarcoma?
Metaphysis of long bone, especially the knee region
A sprinter would have a higher proportion of which type of muscle fibers?
White type II.
What nerve roots make up the pudendal nerve?
L2 - 4
What is the underlying pathophysiology of Paget disease of bone (osteitis deformans)?
Increases in both osteoblastic and osteoclastic activity, resulting in localized, pathologic bone remodeling
What happens when ATP binds to a myosin head that is attached to the actin filament?
Release of the myosin head; hydrolysis of ATP to ADP puts myosin in a cocked position for the next contraction cycle; Ca2+ is resequestered
How do osteoblasts build bone?
They secrete collagen and catalyze mineralization via alkaline phosphatase (osteoblasts build bone)
What x-ray findings are associated with vitamin D deficiency?
Osteopenia and Looser zones in osteomalacia; epiphyseal widening and metaphyseal cupping/fraying in rickets
What neurologic lesions may result from osteopetrosis?
Cranial nerve palsies due to narrowed foramina in the skull, which impinges the nerve
At what age is a 1-time screening for osteoporosis recommended for women?
65 years or older
Which benign bone tumors are more common in boys?
Osteochondroma, Osteoma, Osteoid osteoma, Osteoblastoma; benign bone tumors that start with O are more common in boys
What are some causes of primary hyperparathyroidism?
Parathyroid hyperplasia, a parathyroid adenoma or carcinoma, or idiopathic
Parathyroid hormone is increased in osteomalacia (rickets in children). What effect does this have on osteoblasts? Hence Vitamin D is needed to avoid to control parthyroid?
Osteoblasts are stimulated to make alkaline phosphatase because they require an alkaline environment to function properly
When calcium levels are low, parathyroid hormones are released by the body to help counteract this deficiency. … As vitamin D deficiency and elevated parathyroid hormone levels are extremely common in older adults, it is important that adults get enough calcium and vitamin D to promote cardiovascular health
Explain how type I slow-twitch muscle fibers utilize oxidative phosphorylation.
They have a relative increase in oxidative phosphorylation, which leads to sustained muscle contractions (think “1 slow red ox”)
What is oxidative phosphorylation?
the synthesis of ATP by phosphorylation of ADP for which energy is obtained by electron transport and which takes place in the mitochondria during aerobic respiration.
Why are type II muscle fibers white?
Lower myoglobin and lower mitochondria
What is the fundamental mechanism of rheumatoid arthritis?
Autoimmune; inflammation causes proliferation of granulation tissue (pannus formation), which erodes articular cartilage and bone
How is the synovial fluid in rheumatoid arthritis (RA) different from that in osteoarthritis (OA)?
In RA, the fluid is inflammatory (WBC >2000 mm3); in OA, the fluid is noninflammatory (WBC <2000 mm3)
Which hormone is likely chronically elevated in a patient with osteitis fibrosa cystica?
Parathyroid hormone, leading to excess bone catabolism (patient may have primary hyperparathyroidism)
How are osteoclasts activated?
RANKL (RANK ligand expressed on osteoblasts) stimulates RANK receptors on osteoclasts
You believe a patient has myasthenia gravis. What class of drugs would you prescribe to treat this disease?
Acetylcholinesterase inhibitors (such as pyridostigmine)
What are the classic physical exam findings in a patient with fibromyalgia?
Tender points and stiffness
Most common in women 20–50 years old. Chronic, widespread musculoskeletal pain associated with “tender points,” stiffness, paresthesias, poor sleep, fatigue, cognitive disturbance(“fibro fog”). Treatment: regular exercise, antidepressants(TCAs, SNRIs), neuropathic pain agents (eg, gabapentin
Osteitis deformans (Paget disease of bone) represents disordered activity of osteoclasts and osteoblasts. Which is disrupted first?
Osteoclasts (4 stages of Paget disease: lytic, mixed, sclerotic, quiescent)
Which malignant bone tumor presents as an enlarging mass that produces pain or occurrence of pathologic fractures?
Osteosarcoma
An x-ray obtained from a 12-year-old boy who has frequent fractures has a bone-in-bone appearance (image). What enzyme is likely deficient?
Carbonic anhydrase II, which is defective in osteopetrosis
Mutations (eg, carbonic anhydrase II) impair ability of osteoclast to generate acidic environment necessary for bone resorption. Overgrowth of cortical bone fills marrow space pancytopenia, extramedullary hematopoiesis. Can result in cranial nerve impingement andpalsies due to narrowed foramina.
X-rays show diffuse symmetric sclerosis(bone-in-bone, “stone bone” ). Bonemarrow transplant is potentially curative as osteoclasts are derived from monocytes
What is the most common cause of short-limbed dwarfism?
Achondroplasia
What are muscle proprioceptors?
Specialized sensory receptors that transmit information regarding muscle dynamics
Why might you expect to see abnormal red and white cells in the peripheral smear of a patient with osteopetrosis?
The marrow-filling process squeezes out normal cell lines (eg, one might see dacryocytes)
How does smooth muscle respond to intracellular Ca2+ vs nitric oxide?
Ca2+ = Contraction, nitric oXide = relaXation
Will see myosin light chain kinase /and MLC phospholate
Steps involved in smooth muscle cell contraction:
Depolarization of membrane or hormone/neurotransmitter activation.
L-type voltage-gated calcium channels open.
Calcium-induced calcium release from the SR.
Increased intracellular calcium.
Calmodulin binds calcium.
Myosin light chain kinase activation.
Smooth muscle contraction is dependent on calcium influx. Calcium is increased within the smooth muscle cell through two different processes. First, depolarization, hormones, or neurotransmitters cause calcium to enter the cell through L-type channels located in the caveolae of the membrane
Intracellular calcium then stimulates the release of calcium from the sarcoplasmic reticulum (SR) by way of ryanodine receptors and IP3; this process is referred to as calcium-induced calcium release.[7] Unlike skeletal muscle, smooth muscle calcium release from the sarcoplasmic reticulum is not physically coupled to the ryanodine receptor. Once calcium has entered the cell it is free to bind calmodulin, which transforms into activated calmodulin. Calmodulin then activates the enzyme myosin light chain kinase (MLCK), MLCK then phosphorylates a regulatory light chain on myosin. Once phosphorylation has occurred, a conformational change takes place in the myosin head; this increases myosin ATPase activity which promotes interaction between the myosin head and actin. Cross-bridge cycling then occurs, and tension is generated.
The tension generated is relative to the amount of calcium concentration within the cell. ATPase activity is much lower in smooth muscle than it is in skeletal muscle.
What are the two types of smooth muscle?
Visceral smooth muscle - All cells work together at the same time as one unit.
Multi-unit smooth muscle - Cells can act and function independently of the others.
Which bones are formed by membranous ossification?
Bones of the calvarium, face, and clavicle
