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FoundSci Unit 6 > Clinical Correlations > Flashcards

Clinical Correlations Flashcards

1
Q

What are muscular dystrophies?

A

Genetic conditions that cause progressive weakness and atrophy of skeletal muscles, starting in childhood

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2
Q

What is the most common muscular dystrophy and what are its characteristics?

A

Duchenne muscular dystrophy (DMD)

X-linked recessive mutation of gene encoding dystrophin

Dysfunctional dystrophin leads to uneven transfer of force through sarcolemma to external lamina and endomysium during contraction.

Leads to weaker contractions and damage to sarcolemma and external lamina

Damage to EL also damages satellite cells - tissue less able to repair and regenerate, death of muscle fibers and satellite cells

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3
Q

What happens within a few days after minor damage to skeletal muscle repair?

A

Satellite cells activate, proliferate, and differentiate into myoblasts

Myoblasts align and fuse end to end to form myotubes and myotubes fuse side to side to form muscle fibers

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4
Q

What occurs with satellite cells with age or injury?

A

Number of satellite cells decreases with age - slower healing as age increases

Muscle injury damages external lamina usually damages/kills satellite cells - intact EL is important for muscle cell repair

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5
Q

If damage to skeletal muscle fibers is extensive, what occurs?

A

Fibers not repaired and eventually replaced with scar tissue and fat

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6
Q

Why does cardiac muscle tissue not regenerate after cell damage?

A

No satellite cells

Dead cells replaced with collagenous CT scar tissue

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7
Q

What occurs with the tau protein in patients with Alzheimer’s Disease?

A

Hyperphosphorylation of tau protein causes it to aggregate in an insoluble form

Makes tau protein unable to bind to microtubules - they become unstable and start disintegrating

Unbound tau forms clumps, neurofibrillary tangles, that disrupt cell function and can lead to neuronal death

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8
Q

What causes dendritic spines to decrease in number?

A

Dendritic spines decrease with age and with poor nutrition

Patients with trisomy 21 or trisomy 13 also have fewer dendritic spines

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9
Q

What do some viruses use to travel from neuron to neuron in CNS?

A

Viruses like HSV and rabies use retrograde transport

Also method that toxins are transported from body periphery to CNS

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10
Q

What are most primary brain tumors in adults derived from?

A

Fibrous astrocytes

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11
Q

How often does the process of PNS axon regeneration occur?

A

3-4 mm/day

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12
Q

Are tracts in the CNS able to regenerate?

A

No

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13
Q

What is hyperuricemia?

A

Elevated uric acid

Deposition of sodium urate crystals

Caused by:
Decreased renal clearance of urate - renal insufficiency and metabolic acidosis

Increased urate production - hemolytic disease and chemotherapy

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14
Q

What is gout?

A

Recurrent attack of inflammatory arthritis

Deposition of sodium urate crystals in the joints of the extremities

Triggers an inflammatory response with pain and join swelling

Can progress to acute gouty arthritis

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15
Q

What are kidney stones?

A

Common in patients who suffer gout

Deposition of uric acid stones in the kidney - uric acid urolithiasis

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16
Q

What is allopurinol?

A

Analog of hypoxanthine converted to oxypurinol by xanthine oxidase

Inhibit xanthine oxidase and conversion of hypoxanthine and xanthine to uric acid

Hypoxanthine and xanthine more soluble than uric acid - eliminated in urine

Reduces uric acid formation

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17
Q

What is the rare hereditary condition that presents with high levels of orotic acid in the urine and hypochromic megaloblastic anemia?

A

Orotic aciduria

High levels of orotic acid in urine causes crystalluria

Hypochromic megaloblastic anemia - unresponsive to B12 and folic acid

Growth retardation

Neurologic abnormalities

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18
Q

What is severe combine immunodeficiency syndrome (SCID)?

A

Group of immune disorders impacting both B cell and T cell function

15% of cases due to mutation in adenosine deaminase

Adenine metabolites build up

Accumulation of dATP inhibits ribonucleotide reductase

Conversion of NDPs to corresponding dNDPs blocked

Lack of purine and pyrimidine deoxyribonucleotides block DNA replication

Inability to replicate DNA prevent cell proliferation events required for effective immune response

Alternatively, adenine metabolites directly toxic to lymphocytes

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19
Q

What occurs with inhibition of thymidylate synthase?

A

Blocks de novo dTMP synthesis

Reduced dTTP available for DNA synthesis and blocks cell proliferation

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20
Q

What is 5-fluorouracil?

A

Analog of uracil

Cancer treatment for colon carcinoma

For dermatology uses - topical for actinic keratosis

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21
Q

What is methotrexate?

A

Folate analog

Used in treatment of various cancers, severe psoriasis, and sever rheumatoid arthritis

Inhibits dihydrofolate reductase

Lack of N5N10-methylene THF inhibits thymidylate synthase

Lack of pyrimidine synthesis blocks cell proliferation

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22
Q

What is Lesch-Nyhan syndrome?

A

Hereditary syndrome

Severe or complete deficiency of HGPRTase activity

Results in hyperuricemia - causes tiny, orange crystals of sodium urate in infant’s diapers

Also results in uric acid stones, intellectual disability, and self-injurious behavior (biting fingers)

23
Q

What drug can help with fungal infections by fungi like Cryptococcus neoformans? Caused headache, nausea, fatigue, and altered mental state

A

Flucytosine

Systemic fungal infection prevalent in those with compromised immune systems (AIDS, patients on immunosuppressants)

Flucytosine (5-fluorocytosine) is an analog of cystine. Fungi express cytosine deaminase (humans do not). This enzyme converts cytosine/5-fluorocytosine to 5-fluorouracil which is then converted to FUMP. 5-fluorocytosine is toxic to fungi and relatively non toxic to humans

24
Q

Chronic Granulomatosis Disease

A

Deficiency in NADPH oxidase in phagocytes

Leads to recurrent infections because NADPH oxidase is activated in response to bacterial infection

25
Q

Where is iron found in the body?

A

Iron found in tetrapyrroles (heme, cytochromes)

Bound to ferritin (cell storage)

Bound to transferrin (blood transport)

26
Q

What are diseases leading to iron overload?

A

Hereditary hemochromatosis

Thalassemia (alpha and beta)

Sickle cell anemia

Frequent blood transfusions

27
Q

What is hereditary hemochromatosis?

A

Mutation in HFE gene

Causes excessive iron accumulation in tissues and organs

Leads to organ destruction

28
Q

How does thalassemia (alpha and beta) and sickle cell anemia lead to iron overload?

A

Leads to excessive destruction of red blood cells causing iron overload

29
Q

What is amyotrophic lateral sclerosis (ALS)?

A

Deficiency in Cu/Zn-superoxide dismutase (SOD1) or misfolded Cu/Zn-SOD1 (sporadic)

Progressive degeneration of motor neurons

Leads to muscle weakness, paralysis, death within 3-5 years of diagnosis (adult onset)

30
Q

Where is adipose CT present in a fatty heart?

A

Present along other parts of the heart’s surface other than in sulci/grooves or surrounding coronary vessels

31
Q

What is thickness of epicardial fat on heart surface positively correlated with?

A

Obesity

Diabetes 2

Pro-inflammatory cytokine level

Vascular aging

Subclinical atherosclerosis

32
Q

What occurs to contractile cardiomyocytes after a myocardial infarction?

A

During and following a MI, contractile cells in the affected part of the myocardium undergo necrosis

Rupture of membranes releases cardiac-specific troponin T and troponin I into surrounding ECM, which goes to tissue fluid, lymph vessels, and then blood

Serum troponin T levels are elevated about 2-3 hours following chest pain onset and peak 12-48 hours

33
Q

What can cause an arrhythmia?

A

Abnormalities in the spatial distribution of gap junction in intercalated discs

34
Q

What is ANP?

A

Atrial Natriuretic Peptide

35
Q

What is BNP?

A

B-type natriuretic peptide

36
Q

what are the serum levels of ANP and BNP during congestive heart failure?

A

Both are elevated

Heart still is beating, but is weak and cannot pump enough blood to meet oxygen demands

ANP and BNP increase kidney filtration rate by natriuresis (increased sodium excretion) and diuresis (increased fluid excretion)

Both ANP and BNP are vasodilators

37
Q

What is BNP a more sensitive biomarker of?

A

Heart failure

Especially left ventricular dysfunction because levels of BNP increase as failure worsens

Used to track treatment progress

38
Q

What is SARS-CoV-2 infection associated with?

A

Can trigger myocarditis (inflammation of the myocardium)

Estimates of incidence vary greatly, but it occurs even in asymptomatic of mildly symptomatic patients (including children and athletes) and can occur following COVID-19 vaccination

Also associated with:
Fibrin clots and microclots (platelet clots) in myocardium capillaries

Recruitment of megakaryocytes to myocardium

Clotting of myocardium capillaries can cause localized tissue damage (ischemia)

39
Q

What does pacemaker cells and heart rate have to do with each other?

A

Number of SA nodal cells (pacemaker cells) determines maximum HR

40
Q

What does SA nodal cell do with age?

A

SA nodal cell number decreases with age - progressive slowing of conduction velocity and voltage loss

Highest number of SA nodal cells in fetuses - this is why fetal HR is so high

Reduction in SA nodal cell number drives the decrease in max (and target HR) that occurs with age

This is a reduction in intrinsic heart rate - it happens whether sedentary or active, even in elite athletes

41
Q

What are Purkinje fibers vulnerable to?

A

Vulnerable during infection of the endocardium (ex. infective endocarditis (microbial infection of the endocardium))

Subendocardium is very close to the chamber lumen and Purkinje fibers are critical for heart function

42
Q

What does having extra glycogen make Purkinje fibers more resistant to?

A

Resistant to hypoxia vs contractile cardiac cells

43
Q

Valvular Degeneration

A

Valves with comprised structure have compromised function

Valvular diseases often result in inefficient blood flow - patent valve (too much flow when shut), stenosis (too little flow when open), and valvular regurgitation (backflow)

Consequence of valvular degeneration - cardiac muscle tissue is often weakened from the extra strain caused by inefficient blood flow through the heart

44
Q

What is important about pericytes and how they can differentiate into fibroblasts, smooth muscle cells, and endothelial cells?

A

Important role during blood vessel formation and repair - these are the cells you would need to synthesize a new endothelium, tunica media (smooth muscle), and tunica externa (CT)

45
Q

What are continuous capillaries necessary for given their solid walls?

A

Necessary for proper function of the blood-brain barrier and blood-gas barrier (alveolar wall in lungs)

46
Q

What are varicose veins?

A

Weakened or incompetent valves allow blood to pool or backflow in veins

Valves stays partially open

Instead of being pushed toward the hear, blood backflows (gravity)

Blood settles in valve leaflets, pools, and causes bulging

47
Q

What is often used as a coronary artery bypass graft?

A

Great saphenous vein

Because it has thick and muscular walls and is of similar size to coronary arteries

48
Q

How does edema relate to lymphatic drainage?

A

Tissue edema occurs when the capacity for lymphatic drainage is exceeded:

Hydrostatic pressure is too high

Oncotic pressure is too low

Lymph capillaries are damaged or blocked (lymph flow impeded)

49
Q

What occurs with patients with low levels or malformed von Willebrand factor?

A

Have bleeding problems

Clots either take longer to form or form incorrectly

Leads to easy bruising, heavy menses, and bleeding gums

50
Q

What is von Willebrand disease?

A

Most common hereditary blood clotting disorder

Affects 1% of the population worldwide, affects men and women equally

Severity of bleeding varies by subtype

51
Q

What are the effects of aging on the aorta?

A

The number of elastic lamellae in the tunica media increases from birth to adult age

52
Q

What are the effects of aging on all elastic arteries?

A

Moderate intimal fibrosis - thickening of tunica intima by addition of collagen I fibers

Minor fragmentation of elastic lamellae (media) - elastin protein starts to break down and wear out

53
Q

Acute tonsillitis

A

Infectious mononucleosis (mono)

Caused by Epstein Barr virus and spread via saliva

Fatigue and fever

Severe pharyngitis (inflammation of pharynx) usually with tonsillitis (inflammation of tonsils)

Lymph nodes also usually swollen and splenomegaly

54
Q

DiGeorge Syndrome

A

Patients are born with cleft palate and have other distinct facial features

Leads to absence/hypoplasia of the parathyroid glands and the thymus

Lack of thymus causes severe T cell deficiency or complete absence of T cells. Patients lack a cell mediated immune response, resulting in frequent and recurring infections

Allergic and autoimmune manifestations

Higher risk of some autoimmune conditions

Absence of parathyroid glands cause issues regulating calcium (too low) and phosphorus (too high)

FoundSci Unit 6 (14 decks)

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