Pathology and ? Flashcards
(28 cards)
35yo African-American woman presents with exertional dyspnea, cough, bilateral hilar adenopathy, and noncaseating granulomas on LN biopsy? Reason for elevated Ca2+?
Sarcoidosis
Activated macrophages have increased 1alpha-hydroxylase activity which increases active vitD to increase Ca2+ levels
Rhomboid crystals with weak positive birefringence made of?
Calcium pyrophosphate (pseudogout)
What feedback system monitors and maintains muscle force?
What feedback system monitors and maintains muscle length?
The Golgi tendon system (connected in series with the contracting extrafusal skeletal muscle fibers) is a negative feedback system that regulates and maintains muscle tension/force.
When a muscle exerts too much force, the GTOs inhibit contraction of the muscle, causing sudden muscle relaxation to prevent damage to the musculoskeletal system.
The muscle spindle system / intrafusal muscle fibers (connected in parallel with extrafusal fibers) is a negative feedback system that monitors and maintains muscle length.
Muscle spindles mediate the stretch reflex (deep tendon reflexes) to create a contraction that resists the stretch.
Dystonia? Myoclonus? Chorea?
Dystonia - sustained, involuntary muscle contractions
most common is cervical dystonia (involuntary prolonged deviation of head to one side with pain in neck)
Myoclonus - sudden, brief, sometimes severe (shock-like) muscle contraction (hiccups and hypnic jerks when falling asleep)
Chorea - involuntary muscle activity that “flows” from one muscle group to another; may be fragmented or jerky, and pt may display “dancing” gait
Types of muscle fibers:
- high mitochondria, myoglobin-rich, glycogen poor?
- low mitochondria, myoglobin-poor, glycogen rich?
What kinds of muscles?
Type I (slow twitch, red fibers) = derive ATP primarily from ox-phos/aerobic metabolism Muscles for low-level, sustained force (postural muscles)
Type II (fast twitch, white fibers) = derive ATP from anaerobic glycogneolysis and subsequent glycolysis Muscles for rapid, forceful arm movements (body-building)
What happens to end plate potential in myasthenia gravis?
Decrease in number of ACh receptors on postsynaptic terminal of muscle end plate in MG results in decreased ability of ACh to bind and open postsynaptic cation channels, thereby decreasing the end plate potential.
MG pt with nausea, sweating, diarrhea, abdominal cramps? Treatment?
MG treated with cholinesterase inhibitor (like pyridostigmine) and GI side effects due to excessive cholinergic stimulation in gut.
Treat with scopolamine (selective muscarinic cholinergic receptor antagonist) that reduces the effects in sites mediated by a muscarinic receptor, such as the gut, without affecting skeletal muscle sites which use nicotinic cholinergic receptors.
24yo with sickle cell has constant left hip pain exacerbated by weight-bearing - restriction of movement but no redness or warmth?
Avascular necrosis of the femoral head
Strongly associated with:
- Sickle cell due to thrombotic occlusion of arteries
- SLE due to injury to vessel wall/vasculitis
- high-dose Steroids and Alcoholism (mech unk)
What is a keloid? What is a contracture? Which is associated with matrix metalloproteinases (MMPs)?
Keloid - hypertrophic scars in which excessive collagenous scar tissue deposited by fibroblasts permanently extends beyond the margins of the original wound
Contracture - permanent shortening by scar tissue due to replacement of normally stretchy elastic tissue with nonstretchy inelastic fibrous tissue
MMPs degrade collagen and other proteins in the ECM - important in wound healing since it encourages both myofibroblast accumulation at wound edges and scar tissue remodeling. Amassed myofibroblasts initiate wound contraction during healing by second intention.
Contractures may occur when unusually pronounced MMP activity results in excessive wound contraction.
Pt with nonpitting edema of hands, fingers turn blue when cold, retrosternal burning and regurgitation? What antibody associated?
CREST syndrome (limited scleroderma) associated with anti-centromere antibody
What are the symptoms of limited scleroderma?
CREST syndrome
Calcinosis Raynaud phenomenon Esophageal dysmotility Sclerodactyly Telangiectasia
associated with Anti-Centromere Antibody
All scleroderma: excessive fibrosis and collagen deposition throughout boy with slcerosis of skin manifesting as puffy and taut skin; sclerosis of renal, pulmonary, cardiovascular, GI systems
What causes digital clubbing? In what pts can it be found?
associated with prolonged hypoxia
found in pts with large cell lung cancer, Tb, CF, suppurative lung disease (empyema, brochiectasis, chronic abcesses)
46yo homeless man with recurrent nosebleeds, swollen gums, ecchymoses, hyperkeratosis, and non-healing ulcer on lower left extremity. What does he have and why?
Scurvy
Vitamin C deficiency - abnormal proline and lysine hydroxylation of procollagen
What serum markers are indicative of osteoblast activity? Osteoclast activity?
Osteoblasts: bone-specific alkaline phosphatase
Osteoclasts: tartrate-resistant acid phosphatase, urinary hydroxyproline, and urinary deoxypyridinoline
Urinary deoxypyridinoline is the most reliable of the three
How does Ca2+ module actin binding sites in skeletal muscle?
Calcium binds troponin, together they bind tropomyosin, which moves tropomyosin away from the myosin binding sites on actin
Myosin can bind actin and start muscle contraction
35yo pt with R knee pain and swelling two weeks after diarrheal illness - joint aspirate with no bacteria and ibuprofen relieves pain? Association?
Reactive arthritis
Associated with HLA-B27 individuals
Joint aspirates are always sterile!! (reactive, not infectious)
Post-GI or GU infection with Campylobacter, Shigella, Slamonella, Yersinia, Chlamydia, Bartonella
28yo Type 1 DM man with fever, right flank pain, difficulty walking. Lies supine with right knee flexed and externally rotated - resists simultaneous extension of the leg and thigh, particularly at the hip. Muscle, condition?
Psoas abcess
due to direct spread of infection from an adjacent structure or distant seeding - DM, IV drug use, HIV, and other immunosuppression at risk.
Psoas sign - pain when hip is extended due to inflammation of the psoas muscle
Infant fell off bed and presents with bilateral retinal hemorrhages and an acute subdural hematoma on emergency CT scan?
Shaken baby syndrome
Subdural hematoma + bilateral retinal hemorrhages in an infant
= highly suggestive of shaken baby syndrome!!!!
1yo African-American boy with tender swelling of hands and feet; family history of brother died at infection at age 6. Significant symmetrical swelling of hands and feet bilaterally.
Sickle cell disease - sickle cell dactylitis due to vasoocclusion
What are haptoglobin levels in sickle cell anemia?
Decreased
Haptoglobin binds free hemoglobin in order to prevent its renal excretion – decreased in pts with hemolytic anemias because half-life of haptoglobin-Hb complex is short vs. free haptoglobin.
59yo man with difficulty climbing stairs, diplopia, dry mouth, poor sexual performance, decreased reflexes (especially quads), round mass in lung on CXR?
Lambert-Eaton myasthenic syndrome (LEMS)
looks like MG, but distinguishing features:
- autonomic involvement (dry mouth, impotence)
- hyporeflexia or areflexia
- association with small cell carcinoma
45yo woman with persistent back pain, poor sleep, easy fatigue, pain and stiffness in muscles worse with exercise. Point tenderness in medial fat pad, scapular spine. Normal muscle strength and joint range of motion. Treatment?
Fibromyalgia
usually in women 20-50yo
(vs. Polymyalgia rhematica seen in women over 50)
Diagnosis using point tenderness in 11 / 18 spots.
Treatment with exercise, antidepressants, and anticonvulsants.
(vs. Polymyalgia rheumatica treated with corticosteroids)
Achondroplasia vs. growth hormone/IGF-1 deficiency?
Achondroplasia:
- FGFR3 activating mutation at epiphyseal growth plate
- short appendicular skeleton (limbs), normal axial (spine)
IGF-1 deficiency:
- hypothalamic or pituitary lesions
- axial and appendicular skeleton are PROPORTIONAL
Bone descriptions:
1) trabecular thinning with fewer interconnections?
2) osteoid matrix accumulation around trabeculae?
3) spongiosa filling medullary canal with no mature trabeculae?
4) lamellar bone structure resembling a mosaic?
5) subperiosteal resorption with cystic degeneration?
1) osteoporosis
2) vitamin D deficiency, rickets (increased deposition of unmineralized osteoid - needed for mineralization)
3) osteopetrosis
4) Paget’s disease (new collagen laid now haphazardly)
5) Hyperparathyroidism (increased osteoclast activity/resorption which primarily involves the cortical bones)
