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Usmle > Block 18 > Flashcards

Block 18 Flashcards

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USMLE® Step 1 flashcards
1
Q

Exetrtional dyspnea with medical history significant for pneumonia and hypertension. Decreased breath sounds and bilateral wheezing

A
  • indicative for centriacinar emphysyma seen in COPD.

- dilated airspaces seen on CT

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2
Q

Lingual thyroid

A

Thyroid gland is formed from outpouching of the pharyngeal epithelium and subsequently descends to lower neck.

  • failure of migration, the thyroid can reside anywhere along the thryroglossal duct usual path, including the tongue (hence lingual).
  • it can lead to obstructive symptoms such as dysphaia, dysphonia and dyspnea, especially at timse of highetend thyroid stimulation.
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3
Q

IgG binding site for the complement

A

Its not the same as attachment to phagocytic cells (not lower FC portion)Rather its the part superior to it (closer to the hinge region)

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4
Q

What are the main factors that influence cerebral circulation

A

Systemic BP and arterial blood gas levels.
-when systemic BP is decreased it has no effect on brain due to autoregulation(60-140). (However under 50 -> risk for ischemia, and above 150 risk for increased ICP due to increase cerebral volume)

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5
Q

Arterial PaCO2 role on brain circulation

A
  • its the most important regulator.
  • a drop in PaCO2 due to hypoventilation —> vasoconstriction, —> reduction in cerebral blood volume —> decrease ICP.
  • lowering of PaCO2 is one of the measures employed to reduce ICP in mechanically ventilated patients with cerebral edema
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6
Q

Renal gluconeogenesis is stimulated by

A

Epinephrine is better than glucagon in stimulating “renal” gluconeogenesis, this is done when hypoglycemia is sustained.

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7
Q

ubiquitin proteaosome pathway

A

Its essential for breakdown of ntracellular proteins, both native and foreign and helps recycle them.

  • this process is perforemed by ubiquitin ligases enzymes.
  • this process is essential for MHC class I presentation of infected cells.
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8
Q

Antioxidant enzymes

A

Superoxide dismutase, glutathione peroxidase and catalase.

Converts ROS to O2 and H2O

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9
Q

Posterior urethral valves

A

Occurs only in males, males and males

  • can present with bilateral hydronephrosis, and clyceal dilation due to obstruction of urine flow in the urethra.
  • they occur from a malformation in woliffian duct therefore occurs only in males
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10
Q

Vesicouretral reflux (reflux nephropathy)

A

-normally, after bladder fills, there is a flip valve mechanism that prevents retrograde flow of urine, however of this mechanism doesnt work —> vesicoureteral reflux occur —> can lead to multiple pyelonephritis —> renal scarring commonly in upper and lower poles of kidney —> secondary hypertension and nephron damage may occur

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11
Q

Compound papillae vs simple papillae

A

Compound papillae are always open thus more susceptible to kidney injury.

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12
Q

Clinical manifestation of asbestos exposure

A
  1. Pleural plaques: affects parietal pleura near the diaphragm, dense collagen that beomes calcified.
  2. Asbestosis: progressive diffuse pulmonary fibrosis, asbestos bodies (green-brown beaded rods)
  3. Bronchogenic carcinoma
  4. Mesothelioma
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13
Q

Alkylating agents and benzene exposure associated with

A

Acute leukemias

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14
Q

Hydrocephalus types

A
  1. Communicating hydrocephalus: globular ventricualr dilation and increased ICP without significant CSF flow blockage. Usually due to impaired arachinoid villi due to inflammation or fibrosis.
  2. Normal pressure hydrocephalus: enlarged ventricles in the seeting of normal ICP, it have impaired CSF absorption compensated by decreased formation of CSF.more common in adults
  3. Hydrocephalus ex vacuo : present with normal ICP and increased dilation of ventricles secondary to cortical atrophy(usually occurs with alzehaiemr)
  4. Pseudotumor cereberi presents with elevated ICP and classicaly occurs in young women who are overweight.
    The etiology of the condition isnt well known but its thought to be related to cerberal venous outflow abnormalities due to elevated ICP
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15
Q

Cholesterol gall stones treatment

A
  • decreased amounts of bile acids and phospholipids can cause bile to become supersaturated with cholesterol allowing it to crystalize and form cholesterol gallstones.
  • risk for stone formation including increasing age,obesity, excessive bile salt loss, and female sex.
  • cholecystectomy is the best management
  • medical management : hydrophilic bile acids ( Ursodexycholic acid) reduces cholesterol secretion and increases billiary bile acid concentration —> promotes gallstones dissolution.
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16
Q

Pagets disease of bones clinical presentation

A

Hearing loss(bony deformity of the skull)(due to auditory foramen narrowing)
Increased Hat size
Increased ALP
Long bones chalk stick fractures
High output heart failure (due to increased blood flow from increased AV shunts)

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17
Q

Pagets disease pathogenesis

A
  • initially, excessive osteclastic bone resorption—> increased bone formation by osteoblasts —> this result in high bone turnover (new bone disorganized. Easily fracture)
  • osteclasts originates from mononuclear phagocytic cell lineage and are ultimately formed when sever precursor cells fuse to create multinucleated mature cells.
  • e 2 most importamt factor for osteoclasting differentiation is M-CSF and receptors for activated RANK-L.
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18
Q

Osteoprotegerin

A

Physiologic decoy receptor that decreases binding of RANK-L to RANK —> reduces differntiation and survival of osteoclasts —> increased bone density. (Loss of function results in pagets disease)
- monoclonal antibody : DONOSUMAB used for treatment of osteoporosis (inhibits RANK-L RANK binding

19
Q

GERD histology

A
  • basal zone hyperplasia
  • elongation of lamina propria papillae
  • scattred neutrophils and eosinophils.
20
Q

Pill induced esophagitis is commonly seen in

A
  • tetracycline
  • potassium chloride
  • bisphosphonates
21
Q

Bartonella henselae can cause

A
  • cat scratch disease
  • this organism resides in oral cavity of cats and trismitted by cat scratches and bites.
  • typically present tender regional lymphadenopathy proximal to the lesion
  • axillary lymphadenopathy is extremely common.
  • bacillary angiomatosis is present in immuncomproimised patients
22
Q

Bordotella pertusis

A

Whooping cough , highly contagious , occurs in adults due to vaccinated children.

  • 3 phases : catarrhal, paroxysmal, and convalescent.
  • its a gram negative coccobacillus.
  • pertactin, promotes adherence to ciliated upper respiratory epithelium —> local tissue destruction —> cough.
  • it causes excessive adenylate cyclase activity —> inhibit phagocytosis allows the organism to persist on alveloar macrophages.
23
Q

Enlarged coronary sinus can be caused by

A
  1. Pulmonary hypertension —> elevated RH pressure
  2. Persistant left superior vena cava (not right)
  3. Total anomalous pulmonary venous return
24
Q

Costosternal syndrome (costochondritis)

A
  • usually occurs after repetitive activity and invloves the upper costal cartilage at the costochondral or costosternal junctions.
  • pain typically repoduced with palpation and worsened with movement or changes in position.
25
Q

BP that vary mildly beween arms (more than >10 mmHg)

A

Aortic dissection,

-sudden,tearing chest pain, radiating to the back and BP disparity between the arms.

26
Q

Blotchy red muscle fibers on gomori trichrome stain is characterstic of

A

Mitochondrial myopathy.(Myoclonic epilepsy with ragged red fibers)

27
Q

Chrons disease —> kidney stones why>

A

-bile acid lost with feces —> impaired fat absorption —> excess lipid in bowel lumen binds to calcium ions —> saponification excerted in feces=—> calcium decreased and cant bind oxalate —> oxalate absorption increased —> oxalate kidney stones.

28
Q

Administration of excessively high O2 concentration can lead to

A

It can lead to increased CO2 retention (O2-induced hypercapnia), resulting in confussion and lathergy.this is due to 3 mechanisms:

  1. Hyperoxia revese pulmonary vasoconstriction (stimulated by hypoxia), increasing physiological dead space as poorly ventilated alveoli are perfused (V/Q mismatch)
  2. Increased PaO2 decrease Hb affinity for CO2 resulting in dissociation from Hb and increased PaCO2 blood in plasma (haldane effect)
  3. Peripheral chemoreceptors in carotid sense arterial PaO2 and are normally stimulated by hypoxemia. High flow O2 reduces chemoreceptors —> decreased RR and minute ventilation.
29
Q

Ecthyma gangrenosum

A

Associated with P.aurigenosa bacteremia, usually occurs in neutropenic patients.
- perivascular bacterial invasion of arteries and veins in the dermis and subcutaneous tissue with subsequent release of exotoxins destructive to human tissues.—> skin patches exhibiting necrosis and ulceration.

30
Q

Common cardinal veins give rise to

A

SVC.

31
Q

Phosphoinositol system

A

This is used in alpha 1 receptors, M1 and M3, vasopressin 1, histamine 1, oxytocin, TRH, angiotensin II, and GnRH receptors.
-after changing and activation of phospholipase C —> DAG and IP3 formation —> DAG stimulate protein kinase C, and IP3 mediates release of intracellular Ca+2 stores from ER.

32
Q

Anti emetic drugs

5 classes

A
  1. Antimuscarinic (scopolamine)
  2. Antihistaminic (promethazine, diphenydyramine)
  3. Dopamine receptor antagonists (metoclopramie, prochlorepazine
  4. Serotonin receptor antagnoist (ondansetron)
  5. Neurokinin receptor antagonist (arepitant, fosaprepitant) (prevents substance P release)
    (Last three used for chemotherapy induced emesis)
33
Q

HIV protein glycosylation

A

Only the polyprotein product of env gene is glycosylated to become gp160.
-gp 160 is then cleaved in ER and golgi to form gp120 and gp41. These are responsible for viral attachment to target cells.

34
Q

Atopic eczematous dermatitis

A

Usually present with asthma, hay fever and dermatitis.

  • active eczema shows, intraepidermal vesicels, superfacial epidermal hyperkeratosis producing scales and epidermal hyperplasia (acanthosis).
  • cotricosteroids treat it but it leads to dermal atrophy
35
Q

Turner syndrome pregnancy achievement

A

Pregnancy can be achieved using IVF.
With sufficient E2 and P supplements they may develop thick endometrial lining that is substantial enough to support pregnancy.
(Complication should be checked in order to prevent complication during pregnancy)

36
Q

Lead poisining clinical

A

Weakness, abdominal pain and constipation.
In severe cases neurological manifestation may be present.
Patients may have blue lead lines at junction of teeth and gingivae.
Blood smear shows basophillic sippling on a background of hypochromic microcytic anemia.

37
Q

Metal poisining

A

Lead posining

38
Q

Torsades de pointes can be caused from antiarrythmic class ?

A

Ia and III

39
Q

Patent ductus arteriosus

A
  • continuous murmur (L to R shunt)
  • wide pulse pressure and bounding pulses
  • metabolic acidosis
  • signs of cardiovascular stain (tachycardia, cardiomegaly), esienmenger (from L to R —> R to L)
40
Q

Colchecine mechanism and side effects

A
  • colchecine binds to intracellular tubulin and inhibits its polymerization into microtubules.
  • This in turn disrupt cytoskeletal dependent function such as chemotaxis and phagocytosis.
  • administered at the first signs of a gout flare and can be repeated an hour later.
  • side effects include persistant nausea, diarrhea and abdominal pain.
  • it should be avoided in elderly or have renal dysfunction.
41
Q

Myotonic dystrophy type 1

A
  • slow relaxation of muscles, classic symptoms are difficulty loosening ones grip
  • AD, occurs due to CTG repeats of the gene the codes for myotonia protein kinase. Anticipation is present.
  • catracts are seen in almost all patients, frontal balding and gonadal atrophy are common features
  • light microscopy shows atrophy of muscle fibers, type 1 fibers are more affected.
42
Q

Adenocarcinoma in situ of lung

A
  • the most common type in USA
  • arises from alveolar epithelium and is located at the periphery of the lung, considered preinvasive and lesion charactriazed by growth along intact alveolar septa without vascular or stromal invasion.
  • microscopic examination reveals well differentiated, dysplastic coulmnar cells with or without intracellular mucin.
43
Q

Common fibular nerve

A

Superficial branch: innervates lateral compartment of the leg —> eversion of foot
Deep branch: innervates anterior compartment of the foot —> dorsoflexiors of foot and toes
The superficial provides sensory innervation to the dorsum of the foot. The deep peroneal nerve provides sensory innervation to the region between the first and second digit of the foot

44
Q

Hypercalcemia in sarcoidosis caused by

A

Activated macrophages in the lung and lymph nodes causes PTH independent production of vitamin D (using 1a-hydroxylase)

Usmle (45 decks)

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