Uworld Physio 4

Question 1

The duodenal brush border enzyme ——- activates trypsin from its inactive precursor, trypsinogen. Trypsin degrades complex polypeptides to dipeptides, tripeptides, and amino acids while activating other pancreatic enzymes.

Answer 1

enteropeptidase

Question 2

Enteropeptidase deficiency impairs both protein and fat absorption, leading to

Answer 2

diarrhea, failure to thrive, and hypoproteinemia

Question 3

Unilateral renal artery stenosis causes hypoperfusion and activation of the renin-angiotensin-aldosterone system. Angiotensin II causes arteriolar vasoconstriction and increases aldosterone and antidiuretic hormone synthesis. The resultant hypertension helps reduce the decline in glomerular filtration rate in the affected kidney, but causes a pressure natriuresis with increased —- excretion in the —— kidney.

Answer 3

increased sodium excretion in the unaffected

Question 4

Diffusion speed across a semipermeable membrane increases with —— molecular concentration gradients, larger/smaller membrane surface areas, and ——- solubility of the diffusing substance.

Diffusion speed decreases with increased membrane thickness, smaller pore size, higher molecular weights, and lower temperatures.

Answer 4

higher molecular concentration gradients

larger membrane surface areas

increased solubility of the diffusing substance.

Question 5

Point mutations in neurophysin II underlie most cases of hereditary hypothalamic ——–, a disorder resulting from insufficient ADH release into the systemic circulation.

Answer 5

diabetes insipidus

Question 6

Generalized hyperpigmentation is a manifestation of Addison’s disease, where a primary defect in adrenal cortisol production reduces feedback inhibition of anterior —— synthesis. As a result, —– cleavage products, including ACTH and melanocyte-stimulating hormone (MSH), are secreted in excess. High MSH levels cause increased melanin synthesis by melanocytes.

Answer 6

pituitary pro-opiomelanocortin (POMC)

Question 7

Neurophysins are carrier proteins for — & —- hormones produced within the paraventricular and supraoptic nuclei, respectively, and released from the posterior pituitary.

Answer 7

oxytocin and vasopressin

Question 8

Most patients with thyroid dysgenesis have hypothyroidism, with routine newborn screening findings of increased TSH and decreased thyroxine (T4) levels. However, newborns are typically asymptomatic for the first weeks due to the presence of ——-, which crosses the placenta in small amounts during gestation. The amount of neonatal T4 is still low compared to that in unaffected patients but is sufficient to initially prevent clinical manifestations of hypothyroidism.

Answer 8

maternal T4

Question 9

VIPomas are pancreatic islet cell tumors that hypersecrete vasoactive intestinal peptide (VIP), which increases intestinal chloride loss into the stool and causes excess losses of the accompanying water, sodium, and potassium.

VIP also inhibits —- secretion.

—— inhibits the secretion of VIP and is used to treat the symptoms of VIPoma

Answer 9

gastric acid

Somatostatin

Question 10

Excess —— secretion due to a pancreatic islet cell tumor called —oma can result in watery diarrhea, hypokalemia, and achlorhydria (WDHA) syndrome (pancreatic cholera). — stimulates pancreatic bicarbonate and chloride secretion, and its binding to intestinal epithelial cells leads to adenylate cyclase activation and increased cyclic AMP production, causing sodium, chloride, and water secretion into the bowel (secretory watery diarrhea, often >3 L/day).

Answer 10

vasoactive intestinal peptide (VIP)

Question 11

CCK is produced by – cells of the proximal small bowel mucosa in response to fatty acids and amino acids.

Answer 11

I cells

Question 12

Motilin is produced by the duodenal mucosa and stimulates smooth muscle contraction in the upper GI tract. The antibiotic —– acts as an agonist at motilin receptors in the stomach and duodenum, contributing to the drug’s GI side effects.

Answer 12

erythromycin

Question 13

A glucagonoma is a pancreatic alpha cell tumor that hypersecretes glucagon and can cause —– and necrolytic migratory erythema of the skin.

Answer 13

secondary diabetes mellitus

Question 14

Pregnancy is a prothrombotic state due to increased or decreased

—— procoagulant factors (eg, fibrinogen),

——- anticoagulant factors (eg, protein S),

—– fibrinolysis.

Answer 14

increased procoagulant factors (eg, fibrinogen)

decreased anticoagulant factors (eg, protein S),

and reduced fibrinolysis.

Question 15

Pleural effusion in decompensated heart failure is primarily driven by backward transmission of pressure from the failing left ventricle to the pulmonary circulation, resulting in ——- pulmonary capillary hydrostatic pressure and an ——– rate of fluid inflow to the pleural space. ——- Vascular permeability &

—– vascular oncotic pressure.

Outflow through the parietal pleural lymphatics increases in response to the increased fluid inflow, but it is unable to keep up, resulting in development of pleural effusion.

Answer 15

increased pulmonary capillary hydrostatic pressure and an increased rate of fluid inflow to the pleural space.

Vascular permeability remains normal

normal vascular oncotic pressure

Question 16

In exogenous thyrotoxicosis, radioactive iodine uptake and serum thyroglobulin level are —, indicating suppression of endogenous thyroid metabolic activity. Serum T3 levels are often —–

Answer 16

low

elevated

Question 17

In the absence of ADH, the tubular fluid is most concentrated at the ——– and most dilute in the collecting ducts

Answer 17

junction between the descending and ascending limbs of the loop of Henle

Question 18

Subacute (granulomatous, de Quervain) thyroiditis presents with fever; a painful, tender goiter; and an elevated erythrocyte sedimentation rate. Patients initially develop hyperthyroidism due to the destruction of thyroid follicles and release of preformed thyroid hormone. TSH is —– due to feedback inhibition on the pituitary; as a result, thyroid metabolic activity and organification of iodine are decreased, and radioactive iodine uptake is —-

Answer 18

TSH is suppressed

radioactive iodine uptake is low

Question 19

Erythropoietin (EPO) is produced by peritubular fibroblast cells in the renal cortex in response to decreased renal oxygen delivery. EPO acts on erythrocyte precursors in the bone marrow to increase ——

Answer 19

red blood cell production/ progeniter differation

Question 20

Patients with chronic kidney disease often have damage to renal EPO-producing cells, which results in —– anemia.

Answer 20

normocytic

Question 21

Protoporphyrins (heme precursors) are elevated in patients with —— anemia. Treatment (eg, iron supplementation) leads to the conversion of protoporphyrins to heme, thereby reducing free protoporphyrin level

Answer 21

iron deficiency

Question 22

Warm autoimmune hemolytic anemia is characterized by antibodies against antigens on the red cell membrane that result in phagocytosis in the —— system (eg, spleen). Autoimmune hemolytic anemia is usually treated with immune-suppressing agents (eg, prednisone), which blunt antibody production and reduce red cell destruction

Answer 22

reticuloendothelial

Question 23

thyrotoxicosis due to the intake of liothyronine (exogenous T3) is associated with —- serum T3 and —- T4

Answer 23

high T3

low T4

Question 24

When exogenous thyrotoxicosis is due to levothyroxine or mixed T3/T4 supplements (eg, porcine thyroid extract), total and free thyroxine (T4) levels are —–;

T3 levels also are —–

Answer 24

elevated

Question 25

Because TSH can promote growth of residual malignant cells following thyroidectomy, patients with thyroid cancer at high risk of recurrence (eg, known metastasis) are often prescribed ——- doses that are higher than what is needed for simple replacemen

Answer 25

levothyroxine

Question 26

Key adaptive responses to hypoxemia include hyperventilation to increase blood oxygenation and increased synthesis of —— in erythrocytes (facilitating oxygen offloading into peripheral tissues).

Answer 26

2,3-bisphosphoglycerate

Question 27

Inspiration is driven by an increase in intrathoracic volume. This is mediated predominantly by contraction of the diaphragm, which is innervated by the phrenic nerve that originates from the C- to C- nerve rootlets

Answer 27

C3-C5

Question 28

The membrane is most permeable to potassium ions at which of the following points?

Answer 28

D

Depolarization results from massive influx of Na+ through voltage-gated Na+ channels. Repolarization occurs due to closure of voltage-gated Na+ channels and opening of voltage-gated K+ channels.

K+ ion permeance is highest during the repolarization phase of the action potential.

Question 29

Pleural fluid normally enters the pleural space via filtration from the systemic circulation, primarily from the -—– microvessels of the parietal pleura, and exits the pleural space via stomata in the parietal pleura that drain into the parietal ——

Answer 29

intercostal

parietal pleura lymphatics

Question 30

Duodenal S-cells secrete secretin in response to increasing H+ concentrations. Secretin increases pancreatic —- secretion.

Answer 30

bicarbonate

Question 31

The —– content of pancreatic secretions decreases as the bicarbonate content increases, because — and bicarbonate are exchanged for one another at the apical surfaces of pancreatic ductal cells.

Answer 31

chloride

Question 32

The contractile mechanism in skeletal muscle depends on proteins (—,—-,—-,—–) as well as calcium ions.

Answer 32

myosin II, actin, tropomyosin, and troponin

Question 33

Calmodulin and ——- are elements of the contractile mechanism in smooth muscle

Answer 33

myosin light-chain kinase

Question 34

——- is the neurotransmitter that initiates muscle contraction in response to motor neuron stimulation. ——- release from the motor neuron opens post-synaptic ligand-gated ion channels, resulting in depolarization of the muscle cell. Depolarization then causes release of Ca2+ from the sarcoplasmic reticulum.

Answer 34

Acetylcholine

Question 35

When —– binds troponin C, tropomyosin shifts to expose the actin binding sites for myosin, allowing contraction to occur

Answer 35

Ca2+

Question 36

Gestational thrombocytopenia is common in the third trimester and is typically mild, asymptomatic, and not associated with other laboratory abnormalities. It occurs due to ——- and increased ——- of platelets in the placenta.

Answer 36

hemodilution (ie, maternal plasma volume expansion) and increased sequestration/consumption of platelets in the placenta.

Question 37

Patients with chronic kidney disease (CKD) often develop symptomatic anemia (eg, fatigue, exertional dyspnea) as the glomerular filtration rate declines. Most cases are due to the inadequate secretion of ——-, a glycoprotein hormone produced by peritubular fibroblasts in the renal cortex in response to tissue hypoxia (as is seen with anemia). —- acts on erythrocyte precursor cells (erythroid colony–forming unit cells) in the bone marrow to stimulate red blood cell differentiation and survival

Answer 37

erythropoietin (EPO)

Question 38

Congenital goiter in the setting of hypothyroidism (↑ TSH, ↓ thyroxine) can be caused by transplacental passage of ——-, which inhibit thyroid peroxidase and are used to treat maternal hyperthyroidism.

Answer 38

maternal antithyroid medications (eg, propylthiouracil)

Question 39

Propylthiouracil crosses the placenta, inhibiting production of T4. Positive feedback caused by low T4 leads to increased TSH, which stimulates the thyroid and causes diffuse gland enlargement. TSH and T4 levels typically normalize after 1-2 weeks due to excretion of the maternally derived antithyroid medication. After elimination of propylthiouracil, neonates with mothers who have Graves disease may then develop transient ——- due to transplacental transfer of TSH receptor–stimulating antibodies, which can persist in the neonatal circulation for up to 3 months.

Answer 39

hyperthyroidism (↓ TSH, ↑ T4)

Question 41

Excessive vitamin D intake can lead to hypercalcemia and cause mental status changes, muscle weakness, constipation, and polyuria/polydipsia. Activated macrophages in ——- and other granulomatous diseases express 1-α-hydroxylase, leading to excess production of 1,25-dihydroxyvitamin D and hypercalcemia.

Answer 41

sarcoidosis

Question 42

Normally, 25-hydroxyvitamin D is converted to 1,25-dihydroxyvitamin D (the active form) by —— in the kidneys, a process regulated by parathyroid hormone (PTH)

Answer 42

1-α-hydroxylase

Question 43

—– disease (hepatolenticular degeneration) is characterized by impaired incorporation of copper into ceruloplasmin and defective excretion of excess copper into bile. This leads to elevated blood free copper levels and deposition in the liver (cirrhosis) and brain (motor abnormalities, psychiatric symptoms).

Answer 43

Wilson

Question 44

Airway resistance is high in the trachea and reaches a peak in the ——-, where total cross-sectional area is at a minimum.

Airway resistance then progressively decreases as total cross-sectional area increases through the smaller bronchioles, terminal bronchioles, and alveoli.

Answer 44

medium-sized bronchi

Question 45

In the presence of ADH, the collecting ducts contain the most concentrated fluid in the nephron, while the —— contains the most dilute fluid.

Answer 45

distal convoluted tubule

Question 46

Serum —- levels are useful as an early marker for monitoring abnormal phosphate metabolism in patients with CKD.

Answer 46

FGF23

Question 47

Patients with chronic kidney disease (CKD) can develop hyperphosphatemia due to decreased filtration of phosphate. —— is secreted in response to hyperphosphatemia and lowers plasma phosphate by reducing intestinal absorption and renal reabsorption of phosphate. —- levels are useful as an early marker of abnormal phosphate metabolism in patients with CKD.

Answer 47

Fibroblast growth factor 23 (FGF23)

Question 48

This patient’s clinical presentation (progressive dyspnea, fine crackles, clubbing, diffuse reticular opacities) is consistent with —- lung disease

Answer 48

interstitial

Question 49

Interstitial lung disease is associated with decreased lung volumes and increased lung elastic recoil caused by fibrotic interstitial tissue. The increased elastic recoil results in increased —— on the airways, leading to increased expiratory flow rates when corrected for the low lung volume.

Answer 49

radial traction (outward pulling)

Question 51

Vascular calcifications occur more commonly in patients with chronic kidney disease due to electrolyte abnormalities (eg, —–,——) and chronic inflammation (secondary to atherosclerosis and/or uremia). These changes promote calcification and suppress calcification inhibitors, which can result in extensive vascular calcifications

Answer 51

hyperphosphatemia, hypercalcemia

Question 52

Hyperphosphatemia (decreased filtration and excretion of phosphorus) and/or hypercalcemia (typically iatrogenic due to the administration of calcium products as phosphate binders) promote calcification by stimulating ——

Answer 52

osteogenic differentiation

Question 53

Sunlight exposure catalyzes conversion of ——- to —– (vitamin D3) in the skin.

Subsequent 25-hydroxylation in the liver and 1-hydroxylation in the kidneys produce 1,25-dihydroxyvitamin D, the active form. Inadequate exposure to sunlight can lead to vitamin D deficiency.

Answer 53

7-dehydrocholesterol to cholecalciferol (vitamin D3)

Question 54

Patients with type 1 diabetes mellitus are at increased risk of hypoglycemia because exogenous insulin will continue to be absorbed from the injection site despite falling glucose levels. Those with long-standing diabetes may also have decreased —— secretion and therefore have an even greater risk of rapid hypoglycemia.

Answer 54

decreased glucagon secretion

Question 55

Progressive hypoglycemia prompts a —– surge, which increases hepatic glucose production and triggers many of the characteristic hypoglycemic symptoms (eg, arousal, tremor)

Answer 55

catecholamine (eg, epinephrine)

Question 56

Mutations in the potassium-ATP channel causing increased affinity for ATP result in fewer open channels and depolarization at lower glucose concentrations. This causes continued secretion of insulin despite falling blood glucose levels, leading to —–

Answer 56

congenital hypoglycemia

Question 57

Mutations of the potassium-ATP channels that decrease ATP affinity prevent appropriate depolarization in response to rising glucose levels, causing a familial form of ——. These patients can be treated successfully with sulfonylureas, which bind to KATP channels and cause closure independent of ATP.

Answer 57

neonatal diabetes mellitus

Question 58

In pregnancy, —- is secreted by the corpus luteum and later by the placenta. Although prolactin secretion increases as pregnancy progresses, high —— levels inhibit lactation by preventing binding of prolactin to receptors on alveolar cells in the breast.

Answer 58

progesterone

Question 59

In the second and third trimesters, progesterone is produced by the placenta and suppresses —- and — though action on the anterior pituitary

Answer 59

suppresses FSH and LH

Question 60

Prolactin is a peptide hormone that promotes lactogenesis (ie, maturation of breast alveolar cells) and milk production. It is released by the anterior pituitary gland due to stimulation by —— hormone

Answer 60

thyrotropin-releasing hormone (TRH)

Question 61

Creatinine, a waste product generated by the breakdown of creatine in the muscles, is used to estimate the glomerular filtration rate (GFR). Creatinine formation is dependent on muscle mass and meat intake; therefore, patients with low —- mass or low intake —- can have significantly lower GFRs for any given creatinine level (2 pts with same creatinine level but one has a lot lower GFR)

Answer 61

low muscle mass (eg, elderly patient, those with amputations)

(eg, low-protein vegetarian diet)

Question 62

Normal aging in men is associated with a slow decline in gonadal testosterone production, a compensatory rise in –, and rising serum levels of——. Common, nonspecific symptoms include decreased ejaculate volume, increased erectile latency and sexual refractory time, and moderately impaired erectile function.

Answer 62

rise in LH

rising serum levels of sex hormone–binding globulin

Question 63

Pulse pressure is the amount that arterial pressure increases above diastolic pressure during left ventricular contraction; it is directly related to stroke volume and inversely related to —–

Answer 63

aortic compliance

Question 64

Systolic blood pressure is the summation of diastolic pressure and — pressure.

Answer 64

pulse

Question 65

Age-related ——- is the primary driver of characteristic blood pressure changes that occur in those age >65. The reduced aortic compliance in the setting of unchanged stroke volume leads to increased pulse pressure.

Answer 65

stiffening of the aorta

Question 66

The systolic hypertension induced by aortic stiffening likely contributes to mild —– left ventricular hypertrophy, another common finding in elderly individuals.

Answer 66

concentric

Question 67

Osteoclasts originate from hematopoietic progenitor cells. Macrophage colony-stimulating factor and ——play an important role in osteoclast differentiation.

Paget’s disease of bone is characterized by increased numbers of abnormal osteoclasts, excessive bone turnover and disorganized bone remodeling.

Answer 67

receptor for activated nuclear factor kappa-B ligand (RANK-L)

Question 68

Osteoblasts are cells with a single nucleus that arise from —– cells found in the periosteum and bone marrow.

Answer 68

mesenchymal stem cells

Question 69

osteoclasts originate from the mononuclear phagocytic cell lineage and are ultimately formed when several precursor cells fuse to create a ——–.

Osteoclasts in Paget’s disease are typically very large and can have up to 100 nuclei

Answer 69

multinucleated mature cell

Question 70

Fibroblast growth factors (FGFs) regulate chondrogenesis and osteogenesis. FGFs induce proliferation of osteoblastic precursor cells and anabolic function of mature osteoblasts. Abnormalities in the FGF receptor result in the congenital ——

Answer 70

short-limbed dwarfism known as achondroplasia.

Question 71

—– stimulates appetite and promotes weight gain.

—– and —– act in the CNS to decrease appetite.

Answer 71

Ghrelin

Leptin and insulin

Question 72

Caloric restriction leads to increased —— levels along with decreased —– and —— levels, causing an increase in appetite that can make it difficult to maintain weight loss.

Answer 72

increased ghrelin levels

decreased insulin and leptin levels

Question 73

Overeating and weight gain suppress —– secretion and increase secretion of leptin and insulin.

Answer 73

ghrelin

Question 74

Patent ductus arteriosus results in increased left ventricular preload (due to increased pulmonary venous return to the left atrium) and ——- systemic vascular resistance (due to the continuous left-to-right shunt). This combination of higher preload and lower afterload leads to an early increase in left ventricular cardiac output.

Answer 74

decreased systemic vascular resistance

Question 75

Myocardial oxygen extraction exceeds that of any other tissue or organ; therefore, the cardiac venous blood in the —— is the most deoxygenated blood in the body.

Answer 75

coronary sinus

Question 76

Ventricular septal defect causes left-to-right shunting with —— right ventricular pressure and, if large, left-sided volume overload with —– left ventricular and left atrial pressures. Unchangged right atrium pressure. A holosystolic murmur is characteristic, and failure to thrive and signs of heart failure (eg, poor feeding, diaphoresis) can occur.

Answer 76

increased

Question 77

Advanced chronic kidney disease typically involves the accumulation of unmeasured acidic compounds in the blood; therefore, anion gap metabolic —– with respiratory compensation is expected.

Answer 77

acidosis

Question 78

—— is produced by S cells in the duodenal mucosa in response to stimulation by intraluminal acidity. —- stimulates the release of bicarbonate-rich secretions from the exocrine pancreas, which is the major source of acid-neutralizing bicarbonate entering the duodenum.

Answer 78

Secretin

Question 79

acute heart failure can be treated with an infusion of sodium nitroprusside. Sodium nitroprusside is a short-acting agent that causes balanced vasodilation of the veins and arteries; as such, it —— left ventricular (LV) preload and afterload, allowing for maintenance of cardiac output (unchanged stroke volume) at a lower LV pressure (decreased LV work). LV contractility is essentially unchanged.

Answer 79

decreases left ventricular (LV) preload and afterload

Question 80

During the normal cardiac cycle, central aortic pressure is higher than right ventricular pressure during systole and diastole. Consequently, an intracardiac fistula between the aortic root and right ventricle will most likely demonstrate a left-to-right cardiac shunt as blood continuously flows from the —- to —-

Answer 80

aortic root (high pressure) to the right ventricle (low pressure).