Uworld Physio 2

Question 1

Hepcidin influences body iron storage through its interaction with ———-, a transmembrane protein responsible for transferring intracellular iron to the circulation. Upon binding hepcidin,———— is internalized and degraded, decreasing intestinal iron absorption and inhibiting the release of iron by macrophages.

Answer 1

ferroportin

Question 2

———— is a polypeptide synthesized by the liver that acts as the central regulator of iron homeostasis

Answer 2

Hepcidin

Question 3

High iron levels and inflammatory conditions ———– the synthesis of hepcidin;

hypoxia and increased erythropoiesis act to ——– hepcidin levels. —— hepcidin levels increase intestinal iron absorption and stimulate iron release by macrophages.

Answer 3

increase

lower

low

Question 4

Activation of muscarinic receptors by acetylcholine or cholinergic agonists results in peripheral ———– due to synthesis of nitric oxide in endothelial cells, which leads to vascular smooth muscle relaxation (eg, hypotension).

Answer 4

vasodilation

Question 5

Activation of —- receptors in other sites (nnon periphery) leads to a G-protein-coupled increase in intracellular calcium, resulting in smooth muscle contraction. Clinically, this contraction manifests as detrusor bladder muscle contraction (Choice A), pupillary constriction or and exocrine gland secretion (eg, salivation)

Answer 5

M3

Question 6

Muscarine, a toxin found in certain mushrooms, acts as a muscarinic (M) agonist in place of acetylcholine, resulting in an increase in ———- nervous system activity.

Answer 6

parasympathetic

Question 7

A ———– maneuver sometimes helps ppl with dsypagia from strokes. The maneuver seems to decrease the distance from the hyoid bone to the larynx (simulating elevation of the larynx), as well as to narrow the distance of the laryngeal entrance, leading to decreased aspiration

Answer 7

chin-tuck

(ie, flexion of the head and neck during swallowing)

Question 8

The most important airway-protective movements during swallowing are the anterior/superior displacement of the larynx, the tilting of the epiglottis to block the airway, and ———–. A chin-tuck maneuver can be helpful in some patients with aspiration by simulating the airway-protective movement of the larynx.

Answer 8

vocal fold adduction

Question 9

In adolescent users, high circulating estrogen levels (by result of ———– usage) can cause premature epiphyseal closure and short stature.

Answer 9

steriod/anabolic

Question 10

Androgen abuse suppresses —,—-,—– secretion, leading to reduced endogenous testosterone secretion, impaired spermatogenesis, and testicular atrophy. In addition, excess testosterone is converted by aromatase to estradiol, which can lead to gynecomastia.

Answer 10

GnRH, LH, and FSH

Question 11

———— syndrome occurs after the reintroduction of carbohydrates (dextrose IV fluids) in patients with chronic malnourishment, which stimulates insulin secretion and drives phosphorus intracellularly into hepatic and muscle cells, in an effort to maintain cellular energy metabolism (eg, ATP production); this redistribution of phosphorus can result in severe hypophosphatemia

Answer 11

Refeeding

Question 12

Presbyopia occurs due to denaturation of structural proteins within the lens, leading to loss of lens elasticity which can result in improved vision in patients with mild ——-

Answer 12

myopia

Question 13

In the management of septic shock, rapid restoration of intravascular volume and adequate end-organ perfusion is critical. This is best accomplished with the administration of boluses of ———–

Answer 13

isotonic crystalloid in the form of 0.9% (normal) saline or lactated Ringer solution

Question 14

Prolactin production is regulated primarily by inhibitory effects of hypothalamic dopaminergic pathways. However, prolactin secretion is stimulated by ————.

In patients with primary ————, the increased production of —– by the hypothalamus can lead to hyperprolactinemia

Answer 14

thyrotropin-releasing hormone (TRH)

hypothyroidism

Question 15

Voltage-gated sodium channels are important for the generation and propagation of action potentials. When the action potential reaches the axon terminal, voltage-gated calcium channels open and allow the influx of calcium, which is essential for the————- into the synaptic cleft.

Answer 15

fusion and release of neurotransmitter vesicles

Question 16

Decreased numbers of functional T-tubules in affected muscle fibers lead to—————-, which manifests as muscle weakness

Answer 16

uncoordinated contraction of myofibrils

Question 17

During muscle contraction, T-tubules allow the depolarization impulse to rapidly propagate through the interior of the muscle fiber. This ensures that calcium release from the sarcoplasmic reticulum occurs uniformly throughout the fiber, allowing for ———– in each muscle cell.

Answer 17

synchronized contraction of myofibrils

Question 18

Decremental force generated on repeated stimulation characterizes ————, an autoantibody disorder inhibiting postsynaptic acetylcholine receptors in the neuromuscular junction

Answer 18

myasthenia gravis

Question 19

Brown adipose tissue is found in newborns and in hibernating mammals. Brown adipose cells contain several intracytoplasmic fat droplets and many more mitochondria than white adipose cells. They function to produce heat by ————–

Answer 19

uncoupling oxidative phosphorylation with the protein thermogenin

Question 20

—- ratio is increased in COPD

Answer 20

RV/TLC

Question 21

Selective impairment in Sertoli cell function would cause decreased production of —— and lead to increased —- levels, as well as infertility due to impaired sperm production. However, the Leydig cells are unaffected, so no changes in testosterone or LH levels would be expected

Answer 21

inhibin

FSH

Question 22

Leydig cells, which are analogous to female theca cells, produce testosterone in response to stimulation by ——

——- is released from the anterior pituitary in response to gonadotropin-releasing hormone (GnRH) from the hypothalamus. Testosterone causes feedback inhibition of both LH and GnRH release.

Answer 22

luteinizing hormone.

Question 23

——- cells, which are analogous to female granulosa cells, produce the hormone inhibin in response to FSH from the anterior pituitary. Inhibin suppresses FSH production by the anterior pituitary, although it does not feed back on the hypothalamus. —— cells also facilitate spermatogenesis within the seminiferous tubules.

Answer 23

Sertoli

Question 24

Type I fibers perform actions requiring low-level sustained force (eg, postural maintenance) and function primarily via aerobic metabolism, meaning they have high myoglobin (oxygen storage) and mitochondrial (aerobic respiration) concentrations. The —- and —– muscle are postural muscles predominantly composed of Type I fibers.

Answer 24

soleus muscle of the lower leg and paraspinal muscles of the back

Question 25

Type II fibers are specialized for generating rapid forceful movements and they fatigue quickly. These fibers derive ATP energy mainly via glycogenolysis and subsequent anaerobic glycolysis. Muscles that maneuver the ——- extremities (—-,—-,—–, —–) are primarily geared toward rapid forceful movements and are more likely to have a higher percentage of Type II than Type I muscle fibers.

Answer 25

uuper extremeties: biceps brachi, deltiod, lat dorsi and pec major

Question 26

Parietal cells release hydrogen ions into the gastric lumen by means of the H/K ATPase, which requires hydrolysis of ATP and is therefore an active transport mechanism. ———- inhibitors suppress the activity of the gastric parietal cell H/K ATPase leading to an increase in the pH of the gastric lumen

Answer 26

Omeprazole and other proton pump

Question 27

Tetrodotoxin, a potent neurotoxin found in pufferfish, functions by blocking the ———– in nerve cell membranes. It inhibits passive transport of ——-

Answer 27

voltage-gated sodium channels

sodium

Question 28

Verapamil blocks ——– channels, thus inhibiting passive transport of——– ions in cardiomyocytes.

Answer 28

L-type calcium

calcium

Question 29

Lidocaine is a local anesthetic and a class IB antiarrhythmic agent that functions by blocking voltage-gated ——– channels in sensory neurons, Purkinje fibers and ventricular cells

Answer 29

sodium

Question 30

Dofetilide is a class III antiarrhythmic drug that blocks passive transport of ——-, specifically the delayed outward rectifier ———- current, in cardiomyocytes leading to a prolongation of the refractory period and of the QT interval.

Answer 30

potassium

Question 31

During pregnancy, the maternal cardiovascular system undergoes physiologic adaptations to increase cardiac output and optimize fetal perfusion. The most significant hemodynamic change is a marked decrease in ————–, which occurs due to increased release of peripheral vasodilators (eg, nitric oxide, prostacyclin) and decreased vascular sensitivity to vasoconstrictors (eg, norepinephrine, angiotensin II).

Answer 31

systemic vascular resistance (SVR)

Question 32

———— refers only to the volume of new air reaching the gas exchange areas (ie, alveoli and respiratory bronchioles) per minute. It can be calculated by subtracting dead space volume (which does not participate in gas exchange) from the tidal volume) x breathes per min

Answer 32

Alveolar ventilation

Question 33

-

Question 34

Intense exercise creates a high demand for ATP, and the primary method of ATP production varies with the duration of exercise. The ——- shuttle is the primary source of ATP at the beginning of exercise (first 10 secs), followed sequentially by anaerobic glycolysis and then oxidative phosphorylation.

Answer 34

phosphocreatine

Question 35

During physical exercise, there is increased skeletal muscle CO2 production that increases the CO2 content of ——– blood.

Arterial O2 and CO2 content remains constant via increases in alveolar ventilation and gas exchange efficiency. Venous O2 content remains constant or is decreased due to increased O2 extraction by the tissues that matches or exceeds the rate of oxygen delivery (ie, O2 consumption during exercise is limited by cardiac output).

Answer 35

venous

Question 36

Bone-specific alkaline phosphatase levels correlate with ——- activity. Other markers of ——- activity include N-terminal propeptide of type 1 procollagen, which is released during post-translation cleavage of type 1 procollagen

Answer 36

osteoblast

Question 37

Parathyroid hormone analog (eg, teriparatide), which promotes bone formation by stimulating maturation of ————-

Answer 37

pre-osteoblasts into osteoblasts.

Question 38

——— is the hormone responsible for gallbladder contraction. It is made in the duodenum and jejunum in response to fatty acids and amino acids

Answer 38

Cholecystokinin (CCK)

Question 39

———— is produced in the pancreas and stimulates intestinal water secretion, counteracts gastrin in the stomach, and promotes bicarbonate secretion for the pancreas

Answer 39

Vasoactive intestinal peptide (VIP)

Question 40

———- is a hormone made in numerous tissues (hypothalamus, stomach, intestine, pancreas) in response to low pH. Its production is inhibited by vagal stimulation. It inhibits the release of growth hormone (GH) and thyroid stimulating hormone (TSH), and suppresses the release of myriad other molecules (e.g. gastrin, CCK, VIP, secretin, insulin, glucagon).

Answer 40

Somatostatin

Question 42

Thyroid follicular cells take up iodide (I−), which is then transported into the thyroid follicular lumen, where it is oxidized to iodine (I2). Following oxidation, in a process referred to as organification, iodine reacts with tyrosine residues in thyroglobulin to form monoiodotyrosine (MIT) and diiodotyrosine (DIT) (iodination). While still attached to thyroglobulin, DIT and MIT participate in 2 coupling reactions: The coupling of 2 DITs results in formation of ——–; the combination of 1 DIT and 1 MIT leads to the formation of ——–

Answer 42

thyroxine (T4)

triiodothyronine (T3)

Question 43

Thyroid peroxidase (TPO) catalyzes the oxidation of ——-, ———, ————. Antibodies against TPO are present in >90% of patients with chronic lymphocytic (Hashimoto) thyroiditis.

Answer 43

iodide to iodine

the iodination of thyroglobulin tyrosine residues, and

the iodotyrosine coupling reaction that forms T3 and T4

Question 44

Pregnant women > 20 weeks gestation can experience compression of the inferior cava by the gravid uterus while in the supine position. This reduces ——– and cardiac output, which can result in hypotension and syncope.

Answer 44

venous return

Question 45

Supine hypotension syndrome (or aortocaval compression syndrome) is characterized by hypotension, pallor, sweating, nausea, and dizziness that occur when a pregnant woman lies supine (on her back). Symptoms resolve with sitting, standing up, or when assuming a left lateral decubitus position. It occurs predominantly in women > 20 weeks gestation, and is due to the gravid uterus compressing and obstructing the ————-

Answer 45

inferior vena cava

Question 46

Aging is associated with steady decreases in chest wall compliance but increases in lung compliance due to a loss of elastic recoil. This results in a marked increase in ———-, a decrease in ———-, and relatively unchanged total lung capacity.

Answer 46

residual volume

FVC

Question 47

Direct factor Xa inhibitors (eg, apixaban) are often used for stroke prevention in atrial fibrillation as they are administered orally and do not require monitoring of drug levels (unlike warfarin). This class of medications blocks the active site of factor Xa, which prevents it from converting —– to —–. Direct factor Xa inhibitors are denoted by names that end in “Xa-ban.”

Answer 47

prothrombin to thrombin

Question 48

———– is defined as a hematocrit level > 52% in men and > 48% in women. It may be the result of a true increase in the red blood cell (RBC) mass (absolute erythrocytosis) or decrease in the plasma volume (relative erythrocytosis)

Answer 48

Polycythemia (erythrocytosis)

Question 49

Secretin is a hormone produced by intestinal S cells that increases ——— secretion from the pancreas. Secretin stimulates the exocrine pancreatic ductal cells to release a high volume of ——-rich and chloride-poor fluid into the small bowel. The release of gastric acid into the duodenum is the most potent stimulus for secretin release, which begins as the duodenal pH drops below 5

Answer 49

bicarbonate

Question 50

Anovulation is a common cause of infertility. Menotropin (human menopausal gonadotropin) is a treatment option that acts like —- hormone and triggers the formation of a dominant ovarian follicle. Ovulation is then induced by administration of human chorionic gonadotropin, which mimics the — surge

Answer 50

FSH

LH

Question 51

Peak ——- levels are seen just before the LH surge.

Answer 51

estrogen

Question 52

——— increases substantially during pregnancy and peaks at delivery to prepare the breast for lactation. Elevated levels lead to anovulation (eg, lactational amenorrhea)

Answer 52

Prolactin

Question 53

An array of physiologic responses takes place to maintain adequate O2 delivery to the tissues in the hypoxic environment at high altitude. These include hypoxic pulmonary vasoconstriction (increased ———), increased sympathetic activity to increase cardiac output, and aldosterone suppression to reduce plasma volume

Answer 53

(pulmonary vascular resistance)

Question 54

Individuals who remain at high altitude for an extended period will experience the full benefit of increased ———- and upregulation of HIF (hypoxia inducible factor), as secondary polycythemia (increased O2 carrying capacity) and angiogenesis are maximized after several weeks.

Answer 54

erythropoietin secretion

Question 55

cocaine-induced myocardial infarction can cause acute hypokalemia due to stress-related beta-adrenergic hyperactivity, which causes potassium to ———

Answer 55

shift intracellularly

Question 56

Epinephrine activates the —– receptor, leading to increased activity of the sodium-potassium ATPase pump and the sodium-potassium-2-chloride cotransporter, both of which transport potassium intracellularly.

Adrenergic activity also stimulates the release of insulin, which further promotes intracellular potassium shifting.

Answer 56

beta-2

Question 57

In patients with 1 testicle, the mass of ——– cells is significantly reduced. Therefore, the circulating levels of inhibin B are likely to be low in these patients. Low inhibin B levels will not provide adequate negative feedback on FSH secretion, thus FSH levels will tend to be elevated in males who only have 1 testicle.

Answer 57

Sertoli cells

Question 58

The ———- of the loop of Henle is impermeable to water regardless of serum vasopressin levels. Reabsorption of electrolytes by the Na+/K+/2Cl- cotransporter occurs in the thick ascending limb and contributes to formation of the corticomedullary concentration gradient.

Answer 58

ascending limb

Question 59

Hypothyroidism causes decreased expression of ——– in the liver, leading to decreased clearance of —– and increased blood levels. It also causes hypertriglyceridemia due to decreased expression of lipoprotein lipase. The adverse effects of hypothyroidism on lipid levels can increase the risk of coronary atherosclerosis

Answer 59

LDL receptors

Question 60

Male neonates with ——- defeciency are born with feminized external genitalia that typically masculinize at puberty. A small phallus and hypospadias are common.

Answer 60

5α-reductase deficiency

Question 61

——- converts testosterone to dihydrotestosterone, which mediates development of the external genitalia in the male fetus

Answer 61

5α-reductase

Question 62

——— catalyzes the conversion of androgens to estrogens in the gonads and peripheral tissues. —— deficiency presents with virilization of female infants; male patients are not affected phenotypically

Answer 62

Aromatase

Question 63

——– converts 17-hydroxyprogesterone to 11-deoxycortisol, and progesterone to 11-deoxycorticosterone.

Deficiency of ——– causes corticosteroid precursors to be shunted toward androgen production, resulting in virilization of the female fetus and salt wasting.

Male children have salt wasting and normal genitalia.

Answer 63

21-hydroxylase

Question 64

Deficiency of ———- results in decreased secretion of cortisol and sex steroids and an increased level of mineralocorticoids. This deficiency manifests clinically with sodium retention, leading to hypertension and undervirilization of male infants (female-type genitalia)

Answer 64

17-hydroxylase