Deck X

Question 1

How is muscle contraction different in cardiac myocytes compared to skeletal muscle cells?

Answer 1

In skeletal muscle cells, contraction is dependent on both proteins (myosin II, actin, tropomyosin, and troponin) as well as calcium ions.

Question 2

What is the length constant in neuronal conduction?

Answer 2

A measurement of how far along an axon an electrical impulse can propagate; a low length constant reduces the distance an impulse can travel.

Question 3

Why is skeletal muscle resistant to the effects of calcium channel blockers?

Answer 3

Because skeletal muscle does not require an influx of extracellular calcium for excitation-contraction coupling; cardiac and smooth muscle depend on extracellular calcium entering the cell via voltage gated L-type calcium channels for excitation contraction coupling. These channels are the target of Ca2+ channel blockers.

Question 4

Describe the sites and amounts of potassium resorption in the nephron.

Answer 4

K+ is freely filtered across the glomerular membrane; 2/3 of the filtered load is then reabsorbed in the proximal tubule; the thick ascending limb further resorbs 25-30%. Th late distal and cortical collecting tubules are the primary mediators of potassium regulation and are the primary sites of K+ reabsorption

Question 5

How does cortisol interact with catecholamines in terms of vascular reactivity?

Answer 5

Cortisol augments the vasoconstrictive effects of catecholamines; cortisol has permissive effects on catecholamines by allowing them to achieve their full vasoconstrictive potentials

Question 6

What are the two principle actions of ANP (atrial natriuretic peptide)?

Answer 6

Peripheral vasodilation and increased urinary excretion of sodium and water.

Question 7

Which thyroid hormone is produced in the greatest quantity?

Answer 7

T4

Question 8

Which thyroid hormone is the most active form?

Answer 8

T3 (rT3 is inactive)

Question 9

How is T4 converted to T3?

Answer 9

By deiodinase enzymes into T3 and rT3

Question 10

How many calories per gram are generated in protein/carbohydrate, fat, and ethanol metabolism?

Answer 10

carbohydrate/ protein = 4 cal/ gram; fats 9 cal/ gram; ethanol 7 cal/gram of energy

Question 11

What serum marker reflects osteoblastic activity?

Answer 11

Bone specific alkaline phosphatase

Question 12

Name three serum markers that reflect osteoclastic activity.

Answer 12

Tartrate-resistant acid phosphatase, urinary hydroxyproline, urinary deoxypyridonoline

Question 13

Where are androgens that are synthesized in the ovaries converted into estradiol?

Answer 13

LH stimulates the theca interna cells of the ovarian follice to produce androgens that are converted to estradiol in granulosa cells via aromatase in a reaction stimulated by FSH.

Question 14

What enzyme catalyzes activation of trysinogen to trypsin?

Answer 14

Enteropeptidase (or enterokinase) secreted from the duodenum.

Question 15

What type of compound is D-xylose?

Answer 15

A carbohydrate.

Question 16

Which dietary compounds can be readily absorbed by the intestine without pancreatic enzymes?

Answer 16

carbohydrates.

Question 17

What type of drug is diphenoxylate?

Answer 17

Opiate anti-diarrheal.

Question 18

In ascites, esophageal varices are the result of chronic shunting of portal blood to systemic circulation through which vein?

Answer 18

Left gastric vein (to esophageal vein)

Question 19

In ascites, hemorrhoids are the result of chronic shunting of portal blood to systemic circulation through which vein?

Answer 19

Superior Rectal Vein (to middle and inferior rectal veins)

Question 20

In ascites, caput medusae are the result of chronic shunting of portal blood to systemic circulation through which vein?

Answer 20

Paraumbilical veins (to superficial and inferior epigastric veins)

Question 21

What pathology is associated with H. pylori antral gastritis?

Answer 21

Duodenal ulcers caused by unchecked gastrin production due to destruction of somatostatin secreting cells in the gastric antrum.

Question 22

What malignancies are associated with H. pylori infection?

Answer 22

Gastric adenocarcinoma and gastric lymphoma.

Question 23

What are the clinical manifestations of a leptin gene or receptor mutation?

Answer 23

Human obesity and hyperphagia

Question 24

What is leptin?

Answer 24

Protein hormone produced by adipocytes in proportion to stored fat quantity; it acts on the arcuate nucleus of the hypothalamus to inhibit production of neuropeptide Y and to stimulate production of a-MSH which decrease appetite and increase satiety respectively

Question 25

Where is the most common location for intussuception?

Answer 25

Ileocolic junction.

Question 26

What is the mechanism of action of statins?

Answer 26

Inhibition of HMG CoA reductase; in response to these changes, hepatocytes increase surface expression of the LDL receptor to increase uptake of circulating LDL

Question 27

What causes pancreatic autodigestion in acute necrotizing pancreatitis?

Answer 27

Damage to the pancreatic acinar cells triggers abnormal activation of trypsin inside the acinar cells by lysosomal enzymes. Trypsin then activates other proteolytic enzymes causing pancreatic autodigestion.

Question 28

What is the most common benign liver tumor?

Answer 28

Cavernous hemangioma

Question 29

How do cavernous hemangiomas appear microscopically?

Answer 29

As cavernous, blood filled vascular spaces of variable size, lined by a single epithelial layer.

Question 30

Which types of liver tumors are associated with oral contraceptive use and may regress with discontinuation?

Answer 30

Hepatic adenomas.