Quiz Night: Physiology

One of the following steps in the excitation contraction coupling is similar to both skeletal and smooth muscles:

• activation of myosin

• exposure of active sites in actin

• release of calcium from sarcoplasmic reticulum

• binding of calcium to troponin C

Answer explanation

release of calcium from sarcoplasmic reticulum

Force of contraction of the heart may be increased by

• successive application of supramaximal stimuli

• stimulation of the Na-Ca pump

• inhibition of beta-1 receptor

• inhibition of the Na-K pump

Answer explanation

Answer: Inhibition of the Na-K pump

Inhibition of Na,K-ATPase causes high intracellular Na⁺ ion levels and subsequent increases in intracellular Ca²⁺ ion through the Na⁺/Ca²⁺ exchanger.

At rest, this response is unexpected

• gastric enzyme secretion

• increased salivary secretion

• relaxation of gastrointestinal sphincter

• mydriasis

Answer explanation

Mydriasis

Cholecystokinin inhibits

• pancreatic HCO3- secretion

• gastric emptying

• contraction of gallbladder

• relaxation of sphincter of Oddi

Answer explanation

Cholecystokinin inhibits gastric emptying.

This is a lineage specific growth factor for megakaryocytes

• G-CSF

• GM-CSF

• EPO

• TPO

Answer explanation

Thrombopoietin (TPO) is the principal physiologic regulator of platelet production. In vitro, TPO induces the growth of colony-forming units-megakaryocyte (CFU-MK) and the generation of mature polyploid megakaryocytes, which subsequently form extended cytoplasmic processes, termed proplatelets.

This is a fetal form of hemoglobin

• alpha 2, gamma 2

• alpha 2, delta 2

• alpha 2, beta 2

• alpha 2, epsilon 2

Answer explanation

alpha 2, gamma 2

The following statements are correct except

• The intrinsic pathway is usually triggeredby thrombin formed by the extrinsic pathway.

• Intrinsic pathway begins with exposure ofblood to collagen from traumatized tissue.

• The prothrombin time measures the intrinsic to common pathway.

• Hemophiliacs have a defect in the intrinsicpathway.

Answer explanation

Remember:

P(E)T

- (P)ro(T)hombin

- (E)xtrinsic

P(I)TT

- (P)artial

- (I)ntrinsic

- (T)hrombplastin

- (T)ime

Heparin is a potent anti-coagulant and its action is manifested by

• prolonged bleeding time

• prolonged PT

• prolonged PTT

• all of the above

Answer explanation

Heparin is an anticoagulant and will prolong a PTT, either as a contaminant of the sample or as part of anticoagulation therapy.

An increase in this parameter will decrease blood pressure:

• total peripheral resistance

• afterload

• venous return

• aldosterone

Answer explanation

Stroke volume is reduced because increased afterload reduces the velocity of muscle fiber shortening and the velocity at which the blood is ejected.

Characteristic of a cephalic phase of an integrated response to a meal

• increase in sympathetic outflow

• chewing occurs

• stimulation of salivary gland secretion

• bolus of food stimulating mechanical receptors

Answer explanation

The cephalic phase of digestion is the stage in which the stomach responds to the mere sight, smell, taste, or thought of food.