Top 550+ Solved Physiology MCQ Questions Answer

a. baroreceptors causes stimulation

b. chemoreceptors cause inhibition

c. baroreceptors provide significant input below 70mmhg mean arterial pressure

d. atrial stretch receptors inhibit the vasomotor centre

e. direct inputs include pO2

a. volume is about 600ml

b. normal pressure is 5-10cm CSF

c. has a higher concentration of creatinine than plasma

d. has a higher concentration of urea than plasma

e. is formed solely in the choroid plexus

a. the right bundle branch (of HIS) divides into anterior and posterior fasicles

b. the AV node contains P cells

c. myocardial fibres have a resting membrane potential of -60mV

d. action potential in the SA and AV nodes are largely due to Na+ influx

e. there are two types of K+ channels in pacemaker tissue – transient and long acting

a. the peak left ventricular pressure is 160mmHg

b. contraction of the atria propels 70% of the ventricular filling

c. the period of isovolumetric ventricular contraction is 0.5sec????

d. the end systolic ventricular volume is about 50mL

e. coronary blood flow to subendocardial portions of the left ventricle occur only in systole

a. “energy of contraction is proportional to the initial length of the cardiac muscle fibre” is Fick’s Law of the heart

b. cardiac index is the correlation between resting cardiac output and height

c. sleep decreases cardiac output

d. basal O2 consumption by the myocardium is 2ml/g/min

e. standing normally decreases the length of ventricular cardiac muscle fibres

a. PR interval increases in hyperkalaemia

b. in hyperkalaemia, the heart stops in systole

c. hypercalcaemia causes prolongation of the ST segments

d. hypernatraemia is associated with low voltage electrocardiographic complexes

e. magnesium counteracts digitalis toxicity

a. cardiac muscle fibres are multinucleated

b. they are smaller than skeletal muscle fibres

c. Ca2+ release is triggered by membrane repolarisation

d. the elastic ‘Titin” protein component is greater than in skeletal muscle, adding stiffness

e. the amount of Ca2+ in the sarcoplasmic reticulum is decreased by catecholamine stimulation

a. the energy applied to the blood stream is defined as kinetic plus potential

b. potential energy involves consideration of energy stored in elastic arterial walls and gravity

c. there is an exchange between kinetic and potential energy

d. the largest drop in energy occurs at the level of the precupillary sphincters

e. the higher resistance in smaller calibre vessels corresponds to greater energy losses

a. cardiac output = stroke volume x heart rate

b. the volume of blood pumped through the lungs equals the volume entering the heart

c. Poiseville’s Law predicts the effects of pressure and resistance on cardiac output

d. the resistance of the systemic circulation is 5 to 10 times the pulmonary vascular resistance

e. with constant pressure, a vessel with radius ‘2X ‘ has 16 times the flow of vessel with radius ‘X’

a. viscosity of blood with haematocrit of 40 is three times that of water

b. ‘arterial’ blood volume is 10-15% total volume

c. ‘elastance’ measures a vessel’s stiffness or recoil

d. aging causes increased elastance and therefore decrease in resting (unstressed) arterial volume

e. an increase in total peripheral resistance leads to increased arterial volume and BP

a. Perkinje fibres are subepicardial and are the largest fibres, 4-7 times the width of other fibres

b. Perkinje fibres are ‘fast fibres’, and can conduct a wave of depolarisation at a speed of 4m/sec

c. the duration of the action potential and refractory period in fast fibres is shorter than slow fibres

d. initial depolarisation occurs in fast fibres with a rapid influx of Ca2+ ions from the sarcoplasmic reticulum

e. none of the above statements are true

a. the liver is approximately 50% blood by volume

b. zone 3 of the hepatic acinus is well oxygenated

c. abdominal viscera receive at 30% cardiac output

d. liver receives blood from hepatic artery (1000???ml/min) and hepatic ??? vein (500ml/min)

e. muscular layer of intestinal wall has higher flow of mucosal layer

a. the sounds of Korotkoff when taking blood pressure are caused by laminar flow

b. the diastolic pressure in resting adults correlates to the muffling of Korotkoff sound

c. pressures obtained by palpation of auscultation methods are usually 2-5mmHg higher

d. if cuff is inflated for some time, it can give falsely low BP readings

e. sounds of Korotkoff occur when velocity of flow through constriction exceeds critical velocity

a. left coronary artery has greater flow in 50% of people

b. thebesian veins connect arterioles to the heart chambers

c. cusps of the aortic valve occlude orifices of coronary arteries during LV ejection

d. coronary flow at rest is 250ml/min

e. at rest, heart extracts 50% O2 / unit of blood delivered

a. the primary function of the CVS uses convection

b. secondary function involves heat control

c. the heart is two pumps operating in parallel

d. the same volume of blood passes through each semilunar valve over time

e. the Frank Starling mechanism is used in balancing the output of both ventricles