Physiology concepts in Cardiology

Question 1

Most efficient extractor of oxygen from the blood

Answer 1

Heart

Question 2

Intercellular junctions responsible for the cardiac syncytium

Answer 2

Gap junctions

Question 3

Substance that dilates upstream blood vessels

Answer 3

Endothelium-Derived Relaxing Factor (EDRF) aka Nitric Oxide (NO)

Question 4

An increase in venous return will increase the heart rate

Answer 4

Bainbridge Reflex

Question 5

An increase in venous return will increase the stroke volume, Basis: stretching of cardiac sacromeres will increase contraction

Answer 5

Frank- Starling Mechanism

Question 6

Formula for Blood Pressure (BP) based on Ohm’s Law

Answer 6

Blood Pressure= Cardiac Output x Total Peripheral Resistance (TPR) = (Heart rate x Stroke Volume) x TPR
TPR is synonymous with Systemic Vascular Resistance and increases when arterioles vasoconstricted

Question 7

Hypertension, irregular respiration and bradycardia due to activation of the CNS ischemic response and baroreceptor reflex in increased intracranial pressure

Answer 7

Cushing Reflex

Question 8

Normal pressure at various parts of the adult circulation

Answer 8

Large Arteries: < 120/80 mmHg
Systemic Capillaries:17 mHg
Vena Cava: 0 mmHg
Pulmonary Artery: 25/8 mmHg
Pulmonary Capillaries: 7 mmHg