Cardiovascualr system

Question 1

normal resting cardiac output (CO)

Answer 1

~5 L/min (CO = HR × SV)

Question 2

Frank-Starling law of the heart

Answer 2

Increased venous return stretches the myocardium, enhancing contractility and stroke volume.

Question 3

components of the cardiac cycle

Answer 3

Atrial systole, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, and ventricular filling

Question 4

Ejection fraction (EF) & is its normal value

Answer 4

EF = (SV/EDV) × 100%; normal: 55–70%

Question 5

preload

Answer 5

The degree of myocardial stretch before contraction, related to end-diastolic volume (EDV)

Question 6

afterload

Answer 6

The resistance against which the heart pumps, mainly determined by arterial pressure

Question 7

What is cardiac contractility & what factors influence it?

Answer 7

The intrinsic strength of heart muscle contraction, influenced by calcium levels, sympathetic stimulation, and inotropic drugs

Question 8

What is stroke volume (SV) & how is it calculated

Answer 8

V = EDV - ESV; normal: ~70 mL

Question 9

What is the Fick principle for measuring cardiac output

Answer 9

CO = Oxygen consumption / (Arterial O2 - Venous O2)

Question 10

normal pacemaker of the heart

Answer 10

Sinoatrial (SA) node

Question 11

What is the normal resting heart rate generated by the SA node

Answer 11

~60–100 bpm

Question 12

What is the PR interval in an ECG

Answer 12

Time from atrial depolarization to ventricular depolarization (normal: 120–200 ms)

Question 13

QT interval

Answer 13

Duration of ventricular depolarization and repolarization (varies with HR)

Question 14

role of the AV node

Answer 14

Delays impulse transmission to allow ventricular filling

Question 15

What is the RMP of cardiac muscle cells

Answer 15

-90 mV

Question 16

Poiseuille’s law

Answer 16

Flow (Q) = (πΔP r⁴) / (8ηL), showing how resistance depends on vessel radius

Question 17

What is the equation for mean arterial pressure (MAP)

Answer 17

MAP = DBP + 1/3 (SBP - DBP).

Question 18

What is total peripheral resistance (TPR)

Answer 18

The resistance to blood flow in systemic circulation

Question 19

major determinant of blood viscosity

Answer 19

Hematocrit.

Question 20

How does Laplace’s law apply to blood vessels

Answer 20

Wall tension (T) = Pressure (P) × Radius (r)

Question 21

What are the primary short-term regulators of blood pressure

Answer 21

Baroreceptors, chemoreceptors, and autonomic nervous system.

Question 22

What is the baroreceptor reflex

Answer 22

Stretch receptors in the carotid sinus and aortic arch regulate BP via the autonomic system

Question 23

What role does the renin-angiotensin-aldosterone system (RAAS) play in BP regulation

Answer 23

Increases blood volume and vasoconstriction to raise BP

Question 24

What is the role of atrial natriuretic peptide (ANP) in BP control

Answer 24

Promotes sodium excretion and vasodilation to lower BP.

Question 25

What is the Cushing reflex

Answer 25

Hypertension, bradycardia, and irregular respiration due to increased intracranial pressure

Question 26

What are the primary mechanisms of capillary exchange

Answer 26

Diffusion, filtration, osmosis, and vesicular transport

Question 27

Starling’s equation

Answer 27

Net Filtration Pressure (NFP) = (Pc - Pi) - (πc - πi)

Question 28

What is the role of the lymphatic system in circulation

Answer 28

Drains excess interstitial fluid and returns proteins to circulation.

Question 29

What causes edema

Answer 29

Increased capillary pressure, decreased plasma proteins, lymphatic obstruction, or increased capillary permeability.

Question 30

main arteries supplying the heart

Answer 30

Right coronary artery (RCA), left main coronary artery (LCA), left anterior descending (LAD), left circumflex (LCX)

Question 31

How is coronary blood flow regulated

Answer 31

Autoregulation, metabolic demand, adenosine, nitric oxide.

Question 32

When does most coronary blood flow occur

Answer 32

During diastole, due to reduced myocardial compression.

Question 33

ischemic heart disease (IHD)

Answer 33

Reduced coronary blood supply leading to angina, myocardial infarction.

Question 34

What causes the first and second heart sounds

Answer 34

Back: S1: Closure of mitral & tricuspid valves; S2: Closure of aortic & pulmonary valves

Question 35

What are S3 and S4 heart sounds

Answer 35

Back: S3: Rapid ventricular filling (CHF); S4: Atrial contraction against stiff ventricle.

Question 36

What is the difference between systolic and diastolic murmurs

Answer 36

Systolic: Occurs between S1-S2 (e.g., aortic stenosis); Diastolic: Occurs after S2 (e.g., mitral stenosis)

Question 37

Circulatory shock

Answer 37

Inadequate tissue perfusion leading to organ failure

Question 38

types of shock

Answer 38

Hypovolemic, cardiogenic, obstructive, distributive (septic, anaphylactic, neurogenic)

Question 39

How does the body compensate for shock

Answer 39

Baroreceptor reflex, RAAS activation, vasoconstriction, increased heart rate.