Cardiovascular Physiology: Hemostasis, Cardiac Cycle, and Blood Pressure Regulation

What regulates erythropoiesis?

Erythropoiesis is regulated by oxygen levels through a negative feedback loop involving erythropoietin (EPO) from the kidneys.

What are the steps of hemostasis?

1. Vascular spasm: blood vessels constrict. 2. Platelet plug formation: platelets adhere to damaged tissue. 3. Coagulation: fibrin stabilizes the clot.

What is the importance of the plateau phase in cardiac muscle cells?

The plateau phase allows calcium to enter the cell, prolonging contraction and preventing tetany, ensuring the heart fills properly between beats.

What is the path of the electrical conducting system in the heart?

SA node → AV node → AV bundle (Bundle of His) → right & left bundle branches → Purkinje fibers.

How does the cardiac cycle relate to valves and blood flow?

Atrial systole: AV valves open, blood flows into ventricles. Ventricular systole: AV valves close, semilunar valves open, blood is ejected. Diastole: heart relaxes, AV valves open, ventricles fill.

How is cardiac output defined and calculated?

Cardiac output (CO) = Heart Rate (HR) × Stroke Volume (SV).

What factors regulate cardiac output?

Cardiac output depends on heart rate and stroke volume, which is influenced by preload, contractility, and afterload.

What is blood pressure?

Blood pressure is the force of blood against vessel walls, affected by cardiac output, peripheral resistance, blood volume, and viscosity.

How do the autonomic nervous and endocrine systems regulate blood pressure?

Sympathetic nervous system increases heart rate and causes vasoconstriction. Parasympathetic lowers heart rate. Hormones like ADH and aldosterone increase blood volume, while angiotensin II causes vasoconstriction and ANP decreases blood volume and BP.