Blood and Heart Physiology

These flashcards cover key vocabulary and concepts related to blood and heart physiology, providing definitions and explanations for each term.

Plasma

The liquid portion of blood, making up approximately 55%, composed mainly of water, proteins, and solutes.

Erythrocytes

Red blood cells (RBCs) responsible for transporting oxygen (O₂) and some carbon dioxide (CO₂).

Leukocytes

White blood cells (WBCs) involved in immune defense, including various types like neutrophils and lymphocytes.

Platelets

Also known as thrombocytes, these are involved in blood clotting by forming a plug and releasing clotting factors.

Hemoglobin (Hb)

A protein found in red blood cells with a structure of 4 subunits that binds oxygen and helps transport carbon dioxide.

Hematopoiesis

The process of blood cell formation, occurring in the red bone marrow from hematopoietic stem cells.

Hypoxia

A condition of low oxygen levels in the tissues, which stimulates the kidneys to release erythropoietin (EPO) to increase RBC production.

Anemia

A condition characterized by a deficiency of red blood cells or low hemoglobin, resulting in reduced oxygen delivery.

Polycythemia

A condition where there are too many red blood cells, leading to thick blood and increased viscosity.

ABO Blood Typing System

A classification of blood based on the presence of antigens on RBCs and antibodies in plasma.

Starling’s Law of the Heart

The principle that the more the heart fills and stretches, the stronger its contraction will be, affecting stroke volume.

Cardiac Output (CO)

The amount of blood pumped by the heart per minute, calculated as CO = HR × SV, where HR is heart rate and SV is stroke volume.

Preload

The stretch of the ventricles before contraction, directly related to end-diastolic volume (EDV).

Afterload

The resistance the heart must overcome to pump blood, influencing stroke volume inversely.

Mean Arterial Pressure (MAP)

An average blood pressure in a person's arteries during one cardiac cycle, important for ensuring adequate blood flow.

Baroreceptor Reflex

A mechanism that helps maintain blood pressure by adjusting heart rate and vessel diameter in response to changes in blood pressure.

Hormonal Regulation of Blood Pressure

The process by which hormones like angiotensin II, aldosterone, and ADH regulate blood pressure through various physiological responses.

Diuretics

Medications that increase urine output, thereby reducing blood volume and consequently lowering blood pressure.

ACE Inhibitors

Drugs that inhibit the formation of angiotensin II, reducing vasoconstriction and lowering blood pressure.

Vasodilators

Medications that directly relax blood vessels, reducing systemic vascular resistance (SVR) and lowering blood pressure.