Physiological Processes of Life - Circulation, Body Fluids, and Heart Anatomy

A comprehensive vocabulary review of key physiological concepts including cardiovascular disorders, blood components, blood typing, coagulation mechanisms, and heart junctional tissues.

Hypertension

A chronic medical condition, also called arterial hypertension, in which the blood pressure in the arteries increases.

Liver Cirrhosis

A condition resulting from advanced liver disease, characterized by the replacement of liver tissue by fibrosis (scar tissue) and regenerative nodules.

Type 1 Diabetes Mellitus

A disorder that occurs when the pancreas does not produce and secrete enough insulin, with symptoms including excessive thirst, excessive urination, hunger, and weight loss.

Type 2 Diabetes

A disorder that occurs when the body cannot respond normally to insulin, presenting symptoms similar to those of type 1 diabetes.

Circulation

The process by which transport of essential materials like nutrients, oxygen, hormones, enzymes, minerals, and metabolic wastes to different parts of the body takes place through a fluid medium.

Blood

A fluid connective tissue consisting of plasma and blood cells that appears red due to the presence of hemoglobin and functions chiefly to carry $O_2$ and $CO_2$.

Artery

A thick, elastic blood vessel with plain muscle that carries blood away from the heart; all arteries carry oxygenated blood with the exception of the pulmonary artery.

Vein

A thin-walled blood vessel with a wide bore and valves that brings blood back to the heart; all veins carry deoxygenated blood with the exception of the pulmonary vein.

Capillary

A fine blood vessel situated between arterioles and venules with a diameter of $7\text{--}9\text{ }\frac{1}{\text{m}}$ (7\text{--}9\text{ }\text{̢m}) made of a single layer of endothelial cells, across which material exchange occurs.

Heart

The central hollow muscular pumping station of the circulatory system that circulates blood throughout the body via contraction (systole) and relaxation (diastole).

Heart Beat

Each contraction of the heart (also called pulse beat), which occurs at a normal frequency of $72$ per minute in adult humans.

Open Circulation

A pattern of circulation in which blood from the heart flows through blood vessels into the body cavity (haemocoel) to directly bathe tissue cells for material exchange.

Haemolymph

The colorless blood fluid present in organisms with open circulatory systems, such as cockroaches.

Closed Circulation

A pattern of circulation in which blood always flows continuously through the heart and blood vessels and never enters the body cavity.

Systemic Circulation

The circulation of blood between the heart and other body organs, transporting pure (oxygenated) blood to organs and returning polluted (deoxygenated) blood to the heart.

Portal Circulation

A pathway that establishes vascular communication directly between two organs, such as the hepatic portal circulation between the small intestine and the liver.

Plasma

The straw-colored, alkaline, slightly viscous fluid portion of blood remaining after cell removal, constituting about $55\%$ of total blood volume.

Red Blood Corpuscles (RBC)

Circular, non-nucleated (when mature) blood cells containing hemoglobin that carry $O_2$ and $CO_2$, formed in red bone marrow after birth with a lifespan of $120\text{ days}$.

White Blood Corpuscles (WBC)

Irregularly shaped, nucleated blood cells with a lifespan of $2\text{--}14\text{ days}$ that destroy foreign germs via phagocytosis and form antibodies.

Platelets (Thrombocytes)

Round or oval, non-nucleated blood elements originating from megakaryocytes, measuring $2.5\text{ }\mu m$ in diameter with a lifespan of $2\text{--}5\text{ days}$, which assist in blood coagulation.

ABO Blood Grouping

A classification system defined by Karl Landsteiner in 1900 dividing human blood into groups A, B, AB, and O based on agglutinogens (antigens A, B) on RBCs and agglutinins (antibodies a, b) in plasma.

Rh Factor

A special agglutinogen factor originally discovered in Rhesus monkey RBCs, present on the RBCs of approximately $85\%$ of humans ($\text{Rh}^+$).

Erythroblastosis Foetalis

A severe hemolytic condition in an $\text{Rh}^+$ fetus carried by an $\text{Rh}^-$ mother, where maternal Anti-Rh antibodies cross the placenta and destroy fetal red blood cells.

Universal Donor

Blood group O, which has no agglutinogens on its RBC surface and can donate red blood cells to all blood groups without interaction or agglutination.

Universal Recipient

Blood group AB, which has no agglutinins in its plasma and can receive red blood cells from all blood groups without interaction or agglutination.

Blood Coagulation

The physiological process by which shed blood loses its fluidity and is converted into a semisolid jelly-like clot within $4\text{--}8\text{ minutes}$.

Heparin

An anticoagulant substance produced by basophil cells that prevents the coagulation of blood within intact blood vessels.

Bleeding Time (BT)

The time required for bleeding to continue from an injured spot from the moment of injury, normally lasting $1\text{--}3\text{ minutes}$.

Clotting Time

The time required for blood to undergo complete coagulation after being shed, normally lasting $2\text{--}6\text{ minutes}$.

Pericardium

The double-walled membrane that surrounds and protects the human heart.

Sino-atrial (SA) Node

A specialized junctional tissue located in the right atrium at the junction of the superior vena cava that initiates and conducts cardiac impulses.

Atrio-ventricular (AV) Node

A specialized junctional tissue situated in the right atrium near the opening of the coronary sinus at the posterior part of the interatrial septum.

Eustachian Valve

A functional foetal valve located in the upper portion of the inferior vena cava that directs oxygenated blood toward the foramen ovale.

Thebesian Valve

A semi-lunar fold of membrane in the right atrium located at the orifice of the coronary sinus.

Pulmonary Circulation

The circulation of blood between the heart and lungs, transporting deoxygenated blood from the right ventricle to the lungs and returning oxygenated blood to the left atrium.

Double Circulation

The circulatory pattern in humans comprising both systemic circulation and pulmonary circulation working concurrently in two separate circuits.