Circulation and Cardiovascular Diseases

Comprehensive practice flashcards covering circulatory system types, blood components, haemoglobin kinetics, cardiovascular anatomy, disease pathogenesis, and treatment methods based on the lecture transcript.

Mass transport system

A mechanism that moves substances in bulk quantities over long distances within an organism, driven by a pressure difference.

Surface Area to Volume Ratio

A comparison of the surface area of an organism to its internal volume; as size increases, this ratio decreases, necessitating a transport system.

Open Circulation

A system where a heart is present but blood is not contained within vessels, instead circulating in large open spaces called sinuses.

Closed Circulation

A system where both a heart and blood vessels are present, and blood remains enclosed within the vessels.

Single Circulation

A closed system where blood passes through the heart only once per complete cycle, typically moving from heart to gills, then to tissues, and back to the heart.

Double Circulation

A closed system consisting of pulmonary and systemic circuits where blood passes through the heart twice per complete cycle.

Pulmonary Circulation

The circuit where the right side of the heart pumps deoxygenated blood to the lungs for oxygenation, after which it returns to the left side of the heart.

Systemic Circulation

The circuit where oxygenated blood is pumped from the left side of the heart to all body tissues and returns as deoxygenated blood to the right side.

Sinuses

Body cavities in an open circulatory system through which blood flows over organs before draining back into the heart.

Plasma

A transparent yellow liquid making up over $50\%$ of blood volume, consisting of $90\%$ water and $10\%$ dissolved substances like glucose, urea, and hormones.

Erythrocytes

Red blood cells responsible for transporting oxygen; they are bi-concave, flexible, lack a nucleus, and contain haemoglobin.

Leukocytes

White blood cells made in the bone marrow that defend the body against infections and participate in inflammatory responses.

Thrombocytes

Platelets; tiny fragments of megakaryocytes involved in the blood clotting process.

Haemoglobin

An oxygen-carrying protein in red blood cells made of four polypeptide chains, each containing an iron-containing Haem group.

Partial Pressure ($PO_2$)

The pressure that would be exerted by one component gas in a mixture if it occupied the same volume on its own.

Oxygen Dissociation Curve

A graph showing the relationship between oxygen partial pressure (horizontal axis) and haemoglobin oxygen saturation (vertical axis).

Conformational change

The change in the shape of a haemoglobin molecule after the first oxygen molecule binds, making subsequent binding easier.

Cooperative binding

The process by which the binding of one oxygen molecule to haemoglobin facilitates the binding of the next two oxygen molecules.

Fetal haemoglobin

A form of haemoglobin with a higher affinity for oxygen than the adult form, allowing the fetus to extract oxygen from the mother's blood.

Carbonic Anhydrase

The enzyme that catalyzes the reaction between $CO_2$ and $H_2O$ to form carbonic acid ($H_2CO_3$).

Chloride Shift

The movement of chloride ions ($Cl^-$) into red blood cells to balance the exit of hydrogencarbonate ions ($HCO_3^-$).

Haemoglobinic acid

The compound formed when haemoglobin acts as a buffer by accepting hydrogen ions, preventing changes in blood $pH$.

The Bohr Effect

The phenomenon where increased levels of $CO_2$ (and thus hydrogen ions) cause oxyhaemoglobin to dissociate more quickly, shifting the curve to the right.

Thromboplastin

An enzyme released by platelets and damaged tissue that triggers the cascade of events leading to a blood clot.

Thrombin

The active soluble enzyme converted from prothrombin that catalyzes the conversion of fibrinogen into fibrin.

Fibrin

An insoluble protein formed from fibrinogen that creates a mesh or net to trap blood cells and form a clot.

Artery

A blood vessel with a thick wall and narrow lumen that carries blood under high pressure away from the heart.

Vein

A blood vessel with a wide lumen, thin walls, and valves that carries blood under low pressure toward the heart.

Capillary

The smallest blood vessel, featuring a one-cell thick wall and pores to facilitate substance exchange between blood and tissues.

Tunica Media

The middle layer of an artery or vein wall, containing smooth muscle and elastic fibers.

Aorta

The major artery of the body that carries oxygenated blood under high pressure from the left ventricle to systemic circulation.

Myoglobin

A protein in the heart muscle that stores oxygen due to its high affinity for the molecule.

Sinoatrial node (SAN)

The tissue in the right atrium that generates the heart's intrinsic rhythm, acting as a natural pacemaker.

Atrioventricular (AV) valves

Valves (tricuspid and bicuspid/mitral) that allow blood flow from atria to ventricles while preventing backflow during ventricular contraction.

Semilunar (SL) valves

Valves located between the ventricles and major arteries (aorta and pulmonary artery) that prevent backflow of blood into the heart.

Diastole

The phase of the cardiac cycle when the heart muscle relaxes and the chambers fill with blood.

Systole

The phase of the cardiac cycle when the heart muscle (atria or ventricles) contracts to pump blood.

Hypertension

A chronic condition characterized by a sustained resting blood pressure reading above $140/90\,mmHg$.

Atherosclerosis

A disease involving the thickening and hardening of artery walls due to the accumulation of fibro-fatty plaques.

Atheroma

The build-up of cholesterol and white blood cells in the endothelial lining of an artery during the early stages of atherosclerosis.

Angina pectoris

Severe chest pain caused by reduced blood supply to the heart muscle, often resulting in anaerobic respiration and lactic acid buildup.

Myocardial Infarction

A heart attack; the death of cardiac muscle tissue due to a complete blockage of a coronary artery.

Stroke

Brain damage caused by a complete blockage of a cerebral artery or bleeding from damaged capillaries in the brain.

Aneurysm

The bulging of an arterial wall behind a blockage, which may split open and lead to massive internal bleeding.

High-density lipoproteins (HDL)

Good lipoproteins that carry cholesterol from the body to the liver for breakdown, reducing blood cholesterol levels.

Low-density lipoproteins (LDL)

Harmful lipoproteins that transport cholesterol to cells; high levels saturate cell membranes, causing cholesterol to remain in the blood.

Body Mass Index (BMI)

An obesity indicator calculated as $\text{body mass (kg)} / \text{height}^2\,(\text{m}^2)$; the normal range is $18$ to $25$.

Dietary Antioxidants

Substances like Vitamin C and E that stabilize free radicals by supplying hydrogen atoms, preventing cell damage and plaque formation.

Diuretics

Antihypertensive drugs that increase urine flow to decrease blood volume and lower blood pressure.

Beta Blockers

Drugs that bind to heart muscle receptors to prevent adrenaline from increasing heart rate and workload.

ACE inhibitors

Drugs that block the angiotensin-converting enzyme, preventing vasoconstriction and promoting vasodilation to lower blood pressure.

Statins

Drugs that lower cholesterol by blocking the enzyme responsible for its synthesis in the liver, thereby decreasing LDL production.

Anticoagulant

A drug, such as Warfarin, that interferes with the formation of prothrombin in the liver to decrease clot formation.

Coronary angioplasty

A surgical procedure using a balloon catheter to inflate and dilate a blocked coronary artery, often followed by stent placement.

Stent

A tiny mesh tube inserted into a diseased artery to hold the lumen open after it has been widened.