Biological Molecules, Circulatory Systems, and Cardiovascular Health

Flashcards covering the properties of water, carbohydrate and lipid structures, the circulatory system, gas transport via haemoglobin, and the causes and treatments of cardiovascular disease.

Dipole

An uneven distribution of charge within a molecule, such as in water where there is a slightly negative charge near the oxygen atom and a slight positive charge near the hydrogen atoms.

Saccharides

The sugar units that make up carbohydrates; they can be categorized as monosaccharides, disaccharides, or polysaccharides.

Glycosidic bond

A bond formed between two monosaccharides during a condensation reaction, containing a single oxygen atom.

Condensation reaction

A chemical reaction that joins two molecules together through the release of a small molecule, often water.

Glucose

A common monosaccharide containing six carbon atoms ($C_{6}$) that serves as the main substrate for respiration.

Maltose

A disaccharide formed by the condensation of two glucose molecules.

Sucrose

A disaccharide formed by the condensation of glucose and fructose.

Lactose

A disaccharide formed by the condensation of glucose and galactose.

Glycogen

The main energy storage molecule in animals, formed from glucose molecules joined by $1,4$ and $1,6$ glycosidic bonds with many side branches.

Starch

The primary energy store in plants, consisting of a mixture of two polysaccharides: amylose and amylopectin.

Amylose

An unbranched chain of glucose molecules joined by $1,4$ glycosidic bonds that coils into a compact shape.

Amylopectin

A branched polysaccharide made of glucose molecules joined by $1,4$ and $1,6$ glycosidic bonds, allowing for rapid digestion by enzymes.

Hydrolysis reaction

A reaction where a water molecule is added to break a glycosidic bond, splitting a larger molecule into smaller ones.

Saturated lipids

Lipids, often found in animal fats, that do not contain any carbon-carbon double bonds ($C=C$).

Unsaturated lipids

Lipids, often found in plants, that contain carbon-carbon double bonds ($C=C$) and melt at lower temperatures than saturated fats.

Triglyceride

A lipid molecule made of one molecule of glycerol and three fatty acids joined by ester bonds.

Ester bond

The bond formed between glycerol and a fatty acid in a triglyceride through a condensation reaction.

Arteries

Blood vessels with thick, muscular, and elastic walls that carry oxygenated blood away from the heart at high pressure.

Capillaries

Highly branched blood vessels with walls only one cell thick to allow for quick diffusion of substances between blood and cells.

Veins

Blood vessels with thin walls and wide lumens that carry deoxygenated blood back to the heart at low pressure and contain valves to prevent backflow.

Atrioventricular valves

Valves located between the atria and the ventricles that prevent blood from flowing backward into the atria.

Semilunar valves

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

Atrial systole

The stage of the cardiac cycle where the atria contract, forcing blood into the ventricles.

Ventricular systole

The stage of the cardiac cycle where the ventricles contract, closing the atrioventricular valves and opening the semilunar valves to pump blood out of the heart.

Cardiac diastole

The stage of the cardiac cycle where atria and ventricles relax, lowering internal pressure and allowing blood to be drawn in from the veins.

Haemoglobin

A water-soluble globular protein consisting of two alpha and two beta polypeptide chains, each bound to a haem group ($Fe^{2+}$) that can carry one oxygen molecule.

Bohr effect

The phenomenon where the affinity of haemoglobin for oxygen decreases in the presence of high partial pressures of carbon dioxide, causing oxygen to be released.

Atherosclerosis

The hardening of arteries caused by the build-up of fibrous plaque called an atheroma.

Thrombosis

A condition where a blood clot forms inside a blood vessel, restricting blood flow and potentially causing a blockade.

Thromboplastin

A clotting factor released by platelets and damaged tissues that triggers the conversion of prothrombin into thrombin.

Fibrin

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

Antioxidants

Molecules that donate electrons to stabilize free radicals of oxygen without becoming unstable themselves, reducing oxidative stress.

HDL (High-density lipoproteins)

Lipoproteins formed from unsaturated fats and proteins that transport cholesterol to the liver to be expelled, reducing cholesterol levels.

LDL (Low-density lipoproteins)

Lipoproteins formed from saturated fats and proteins that transport cholesterol to the arteries, increasing the risk of plaque build-up.

Statins

A class of drugs used to lower cholesterol levels and relax blood vessels to reduce the risk of cardiovascular disease.

Platelet inhibitors

Drugs that interrupt the cascade of blood clot formation, often by stopping thrombus formation.

BMI (Body Mass Index)

A value used to assess weight status, calculated as: $\frac{\text{Body mass in Kilograms}}{(\text{body height in metres})^{2}}$

Correlation

A description of the relationship between two variables, where a value of $1$ is a perfect positive relationship and $-1$ is a perfect negative relationship.

Causation

A relationship where one variable directly causes a change in another, which is distinct from simple correlation.