1.1 What Is Cardiovascular Disease? Flashcards
Coronary heart disease, CHD
Disease affecting the coronary arteries. These arteries supply blood to the heart muscle. If a branch of one of these arteries becomes narrow or blocked, the area of the heart muscle that it supplies no longer receives a supply of oxygen-rich blood. This is the cause of the chest pain known as angina. If a blood clot blocks the narrowed coronary artery, an area of cardiac muscle dies and this gives rise to a heart attack or myocardial infarction. A frequent cause of narrowing and blockages in the coronary arteries is atherosclerosis.
Stroke
A stroke occurs when a blood vessel supplying blood to the brain is narrowed, blocked or bursts. Brain damage results due to lack of oxygen to the brain. A stroke can be the result of cardiovascular disease. The effects of a stroke will vary according to the part of the brain affected. Symptoms include numbness, slurred speech and blurred vision. There may be paralysis on one side of the body. The more severe the damage, the less likely it is that there will be a full recovery
Purpose of the heart and circulation
To move substances around the body
Diffusion
In very small organisms substances such as oxygen, co2 and digestive produces move around the organism via diffusion.
The movement of molecules from where they are in a high concentration to where they are in a lower concentration. Small molecules such as oxygen diffuse through cell membranes into cells. Other molecules cross cell membranes with the aid of proteins. This form of diffusion is called facilitated diffusion.
Mass transport system
A system that transports substances in bulk from one part of an organism to another. Large organisms cannot rely on diffusion alone to meet their needs. It is too slow. They need mass flow to move substances rapidly over long distances. Examples of mass transport systems are the xylem in a flowering plant and the blood system in an animal.
Mass flow
Movement down a concentration gradient of a liquid or gas and all the particles it contains, for example, blood in the circulatory system.
Open circulatory system
The type of blood system found in insects and some other animal groups in which blood is not contained in blood vessels. Instead of being enclosed in arteries, capillaries and veins, blood circulates through large open spaces.
Closed circulatory systems
The type of blood system found in larger animals such as humans, in which blood is enclosed in blood vessels. Blood flows from the heart in arteries. It then flows through arterioles to capillaries. The capillaries are abundant and they come into contact with most of the cells in the body where’d substances can be exchanged.
It returns to the heart from the capillaries through venules and veins.
Single circulation
A type of blood system where blood passes through the heart once in its passage round the body. Fish have a single circulation. Blood is pumped to the gills from the ventricle of the heart. It then goes to the other organs of the body before returning to the heart. Mammals have a double circulation in which blood passes through the heart twice in its passage round the body.
Double circulation
A type of blood system in which blood passes through the heart twice in its passage round the body. Mammals have a double circulation. Blood is pumped to the lungs from the right ventricle of the heart. It returns to the heart where it is pumped again, this time by the left ventricle. It now goes to the other organs of the body.
-allows birds and mammals to have a high metabolic rate, as oxygen and other substances can be delivered more rapidly to cells to meet the needs of the organism.
Polar molecule
A molecule or part of a molecule is polar when the sharing of the electrons within it is not quite even; one end becomes slightly positive and the rest is slightly negative.
Water molecules are polar
Dipole
A molecule with an unevenly distributed electrical charge, giving a positively charged and a negatively charged end of the molecule, also known as a polar molecule. For example, water is a dipole.
Hydrogen bonding
A weak chemical bond between electropositive hydrogen and other electronegative atoms such as oxygen. Although they require relatively little energy to break, hydrogen bonds are very important in helping to maintain the 3D shapes of some molecules. Molecules held in their 3D shape by hydrogen bonding include DNA, polysaccharides and proteins. It is because of hydrogen bonds that water molecules are able to stick to each other by cohesion.
Solvent properties of water
- many chemicals dissolve easily in water due to their dipole nature.This allows vital biochemical reactions to occur in the cytoplasm of cells
- the dissolve substances can be transported via the blood and lymph systems
- ionic substances dissolve easily as the negative ions are attracted to the positive hydrogen ends of the water molecule and vice versa
- polar molecules easily dissolve in water. E.g -OH and -NH2
- non polar hydrophobic substances like lipids do not dissolve- they combine with proteins to form lipoproteins
Hydrophilic
Water-attracting. For instance, in a phospholipid molecule the phosphate group attracts water molecules, and the fatty acid part of the molecule repels water molecules. These properties are important in the arrangement of phospholipids in cell membranes. The molecules form a double layer or bilayer, with the hydrophilic phosphate groups on the outside and in contact with water in the cytoplasm or outside of the membrane, and the water- repelling fatty acids on the inside, away from contact with water.
Hydrophobic
Water-repelling. In a phospholipid molecule the fatty acid part of the molecule repels water molecules, and the phosphate group attracts water molecules. These properties are important in the arrangement of phospholipids in cell membranes. The molecules form a double layer or bilayer, with the water-repelling fatty acids facing towards the inside, away from contact with water. The hydrophilic phosphate groups are on the outside, and in contact with watery fluids in the cytoplasm or outside the membrane.
Thermal properties of water
- high specific heat capacity as a large amount of energy is required to break the hydrogen bonds between molecules.
- A large input of energy only causes a small increase in temp, so water warms up and cools slowly. This is useful as it helps organisms to avoid rapid changes in their internal temp and enables them to maintain a steady temp when outside conditions vary
- water has a high boiling point due to large amount of hydrogen bonds which require a lot of energy to break them all
Cardiac muscle
Unlike skeletal muscle, cardiac muscle is involuntary, it is myogenic and it does not fatigue. Like skeletal muscle, its fibres are striated (have a striped appearance), however they are branched unlike skeletal muscle.
Structure of the heart
Right side receives deoxygenated blood from the body and pumps to the lungs
Left side receives oxygenated blood from the lungs and pumps it to the body
Collagen
A tough fibrous protein found in animals. Collagen is found in tendons and bones, and in the outer layers of arteries and veins.
Arteries
A blood vessel that takes blood from the heart to the arterioles, which lead to capillaries. In mammals, arteries usually contain blood rich in oxygen. There is one important exception to this. The pulmonary artery takes blood to the lungs. As this blood has come from the tissues it has a low concentration of oxygen.
Comparison to veins • narrow lumen •thicker walls •more collagen, smooth muscle and elastic fibres • no valves
Veins
A vein is a blood vessel which returns blood from the capillaries to the heart. In mammals, veins usually contain blood low in oxygen. There is one important exception to this. The pulmonary vein returns blood from the lungs. It contains blood with a high concentration of oxygen. In plants, veins are found in leaves. They help to support the leaf and contain the vascular tissue: xylem vessels and phloem tubes.
Comparison to arteries • wide lumen • thinner walls • less collagen and smooth muscle, fewer elastic fibres • valves
Cardiovascular disease, Cardiovascular diseases, CVD
A disease that affects the heart or blood vessels. Cardiovascular diseases are the main causes of death in the UK and account for about one in three deaths. The main forms of cardiovascular disease are coronary heart disease and stroke.
