The heart

• What does the right side pump?

  Deoxygenated blood to lungs
• What does the left side pump?

  Oxygenated blood to whole body
• How is the left ventricle adapted?

  Thicker, more muscular walls than right ventricle- allows it to contract more powerfully & pump blood all way around body. Right side less muscular so its contractions only powerful enough to pump blood to nearby lungs.
• How are the ventricles adapted?

  Thicker walls than atria so can push blood out heart whereas atria just need to push blood short distance into ventricles.
• What do the atrioventricular valves (AV) do?

  Link atria to ventricles & stop blood flowing back into atria when ventricles contract.
• What do the semi-lunar valves (SL) do?

  Link ventricles to pulmonary artery & aorta & stop blood flowing back into heart after ventricles contract.
• What do the cords do?

  Attach atrioventricular valves to ventricles to stop them being forced up into atria when ventricles contract.
• What do veins do?

  Carry blood into heart (vena cava & pulmonary vein).
• What do arteries do?

  Carry blood away from heart (aorta & pulmonary artery).
• Describe heart valves:

  Only open 1 way. If higher pressure behind valve its forced open, if higher pressure infront of valve its forced shut. Means blood flow is unidirectional.
• What is the cardiac cycle?

  Ongoing sequence of contraction & relaxation of atria & ventricles that keeps blood continuously circulating around body. Atria & ventricles volume changes as they contract & relax. Pressure changes occur too.
• What are the 3 stages of the cardiac cycle?

  Atrial systole, ventricular systole, diastole
• 1.) Ventricles relax & atria contract:

  Ventricles relaxed. Atria contract, decreasing volume of chambers & increasing pressure inside chambers. Pushes blood into ventricles. Slight increase in ventricular pressure & chamber volume as ventricles receive ejected blood from contracting atria.
• 2.) Ventricles contract & atria relax:

  Atria relax. Ventricles contract, decreasing their volume & increasing their pressure. Pressure becomes higher in ventricles than atria-forces AV valves shut to prevent back-flow. Ventricular pressure also higher than aorta's & pulmonary artery's-forces SL valves open & blood forced out into these arteries.
• 3.) Ventricles & atria relax:

  Ventricles & atria relax. Higher pressure in pulmonary artery & aorta closes SL valves to prevent back-flow into ventricles. Blood returns to heart & atria fill again due to higher pressure in vena cava & pulmonary vein. Starts to increase atria pressure. As ventricles relax, their pressure falls below atria pressure & so AV valves open. Allows blood to flow passively into ventricles from atria. Atria contract & process begins again.
• What is cardiac output?

  Volume of blood pumped by heart per minute. Cm3 min-1
• How do you calculate cardiac output?

  Stroke volume x heart rate
• What is heart rate?

  Number of beats per minute (bpm)
• What is stroke volume?

  Volume of blood pumped during each heartbeat (cm3).
• What is coronary heart disease?

  Occurs when coronary arteries have lots of atheromas in them, restricting blood flow to heart muscle. Can lead to heart attack.
• How are atheromas formed?


  Wall of artery made of several layers-endothelium usually smooth & unbroken. If damage occurs to endothelium (e.g, by high blood pressure) WBC (mostly macrophages) & lipids from blood clump together under lining to form fatty streaks. Overtime, more WBC, lipids & connective tissue build up & harden to form a fibrous plaque (atheroma). Partially blocks lumen of artery & restricts blood flow, causing blood pressure to increase.
• What is an aneurysm?


  Balloon-like swelling of artery. Starts with formation of atheromas. Atheroma plaques damage & weaken arteries & narrow them, increasing blood pressure. When blood travels through weakened artery at high pressure, it may push inner layers of artery through outer elastic layer to form aneurysm. May burst, causing haemorrhage (bleeding).
• What is thrombosis?

  Formation of blood clot. Starts with formation of atheromas. Atheroma plaque can rupture (burst through) endothelium of artery. Damages artery wall & leaves a rough surface. Platelets & fibrin (a protein) accumluate at site of damage & form a blood clot (thrombus). Blood clot can cause a complete blockage of artery or it can become dislodged & block a blood vessel elsewhere in body. Debris from rupture can cause another blood clot to form further down artery.
• Explain myocardial infarction:

  Heart muscle supplied with blood by coronary arteries. If coronary artery becomes completely blocked, an area of the heart muscle will be cut off from blood supply, receiving no oxygen. Causes myocardial infarction. Heart attack can cause damage & death of heart muscle.
• Symptoms of myocardial infarction:

  Pain in chest & upper body, shortness of breath & sweating. If large areas of heart muscle are affected, complete heart failure can occur-often fatal.
• Why is high blood pressure a risk factor for cardiovascular disease?

  High blood pressure increases risk of damage to artery walls-increases risk of atheroma formation, causing further increase in blood pressure. Atheromas can also cause blood clots to form-could block blood flow to heart muscle resulting in heart attack. Being overweight, not exercising & excessive alcohol consumption increase blood pressure.
• Why is cig smoking a risk factor for cardiovascular disease?

  Both carbon monoxide & nicotine (in cig smoke) increase risk of C.D & heart attack. CO combines with hb & reduces amount of oxygen transported in blood. If heart muscle doesn't receive enough oxygen it can lead to heart attack. Smoking decreases amount of antioxidants in blood-these are important for protecting cells from damage. Fewer antioxidants=cell damage in coronary artery walls is more likely-can lead to atheroma formation.
• Why is high blood cholesterol & poor diet a risk factor for cardiovascular disease?

  If blood cholesterol level high then risk of C.D increases as cholesterol is 1 of main constituents of fatty deposits that form atheromas. Can lead to increased blood pressure & blood clots which could cause heart attack. Diet high in saturated fat is associated with high blood cholesterol levels. Diet high in salt increases risk of C.D as it increases risk of high blood pressure.