Cardiovascular system

• What does the cardiac muscle do?

  It constantly contracts to make your heart beat, to pump blood around your body.

  In order to do this it needs to be constantly supplied with oxygen from the blood vessels.
• Cardiac cycle

  1. Atrial diastole - The atria fill with blood from the vena cava and pulmonary veins

  2. SA (sinoatrial node) of the right atrium lets out an impulse, that spreads through the atria walls causing them to contract in unison

  3. Blood is then forced into the ventricles

  4. Impulse is received by the AV (atrioventricular node) and the signal is then delayed by 0.1 second to ensure the atria are empty before the ventricles contract

  5. Signal is then conducted through the Bundle of His, to the purkinje fibres

  6. Purkinje tissue then conducts the signal through the ventricle walls, causing them to contract from the apex up

  7. Pressure increase in each ventricle forces the semi lunar valves to open

  8. Heart chambers then relax to prepare for the next cycle
• What is cardiac output?

  The volume of blood pumped by the left side of the heart per minute.

  This can be used to calculate heart efficiency.
• What is an ECG?

  An ‘electrocardiogram’.

  Attaching electrical sensors (electrodes) to someone’s skin to monitor the electrical activity of the heart.
• What do the PQRST waves stand for?

  • P wave - Atrial systole.

  • Q wave - Initial downwards deflection.

  • R wave - Initial upward deflection.

  • S wave - The fall.

  • T wave - General diastole.
• What is the QRS complex?

  This indicates ventricular systole on an ECG
• What are the functions of the cardiovascular system?

  Transport:

  • nutrients like glucose and amino acids to the tissues.

  • oxygen from the lungs to the tissues.

  • hormones around the body.
• What are the causes of coronary heart disease?

  • Hypertension

  • Smoking

  • Excessive alcohol consumption

  • High cholesterol

  • Diabtetes

  • Age and sex

  • Genetics

  • Ethnicity
• What is CHD?

  Any narrowing or blockage of the coronary arteries, causing the supply of glucose and oxygen to reduce or cut off completely.
• What are the symptoms of CHD?

  Symptoms depend on the degree of and location of the narrowing coronary arteries.

  • Chest pain (angina) as the heart muscles become starved of blood.

  • Shortness of breath as the heart is less able to pump blood around the body.

  • Pain throughout body

  • Feeling faint

  • Feeling sick (nausea)
• How does CHD affect mental health?

  It can cause a decline in mental health as a result of the symptoms, concern over the risk of a heart attack and the need to make lifestyle changes may be stressful.
• How does blood thinning medicines relieve the symptoms?

  These are also known as anticoagulants, and can prevent the formation of blood clots by reducing platelet aggregation or targeting specific clotting factors.

  Therefore reducing the risk of thrombosis.

  However, blood clotting is important for the protective mechanism during injury, so they can cause the person to bleed easily.
• How do statins relieve the symptoms?

  They lower the concentration of LDL cholesterol, reducing the risk of atherosclerosis.

  They reduce the production of cholesterol in the liver, therefore lowering the bad LDL cholesterol levels in the blood.

  This protects against heart disease as lowering cholesterol levels reduces the plaque build up in the arteries, improving blood flow.

  These are taken in tablet for once a day.
• How do betablockers relieve symptoms?

  They block the effects of adrenaline acting on the sinoatrial node and slow down the heart.

  This reduces blood pressure and the workload of the heart. This can relieve chest pain and improve heart function.

  This prevents heart attacks and abnormal heart rhythms.

  They do this by binding to the beta receptors, so when hormones are released they bind to the beta receptors, blocking hormone effects.

  These are taken twice a day.
• How do lifestyle changes relieve the symptoms?

  • Healthy diet

  • Exercise

  • Quit smoking

  • Maintain a healthy weight

  • Manage stress

  • Lower cholesterol and blood pressure
• How does surgery relieve the symptoms?

  An angioplasty

  This involves inserting a balloon to widen narrowed arteries or a wire mesh stent that also helps to keep the artery open. The two procedures are often combined.

  This improves blood flow and therefore oxygen and glucose supply to the heart.
• Explain the process of an angioplasty.

  • A build up of cholesterol blocks the blood flow through an artery.

  • A stent with a balloon is inserted into a partially blocked artery.

  • The balloon is inflated to expand the stent.

  • The balloon is removed from the expanded stent.
• How does a heart transplant treat CHD?

  This a surgery that can be used in cases where a heart attack is not fatal but causes heart failure.

  Heart failure is when the heart is no longer able to maintain an adequate flow of blood throughout the body.