Cardiovascular

• What is the heart referred to as?

  A double pump which pumps at the same time
• Name the 2 circuits of the heart

  • Pulmonary
  • Systemic
• Pulmonary circulation

  • Deoxygenated blood from the body in the right side of the heart is pumped to the lungs
  • Oxygenated blood from the lungs returns the left side of the heart
• Systemic circulation

  • Oxygenated blood in the left side of the heart travels around the body
  • Deoxygenated blood from the body returns to the heart in the right side of the heart
• Name the 4 chambers

  • Right atrium
  • Left atrium
  • Right ventricle
  • Left ventricle
• Describe the pathway of deoxygenated blood

  1. Deoxygenated blood from the body enters the right atrium via the vena cava
  2. Passes through the tricuspid valve into the right ventricle
  3. Ventricle contacts pushing blood out of the heart towards the lungs through the pulmonary artery through the pulmonary/semilunar valve
• Describe the pathway of oxygenated blood

  1. Oxygenated blood from the lungs enters the rleft atrium via the pulmonary vein
  2. Passes through the bicuspid valve into the left ventricle
  3. Ventricle contacts pushing blood out of the heart towards the rest of the body through the aorta through the aortic/semilunar valve
• Arteries carry oxygenated blood AWAY from the heart at high pressure.
• Artery adaptations

  • Thick muscular walls with elastic fibres to withstand the high pressure
  • Have a narrow lumen
• Capillaries are 1 cell thick an have leaky walls to allow the exchange of substance between the cells and the blood
• Capillary adaptations

  • 1 cell thick to reduce the diffusion distance
  • Leaky walls
  • A have narrow lumen to slow blood flow and increase the time for exchange
• Veins carry blood towards the heart at low pressure
• Vein adaptations

  • Thinner muscular walls and less elastic fibres due to low pressure
  • Wider lumen to maintain blood flow
  • Valves to prevent backflow
• Faulty valves

  Varicose veins
• Closed circulatory system

  Blood goes within blood vessels
• Open circulatory system

  Blood bathes cells directly, no blood vessels
• Systole

  Contraction
• Diastole

  Relaxation
• SAN

  Sinoatrial node
• AVN

  Atrioventricular node
• Name the 3 parts of the cardiac cycle

  Cardiac diastole

  Atrial systole

  Ventricular systole
• The heart is myogenic which means that contractions are initiated from within the heart without interaction with the nervous system
• Cardiac diastole is when the atria and ventricles are both at rest. Blood is at low pressure in the veins. Pressure increases as the atria begin to fill. Some blood trickles through the open atrioventricular valves into the relaxed ventricles.
• Atria systole is when pressure in the atria is the highest causing the atria walls to contract and push blood into the ventricles. Pressure in the ventricles begins to increases as they fill.
• Ventricular systole is when the pressure in the ventricles is the highest which causes the ventirlces to contract from the apex upwards, pushing blood aout of the heart through the aorta and pulmonary artery. Ventricular pressure increases more than the atria causing the atrioventricluar valves to shut to prevent backflow. The pressure causes the semilunar valves to open.
• How is the heart beat controlled?

  1. SAN starts waves of depolarisation which spread to the atria causing them to contract (atrial systole)
  2. There is a of non conductive layer of tissue between the atria and ventricles which has a high electrical resistance. This prevents the ventricles and atria from contracting at the same time.
  3. AVN delays impulses by 0.1 seconds
  4. AVN passes the waves of excitation down the bundle of His and up the Purkinje fibres in the interventricular septum.
  5. This causes the ventricles to contract from the apex upwards, pushing blood out of the heart.
• The SAN is found in the upper right atrium and is known as the pacemaker.
• What is a red blood cell called?

  Erythrocyte
• What is a white blood cell called?

  Leucocyte
• What is are platelets called?

  Thrombocytes
• ECG

  Electrocardiogram
• What does an ECG do?

  Measures the electrical signals of the heart on a trace to shows the hearts activity.
• Name the 3 parts of an ECG

  • P wave
  • QRS complex
  • T wave
• P wave

  Shows atrial systole/depolarisation where the atria are contracting
• QRScomplex

  Shows ventricular systole/depolarisation where the ventricles are contracting
• T Wave

  Shows ventricular diastole/repolarisation where the ventricles are relaxing
• Sinus

  Normal heart rhythm which a rate of 60-100 beats per minute
• Arrhythmia

  Any deviations causing an irregular heart rhythm
• Bradycardia

  Abnormally slow heart rhythm with <60 beats per minute
• Tachycardia

  Abnormally fast heart rhythm with >100 beats per minute