cardiovascular system

• Cardiovascular System


  Transports blood which contains gasses, hormones, nutrients and cells around the body
• Lymphatic System


  Circulates Lymph which primarily assists in defending the body against foreign substances
• Cardiovascular Components


  • Heart
  • Blood Vessels
  • Arteries
  • Capillaries
  • Veins
• Blood


  • Functions as a dynamic tissue: Transport, Immunity, Haemostasis, Homeostasis, Transport of regulatory molecules, Regulation of pH, Maintenance of body temperature, Immunity
  • Total blood volume 4-6 L (depending on body size)
• Components of Blood


  • Plasma: composed of water with some dissolved solutes including proteins, lipids, carbohydrates, amino acids, vitamins, minerals, hormones, wastes, gases and electrolytes
  • Platelets (Thrombocytes): cell like particles, assist with blood clotting
  • White Blood Cells (Leukocytes): primary defence against infection
  • Red Blood Cells (Erythrocytes): main component is haemoglobin
• Heart anatomy


  Blood will flow from the veins into the right atrium then move through the tricuspid valve that separates the right atrium from the right ventricle. The valve has string like projections - chordae tendineae, which sit on capillary muscles inside the interior of ventricles. The capillary muscles help contract and make sure the valves don't invert allowing blood to flow backwards from atrium to ventricle, only wanting one way blood flow.
• Heart anatomy


  The ventricle will push blood through the other valves. The right ventricle pushes blood from the ventricle to the pulmonary artery via the pulmonary semilunar valve. Oxygenated blood enters thorough the pulmonary vein and into the left atrium and move through the bicuspid valve. The left ventricle pushes blood to the aorta via the aortic valve. From ventricles, either push blood to pulmonary circulation or systemic circulation via aorta. In between the right and left ventricle is intraventricular septum.
• Heart anatomy


  Vetricles are separated by muscles - endocardium, myocardium and epicardium. The muscles help push blood in and out of the ventricles.
• Production of red blood cells

  Production of new red blood cells is through a feedback mechanism. Who the body detects a decrease in blood oxygen it stimulates the kidneys to secrete a hormone called erythropoiesis then makes it way up to the bone marrow and tells the bone marrow to increase red blood cell production.
• Diastole


  Diastole is the relation phase.

  • The chambers fill with blood
  • Twice as long as systole
  • Ventricle untwists, lengthens, and unthickens
• Systole


  Contraction phase.

  • Chambers eject blood
  • High pressure
  • Ventricle twists, shortens, thickens
• Diastole and systole


  During diastole, the pulmonary and aortic valve will be closed because it is not pumping blood to the lungs or systemic circulation. The tricuspid valve and bicuspid valve are open because blood is going to fill ventricle, and move from atrium to ventricle. During systole, getting rid of blood from the heart. Pulmonary and aortic valve are going to open, the tricuspid and bicuspid valve are going to close to allow blood to flow from the ventricle to systemic or pulmonary circulation.
• Electrical activity of the heart

  Occurs via an internal pacemaker - sinoatrial node. Nerves cause an electrical impulse which spreads out over the left and right atrium and causes depolarisation or contraction of the atrium. The electrical activity then comes back in from atria, moves towards the atrioventricular node. There is a slight delay between the atria contracting and electrical activity in the AV no. It allows the node to contract before the ventricle contracts.
• Regulation of heart


  Pacemaker - sinoatrial node. Influence by the autonomic nervous system. Has sympathetic and parasympathetic branches. At rest, the parasympathetic stimulation decreases heart rate - the parasympathetic branch telling the pacemaker to slow down. During exercise, withdrawal of vagal tone, concurrent increase in sympathetic nerve innervation to increase heart rate. Hormonal influence. Sympathetic components increase heart rate by release of catecholamines - adrenaline and noradrenaline
• Electrocardiogram


  P wave:

  Impulse rising from the SA node results in depolarisation and contraction of the atria (right atrium contracts slightly before the left atrium). This atrial depolarisation = atrial systole.

  QRS complex:

  Due to ventricular depolarisation, marks the beginning of ventricular systole. Masks the underlying atrial depolarisation signal.

  T wave:

  Ventricular repolarisation. End of T wave marks the end of ventricular systole electrically.
• Cardiovascular terminology 


  Heart rate (HR): the number of times the heart beats per minute

  Stroke volume (SV): volume of blood pumped out of the heart with each beat

  Cardiac output: total volume of blood pumped out of the heart per minute. CO = HR x SV

  Ejection fraction: the fraction of blood pumped out of the left ventricle with each contraction
• Blood pressure


  Systolic blood pressure (~120mm Hg)

  • Maximal pressure of blood against the arterial's walls during systole (heart contraction; ventricle contraction)
  • Estimate of how hard the heart is working and strain on arterial walls during ventricular contraction

  Diastolic blood pressure (~70-80mm Hg)

  • Pr4essure exerted by blood against the arterial walls during diastole (heart relaxation; ventricle relaxation)
  • During relaxation phase of cardiac cycle, arterial blood pressure decrease
  • Indicate peripheral resistance e.g. the ease with which blood flows from arterioles into capillaries
• Blood vessels


  Composed of arteries, capillaries and veins.