Animal Transport

• Atrial fibrillation


  Rapid, random, ineffective contractions of the atrium
• Ectopic heartbeat


  Extra heartbeats that are out of the normal rhythm
• Bradychardia


  A very slow heart beat, typically below 60bpm
• Tachychardia


  A very rapid heart beat, typically over 100 bpm
• Electocardiogram (ECG)


  A recording of the electrical activity of the heart
• Apex

  bottom of the heart
• Bundle of His


  A bundle of Purkyne fibres which penetrate through the septum between ventricles
• Basic rhythm of the heart

  1. A wave of excitation begins in the pacemaker area called the sino-atrial node, causing the atria o contract and so initiating the heartbeat. A layer of non-conducting tissue prevents the excitation passing directly to the ventricles.

  2. The electrical activity form the SAN is picked up by the atrio-ventricular node. The AVN then imposes a slight delay before stimulating the bundle of His

  3. The bundle of His splits into two branches and conducts the wave of excitation to the apex of the heart

  4. At the Apex, the Purkyne fibres spread out through the walls of the ventricles on both sides. The spread of excitation triggers the contraction of the ventricles, starting at the apex, allowing for more efficient emptying of the ventricles
• Lub-dub


  The sound made by the heart valves as they close. The lub is made by blood being forced against the AV valves as the ventricles contract and the dub comes from backflow of blood closing the semilunar valves in the aorta and pulmonary artery as the ventricles relax
• Changes in ventricular volume

  Volume rises as the atria contract and the ventricles fill with blood and then suddenly drops as blood is forced out into the aorta when the semilunar valve opens. Volume increases again as the ventricles fill with blood.
• Changes in ventricular pressure

  It is low at first but gradually increases as the ventricles fill with blood as the atria contract. The left AV valves close and pressure rises dramatically as the thick muscular walls of the ventricle contract. As pressure rises above that of the aorta, blood is forced into the aorta past the semilunar valves. Pressure falls as the ventricles empty and the walls relax
• Changes in atrial pressure

  It is always relatively low because the thin walls of the atrium cannot create much force. It is highest when they are contracting, but drops when the atrioventricular valve closes and its walls relax. The atria then fills with blood, leading to a gradual build-up of pressure until a slight drop when the left atrioventricular valve opens and some blood moves into the ventricle
• Changes in aortic pressure


  Rises when the ventricles contract as blood is forced into the aorta and then gradually falling, but never lower than 12 kPa due to the recoil action caused by the elasticity of its walls. This recoil causes a temporary rise in pressure at the start of the relaxation phase
• Systole

  The atria contract, closely followed by the ventricles. The pressure inside the heart increases dramatically and blood is forced out of the right side of the heart to the lungs and from the left side to the main body circulation. The volume and pressure of the blood in the heart are low at the end of systole and blood pressure in the arteries is at its maximum.
• Diastole


  The heart relaxes, the atria and then the ventricles fill with blood and the volume + pressure of the blood in the heart build as the heart fills, but the pressure in the arteries is at a minimum
• How long is the cardiac cycle?

  0.8 seconds
• Passage of blood through the heart

  Superior and inferior Vena Cava - Right Atrium - Tricuspid Valve - Right Ventricle - Pulmonary Semilunar Valve- Pulmonary Trunk and Arteries to lungs- Pulmonary Veins leaving the lungs - Left Atrium - Bicuspid Valve - Left Ventricle - Aortic Semilunar Valve - Aorta - To the body
• biscupid valve (mitral valve)


  valve between the left atrium and the left ventricle (left atrioventricular valve).
• Septum


  Divides the right and left chambers of the heart
• Semilunar valves


  pulmonary and aortic valves located between the right ventricle and the pulmonary artery and between the left ventricle and the aorta
• Left atrium


  Upper left chamber of the heart that receives oxygenated blood from the pulmonary veins
• Pulmonary veins


  carry the oxygenated blood from the lungs into the left atrium of the heart
• Left pulmonary artery


  transports deoxygenated blood from the right ventricle to the left lung
• Aorta


  The large arterial trunk that carries blood from the heart to be distributed by branch arteries through the body.
• Carotid arteries


  the large neck arteries, one on each side of the neck, that carry blood from the heart to the head
• Right ventricle


  The lower right chamber of the heart that receives deoxygenated blood from the right atrium and pumps it under low pressure into the lungs via the pulmonary artery.
• Tendinous cords


  String-like tendons used to attach the atrioventricular valves of the heart to the sides of the ventricle wall. Sometimes called heart strings.
• atrioventricular valves (AV)


  Valves separating the atria from the ventricles
• Triscupid valve


  valve between the right atrium and the right ventricle (right atrioventricular valves)
• Right atrium


  the right upper chamber of the heart that receives deoxygenated blood from the venae cavae and coronary sinus coming from the body
• Myogenic


  Describes muscle tissue (heart muscle) that generates its own contractions.
• Cardiac muscle

  Involuntary muscle tissue found only in the heart.
• right pulmonary artery

  takes deoxygenated blood from the right ventricle to the right lung
• inferior vena cava


  A vein that is the largest vein in the human body and returns blood to the right atrium of the heart from bodily parts below the diaphragm.
• superior vena cava


  A vein that is the second largest vein in the human body and returns blood to the right atrium of the heart from the upper half of the body.
• How does haemoglobin act as a buffer?

  Hydrogen ions are taken up by the haemoglobin (haemoglobin acts as a buffer) to form haemoglobinic acid (HHb).
• What purpose does the removal of carbon dioxide and its conversion into hydrogen carbonate ions serve?


  It maintains a steep concentration gradient so that CO2 continues to diffuse into the red blood cell
• Chlorine shift

  The movement of negative chlorine atoms into a red blood cell as hydrogen carbonate ions ((HCO3)-) leave the cell to maintain the electrical balance
• Reaction to form carbonic acid

  CO2 + H2O = H+ + HCO3- (Reversible)
• Transport of CO2

  - 5% dissolved in the plasma

  - 10-20% combined with amino groups in the polypeptide chains of haemoglobin to form carbaminohaemoglobin

  - 75-85% converted into carbonic acid (H2CO3) which then breaks down into Hydrogen Carbonate ions (HCO3)- in the cytoplasm of red blood cells (this reaction is catalysed by carbonic anhydrase)