Topic 3.2

• What is affinity?

  The tendency of one substance to bind with another substanc
• What is the aorta?

  The artery that takes oxygenated blood away from the heart to the body
• What is an arteriole?

  A type of blood vessel that connects the arteries and capillaries. The walls of the

  arterioles contain large amounts of smooth muscle, some elastic fibres and some collagen.
• What is an artery?

  A type of blood vessel that carries blood away from the heart to the tissues, under

  high pressure. The walls of the arteries contain collagen, smooth muscle and elastic fibres.
• What is atrial fibrilation?


  An arrhythmia that involves the rapid contraction of the atria, preventing complete ventricular filling.
• What is atrial systole?


  he stage of the cardiac cycle in which the atria contract, pushing blood into the ventricles. The AV valves are pushed open fully and the atria are emptied of blood
• What is the atrioventricular node (AVN)?


  A group of cells located between the atria that slow down the

  wave of excitation and pass it between the ventricles, along the bundle of His
• What are the atrioventricular valves?

  The valves found between the atria and ventricles. They

  prevent the backflow of blood from the ventricles into the atria. There are two types of

  atrioventricular valves: bicuspid and tricuspid
• What are bicuspid valves?


  The atrioventricular valves found between the left atrium and left ventricle
• What is blood?

  The transport medium in the mammalian circulatory system. It consists of plasma,

  red blood cells, white blood cells and platelets.
• What is the bohr effect?

  The loss of affinity of haemoglobin for oxygen as the partial pressure of carbon

  dioxide increases.
• What is bradycardia?

  A slow resting heart rate below 60 bpm.
• what is a bundle of his?

  A collection of Purkyne fibres which run from the Atrioventricular node (AVN) down to the apex of the ventricles.
• What are capilliaries?

  Microscopic blood vessels that form a large network through the tissues of the

  body and connect the arterioles to the venules. They are the site of exchange of substances

  between the blood and the tissues
• What is carbonic anhydrase?

  An enzyme that catalyses the reversible reaction between water and carbon dioxide to produce carbonic acid.
• What is the cardiac cycle?

  Describes the sequence of events involved in one complete contraction and relaxation of the heart. There are three stages: atrial systole, ventricular systole and diastole.
• What is cardiac output?

  The volume of blood pumped by the heart through the circulatory system in one minute
• How is cardiac output calculated?

  Cardiac output = Heart rate x stroke volume
• What is a chloride shift?

  The process by which chloride ions move into the erythrocytes in exchange for hydrogen carbonate ions which diffuse out of the erythrocytes. This maintains the

  electrochemical equilibrium of the cell.
• What is a circulatory system?

  The transport system in animals
• What is a closed circulatory system?

  A circulatory system in which the blood pumped by the heart is

  contained within blood vessels. The blood does not come into direct contact with the cells.
• Where are closed circulatory systems typically found?

  In animals
• What is diastole?

  The stage of the cardiac cycle in which the heart muscle relaxes. The atria and ventricles fill with blood.
• What is a double circulatory system?

  A circulatory system in which the blood flows through the heart

  twice in two circuits. Blood is pumped from the heart to the lungs before returning to the

  heart. It is then pumped around the body, after which it returns to the heart again.
• Where are double circulatory systems found in?

  in animals
• What is an ectopic heartbeat?

  Additional heartbeats outside of the normal heart rythmn
• What is an electrocardiogram (ECG)?

  A technique used to indirectly measure the spread of electrical

  activity through the heart by measuring tiny changes in the skin's electrical conductivity. This

  produces a trace which is used to detect abnormalities in heart rhythm.
• what is haemoglobin?

  The red pigment found in erythrocytes that binds reversibly with four oxygen molecules to form oxyhaemoglobin. It is a globular protein that consists of four polypeptide chains, each with a prosthetic haem group
• What is haemoglobin acid?

  The product formed when haemoglobin accepts free hydrogen ions.

  This enables haemoglobin to act as a buffer, reducing changes in blood pH
• What is heart rate?

  The number of times the heart beats in one minute.
• what is hydrostaic pressure?

  The pressure exerted on the sides a of a vessel by a fluid
• What is the inferior vena cava?

  The vein that returns deoxygenated blood to the heart from the lower body.
• What is lymph?

  Modified tissue fluid that drains into the lymphatic system. It carries less oxygen and fewer nutrients than tissue fluid, but also contains fatty acids.
• Define myogenic?

  Describes cardiac muscle tissue that initiates its own contraction, without outside

  stimulation from nervous impulses.
• Define oncotic pressure?

  The movement of water into the blood by osmosis due to the tendency of

  plasma proteins to lower the water potential of the blood.
• What is an open circulatory system?

  A circulatory system in which the transport medium pumped by

  the heart is not contained within vessels, but moves freely. The transport fluid comes into

  direct contact with the cells.
• Where are open circulatory systems found?

  In insects
• What is an oxygen dissociation curve?

  A graph that describes the relationship between the partial

  pressure of oxygen and the percentage saturation of haemoglobin in the blood
• What is plasma?

  The main component of the blood that carries red blood cells. It is a yellow liquid

  that contains proteins, nutrients, mineral ions, hormones, dissolved gases and waste
• What are pulmonary arteries?

  The arteries that carry deoxygenated blood away from the heart to the

  lungs