AQA A-Level Biology - Mass Transport

• Left Atrium


  The chamber of the heart that holds oxygenated blood from the pulmonary vein

  
• Left Ventricle


  The chamber of the heart that holds oxygenated blood that is forced in from the atrium

  
• Right Atrium


  The chamber of the heart that holds deoxygenated blood from both vena cava

  
• Right Ventricle


  The chamber of the heart that holds deoxygenated blood that is forced in from the atrium

  
• Atrioventricular Valves


  The valves that separate the atria from the ventricles

  
• Bicuspid Valve


  The valve that separates the two chambers responsible for oxygenated blood

  
• Tricuspid Valve


  The valve that separates the two chambers responsible for deoxygenated blood

  
• Semi-Lunar Valves


  The valves that separate the ventricles from the arteries

  
• Aorta


  The artery that transports blood from the ventricle to the entire body

  
• Pulmonary Vein


  The vein that carries oxygenated blood to the heart

  
• Pulmonary Artery


  The artery that carries deoxygenated blood to the lungs

  
• Vena Cava


  The vein that carries deoxygenated blood to the heart

  
• Diastole


  Complete relaxation of the heart. This lowers the pressure in the heart which allows for blood to flow into the atria and partially trickle into the ventricles (due to relaxed atrioventricular valves)
• Sinoatrial Node


  The electrical impulse that is sent across the atria of the heart, stimulating atrial systole
• Atrial Systole


  The process where the atria contract, this decreases the volume of the atria and increases the blood pressure in the atria, forcing the atrioventricular valves open. This allows blood to flow into the ventricles, where the pressure is lower
• Atrioventricular Node


  The electrical impulse that is sent down the centre of the heart, across the bundle of his and to the purkinje fibres of the heart, stimulating ventricular systole
• Ventricular Systole


  The process where the ventricles contract, this decreases the volume of the ventricles and increases the blood pressure in the ventricles, forcing the semi-lunar valves open. This allows blood to flow into the main arteries, where the pressure is lower
• Closing of Valves


  The process that occurs when there is higher pressure in the ventricles or the arteries to prevent any back flow of blood
• Pressure Gradient


  To allow for heart contraction, there needs to be one condition maintained within the heart at all times
• Myogenic


  Muscle contraction that is normal for the body and unaffected by chemicals in the brain
• Blood Pressure


  A measurement showing the ratio of systolic pressure to that of diastolic pressure

  
• Systolic Pressure


  When measuring blood pressure, the numerator represents this type of pressure

  
• Diastolic Pressure


  When measuring blood pressure, the denominator represents this type of pressure. The higher this value is, the higher the overall blood pressure

  
• Cardiac Output


  Heart rate x Stroke volumeCan be measured using graphs like the one shown

  
• ECG


  Electro-cardiogram. This measures the electrical activity of the heart to ensure that everything is working appropriately

  
• P


  The point of the graph which represents atrial systole

  
• QRS Complex


  The point on the graph which represents ventricular systole

  
• T


  The point on the graph which represents ventricular re-polarisation - the recovery of ventricular walls where neurons revert to their original charges

  
• QT Interval


  The point on the graph which represents the contraction time of the ventricles

  
• TP Interval


  The point on the graph which represents diastole - the "filling time" of the heart

  
• Blood Cholesterol

  Low density lipoproteins increase this in the arteries. These lipoproteins transport plaque from the liver to the tissues. High density lipoproteins reduce this as they do the opposite of low density lipoproteins
• Diet


  A factor increasing the risk of heart disease, if you have high saturated fats. The fats cannot be broken down so remain for a while which increases the likelihood of myocardial infarction
• Smoking


  A factor increasing the risk of heart disease. Carbon monoxide binds to red blood cells, which is irreversible for around 24 hours, which decreases the amount of oxygen getting to the heart, which can cause heart cells to die. Nicotine also increases heart rate and blood pressure
• High Blood Pressure


  A factor increasing the risk of heart disease. An increased heart rate increases the amount of adrenaline in the blood, making platelets more sticky and more likely to stick to artery wall, causing a blockage and hence myocardial infarction
• Thrombosis


  A blood clot
• Myocardial Infarction


  A heart attack, can be due to platelets sticking to ruptured artery plaque
• Coronary Heart Disease


  A disease where the coronary artery is more likely to be blocked, causing myocardial infarction
• Double Circulatory System


  A system where blood is confined to blood vessels and pass through the heart twice, to maintain blood pressure in large animals
• Single Circulatory System


  A system where blood is not confined to blood vessels and only passes through the heart once, smaller animals have this system
• Mass Transport System


  This system exists when organisms have:- A large surface area to volume ratio (simple diffusion cannot accommodate for the organisms)- A large activity of the organism (require more substances at one time than smaller organisms)