AQA Pe Definitions paper 1

• Anticipatory rise - an increase in heart rate prior to exercise, due to the release of adrenaline
• A-VO2 difference: Arterio-venous oxygen difference, the difference in the oxygen content of the blood between the arterial blood and the venous blood
• Blood pressure - measure of the force that your blood exerts against blood vessel walls
• Systolic blood pressure - blood pressure while the heart is contracting
• Diastolic blood pressure - blood pressure while the heart is relaxing
• Bohr shift:

  • when the oxyhaemoglobin dissociation curve shifts to the right during exercise
  • occurs as a result of the increased carbon dioxide in the blood, increased blood acidity, decreased blood Ph and increased temperature
  • As a result haemoglobin has a lower affinity for oxygen at the working muscles, giving up oxygen more easily
• Bradycardia - a reduction in resting heart rate below 60 beats per minute
• Cardiac conduction system - a group of specialised cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract
• Sino-atrial node - the heart's pacemaker, which sends an impulse through the atria causing them to contract
• Atrio-ventricular node - delays the impulse to allow ventricular filling
• Bundle of his - conducts the impulse down the septum
• Purkinjie fibres - spreads the impulse through the ventricles causing them to contract
• Cardiac hypertrophy - increase in the thickness of the muscular heart wall, especially around the left ventricle. May also make the size of the ventricular cavity bigger
• Cardiac output - the amount of blood which leaves the left ventricle per minute. HR x SV
• Heart rate - the number of times the heart contracts per minute
• Stroke volume - the amount of blood which leaves the left ventricle per contraction
• Cardiovascular drift - Reduction in stroke volume when exercising in warm conditions for longer than 10 mins

  • results in an increase in Heart Rate to maintain cardiac output
  • Occurs due to sweating which reduces blood volume, leading to decreased venous return and then due to starling's law decreased stroke volume
• Cholesterol - a type of fat which is transported in the blood
• High-density lipoproteins - "good" cholesterol which transports excess cholesterol to the liver to be broken down. This lowers the risk of heart disease
• Low-density lipoproteins - 'bad' cholesterol as too much can lead to fatty deposits in the arteries. This has a negative effect on health increasing blood pressure, and the risk of heart disease
• Haemoglobin - found in red blood cells, combines with oxygen to form oxyhaemoglobin, which is transported round the body
• Heart disease - also known as coronary heart disease. Occurs when coronary blood vessels become blocked by fatty deposits, called atheroma, limiting the supply of oxygenated blood to the heart.

  • This process is known as atherosclerosis
  • This lack of oxygen results in discomfort known as angina
  • If a complete blockage occurs this can result in heart attack
• Myoglobin - found in muscle cells, myoglobin stores and transports oxygen. Has a high affinity for oxygen than haemoglobin, so it aids transport into muscle cells
• Receptors - part of the nervous system that detects changes in the body
• Baroreceptors - located in blood vessels, detect changes in blood pressure
• Chemoreceptors - monitors and detects increases in blood acidity during exercise due to increased carbon dioxide in the blood
• Proprioceptors - detects increases in muscle movement during exercise
• vascular-shunt mechanism - directs blood flow around the body
• Vasodilation - precapillary sphincters will relax, widening the internal diameter of blood vessels. During exercise this will happen in the vessels leading to working muscles allowing more oxygen and nutrient rich blood to reach them
• Vasoconstriction - Precapillary sphincters will contract, decreasing the internal diameter of blood vessels. During exercise this will happen in the vessels leading to non-working muscles and non-essential organs. This allows more blood to be available for the working muscles
• Starling's law - increased venous return will result in a higher stroke volume. This is due to the cardiac muscle being stretched, resulting in a stronger force of contraction and greater ejection fraction
• Stroke - a serious life-threatening medical condition that happens when the blood supply to part of the brain is cut-off
• Ischaemic stroke - occur when a blood clot stops the supply of blood reaching the brain. Most common type of stroke
• Haemorrhagic strokes - result of a weakened blood vessel to the brain bursting
• The autonomic nervous system subconsciously controls heart rate, breathing rate and redistribution of blood:

  • the sympathetic and parasympathetic nervous system are controlled in the medulla oblongata
• Sympathetic nervous system - the body's 'fight or flight' system
• Parasympathetic nervous system - 'rest and digest'
• Valves - found in the veins that prevent the backflow of blood
• Skeletal muscle pump - working muscles contract and compress veins to push blood back towards the heart
• Respiratory pump - Increased respiration/changes in pressure in the thorax compress veins to push blood back towards the heart