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Definition
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Keyword
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The capacity of the heart to generate its own impulses
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Myogenic
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A small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat
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Sinoatrial Node
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This node relays the impulse between the upper and lower sections of the heart
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Atrioventricular Node
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When the heart contracts
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Systole
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A collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles
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Bundle of His
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Muscle fibres that conduct impulses in the walls of the ventricles
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Purkinje fibres
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Part of the autonomic nervous system that speeds up heart rate
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Sympathetic
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Part of the autonomic nervous system that decreases heart rate
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Parasympathetic
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The most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate
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Medulla oblongata
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Tiny structures in the carotid arteries and aortic arch that detect changes in blood acidity caused by an increase/decrease in the concentration of carbon dioxide
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Chemoreceptors
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Special sensors in tissues in the aortic arch, carotid sinus, heart and pulmonary vessels that respond to changes in blood pressure to either increase or drecrease heart rate
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Baroreceptors
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Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement
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Proprioceptors
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A stress hormone that is release by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate
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Adrenaline
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The volume of blood pumped out by the hearts ventricles in each contraction
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Stroke volume
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When the heart relaxes to fill with blood
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Diastole phase
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The percentage of blood pumped out by the left ventricle per beat
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Ejection fraction
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The volume of blood pumped out by the heart ventricles per minute
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Cardiac output
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The thickening of the muscular wall of the heart so it becomes bigger and stronger; also can mean a larger ventricular cavity
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Cardiac hypertrophy
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A decrease in resting heart rate to below 60 beats per minute
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Bradycardia
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Occurs when arteries harden and narrow as they become clogged up by fatty deposits
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Atherosclerosis
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A fatty deposit found in the inner lining of an artery
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Atheroma
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Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted
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Angina
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Occurs when the blood supply to the brain is cut off
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Stroke
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Where the athlete is able to meet the oxygen demand with the oxygen supply
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Steady state
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The force exerted by the blood against the blood vessel wall
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Blood pressure
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The pressure in the arteries when the ventricles are contracting
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Systolic pressure
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The pressure in the arteries when the ventricles are relaxing
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Diastolic pressure
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The return of blood to the right side of the heart via the vena cava
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Venous return
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The fluid part of blood that surrounds blood cells and transports them
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Plasma
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An iron-containing pigment found in red blood cells, which combines with oxygen to form oxyhaemoglobin
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Haemoglobin
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An iron-containing muscle pigment in slow-twitch muscles which has a higher affinity for oxygen than haemoglobin
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Myoglobin
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'Powerhouse' of the cell where energy production occurs
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Mitochondria
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When an increase in blood carbon dioxide and a decrease in pH results in a reduction of the affinity haemoglobin for oxygen
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Bohr shift
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A measure of acidity
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pH
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The redistribution of cardiac output
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Vascular shunt mechanism
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The widening of the blood vessels to increase the flow of blood into the capillaries
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Vasodilation
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The narrowing of the blood vessels to reduce blood flow into the capillaries
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Vasoconstriction
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The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles
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Arterio-venous difference
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