Structure and function of the heart

• Acetylcholine


  Neurotransmitter released by parasympathetic nerve fibres
• Antagonistic


  Having opposite effects
• Arteriole


  Branch of an artery leading to capillaries
• Artery


  Blood vessel that carries blood away from the heart
• Atrial diastole


  Part of cardiac cycle where muscle of atria contracts
• Atrio-ventricular node (AVN)


  Nervous tissue found at the junction between the atria and ventricles
• Atrio-ventricular (AV) valve


  Valve found between the atria and the ventricles
• Autonomic nervous system


  Controls involuntary action of smooth and cardiac muscle and glands
• Capillary


  Narrow, thin-walled blood vessel that exchanges materials with the tissues
• Cardiac cycle


  Contraction and relaxation of heart muscle in one heartbeat
• Cardiac muscle


  Muscle that makes up the heart walls
• Cardiac output


  Volume of blood expelled from one ventricle per minute
• Coronary heart disease


  Condition caused by blockage of coronary arteries
• Deoxygenated blood


  Blood that carries little oxygen
• Diastole


  Part of cardiac cycle during which heart muscle is relaxed
• Electrocardiogram (ECG)


  Record of electrical activity of heart
• Endothelium


  Layer of cells that lines the inner surface of blood vessels
• Hypertension


  Abnormally high blood pressure in arteries
• Lumen


  Central channel of a blood vessel
• Lymph fluid


  Fluid made up from tissue fluid collected into lymph vessels, which circulates around the body
• Lymph vessels


  Tiny vessels in which lymph circulates around the body
• Medulla


  Part of brain controlling heart rate, breathing and peristalsis
• Noradrenaline


  Hormone and neurotransmitter
• Osmosis


  Movement of water from a higher water concentration to a lower water concentration through a selectively permeable membrane
• Oxygenated blood


  Blood containing a high level of oxygen
• Plasma


  Liquid component of blood
• Pressure filtration


  Passage of molecules through membranes under pressure
• Semi-lunar valves


  Valves between ventricles and arteries leaving the heart
• Sino-atrial node (SAN)


  Region of nervous tissue in the wall of the right atrium; receives impulses from the medulla
• Sphygmomanometer


  Instrument used to measure blood pressure
• Stroke


  Occurs when blood supply to part of the brain is cut off
• Stroke volume


  Volume of blood expelled from left ventricle during one cardiac cycle
• Systole


  Part of cardiac cycle during which cardiac muscle is contracted
• Tissue fluid


  Fluid which bathes cells in tissues; derived from blood
• Vasoconstriction


  Narrowing of blood vessels to decrease blood flow
• Vasodilation


  Widening of blood vessels to increase blood flow
• Vein


  Blood vessel which carries blood back to the heart
• Venule


  Small branch of a vein
• Structure and Function of Cardiovascular System

  1. The heart is muscular organ which pumps blood around the body

  2. It has four chambers: two atria which receive blood from the main veins, two ventricles which pump blood into the main arteries
• Flow diagram illustrating blood flow round the heart and body

  • Right atrium -> Pulmonary artery -> Lungs -> Pulmonary vein -> Left atrium -> Left ventricle -> Aorta -> Body -> Vena cava -> Right atrium