3The heartThe cardiovascular system is composed of three main parts: the heart, the blood vessels and the blood. Its function is to deliver oxygen and nutrients and excrete waste products from all the cells of the body.
4The heartThe heart is about the size of a closed fist, and shaped like a cone. It is located behind the sternum and ribs, slightly to the left of the centre of the chest.It is made up of four chambers, two upper atria and two lower ventricles.
5Structure The heart is divided into four chambers: The two chambers at the top are called atriaThe two lower chambers are called ventriclesBlood travels from the atria to the ventricles. They are separated by valves, (atrioventricular valves), to ensure that blood flows in one direction only.
6Cardiac muscleThe chambers are surrounded by a wall of muscle, called the myocardium. This muscle is specific to the heart and is termed cardiac muscle. Cardiac muscle:Is involuntary and contracts automaticallyHas interwoven muscle fibresContains many mitochondria.The walls of the ventricles are more muscular than the atria since more force is required to pump blood out of the heart to the lungs and body.
7StructureThe heart can also be divided into left and right halves. Each side has a different role / function:The left side is responsible for circulating blood (rich in oxygen) around the whole bodyThe right side is responsible for pumping blood (low in oxygen) to the lungs to collect more oxygen
8Blood vesselsThe blood and blood vessels are responsible for carrying blood and nutrients around the body. There are 3 types of blood vessels: arteries, veins and capillaries.The arteries carry blood away from the heart to the working muscles and other parts of the body where oxygen and nutrients are required. The arteries branch off and progressively become smaller vessels known as arterioles.
9Blood vesselsThese arterioles then join even smaller vessels known as capillaries where diffusion takes place. The capillaries are the essential link between arteries and veins; they are tiny vessels with semi permeable membranes allowing oxygen and nutrients to be delivered to the tissues and waste products such as carbon dioxide and water to be removed.
10Blood vesselsFollowing diffusion the blood moves from the capillaries into venules (small veins); these then join together to form larger veins as the blood is moved back towards the heart. Because the pressure of the blood in the veins is low they have valves to prevent back flow which helps the blood to travel in the right direction.
11Blood Vessels Arteries Veins Capillaries Vessel wall Thick & muscular ThinVery thin(one cell thick only)DiameterSmallLargeVery smallValvesNoYesPressureHighVery lowLowBloodOxygenated*De-oxygenated*BothBlood flowAway from heartTowards heartFrom artery to veinFunctionCarry nutrients and oxygen to working tissuesCarry waste products including carbon dioxide away from working tissuesAllow diffusion of nutrients, oxygen and carbon dioxide between blood and working tissues
12Blood VesselsThe pulmonary artery and vein are the exception. The pulmonary artery carries deoxygenated blood away from the heart to the lungs and the pulmonary vein carries the freshly oxygenated blood from the lungs back to the heart.Arterioles and venules are small extensions of the arteries and veins which distribute blood from the arteries to the capillaries and back to the veins.
13The Blood Functions: Transport oxygen from the tissues Return carbon dioxide from the tissues to the lungsCarry waste products from the tissues to the liver and kidneys to be broken down/excretedDistribute hormonesCarry essential nutrients
14The blood Characteristics: Thick and more viscous than water Temperature 30ocVolume, 4-6 litres (typical man/woman)
15The blood Component Description / function Plasma Straw coloured liquid, mainly waterCarries nutrientsRed blood cellsKnown as erythrocytesContain haemoglobin which carries oxygenProduced in bone marrowTypically 40-45% of total blood volumeWhite blood cellsKnown as leucocytesFight infectionsFewer in number than red blood cellsPlateletsThrombocytesControl bleeding after injuryHelp in process of blood clotting and repairing damaged tissues
16Short term effects of exercise on the cardiovascular system Exercise has the following short term effects on the cardiovascular system:There is an increase in heart rate at the onset of exercise. This is due to the release of the hormone adrenalin. Adrenalin prepares the body for action by stimulating the respiratory and circulatory systems. It is often associated with nerves, butterflies, rapid breathing, and sweating palms
17Short term effects of exercise on the cardiovascular system There is an increase in stroke volume (the amount of blood pumped out of the heart per beat). Because there is an increase in both heart rate and stroke volume cardiac output (the amount of blood pumped by the heart per minute) also increases. (Cardiac output (Q) = SV x HR)
18Short term effects of exercise on the cardiovascular system The working muscles’ demand for oxygen means that blood is redirected away from areas which need it less. For example, when cycling blood may be redirected from the gut to the legsThe body's temperature increases as does the temperature of the blood. To cope with this increase in temperature more blood is shunted to the skin surface to help it cool. Sweating cools you by evaporationBlood pressure increases at the onset of exercise
19Long term effects of exercise on the cardiovascular system Exercise has the following long term on the cardiovascular system:The heart muscle will also increase in size (cardiac hypertrophy), particularly that of the left ventricle leading to a more forceful contraction. More blood is pumped per beat (stroke volume) and therefore per minute (cardiac output)Resting HR decreases (bradycardia), but SV increases so the same amount of blood is pumped out per beat at rest
20Long term effects of exercise on the cardiovascular system There is an increase in the size and number of blood vessels feeding the muscles and lungsAfter endurance training (low intensity, long duration) the quantity and quality of the blood improves. More red blood cells are produced. This means that more oxygen can be transported to and used by the musclesBlood pressure is decreased in individuals with hypertension.All of these effects only occur if regular exercise is maintained. If the exercise is stopped for a period of time then the training effects will be lost.
21COMPARISON OF BLOOD VESSELS ArteryVeinExplain differencesStructure:Vessel wallThick & muscularThinThe artery wall allows constriction when the muscle contracts, which increases blood flowValvesNoneYesVeins have little muscle in the walls to change shape, so movement of blood is supported by pocket valves which prevent the backflow of blood
22COMPARISON OF BLOOD VESSELS Function:Blood flowAway from heart, oxygenated bloodTowards the heart, de-oxygenated bloodThe exceptions are the pulmonary artery, carrying deoxygenated blood from the heart to the lungs, and the pulmonary vein, carrying oxygenated blood from the lungs to the heartPressureHigh pressureLow pressurePressure is highest in the arteries due to the elastic nature of the vessel wall, the movement if blood is much slower in the veinsTransportOxygen to working musclesCarbon dioxide away from working musclesArteries transport oxygen to the capillaries where gaseous exchange can take place, and as a result carbon dioxide enters capillaries as oxygen enters the muscle, this is then passed on to the veins where it is transported back to the lungs for re-oxygenation
23Capillary walls are composed of a single cell Capillary walls are composed of a single cell. They are very thin and allow oxygen and carbon dioxide to squeeze through. A membrane which allows gases to pass through can be termed semi-permeable. The main function of capillaries is for gaseous exchange. This process is efficient owing to a dense capillary network surrounding the muscle.
24CirculationThe vascular system has two pathways of circulation, the pulmonary circulation (to the lungs) and the systemic circulation (to the body).
25The Double Circulatory System Humans have a double circulatory system where blood passes through the heart twice. The route around the body of blood leaving the left and right sides of the heart are different. These routes or systems, are referred to as pulmonary circulation and systemic circulation.
26Pulmonary Circulation Transport of blood between heart and lungsBlood, low in oxygen, is transported to the lungs where it becomes oxygen rich, then returns to the heart
27Systemic CirculationTransport of blood from the heart to the rest of the body and vice versaBlood rich in oxygen is distributed from the heart to the rest of the body and working tissues to deliver oxygen. Blood then returns to the heart, oxygen poor
28Vasodilation & Vasoconstriction Vasodilation (definition) = the increase in the internal diameter of blood vessels that is caused by relaxation of smooth muscle within the wall of the vessels, thus causing an increase in blood flow. The opposite effect is Vasoconstriction. The opposite effect is vasoconstriction, when blood vessels dilate, the blood flow is increased due to a decrease in vascular resistance.
29Venous Return Blood returning to the right side of the heart Blood returning to the right side of the heartThe heart can only pump as much blood out as it receives, so cardiac output is dependent upon venous returnThe process is aided by a muscle pump, as the muscle contracts, the veins are compressed slightly and squeeze blood back towards the heart
30Blood flow through the heart and lungs Deoxygenated blood is returned from the muscles and the rest of the body via the superior and inferior vena cava into the right atrium. It then passes into the right ventricle and from here it is pumped into the pulmonary artery where it travels to the lungs. It is in the lungs that pulmonary diffusion occurs; the blood is removed of its waste produces and enriched with oxygen.
31The blood is then returned to the heart via the pulmonary vein into the left atrium. It is then pumped into the left ventricle and from here into the aorta where the oxygenated blood is then delivered the working muscles.
32Within the heart there are a number of valves which ensure that the blood can only flow in one direction. Valves are found between atria and ventricles (atrio-ventricular valves) and between ventricles and the main vessels transporting blood away from the heart (semi-lunar valves). The blood flow pushes the valve open and it is then closed by connective tissue called chordae tendineae.
33The Cardiac CycleThe heart muscle needs to contract in order to eject blood from the heart and be transported around the body.How the heart works.Cardiac muscle contractions are initiated by an impulse from a pacemaker, called the sino-atrial node (SAN) within the right atrium wall.The contraction spreads throughout the walls of the atria and through branched fibres within the ventricle walls.The cardiac cycle refers to the sequence of events occurring as this impulse spreads through the heart.One complete contraction / cycle of the heart is one heartbeatThe cycle usually lasts for about 0.8 seconds, and occurs about 72 times per minute.
35Stages of the cardiac cycle Atrial diastoleAtria fill with bloodAtrioventricular valves closedVentricular diastolePressure builds in atriaValves pushed openVentricles begin to fill with bloodSemi-lunar valves closed
36Stages of the cardiac cycle Atrial systoleAtria walls contractRemaining blood forced into ventriclesSemi-lunar valves closedVentricular systoleVentricle walls contractAtrio-ventricular valves closedBlood forced into circulatory systemSemi-lunar valves pushed open Heart Sounds The closing of the valves within the heart and the circulatory system are responsible for the ‘lub-dup’ sounds of the heart.
37Heart Rate, Stroke Volume and Cardiac Output The number of times the heart beats per minute Stroke VolumeThe amount of blood ejected from the heart every time it beatsTypically about 70-80cm3 at rest
38Heart Rate, Stroke Volume and Cardiac Output The volume of blood ejected from the left ventricle in one minuteTypically about 5000cm3 at restCan be determined from knowing an individuals heart rate and stroke volume:Cardiac Output = Stroke Volume x Heart RateQ = SV x HR
39Heart rate can speed up or slow down in response to feedback Heart rate is controlled through the nervous system, originating in the brain.Heart rate can speed up or slow down in response to feedbackFor example, during exercise, the heart rate speeds up to ensure a greater supply of blood and oxygen to the working tissues. However, when blood pressure rises, there is a need to slow down the heart rate (and subsequent blood flow rate).
40Blood PressureThe force exerted by the blood against the walls of the blood vesselsFactors affecting blood pressure:Cardiac outputResistanceMeasurements of blood pressure are taken as systolic pressure (when the heart is contracting) over diastolic pressure (when the heart is relaxing).A typical reading for resting blood pressure is / 80 mmHg
41Vasomotor ControlVessels constrict and dilate in order to control blood flow around the bodyThe vasomotor and venomotor control centre in the brain sends signals via the nervous system in response to the body’s demands, for vessels to either increase or decrease the flow of blood.
42Pulse RateWhen the heart contracts, a wave of pressure is generated through the vessels and there is a slight dilation of the arteries.This can be felt at various sites in the bodyMost common sites:Carotid arteryRadial arteryBrachial artery
43Factors affecting blood pressure Blood pressure is taken to give an indication of general health. There are a number of factors which affect blood pressure:exercise - blood pressure increases when you exercise. This is because the heart is working harder to supply your muscles with more oxygen. Regular exercise helps to lower resting blood pressure and prevent cardio-vascualr disease.diet - high levels of fat and salt cause the arteries to stiffen or clog up. This clogging leads to an incresae in blood pressure.age - blood pressure increases as you grow older. This is because the arteries lose their elasticity and do not expand so much when blood is pumped through them.stress and tension - increases blood pressure. This is because hormones are released into the bloodstream when the body becomes stressed or anxious.smoking - cigarette smoking increases blood pressure because nicotine reduces the efficiency of the capillaries.
45Structure and route of air to lungs NoseAir enters here and is filtered by tiny hairs and warmedPharynxBoth food and air pass through the pharynxFood is then directed into the oesophagusLarynxCommonly known as voice boxOpening covered by epiglottis (a flap of cartilage) which prevents food entering hereTracheaWindpipe, about 10cm long, supported by rings of cartilageContains cells which remove foreign particles from the airBronchiRight and left branches, which further divide into bronchiolesBronchiolesFurther divide into smaller pathways, leading to alvoliAlveoliSmall air filled sacsLarge surface areThin wallsSurrounded by capillariesLungsThe bronchi extend into the lungs2 cone shaped organs separated by the heartSurrounded by a protective membrane
46Mechanics of breathing An average adult will inhale and exhale approximately 12 to 15 breaths per minute. For air to be drawn into the lungs, the pressure of the air within the lungs must be lower than that in the atmosphere. The greater the difference in pressure, the faster air can be drawn into the lungs. The pressure difference is created by altering the size of the thoracic cavity.
47 InspirationWhen an individual breathes in it is referred to as inspiration. During inspiration the intercostal muscles contract pulling the ribs upwards and outwards at the same time as the diaphragm contracts and flattens. These combined actions increase the area inside the lungs meaning that air is then drawn into the lungs until the pressure inside the lungs is equal to the atmospheric pressure.
48ExpirationWhen an individual breathes out it is known as expiration. During expiration the intercostal muscles relax lowering the rib cage to its resting position. The diaphragm also relaxes (moving upwards). This causes the area inside the lungs to decrease, increasing the pressure inside. This greater pressure forces the air out of the body until the pressure is equal to that of the atmosphere.
50Gaseous ExchangeOxygen passes into the body and carbon dioxide leaves the body through the process of gaseous exchange.Movement of oxygen and carbon dioxide occurs from a high concentration to a low concentration, known as diffusion.The amount of each gas which moves is controlled through a semi-permeable membrane
51Gas exchange at the lungs There is a high concentration of oxygen in the lungs as we breathe in, and a low concentration in the capillaries surrounding the alveoli.There is a high concentration of carbon dioxide in the blood and capillaries then in the alveoli air from breathing inTwo way processAs oxygen diffuses into the capillaries to be delivered to the tissues, carbon dioxide diffuses into the alveoli to be expiredThe capillary wall is thin to allow efficient gaseous exchangeThe alveoli have a large surface are to allow optimal exchange of gases
52Transport of Oxygen and Carbon Dioxide Oxygen combines with haemoglobin in the red blood cells to form oxy-haemoglobinIn the lungs, where there is little carbon dioxide haemoglobin is said to be 100% saturated with oxygenWhen large amounts of carbon dioxide are present, the saturation of haemoglobin with oxygen is reduced, enabling oxygen to disassociate (unload) and feed the working tissuesAt the site of the tissues, most oxygen has been unloadedMost carbon dioxide is transported in the form of bicarbonate ion, and some combines with haemoglobin to form carbaminohaemoglobin
53Gas exchange at the muscles and tissues Oxygen is rich in the capillary blood, and low in the muscle cell. Oxygen can disassociate from haemoglobin and pass across the capillary wall into the muscle cytoplasmOxygen forms with myoglobinCarbon dioxide produced in the muscle passes into the capillary and can be transported to the lungs in the veins
54Approximate normal values Respiratory volumesThere are a number of measures or capacities that can be taken of the amount of air moving into and out of the lungs:Lung volume / capacityDefinitionApproximate normal valuesTidal volume (TV)The amount of air inspired / expired per breath500mlInspiratory reserve volume (IRV)The amount of air forcibly inspired above tidal volume3300mlExpiratory reserve volume (ERV)The amount of air forcibly expired above tidal volume1000 – 1200mlResidual volume (RV)The lungs never completely empty, and the air that is left after a maximum exhalation is the residual volume.1200mlVital capacity (VC)Vital capacity is the maximum amount of air that you can breathe out after breathing in as deeply as you can.IRV + TV + ERV5500mlTotal lung capacityVC + RVUp to 8000mlMinute ventilationThe volume of air inspired / expired per minute.Minute volume = TV x RR7500mlRespiratory rate (RR)How many breaths you take per minuteAverage is 12-15
55Short term effectsWhen you take part in sport or exercise the body places a number of demands on the oxygen transport systems, these demands are also referred to as the short term effects of exercise:even before you start to exercise your body releases the hormone adrenalin. It prepares you for action by stimulating the respiratory and circulatory systems. It is often associated with nerves, butterflies in your tummy, rapid breathing, a quickened heart rate, sweating palms and sometimes it even makes people feel sick.during exercise the working muscles need more oxygen. This process is referred to as internal or cell respiration and as a result the levels of carbon dioxide (CO2) in the blood start to rise.
56Short term effectsincreased levels of CO2 in the blood are detected by the brain. The brain then sends a message to the lungs to breathe faster and deeper in order to expel the CO2 and so the respiratory rate increases. Levels of CO2 dictate the rate of breathing of the body during exercise.the process of gas exchange in the lungs speeds up as a result of the increase in the rate of breathing. More CO2 is absorbed out of the blood and more oxygen is drawn in.in order to cope with the working muscles demand for more oxygen, the brain sends a message to the heart to speed up.
57Short term effectsas a response to this message, the heart rate increases. More blood is pumped with each beat of the heart to provide more oxygen to the working muscles and so the stroke volume increases. If stroke volume and heart rate both increase then so too does cardiac Output.increased cardiac output means that more blood and therefore oxygen is being pumped each minute to the working muscles, and more carbon dioxide is being carried away.the arteries and arterioles dilate in order to accommodate the increased flow of blood. Dilation of the blood vessels also keeps blood pressure low.
58Short term effectsmuscles can receive up to three times the resting amount of oxygen. Blood flow can be increased up to 30 times the resting rate. The working muscles therefore can receive up to 90 times the resting amount of oxygen.the working muscles demand for oxygen means that blood is redirected away from areas which need it less. For example, when cycling blood may be redirected from the gut to the legs.the body's temperature increases as does the temperature of the blood. To cope with this increase in temperature more blood is shunted to the skin surface where it cools. Sweating cools you be evaporation.
59Short term effects Effects / Changes Heart rate Increases Stroke volumeIncreaseCardiac outputBody temperatureBlood flowRe-distribution to working tissuesBlood pressureAerobic exercise – increase in systolic pressureAnaerobic exercise – increase in both systolic and diastolic pressureBreathing rateTidal volumeInspiratory reserve volumeDecreaseExpiratory reserve volumeSlight decreaseResidual volumeSlight increaseVital capacity
60Short term effects Effects / Changes Total lung capacity Slight decreaseRespiratory musclesIncreased rate of contractionOxygen disassociationIncreaseCarbon dioxide production
61Long TermExercise has the following long term effects on the respiratory system:The intercostal muscles become stronger helping to make the respiratory system more efficientThe lungs get bigger, increasing their capacity to draw in oxygenThere is an increase in the rate at which carbon dioxide is drawn out of the lungs and oxygen is drawn inVital capacity increasesThe combined respiratory and circulatory systems become more efficientThere is an increase in capillary density surrounding the alveoli thus improving gaseous exchangeAll of these effects only occur if regular exercise is maintained. If the exercise is stopped for a period of time then the training effects will be lost.
62LONG TERM EFFECTS OF EXERCISE BODY SYSTEMLONG TERM EFFECTS OF EXERCISEMUSCULARmuscles develop a bigger blood vessel network. This feeds more blood (oxygen and energy) to the musclemuscles adapt to using more oxygen. They can therefore work more efficiently and for a longer timeincreased muscle tone and maybe a reduction in body fatRESPIRATORYthe muscles used for breathing become strongerthe lungs get bigger, increasing their capacity to draw in oxygenan increase in the rate at which carbon-dioxide is drawn out of the lungs and oxygen is drawn inCIRCULATORYthe heart becomes larger and stronger. More blood is pumped per beat (stroke volume) and therefore per minute (cardiac output)each heartbeat pumps more blood, so your resting heart rate falls, while the same amount of blood is pumpedthere is an increase in the size and number of blood vessels feeding the musclesafter endurance training (low intensity, long duration) the quantity and quality of the blood improves. More red blood cells are produced. This means that more oxygen can be transported to and used by the musclesCARDIO-VASCULARthe combined respiratory and circulatory systems become more efficient. They take more oxygen and carbon dioxide to and fro, and they do it more quickly.
63Cardio-Respiratory Function AdaptationsHeartCardiac hypertrophyIncreased size of ventricles & wallsHeart rateDecreased maximum heart rateBradycardia (decreased resting heart rate)Stroke volumeIncreasedBlood pressureDecreasedBloodIncreased haemoglobin levelsBlood vesselsIncreased capillary density surrounding muscles and lungsStronger muscle in vessel wallsGaseous exchangeIncreased alveoliIncreased strength of respiratory musclesLung VolumesIncreased tidal volume