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The Circulatory System Recap of the Circulatory System The following slides have information you learnt last week but there are several words missing. In your book write the words you think should be there. 2 of 36 © Boardworks Ltd 2006 Functions of the circulatory system The circulatory system has three functions: A 1. Transporting substances around the body. These include oxygen, glucose, carbon dioxide, nutrients, water and waste products. B 2. Controlling body temperature. 3. Protecting the body. Blood contains C cells and anti-bodies that fight infection and clotting agents to stop bleeding. D The circulatory system is described as a double system because it has two loops. 3 of 36 © Boardworks Ltd 2006 Blood vessels E There are three types of blood vessels, as shown in this magnified part of the circulatory system. blood to the heart blood from the heart H vein F artery carries blood away from the heart G carries blood back into the heart carries blood to and from the body’s cells Why are there different types of blood vessels? 4 of 36 © Boardworks Ltd 2006 Blood vessels thick outer wall thick inner layer of muscle and elastic fibres narrow central tube (lumen) I ARTERY thin outer wall thin inner layer of muscle and elastic fibres J VEIN wide central tube (lumen) K CAPILLARY wall only one cell thick 5 of 36 © Boardworks Ltd 2006 Answers • • • • • • • • A = Transporting B = Temperature C = Infection D = Double E = Blood Vessels F = Artery G = Capillary H = Vein 6 of 36 • I = Artery • J = Vein • K = Capillary © Boardworks Ltd 2006 The circulatory system 7 of 36 © Boardworks Ltd 2006 The heart during exercise Heart rate (or pulse rate) is the number of times your heart beats every minute. You can measure how fast your heart is beating by taking your pulse. It is expressed in beats per minute (bpm). Resting heart rate varies from individual to individual and is affected by fitness. The fitter you are, the lower your resting heart rate will be. The average resting heart rate is about 70–75 bpm. 8 of 36 This can be done at the groin, temple and more usually at wrist or the neck. At these points the arteries are easy to locate and the pulse is strong Count how many times your heart beats in 1 minute. © Boardworks Ltd 2006 The heart during exercise As we learnt last year - Each individual has a maximum heart rate – the fastest that their heart is able to beat. Testing it properly is difficult and unpleasant, as it involves pushing your body to its absolute limit. However, maximum heart rate can be estimated using a simple formula: you remember this formula? MaximumCan Heart Rate (MHR) = 220 – age So, a 25 year-old would have a maximum heart rate of 220 – 25 = 195 bpm What would your maximum heart rate be? 9 of 36 © Boardworks Ltd 2006 Heart rate, stroke volume and cardiac output The pulse rate is not the only way of measuring the heart. Stroke volume is the amount of blood pumped out of the left ventricle per beat. Cardiac output is the amount of blood pumped out of the left ventricle of the heart per minute. Cardiac output can be calculated by multiplying the stroke volume by the heart rate: cardiac output = stroke volume × heart rate What is the cardiac output of someone with a heart rate of 60 bpm and stroke volume of 90 ml? 10 of 36 © Boardworks Ltd 2006 The heart during exercise During exercise, the body uses up oxygen and nutrients at a much faster rate. To keep the body supplied with what it needs, the heart beats faster and with greater force. This means that the heart rate and stroke volume increase. What do you think happens to the cardiac output? Regular exercise causes changes to the heart. The heart gets larger The muscular wall become thicker and stronger Stroke volume at rest increases, leading to a lower resting heart rate. 11 of 36 © Boardworks Ltd 2006 Blood pressure Blood Pressure is ‘the amount of pressure the blood applies on the blood vessels walls’ Blood pressure indicates how fit the circulatory system is. The instrument used to measure Blood Pressure is a Sphygmomanometer Two readings are given: The SYSTOLIC pressure, and The DIASTOLIC pressure 12 of 36 © Boardworks Ltd 2006 Blood Pressure • An average reading for a healthy adult is 120 Systolic 80 Diastolic • When exercise begins, blood pressure increases. This increases the blood flow, meeting the demand for oxygen by the working muscles. 13 of 36 © Boardworks Ltd 2006 Blood pressure An individual’s blood pressure is affected by a number of factors. Age – it increases as you get older. Gender – men tend to have higher blood pressure than women. Stress can cause increased blood pressure. Diet – salt and saturated fats can increase blood pressure. Exercise – the fitter you are the lower your blood pressure is likely to be. Having high blood pressure puts stress on your heart. It can lead to angina, heart attacks and strokes. 14 of 36 © Boardworks Ltd 2006 Effects of exercise on blood pressure The immediate effect of exercise is to raise the blood pressure as the heart beats faster and more powerfully. During intense exercise, blood flow to the muscles can increase to 35 times its normal volume. Higher blood pressure is necessary in order to get this extra blood to the muscles. However, in the long-term, regular exercise reduces blood pressure. The fitter you are, the lower your blood pressure is likely to be. 15 of 36 © Boardworks Ltd 2006 Blood flow and body temperature The circulatory system plays an important role in regulating body temperature. Capillaries Sweat gland If the body gets too hot, capillaries near the surface of the skin widen. Blood is diverted to the skin where the heat can easily radiate away. This is called vasodilation. Water from the blood is excreted as sweat to cool the body. 16 of 36 © Boardworks Ltd 2006 Blood flow and body temperature Capillaries Sweat gland If the body gets too cold, capillaries near the surface of the skin get narrower. Blood is diverted away from the skin to limit heat loss. This is called vasoconstriction. Sweating stops. 17 of 36 © Boardworks Ltd 2006 Worksheet You have two choices of worksheet – Worksheet 1 should be chosen if you are aiming to achieve a B grade or above at GCSE Worksheet 2 should be chosen if you are aiming to achieve up to a C grade in GCSE PE (it is slightly as you have to fill in missing words) easier DO NOT WRITE ON THE WORKSHEETS 18 of 36 © Boardworks Ltd 2006 Exam-style questions 1. During exercise, extra demands are placed on the circulatory system. a) Describe what happens to heart rate, stroke volume and cardiac output during intensive physical activity. b) Describe how the circulatory system helps to regulate body temperature during exercise. c) What affect does exercise have on Blood Pressure in the Short Term. d) What affect does exercise have on Blood Pressure in the Long Term. 19 of 36 © Boardworks Ltd 2006