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Where Is Your Heart?. Circulation of blood Pulmonary circulation - Blood from heart to lungs and back again Systemic circulation – blood from heart to.

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Presentation on theme: "Where Is Your Heart?. Circulation of blood Pulmonary circulation - Blood from heart to lungs and back again Systemic circulation – blood from heart to."— Presentation transcript:

1 Where Is Your Heart?

2 Circulation of blood Pulmonary circulation - Blood from heart to lungs and back again Systemic circulation – blood from heart to the rest of the body and back again In mammals there is double circulation because of lungs. Blood passes the heart twice in a complete circuit: Double Circulation

3 Advantages of double circulation Blood entering lungs is at low pressure compared to blood leaving. This ensures that blood flows slowly in lungs allowing more time for blood to be well oxygenated. Heart pumps blood at high pressure to rest of body so that oxygenated blood can be distributed more quickly to tissue cells.

4 Structure of heart The whole heart is surrounded by a ‘bag’ called pericardium. Pericardium made up of 2 layers of membrane with inner layer in contact with heart. Between the 2 membranes is a fluid that reduces friction when heart is beating. pericardium

5 Heart Chambers 4 chambers: - 2 smaller upper chambers (atria) - 2 bigger lower chambers (ventricles) The right side of heart is completely separated from the left by a muscular wall called median septum. This is to avoid mixing of blood which when occur, will reduce the amount of oxygen carried to tissue cells. Median septum Why does the left ventricle has a much thicker wall than the right ventricle?

6 Did you know? The walls of the ventricles of the heart are more muscular than those of the atria because the ventricles have to force blood out of the heart, higher pressure is needed whereas the atria only force blood into the ventricles. (does not require high pressure) The right ventricle has thinner walls than the left ventricle as it pumps blood to lungs which is a short distance away. Left ventricle needs thick wall to withstand high pressure as it pumps blood to aorta and round the body.

7 Pathway of blood (Cord-like tendons that help attach valves to walls)

8 Label the structure of the heart What is the purpose of valves in the heart? Valves – Maintain 1 way flow of blood (prevent backflow) Anterior (Superior) vena cava Right atrium Posterior (Inferior) vena cava Tricuspid valve Right ventricle Left ventricle Bicuspid valve (mitral valve) Aortic valve (semi-lunar valve) Left atrium Pulmonary veins Pulmonary artery Aortic arch/Aorta Pulmonary valve (semi-lunar valve) Pulmonary arch

9 Did you know? The walls of the ventricles of the heart are more muscular than those of the atria because the ventricles have to force blood out of the heart, higher pressure is needed whereas the atria only force blood into the ventricles. (does not require high pressure) The right ventricle has thinner walls than the left ventricle as it pumps blood to lungs which is a short distance away. Left ventricle needs thick wall to withstand high pressure as it pumps blood to aorta and round the body.

10 Pathway of blood (explained) 1.Deoxygenated blood from various parts of the body return to the right atrium of heart via the anterior (superior) vena cava (head, neck and arms) and posterior (inferior) vena cava (other parts of body). 2.Right atrium contracts allowing blood to flow into right ventricle. Tricuspid valve opens when the pressure in right atrium is higher than that in right ventricle to allow blood to flow through. The tricuspid valve consists of 3 flaps that are attached to walls via chordae tendineae and point downwards to allow easy flow of blood.

11 Pathway of blood (explained) 3.Right ventricle contracts and high blood pressure closes tricuspid valve preventing backflow of blood into right atrium. Blood leaves the right ventricle via the pulmonary arch which divides into 2 pulmonary arteries, one to each lung. Semi-lunar valves in the pulmonary arch prevents the backflow of blood into right ventricle. 4.Blood in pulmonary arteries is at low pressure, thus rate of blood flow is slow which gives more time for gaseous exchange in lungs.

12 Pathway of blood (explained) 5.Oxygenated blood from lungs is brought back to left atrium via pulmonary veins. Left atrium contracts causing blood pressure in left atrium to be higher than that in left ventricles. Bicuspid valve (mitral valve) with two flaps opens to allow blood to enter left ventricle. When left ventricle contracts, blood leaves through the aortic arch. 6.From aortic arch, blood is distributed to all parts of body except lungs. The aortic arch possess a semi-lunar valve to prevent backflow of blood into left ventricle. Blood entering aortic arch is at a high pressure. 2 coronary arteries, which originate from the aortic arch bring food and oxygen to heart muscles.

13 The cardiac cycle Sequence of events that take place during the completion of one heartbeat. Involves repeated contraction (systole) and relaxation (diastole)

14 The Cardiac cycle 1.Both atria and ventricles are relaxed. Blood returns to both atria.

15 2.Atria contracts, forcing blood into relaxed ventricles. (Atrial systole) semilunar valves closed

16 What happens during During Ventricular systole… Tricuspid and Bicuspid valves closed to prevent flow of blood into atrium Semi-lunar valve opened for blood to flow into aorta and pulmonary arteries Blood flow from ventricle into aorta and pulmonary artery

17 3.After a short pause, ventricles contract (ventricular systole), atria relax. Increase in blood pressure in ventricles closes bicuspid and tricuspid valves. (prevent backflow of blood into atria) This produces a loud ‘ lub ’ sound. When pressure in ventricles are higher than in aorta and pulmonary artery, semi-lunar valves open to allow blood to flow into aortic arch and pulmonary arch.

18 What happens during During Ventricular diastole… Tricuspid and Bicuspid valves open if atrial contraction had taken place OR closed if atrial relaxation. Semi-lunar valves closed to prevent backflow of blood in aorta and pulmonary artery. Blood flow from superior vena cavae into right atrium and pulmonary vein into left atrium.

19 4.Ventricles relax (ventricular diastole) Drop in pressure in ventricles (increase pressure in pulmonary artery and aorta) closes semi lunar valves in both arches to produce a soft ‘ dub ’ sound (prevent backflow of blood) Blood returns to relaxed atria and whole cycle repeats.

20 Right Atrium Tricuspid valve Superior & inferior vena cava Pulmonary arteries Right Ventricle Aorta Bicuspid valve Pulmonary veins Left Ventricle Left Atrium Semilunar valve / Aortic valve Pulmonary Semilunar valve Lung tissue (pulmonary circulation) Body tissue (Systemic circulation) Route taken by blood flow through the heart

21 How do we identify the side of the heart that contains oxygenated blood? The side with a thicker muscular wall. Does that mean that the whole half of the heart will be thicker than the other? There is NO difference in thickness between the left and right atria. Questions...

22 Why do you think the separation of deoxygenated and oxygenated blood is important? What happens if the septum is broken or removed? Hole in the heart or septal defect http://www.webmd.com/video/helex-heart-patch Septum


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