1. The Circulatory System Lesson Objectives To have basic knowledge of the structure of the heart and the production of the heart beat Be familiar with locating and recording the pulse Be familiar with the terms blood pressure and know what pressure points are To know the function and role of the blood

2. Components of the Circulatory System There are three components of the Circulatory system. They are:

3. The Heart Left Ventricle Pulmonary Artery Left Atrium Pulmonary Vein Vena Cava Right Atrium Right Ventricle Aorta Oxygenated blood carried through Deoxygenated blood carried through Can you identify the chambers and blood vessels of the heart correctly?

4. Path of blood through the heart Blood enters the heart via the Vena Cava and the Pulmonary Vein and fills the Right Atrium and Left Atrium. Both Atria contract, squeezing the blood and pushing it down in the the Ventricles below The blood flows through in to the Right Ventricle and Left Ventricle. As the blood fills both Ventricles the muscular walls contract. Blood is forced up in to the Pulmonary Artery and the Aorta. The blood in the Pulmonary Artery is delivered to the Lungs to be oxygenated. Blood in the Aorta is then delivered to the rest of the body. The contractions of the atria and the ventricles are responsible for the heart beating

5. Blood Vessels Oxygenated blood is carried in the Arteries and arterioles Deoxygenated blood is carried in the venules and veins

6. Composition of Blood BLOOD Red Blood Cells are used to deliver oxygen to the muscles Plasma mainly contains water. The liquid helps to transport protein, glucose and waste products White Blood Cells form part of the body’s immune system. They help to fight infection. Platelets help to clot the blood. When the skin is wounded they stick together to cover the wound.

7. Functions of Blood Delivers oxygen to the muscles Forms part of the body’s immune system Takes CO 2 to the lungs to be exhaled Used for Homeostasis Delivers valuable nutrients and glucose to the muscles Helps to remove waste products

8. Blood Pressure BLOOD PRESSURE As blood travels around the body in the blood vessels it is constantly placed under pressure. The massive force exerted by the left ventricle contracting creates the largest amount of pressure in the Aorta. As the blood travels from the arteries to the veins the pressure of the blood decreases. PRESSURE POINTS These are areas in the body where pressure can be measured. Blood pressure is usually measured at the Brachial Artery (under bicep tendon) in the upper arm. An inflatable cuff is wrapped around the arm and is pumped up until the blood stops flowing. A pressure reading is taken at that point. The cuff in then deflated and when the blood starts to flow again another reading of pressure is taken.READINGS The two readings taken for blood pressure represent the systolic and diastolic pressure. Systolic is the pressure created by the heart contracting and the diastolic is when the heart is in its relaxation phase. The pressures are given as two numbers. Average adult 120 80 (Systolic) (Diastolic) Ok Mrs Smith your blood pressure is 110 70

9. Heart Rate How is the heart rate measured? The heart rate can be measured at many points in the body. Usually the HR can be taken at the Radial artery (wrist) or at the Carotid Artery (neck). Each beat can be felt as a pulse.

10. Stroke Volume and Cardiac Output Cardiac Output Stroke Volume x Heart Rate As we exercise, take running for example, the cardiac output increases. This is because the stroke volume and the heart rate increase. Why do you think they need to increase?

11. Homeostasis (body temperature regulation) Blood helps to regulate body temperature by the blood vessels moving closer to the skin or further away depending on whether the body is hot or cold. In hot weather or whilst exercising the blood vessels experience a process called Vasodilation. Blood vessels move closer to the skin surface to allow the heat to radiate from the skin. Sweating is also included within this process. Vasoconstriction is the opposite effect where the blood vessels move away from the skin when the body is cold.