Topic 9 7 The Circulatory System 1 of

Topic 9. 7 The Circulatory System 1 of 49 © Boardworks Ltd 2004

Contents The Heart and Circulatory System The circulatory system Structure of the heart Valves in the heart How the heart pumps blood 2 of 49 © Boardworks Ltd 2004

How do substances move around the body? The body has its own transport system that carries substances around the body. Which organs are involved in this system? heart blood vessels blood The body’s transport system is called the circulatory system. Why is it given this name? 3 of 49 © Boardworks Ltd 2004

What is carried by the circulatory system? Which gases are transported to and from the body’s cells by the blood flowing in the circulatory system? oxygen carbon dioxide Oxygen is the gas needed for respiration and is transported to the body’s cells. Carbon dioxide is the waste gas produced by respiration that must be carried away from the body’s cells. 4 of 49 © Boardworks Ltd 2004

Two types of blood The circulatory system carries two types of blood: oxygen-rich blood oxygen-poor blood l blood travelling c to the body cells l blood travelling away from the body cells l high oxygen content l low carbon dioxide content l high carbon dioxide content The arrangement of the circulatory system means that these two types of blood do not mix. Why is this important? 5 of 49 © Boardworks Ltd 2004

At the heart of the circulatory system The heart is the organ at the centre of the circulatory system. It pumps blood around the body. How are the two types of blood (oxygen-rich and oxygen-poor) kept apart inside the heart? 6 of 49 © Boardworks Ltd 2004

Inside the heart The inside of the heart is divided into two sections so that the two types of blood (oxygen-rich and oxygen-poor) are kept apart. right side of the heart left side of the heart oxygen-poor blood oxygen-rich blood Remember that the heart is always labelled as if it is in a body facing you, so the right side of the heart is on the left of the diagram. 7 of 49 © Boardworks Ltd 2004

The two sides of the heart 8 of 49 © Boardworks Ltd 2004

How does blood circulate around the body? Blood is pumped around the body by the heart. It takes about 30 seconds for blood to go once around the body. Starting with the left side of the heart, what route does the blood follow to complete one circuit of the body? 9 of 49 © Boardworks Ltd 2004

How does blood circulate around the body? The left side of the heart pumps oxygen-rich blood to the rest of the body. This blood supplies the body’s cells with oxygen. What gas does the blood pick up from the body’s cells and where does the blood go next? 10 of 49 body’s cells © Boardworks Ltd 2004

How does blood circulate around the body? Blood picks up carbon dioxide from the body’s cells. This oxygen-poor blood then travels back to the right side of the heart. The oxygen-poor blood needs to lose the carbon dioxide and pick up more oxygen. How does it do this? 11 of 49 body’s cells © Boardworks Ltd 2004

How does blood circulate around the body? Next, the right side of the heart pumps oxygen-poor blood to the lungs In the lungs the blood gets rid of the waste carbon dioxide and collects more oxygen. Where does this oxygen-rich blood then travel to? 12 of 49 body’s cells © Boardworks Ltd 2004

How does blood circulate around the body? The oxygen-rich blood then returns to the left side of the heart. lungs This completes the blood’s journey around the body. Why is the journey of blood through the circulatory system called a double circulation? 13 of 49 body’s cells © Boardworks Ltd 2004

A double circulatory system During one complete circuit of the body, blood passes through the heart twice. lungs The heart has two jobs to do and so the circulatory system involves a double circulation. What are the two jobs that the heart carries out during this double circulation? 14 of 49 body’s cells © Boardworks Ltd 2004

Which way does blood flow? 15 of 49 © Boardworks Ltd 2004

Contents The Heart and Circulatory System The circulatory system Structure of the heart Valves in the heart How the heart pumps blood Summary quiz 16 of 49 © Boardworks Ltd 2004

The structure of the heart – exterior The heart pumps blood around the circulatory system. What is the heart made of? muscle tissue The heart is made of muscle and keeps pumping blood around your body, even when you are asleep! What do the blood vessels on the outside of the heart do? 17 of 49 © Boardworks Ltd 2004

The heart needs blood too! The heart is full of blood but also needs its own blood supply so that the muscle can keep pumping. muscle tissue blood vessels supply blood to muscle tissue The blood vessels on the outside of the heart carry oxygen-rich blood to the heart muscle cells. Oxygen-poor blood is then carried away from these cells by outer blood vessels and back into the heart. 18 of 49 © Boardworks Ltd 2004

The structure of the heart – interior The inside of the heart is divided into two sections to keep oxygen-rich and oxygen-poor blood separate. Each side of the heart is also divided into two sections. right side of the heart left side of the heart Each section of the heart is called a chamber. How many chambers are there? 4 19 of 49 © Boardworks Ltd 2004

The chambers of the heart The four chambers of the heart have special names: An upper chamber is called an atrium (plural atria). right atrium left atrium right ventricle left ventricle A lower chamber is called a ventricle. 20 of 49 © Boardworks Ltd 2004

What do atria and ventricles do? The chambers of the heart have different functions. blood to the lungs blood from the body blood to the body blood from the lungs The atria collect blood that enters the heart. The ventricles pump blood out of the heart. 21 of 49 © Boardworks Ltd 2004

Inside the heart – labels 22 of 49 © Boardworks Ltd 2004

Inside the heart – labelling activity 23 of 49 © Boardworks Ltd 2004

Chambers of the heart – activity 24 of 49 © Boardworks Ltd 2004

Contents The Heart and Circulatory System The circulatory system Structure of the heart Valves in the heart How the heart pumps blood Summary quiz 25 of 49 © Boardworks Ltd 2004

Preventing backflow Blood always flows in the same direction as it moves through the heart during each circulation of the body. Why is it important that blood does not flow backwards? 26 of 49 © Boardworks Ltd 2004

Heart valves The chambers of the heart are separated by valves which prevent blood from flowing in the wrong direction. valve leading out of right ventricle valve between right atrium and right ventricle valve leading out of left ventricle valve between left atrium and left ventricle There are valves between the atria and the ventricles… …and there are valves leading out of the ventricles. 27 of 49 © Boardworks Ltd 2004

Naming the heart valves 28 of 49 © Boardworks Ltd 2004

How are valves held in place? The valves between the atria and ventricles are connected to the inner walls of the heart by tough tendons. valve open 29 of 49 © Boardworks Ltd 2004

How are valves held in place? The tendons allow the valves to close and hold the valve flaps in place. They prevent the valves from flipping up and turning inside out. Why is this important? valve open 30 of 49 valve closed © Boardworks Ltd 2004

How do valves work? A valve acts like a door that only opens in one direction. If the door is held by someone at a fixed point, only the arm moves as the door opens and closes. When the door is closed the arm is fully extended, so the door can only be opened in one direction. 31 of 49 © Boardworks Ltd 2004

How do valves work? A valve acts like a door that only opens in one direction. In the heart, the tendons holding the valve are like the arm holding the door. One end of each tendon is fixed to the wall of the heart and so the valve can only open in one direction. 32 of 49 © Boardworks Ltd 2004

Contents The Heart and Circulatory System The circulatory system Structure of the heart Valves in the heart How the heart pumps blood 33 of 49 © Boardworks Ltd 2004

How does the heart pump blood? Imagine the force needed to squeeze a tennis ball. That’s how much force the heart uses to pump blood around the body! How does the heart produce enough force to keep doing this 24 hours a day? The heart can pump blood because it is made of muscle. Muscle tissue works by contracting (squeezing) and relaxing. 34 of 49 © Boardworks Ltd 2004

How does the heart pump blood? All the parts of the heart on either side, work together in a repeated sequence. The two atria contract and relax; then the two ventricles contract and relax. This is how blood moves through the heart and is pumped to the lungs and the body. One complete sequence of contraction and relaxation is called a heartbeat. 35 of 49 © Boardworks Ltd 2004

Heartbeat animation 36 of 49 © Boardworks Ltd 2004

Stages of a heartbeat Stage 1: A heartbeat begins with the heart muscle relaxed and valves closed. Blood flows into the two atria and both sides fill up with blood. This blood has to be pushed through the valves to get into the ventricles. How does this happen? 37 of 49 © Boardworks Ltd 2004

Stages of a heartbeat Stage 2: The atria contract and the blood is squeezed which causes the valves leading to the ventricles to open. Blood then flows from the atria into the ventricles. What happens to the open valves when the atria are empty? 38 of 49 © Boardworks Ltd 2004

Stages of a heartbeat Stage 2 (continued): The valves between the atria and the ventricles close. This prevents any backflow. What happens next to the blood in the ventricles? 39 of 49 © Boardworks Ltd 2004

Stages of a heartbeat Stage 3: Almost immediately, the ventricles contract and the blood is squeezed again. The pressure of the blood forces open the valves leading out of the heart. Blood is pumped out of the heart. What happens to the open valves when the ventricles are empty? 40 of 49 © Boardworks Ltd 2004

Stages of a heartbeat Stage 3 (continued): When the ventricles are empty, the valves leading out of the heart close and the heart muscle relaxes. This completes the sequence of contraction and relaxation in one heartbeat. What will happen next? 41 of 49 © Boardworks Ltd 2004

Stages of a heartbeat Stage 1 (again): The atria fill up with blood as the heartbeat sequence begins again. Why are the walls of the atria thinner than the walls of the ventricles? Why is the wall of the left ventricle thicker than the right ventricle? 42 of 49 © Boardworks Ltd 2004

Listening to a beating heart: lub-dub What does a doctor hear when they listen to a patients’ heart? lub-dub, lub-dub, lub-dub… The sound of a heartbeat is the sound of the heart valves. The “lub” is caused by the closing of the valves leading to the ventricles. 43 of 49 The “dub” is caused by the closing of the valves leading out of the heart. © Boardworks Ltd 2004

Measuring a beating heart You can measure how fast your heart is beating by taking your pulse. Place the fingertips of one hand on the opposite wrist, where an artery passes near the surface of the skin. Each pulse that you feel is due to the pressure of blood leaving the heart as the left ventricle contracts. What is your heart rate, in beats per minute, right now? 44 of 49 © Boardworks Ltd 2004

How many heartbeats? If your heart beats at an average rate of 70 times per minute, how many heartbeats are there… …in one hour? 70 x 60 = 4, 200 …in one day? 4, 200 x 24 = 100, 800 …in one year? 100, 800 x 365 = 36, 792, 000 …in 70 years? 36, 792, 000 x 70 = 45 of 49 2, 575, 440, 000 © Boardworks Ltd 2004

The sequence of a heartbeat 46 of 49 © Boardworks Ltd 2004

Journey of blood around the body 47 of 49 © Boardworks Ltd 2004

48 of 49 © Boardworks Ltd 2004

SUMMARY: Flow of Blood Superior and Inferior vena cava right atrium tricuspid valve right ventricle pulmonary valve pulmonary artery lungs (exchange of gases O 2 & CO 2) pulmonary vein left atrium mitral valve left ventricle aortic valve aorta arteries body systems 49 of 49 © Boardworks Ltd 2004

Types of Blood Circulation Pulmonary Circulation – blood flows from the heart to the lungs to get O 2 supply. Systemic Circulation – blood flows from the heart to the cells (distribute food and O 2) and from the cells to the heart (carry wastes and to the heart CO 2) 50 of 49 © Boardworks Ltd 2004

Special Circuits (Special Types of Circulation) 51 of 49 a. Portal Circulation – circulation of blood from the arteries to the digestive system. b. Renal Circulation – circulation of blood from the arteries to the excretory system/kidneys c. Coronary Circulation – circulation of the blood within the heart. © Boardworks Ltd 2004

Forensic Science T. Trimpe 2006 http: //sciencespot. net/ 52 of 49 © Boardworks Ltd 2004

What is Blood? Blood is the river of life. It carries oxygen and nutrients to the different body cells. It also collects body wastes and carbon dioxide. 53 of 49 © Boardworks Ltd 2004

What makes up our blood? A. RBC- (erythrocytes) - The blood cells that carry oxygen. Red cells contain hemoglobin and it is the hemoglobin which permits them to transport oxygen (and carbon dioxide). Hemoglobin, aside from being a transport molecule, is a pigment. It gives the cells their red color (and their name) 54 of 49 © Boardworks Ltd 2004

• B. WBC (leukocytes) - White blood cells are responsible for the defense system in the body. There approximately 6, 000 white blood cells per millimeter of blood or ½ a million white blood cells in every drop of human blood. White blood cells fight infections and protect our body from foreign particles, which includes harmful germs and bacteria. 55 of 49 © Boardworks Ltd 2004

• C. Platelets - Platelets help the blood clot. They are smaller than red or white blood cells. 56 of 49 © Boardworks Ltd 2004

• D. Plasma - is the liquid part of blood; it transports dissolved substances around the body and defends it against disease. 57 of 49 © Boardworks Ltd 2004

BLOOD TYPE If your blood type is. . . You Can Give Type Blood To A+ A+ AB+ O+ O+ A+ B+ AB+ B+ B+ AB+ AA+ A- AB+ ABOEveryone BB+ B- AB+ AB- AB+ AB 58 of 49 You Can Receive Blood From A+ A- O+ OB+ B- O+ OEveryone A- OOB- OAB- A- B- O© Boardworks Ltd 2004

* Blood Types * Almost 40% of the population has O+ blood * Patients with Type O blood must receive Type O blood * About half of all blood ordered by hospitals in our area is Type O * Type O blood is the universal blood type and is the only blood type that can be transfused to patients with other blood types * Only about 7% of all people have Type O negative blood * Type O negative blood is the preferred type for accident victims and babies needing exchange transfusions * There is always a need for Type O donors because their blood may be transfused to a person of any blood type in an emergency 59 of 49 © Boardworks Ltd 2004

Forensic Science T. Trimpe 2006 http: //sciencespot. net/ 60 of 49 © Boardworks Ltd 2004

* Blood from the heart gets around the body through blood vessels There are 3 types of blood vessels 1. ARTERY *Aorta – largest artery *Arterioles – smallest artery 2. VEIN * Vena Cava – largest vein * Venules – smallest vein 3. CAPILLARY 61 of 49 © Boardworks Ltd 2004

62 of 49 © Boardworks Ltd 2004

The ARTERY Arteries carry blood away from the heart. the elastic fibres allow the artery to stretch under pressure thick muscle and elastic fibres 63 of 49 the thick muscle can contract to push the blood along. © Boardworks Ltd 2004

The VEIN Veins carry blood back to the heart. veins have valves which act to stop the blood from going in the wrong direction. thin muscle and elastic fibres 64 of 49 body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel. © Boardworks Ltd 2004

The CAPILLARY Capillaries link Arteries with Veins they exchange materials between the blood and other body cells. the wall of a capillary is only one cell thick 65 of 49 The exchange of materials between the blood and the body can only occur through capillaries. © Boardworks Ltd 2004

The CAPILLARY A collection of capillaries is known as a capillary bed artery vein capillaries body cell 66 of 49 © Boardworks Ltd 2004