Presentation on theme: "The Heart and Circulatory System"— Presentation transcript:
1The Heart and Circulatory System KS4 BiologyThe Heart and Circulatory System
2The Heart and Circulatory System ContentsThe Heart and Circulatory SystemThe circulatory systemStructure of the heartValves in the heartHow the heart pumps bloodSummary quiz
3How 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?heartblood vesselsbloodThe body’s transport system is called the circulatory system.Why is it given this name?
4What 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?carbondioxideoxygenOxygen 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.
5oxygen-rich blood c oxygen-poor blood Two types of bloodThe circulatory system carries two types of blood:oxygen-rich bloodcoxygen-poor bloodblood travellingto the body cellshigh oxygen contentlow carbon dioxide contentblood travellingaway from the body cellslow oxygen contenthigh carbon dioxide contentThe arrangement of the circulatory system means that these two types of blood do not mix. Why is this important?
6At 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?
7Inside the heart right side of the heart oxygen-rich blood left side 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 sideof the heartoxygen-richbloodleft sideof the heartoxygen-poorbloodRemember 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.
9How 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?
10How does blood circulate around the body? The left side ofthe heart pumpsoxygen-rich bloodto the rest of the body.This blood suppliesthe body’s cells with oxygen.What gas does the blood then pick up from the body’s cells and where does the blood go next?body’scells
11How 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?body’scells
12How does blood circulate around the body? Next, the right sideof the heart pumps oxygen-poor bloodto the lungs.In the lungs the blood gets rid of the waste carbon dioxide and collects more oxygen.lungsWhere does this oxygen-rich blood then travel to?body’scells
13How does blood circulate around the body? The oxygen-rich blood then returnsto the left side of the heart.This completes the blood’s journey around the body.Why is the journeyof blood through the circulatory system called a double circulation?lungslungsbody’scells
14A double circulatory system During one complete circuit of the body, blood passes through the heart twice.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?lungslungsbody’scells
16The Heart and Circulatory System ContentsThe Heart and Circulatory SystemThe circulatory systemStructure of the heartValves in the heartHow the heart pumps bloodSummary quiz
17The structure of the heart – exterior The heart pumps blood around the circulatory system.What is the heart made of?muscletissueThe 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?
18The heart needs blood too! The heart is full of blood but also needs its own blood supply so that the muscle can keep pumping.blood vessels supply bloodto muscle tissuemuscletissueThe blood vessels on the outside of the heart carryoxygen-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.
19The 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 sideof the heartleft sideof the heartEach section of the heart is called a chamber.How many chambers are there?4
20The chambers of the heart The four chambers of the heart have special names:An upper chamber is called an atrium (plural atria).rightatriumleftatriumrightventricleleftventricleA lower chamber is called a ventricle.
21What do atria and ventricles do? The chambers of the heart have different functions.blood to the lungsblood tothe bodyblood from the bodyblood from the lungsThe atria collect blood that enters the heart.The ventricles pump blood out of the heart.
25The Heart and Circulatory System ContentsThe Heart and Circulatory SystemThe circulatory systemStructure of the heartValves in the heartHow the heart pumps bloodSummary quiz
26Preventing backflowBlood 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?
27right atrium and right ventricle left atrium and left ventricle Heart valvesThe chambers of the heart are separated by valveswhich prevent blood from flowing in the wrong direction.valve leading out ofright ventriclevalve leading out ofleft ventriclevalve betweenright atrium and right ventriclevalve betweenleft atrium and left ventricleThere are valves between the atria and the ventricles……and there are valves leading out of the ventricles.
29How 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
30How 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 openvalve closed
31How 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.
32How 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.
33The Heart and Circulatory System ContentsThe Heart and Circulatory SystemThe circulatory systemStructure of the heartValves in the heartHow the heart pumps bloodSummary quiz
34How does the heart pump blood? Imagine the force neededto squeeze a tennis ball.That’s how much forcethe heart uses to pumpblood around the body!How does the heart produceenough force to keep doingthis 24 hours a day?The heart can pump bloodbecause it is made of muscle.Muscle tissue works by contracting (squeezing)and relaxing.
35How does the heart pump blood? All the parts of the heart on either side, work togetherin 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 andthe body.One complete sequence of contraction and relaxation is called a heartbeat.
37Stages of a heartbeat Stage 1: A heartbeat begins with the heart muscle relaxed and valvesclosed.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?
38Stages 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?
39Stages of a heartbeat Stage 2 (continued): The valves between the atria and the ventricles close.This prevents any backflow.What happens nextto the blood in the ventricles?
40Stages 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 outof the heart.What happens to the open valves when the ventricles are empty?
41Stages of a heartbeat Stage 3 (continued): When the ventricles are empty, the valves leading out of theheart close and the heart muscle relaxes.This completes the sequence of contraction and relaxation in one heartbeat.What will happen next?
42Stages of a heartbeat Stage 1 (again): The atria fill up with blood as the heartbeat sequence begins again.Why are the wallsof the atria thinner than the walls ofthe ventricles?Why is the wall of the left ventricle thicker than the right ventricle?
43Listening to a beating heart: lub-dub What does a doctor hear when they listen to a patients’ heart?lub-dub,lub-dub,lub-dub,lub-dub,lub-dub,lub-dub…The sound of a heartbeat is the sound of the heart valves.The “lub” is caused bythe closing of the valves leading to the ventricles.The “dub” is caused bythe closing of the valvesleading out of the heart.
44Measuring 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 passesnear the surface of the skin.Each pulse that you feelis due to the pressure ofblood leaving the heart asthe left ventricle contracts.What is your heart rate, in beats per minute, right now?
45How many heartbeats?If your heart beats at an average rate of 70 times per minute, how many heartbeats are there……in one hour?…in one day?…in one year?…in 70 years?4, 20070 x 60 =100, 8004, 200 x 24 =36, 792, 000100, 800 x 365 =2, 575, 440, 00036, 792, 000 x 70 =