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### Understanding the Circulatory System: The Heart and Blood Functions ###

Explore the incredible work of the circulatory system with its main components, including the heart, blood, and blood vessels. Learn about the functions of each part and how they work together to keep your body healthy and functioning properly. ###

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### Understanding the Circulatory System: The Heart and Blood Functions ###

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  1. MondayMarch 23rd 2015 • Bell Ringer (index card) • About how much blood (in liters) does your body hold? About 5 Liters! That’s 2 ½ soda bottles

  2. The Circulatory System

  3. The Circulatory System • Also called the cardiovascular system • Is made of 3 parts: • Heart • Blood • And blood vessels • Allows blood to flow to all parts of your body • Has 3 main jobs: • Carries needed substances to cells • Oxygen and glucose • Carries waste products away from cells • Carbon dioxide • Contains cells that fight disease - White blood cells

  4. The Heart

  5. The Heart • A hollow muscular organ that pumps blood throughout the body • About the size of your fist • Located in the center of the chest, beneath the sternum and inside the ribcage • Made of cardiac muscle • Contracts over and over without tiring out

  6. The Heart • Acts as two pumps • Right side: pumps blood into the lungs where it picks up oxygen • Left side: pumps blood into the arteries where it is sent throughout the body • The two sides are separated by a wall of tissue called the septum.

  7. The Heart • Each side has two chambers • The upper chambers are called atria. • The lower chambers are called ventricles.

  8. The Atria (Atrium) • The upper chambers of the heart • Job is to receive blood that comes into the heart • The right atrium has a group of cells called the pacemaker (sinoatrial node) that sends signals to make the heart muscle contract

  9. Pacemaker • Whenever someone has problems with an irregular heartbeat, doctors may give them an artificial pacemaker. • This helps their heart maintain a normal rhythm.

  10. Ventricles • The lower chambers • Job is to pump blood out of the heart • Right ventriclepumps blood to the lungs • Left ventriclepumps blood into the body

  11. Valves • The ventricles are separated from the atria by valves • Flaps of tissue that prevents blood from flowing backward • Also located between the ventricles and the large blood vessels that carry blood out of the heart

  12. How the Heart Works • Two phases • Heart muscle relaxes and atria fill with blood • Heart muscle contracts and blood pumps forward • This closes the valves between the atria and the ventricles • Creates the lub sound • The valves between the ventricles and the blood vessels snap shut • Creates the dup sound

  13. Two Loops • Overall pattern of blood flow in the body is like the figure eight. • In the first loop, blood travels from the heart to the lungs and then back to the heart. • In the second loop, blood is pumped from the heart throughout the body and then returns to the heart. • Blood travels in only one direction. • One drop of blood could make the journey through both loops in less than a minute.

  14. Video http://www.youtube.com/watch?v=18--LFIs-FM

  15. Blood Vessels • There are three kinds of blood vessels • Arteries • Carry blood away from the heart • Veins • Carry blood to the heart • Capillaries • Exchange substances (gases) between the blood and body cells

  16. To be continued…

  17. Blood

  18. Blood • Blood is made of four components, or parts: • Plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets • About 45% of the volume of blood is cells; the rest is plasma

  19. Plasma • Most of the materials transported in the blood travel in the plasma. • Plasma is the liquid part of blood. • 90% of plasma is water • 10% is dissolved materials, such as glucose, fats, vitamins, and minerals • Many waste products are carried away by the plasma

  20. Plasma • Proteins give plasma its yellow color • Three groups of plasma proteins • Helps regulate amount of water in blood • Helps fight disease • Interacts with platelets to form blood clots.

  21. Red Blood Cells(RBCs) • RBCs take up oxygen in the lungs and deliver it to cells throughout your body • Produced in the bone marrow (like other blood cells) • Look like doughnuts that someone forgot to cut out the hole • Because they are thin in the middle, they are able to bend and twist easily • Allows them to squeeze into tiny capillaries

  22. RBCs • Made mostly of hemoglobin, an iron-containing protein that chemically binds to oxygen. • Hemoglobin is also able to pick up some carbon dioxide, but most is carried by the plasma • When hemoglobin and oxygen join together, the cell becomes bright red; without oxygen, the cell is dark red • Arteries have blood that is bright red • Veins have blood that is dark red

  23. RBCs • Mature RBCs have no nuclei • Without a nucleus, it cannot reproduce or repair itself • Only are able to live 120 days • Every second, about 2 million RBCs die • Bone marrow makes new cells at the same rate

  24. White Blood Cells(WBCs) • Produced in the bone marrow • WBCs are the body’s disease fighters. • Some recognize disease causing organisms and alert the body that it has been invaded • Others produce chemicals to fight the invaders • Others surround and kill the invaders

  25. WBCs • There are fewer WBCs than RBCs. • Larger than RBCs • Several different types of WBCs • WBCs have nuclei • Can live for months or even years

  26. Platelets • Platelets are cell fragments that play an important role in forming blood clots

  27. Forming Clots • When a vessel is cut, platelets collect and stick around the cut. • Platelets release a chemical that leads to the production of a protein called fibrin. • Fibrin makes a net of fibers across the wound. • This net traps blood cells. • As more and more of the platelets and cells get caught in the fibrin net, a clot forms. • A scab is a dried blood clot on the skin’s surface

  28. Blood Types • Four major blood types: A, B, AB, O • Types are determined by the proteins known as marker molecules that are on RBCs • A has the A marker, B has the B marker, AB has both A and B, O has no markers on it

  29. Blood Types • Plasma has proteins that recognize cells with foreign markers and they make those cells clump together • A has anti-B proteins • B has anti-A proteins • AB has no anti-proteins • O has both anti-A and anti-B proteins

  30. Why is Blood Type Important? • Your blood type determines what type of blood you can safely receive in a blood transfusion. • If you are A, you can receive A and O blood • If you are B, you can receive B and O blood • If you are AB, you can receive, A, B, AB, and O • “Universal recipients” • If you are O, you can only receive O blood • “Universal donors”

  31. Cardiovascular Diseases • Cardiovascular disease is the leading cause of death in the U.S. today.

  32. Atherosclerosis • Atherosclerosis is a condition in which an artery wall thickens as a result of the buildup of fatty materials such as cholesterol. • This reduces the flow of blood in the affected artery.

  33. Atherosclerosis • When atherosclerosis develops in the coronary arteries, the heart muscle receives less blood (less oxygen), which can lead to a heart attack. • Heart attacks occur when the blood flow to part of the heart muscle is blocked. • Cells die in the part of the heart that does not receive blood and oxygen. This permanently damages the heart

  34. Treating Atherosclerosis • Low-fat diet and exercise for mild cases. • Some medications can be prescribed. • Severe cases may lead to angioplasty, where a small balloon is inserted into the blocked artery to help open it up. • When arteries are completely blocked, a bypass operation may be performed. • In a bypass, a vein from the leg is used to create an alternate path for blood to flow into the heart muscle.

  35. Hypertension • Hypertension is high blood pressure. • A person will have hypertension if their blood pressure is consistently greater than 140/90. • High blood pressure makes the heart work harder to pump blood through the body, possibly damaging the walls of the blood vessel. • Because most people have no obvious signs of the disease it is called the “silent killer”.

  36. Treating High Blood Pressure • Closely related to atherosclerosis. • As arteries narrow, the blood pressure increases. • Diet and exercise help • Limit intake of salt • Sometimes given medications that lower blood pressure

  37. Measuring Blood Pressure • Blood pressure is measured by a device called a sphygmomanometer • The first number in a blood pressure reading is the measurement of the blood pressure when the ventricles contract. • The second number, which is lower, is the blood pressure when the ventricles relax. • The blood pressure is given as a fraction with the contraction pressure, or systolic, over the relaxation pressure, or diastolic. • A healthy blood pressure is 120/80 or lower.

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