The Circulatory System Chapter 9 The Circulatory System

The Circulatory System Chapter 9

The Circulatory System- Definition • The Circulatory System is the way that organisms transport substances in and out of cells.

Circulation in Humans- Oxygen • There are two purposes of the circulatory system in humans. 1. The main focus of the circulatory system in humans is to transport the blood around the body to provide the cells with oxygen. 2. The secondary focus of the circulatory system in humans is to provide the cells with monosaccharides, amino acids and fats for nutrients. The reason that oxygen is primary is that the cells will die after a very short time (minutes) without oxygen. We will focus only on the oxygen aspect of circulation.

Oxygen • Cells need oxygen in order to do aerobic respiration to make ATP. • Oxygen is carried through the blood by Red Blood Cells (RBC).

The Human Circulatory System • The circulatory system has two components: 1. The Heart (the pump) 2. The blood vessels (the pipes)

The Heart • The heart pumps the blood through the blood vessels in two steps: 1. The heart first expands, filling with blood. 2. The heart then contracts, propelling the blood into the blood vessels.

Anatomy of the heart • The heart is divided into four chambers. 1. Right Atrium 2. Right Ventricle 3. Left Atrium 4. Left Ventricle Note: “Left” and “Right” are from the perspective of the person you are looking at, so everything is reversed.

The order of the circulatory system 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Left Atrium Left Ventricle Aorta Arteries Arterioles Capillaries of body Venules Veins Vena Cava Right Atrium Right Ventricle Pulmonary Artery Capillaries of lungs Pulmonary Vein –> Back to #1

1 - Left Atrium • The blood begins in the left atrium. It is full of oxygen (oxygenated). • The left atrium pumps the blood through a valve to the left ventricle. • The valve prevents blood from flowing in the wrong direction. • Notice that the left atrium wall is fairly small/weak. This is because it does not need to be very strong since it only needs to pump the blood a short distance.

2 -Left Ventricle • The blood is then located in the left ventricle. • The left ventricle has the thickest walls (muscles) of all of the four chambers because it must pump the blood the hardest/farthest because from the left ventricle the blood needs to reach the entire body. • The left ventricle pumps the blood into the Aorta – the main artery out of the heart.

Heart Sounds • When listening to a heartbeat, it is not actually a single beat. Instead it sounds like • “Lub dub… lub dub” • http: //www. youtube. com/watch? v=x. S 3 j. X 1 FY G-M • The lub – first sound- is the atrium pumping the blood into ventricle. • The dub – second sound- is the ventricle pumping the blood out into the body.

3 - Aorta • The aorta is the name of the very large artery coming out of the left ventricle. • The aorta then splits off into many smaller arteries that feed the whole body.

4 - Arteries • The aorta breaks off into many different arteries that feed the brain, the liver, the stomach, the kidneys, the legs, the feet etc. • The definition of an artery is “a blood vessel that carries blood away from the heart. ” • The arteries contain strong, expandable, elastic walls to deal with the force of the blood pumping from the heart.

Question Oxygenated • The blood in these arteries is ______ (oxygenated or deoxygenated)?

5 - Arterioles • Each artery breaks off into smaller arteries, called arterioles.

6 - Capillaries • Each arteriole branches into many capillaries. • Capillaries are the smallest size of blood vessels. • Capillaries are where the actual purpose of the circulatory system takes place.

Diffusion in the capillaries • The walls of the capillaries are only one cell thick. • This allows the capillaries and the cells to exchange gases. • The capillaries have a high concentration of oxygen and the cells have a low concentration of oxygen, so oxygen flows from the capillaries to the cell. • The cells have a high concentration of carbon dioxide and the capillaries have a low concentration of carbon dioxide, so carbon dioxide flows from the cells to the capillaries by diffusion.

Oxygenated to deoxygenated blood Before the gas exchange • The blood is high in oxygen (oxygenated) and low in carbon dioxide. • Blood is RED (ish) • The cells are high in carbon dioxide and low in oxygen. After the gas exchange • The blood is low in oxygen and is high in carbon dioxide. • Blood is BLUE (ish) • The cells are high in oxygen and low in carbon dioxide.

7 - Venules • After the gas exchange in the capillaries, the capillaries merge together to form larger tubes called venules.

8 - Veins • Venules merge and form larger tubes called veins. • The definition of veins is “blood vessels that return blood to the heart”. • Question: the blood in these veins is _____ (oxygenated or deoxygenated)

Veins • Once the blood is in the veins, the force from the heart’s pump has mostly run out. • This is why you cannot feel a pulse on a vein. • Since the blood is not flowing forcefully through the veins, there is a concern that the blood might begin to flow in the wrong direction. • Therefore, the veins have valves that ensure that the blood can only flow in the correct direction – toward the heart.

Varicose Veins • Sometimes, the valves in the veins can be damaged and allow blood to flow backwards through the vein. • When this happens, veins swell and contain too much blood and can become painful. • This is called Varicose Veins

9 - Vena Cava • From the veins, the blood flows into the largest vein, the Vena Cava. • Technically, there are two Vena Cavas – the Superior Vena Cava (blood returning from the head) and the Inferior Vena Cava (blood returning from the lower body). • For this class, we will just refer to the Vena Cava.

Summary of blood vessels (after left ventricle) 1. 2. 3. 4. 5. 6. 7. Aorta ____ Arteries ____ Arterioles ____ Capillaries ____ Venules ____ Veins ____ Vena Cava ____

10 - Right Atrium • From the Vena Cava, the blood flows into the Right Atrium. • Like the left atrium, the right atrium has fairly weak walls because it only needs to pump the blood into the right ventricle.

11 - Right Ventricle • The Right Ventricle has intermediate thickness walls. This is because it needs to pump the blood to the lungs and back, which is farther than the atrium but not as much as the left ventricle pumps (the entire body). • The right ventricle pumps the blood into the pulmonary artery.

12 - Pulmonary Artery • The pulmonary artery carries blood to the lungs. • Pulmonary = lungs. • The definition of an artery is _______ A blood vessel that carries blood away from the heart • The Pulmonary Artery is different from all other arteries because it Deoxygenated carries ______ blood.

13 - Capillaries of Lungs • From the pulmonary artery, the blood branches into capillaries. • These capillaries function in the same way that the capillaries in the rest of the body function. • Since the walls of the capillaries are so thin, the blood is able to exchange gases with surrounding tissues.

Alveoli • The capillaries in the lungs surround small sacs of air called alveoli. • The capillaries bring deogygenated blood to the alveoli, which contain the air that we breathe. • The carbon dioxide flows from the blood to the alveoli and the oxygen flows from the alveoli to the blood. • Through this process, the blood becomes oxygenated again. • Opposite process of other capillaries.

14 - Pulmonary Vein • The capillaries of the lungs then merge into larger vessels called the pulmonary vein. • The definition of a vein is blood vessel that carries blood _____ Atowards the heart. • This vein is different from all other veins because it carries Oxygenated _____ blood. • This vein brings the blood back to the left atrium of the heart. • Begin 14 -part cycle again.

Circulatory System- Name • The reason it is called the circulatory system is that the blood travels in a continuous circle. • The circulatory system can be divided into two circuits

Two circuits Systemic • This refers to the circuit that goes from the heart to the rest of the body (brain, liver, arms, etc) and back again. • The purpose of this circuit is to bring oxygen to the cells. Left ventricle, aorta, arteries, arterioles, capillaries in body, venules, veins, vena cava, right atrium Pulmonary • This refers to the circuit that goes from the heart to the lungs and back. • The purpose of this circuit is to replenish the oxygen in the blood. Right ventricle, pulmonary artery, capillaries in lungs,

Summary video • http: //www. youtube. com/watch? v=Pg. I 80 Ue. AMo