Week 7, Day Three

1. Week 7, Day Three HW # 27- Review your notes from the human body unit (skeletal, muscular, circulatory systems) – Check your Have a Heart answers online. Extra Credit- Blood Pressure Worksheet Warm up Do veins always carry blood with no oxygen? Do arteries always carry blood with oxygen? Give examples to support your answer.

2. Warm up Response • No, the pulmonary veins carry oxygen rich blood and the pulmonary arteries carry oxygen poor blood.

3. Homework Response/Check Collect Heart Beat, Health Beat lab report.

4. Goals for Today • Finish • Have a Heart

5. Question: Explain why oxygen-poor blood and oxygen-rich blood never mix in the human body. • Two sides of the heart are separated by the septum. • Each side has an upper chamber and a lower chamber. • Oxygen rich blood is carried in arteries, and oxygen poor blood is carried in vein; they never meet. • The oxygen in oxygen-rich blood diffuses through cell walls and powers the metabolism of cells, leaving oxygen poor blood behind to be collected by veins and transported to the heart and lungs for re-oxygenation.

6. Question: Do all arteries carry oxygen-rich blood? Do all veins carry oxygen poor blood? • No, the pulmonary veins carry oxygen rich blood and the pulmonary arteries carry oxygen poor blood.

7. Question: Starting at the right atrium, describe the path that blood takes through the heart and body, ending again in the right atrium. • Blood circulates in two loops. • First, it travels from the heart to the lungs and then back to the heart. • Second, it is pumped from the heart to the body and then it returns to the heart. • EXTRA DETAILS • Blood enters the heart through the superior and inferior vena cava. These two paths dump deoxygenated blood into the right atrium. Blood passes from the right atrium through the tricuspid valve into the right ventricle. The right ventricle contracts and forces the blood through the pulmonary semilunar valve into the pulmonary arteries. The blood moves into the lungs and gas exchange occurs, oxygenating the blood. The blood then moves through the pulmonary vein, emptying into the left atrium. The oxygenated blood then passes through the bicuspid valve into the left ventricle. The left ventricle contracts and forces the blood out through the aortic semilunar valve and into the aorta. The aorta is the bodies largest artery and blood is distributed to smaller arteries and out to the entire body (except the lungs).

8. Question: how are the structures of an artery, vein, and capillary able to help each do the specific function that they do for the body? • Arteries carry blood from the heart, so their walls have to withstand high blood pressure. • They also have to maintain blood pressure to ensure a continuous blood flow. • Therefore, their three-layered walls are strong, elastic, have smooth muscle cells and collagen fibers.

9. Capillaries exchange material (oxygen, carbon dioxide, nutrients etc.) between the blood and interstitial fluid. • To be able to carry out this function, they have to have very thin, permeable walls.

10. Arteries and veins are the parts of the circulatory system which carry blood between the heart, lungs, and all other areas of the body. • While they both carry blood, they do not have much else in common. Arteries and veins are made of somewhat different tissue, each performing certain functions in a specialized way. • The first and most important difference between the two is that all arteries carry blood away from the heart, and all veins carry blood to the heart from outlying areas. • Most arteries carry oxygenated blood, and most veins carry deoxygenated blood; the pulmonary arteries and veins are the exceptions to this rule.

11. Arterial tissue is designed and specialized in a way to make it particularly suited to the quick and efficient delivery of blood, which carries the oxygen essential for the functioning of every bodily cell. • The outer layer of an artery is made of connective tissue, which covers the muscular middle layer. • These muscles contract between heartbeats in such a reliable way that when we take our pulse, we are not actually feeling our heartbeat per se, but arterial muscle contraction instead.

12. Beyond the arterial muscle is the innermost layer, made of smooth endothelial cells. These cells are specialized to provide a smooth pathway for blood to flow through. • This area of cells is also what can become damaged and compromised over a person's lifetime, leading to two common causes of death, namely heart attack and stroke. • Veins have a different structure and function from arteries. • They are very flexible, and collapse when they are not filled with blood. They usually carry deoxygenated blood, rich in carbon dioxide, to the heart so that it can be sent to the lungs for oxygenation. • The layers of vein tissue are similar in some ways to those of arteries, although the muscle does not contract like arterial muscle does.

13. Unlike other arteries, the pulmonary artery carries deoxygenated blood. Once the veins have brought this blood from the body to the heart, it is pumped to the lungs. • The pulmonary vein moves the oxygenated blood from the lungs back to the heart. • While the location of arteries is very similar from person to person, this is not so much the case with veins, which have greater variability. • Veins, unlike arteries, are used as access points to the bloodstream in the medical field, such as when a person receives medicine or fluids directly into the bloodstream, or when blood is drawn. Because veins do not contract as arteries do, there are valves present in veins which keep blood flow going in one direction only. Without these valves, gravity would quickly cause blood to pool in the extremities, causing injury or at the very least impairing the system's efficiency.

14. Question: An artificial heart actually replaces only the ventricles of a human heart. Suggest a reason why replacing the atria is not necessary? Because the atria only collect blood. The ventricles are needed to pump the blood to the lungs (right) and to the body (left). Thus, they need to be stronger.

15. Question: Explain why chronic heart disorders such as hypertension and atherosclerosis are more of a problem today then they were 200 years ago. Predict how great of a problem it will be in the future. Hypertension- high blood pressure Atherosclerosis- Atherosclerosis (ath-er-o-skler-O-sis) is a disease in which plaque (plak) builds up inside your arteries. Arteries are blood vessels that carry oxygen-rich blood to your heart and other parts of your body. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. Over time, plaque hardens and narrows your arteries. This limits the flow of oxygen-rich blood to your organs and other parts of your body. Atherosclerosis can lead to serious problems, including heart attack, stroke, or even death. They are more common now, because we are living longer and because we lead more sedentary lifestyles.