Chapter 6 Textbook Notes

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Health Studies
Ingrid L.Stefanovic

HEALTH AND AGING TEXTBOOK NOTES Chapter 6: Aging of the Internal Organ System Cardiovascular System %K0.,7L4;,8.:O,788902L89K0-482,L397,385479,9L4388902 ,980388:55OL088:.K,81O:L8 nutrients, hormones, oxygen, and antibodies to tissues in the body while at the same time removing waste products such as carbon dioxide and hydrogen ions. The system is composed of the heart, blood vessels (arteries, arterioles, capillaries, veins, and venules), and blood. In general, arteries carry blood away from the heart, and veins carry blood to the heart. Blood is highly complex fluid composed of water, red, and white blood cells, and platelets, as well as nutrients such as fat globules, carbohydrates, and proteins. Blood also carries electrolytes, to help maintain the acidbase balance, and a host of other chemicals. The heart is the center of the circulatory system. It is located behind the chest wall, in slightly canted position, with the midsection somewhat to the left of the sternum, or breastbone. It is enclosed in a fibrous sac called the pericardium. The left and right sides of the heart each have two upper chambers (atria), which collect the blood, and two lower chambers which pump the blood to the lungs and the rest of the body. The blood from the aorta flows into the large arteries and then to the smaller arteries, arterioles, and capillaries. The capillaries are very small, and ensure that all cells in the body have access to the bloodstream. Veins serve as a huge reservoir for the -48-O448:55O Most people are familiar with the pulse of the carotid artery on the neck and the radial pulse on the outer edge of the wrist. The pulse can be felt in other parts of the body as well, such as the top of the foot (pedal pulse) and the back of the knee (popliteal pulse). To help keep blood moving up to the heart and to prevent it from pooling in extremities, some veins have valves. These valves consist of tissue inside the vein wall that extends into the vein (like a flapper valve) forcing the blood to flow in only one direction, toward the heart. The rate of blood flow is largely determined by physical demands on the body. The heart alters its rate of pumping depending on both external and internal demands. As well as delivering blood and nutrients to all tissues of the body, the cardiovascular system serves as the conduit for communication among the organs. The health of the cardiovascular system, greatly affects the health of every other organ in the body. The first arteries to leave the aorta go to the heart muscle, ensuring that the heart has the most oxygen- rich blood. Age-Related Changes There are a few normal changes in the cardiovascular system with age. Some studies report enlargement of the heart due to increase in size of the muscle cells or myocytes. By age 75 only about 10% of pacemaker cells found in young people remain. There is an increase in the amount of fat tissue around the sinoatrial node, which interferes with the conduction system (leads to bradycardia). This condition is often treated by giving the person an artificial pacemaker that keeps the heart from falling below a preset rate. Changes in the collagen in the middle layer of the large arteries of the body cause them to thicken and become stiff. Over time, the larger size and rigidity of these large arteries require the heart to work harder, eventually increasing blood pressure. Overall, heart function is less efficient with age. There is a decrease in cardiovascular responsiveness to exercise and a reduction in the maximum heart rate that can be reached. Cardiovascular disease is very much common in later life and results in the majority of disability and deaths among older people. Hypertension Optimal blood pressure for adults over the age of 18 is 12080 or lower (the first number refers to the systolic and the second to the diastolic). 1
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