Chapter 6 Book Notes

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University of Toronto Scarborough
Health Studies
Ingrid L.Stefanovic

Health, Illness, and Optimal Aging- Biological and Psychological Perspectives Chapter 6: Aging of the Internal Organ Systems CARDIOVASCULAR SYSTEM Basic Anatomy and Physiology - The cardiovascular system is the bodys main transportation system. - It sends supplies such as fluids, 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 - Blood is a highly complex fluid composed of water, red and while blood cells, and platelets, as well as nutrients such as fat globules, carbohydrates, and proteins. - It is perfused by gases such as oxygen, carbon dioxide, and nitrogen. - Blood also carries electrolytes, to help maintain the acidbase balance, and a host of other chemicals, including hormones, neurotransmitters, and various other peptides necessary to regulate homeostasis, cognition, movement, and every other function of the body. Heart - The heart is the centre of the circulatory system. - It is located behind the chest wall, in a 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 (ventricles), which pump the blood to the lungs and the rest of the body. Anatomically, the atria are thin-walled; the walls of the ventricles are thicker and more muscular, as they do the long-distance pumping. - The right and left sides of the heart each serve as a pump. Blood Pathway - Oxygen-poor blood is collected in the right atrium from the large veins of the body, the superior and inferior vena cava. - From there it flows to the right ventricle and is pumped via the pulmonary arteries into the capillary system of the lungs for carbon dioxide and oxygen exchange. - Oxygen-rich blood is sent via the pulmonary veins to the left atrium, from there it flows to the left ventricle and is pumped out through the aorta. - The blood from the aorta flows into the large arteries and then to the smaller arteries, arterioles, and the capillaries. Health, Illness, and Optimal Aging- Biological and Psychological Perspectives - The rate of blood flow is largely determined by physical demands on the body. Capillaries - Capillaries are very small- one cell wide- fluid, nutrients, electrolytes, hormones, and other substances are exchanged Venules - Collects blood from capillaries and move it into larger and larger veins (reaching superiorinferior vena cava) - 64% blood volume is found in veins - Walls of veins and arteries: flexible smooth muscle, elastic fibers, and collagen Beat Sinoatrial node (pacemaker) upper part of right atrium Spreads down the heart through atrial myocardium to reach atrioventricular node conducted to atrioventricular bundle & purkinje fibers Sent to both ventricles Single moves down and contraction of cardiacheart muscle begins Systole- contraction of heart Diastole relaxation of the heart Asystole- no heartbeat
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