Chapter 11 – Part 6 The Cardiovascular System

1. Chapter 11 – Part 6The Cardiovascular System

2. Human normal range is variable • Normal • 140–110 mm Hg systolic • 80–75 mm Hg diastolic • Hypotension – Low blood pressure • Generally considered to be a systolic below 100 mm Hg • Hypertension – Sustained, high blood pressure • 140/90 mm Hg or higher Variations in Blood Pressure

3. Not really a cause for concern • Sometimes it just simply reflects individual differences • Can be caused from: • Physical conditioning • Blood loss • Old age • Elderly people may experience dizziness when they suddenly rise from a sitting position • The nervous system reacts more slowly to postural changes • Making postural changes more slowly usually prevents this problem • Poor nutrition or inadequate levels of blood proteins Hypotension: Causes

4. Can be dangerous if it is chronic • No symptoms for the first 10-20 years • It slowly and surely strains the heart; called the “silent killer” • The heart pumps against increased resistance, it must work harder, and in time enlarges • When finally strained beyond its capacity to respond, the heart weakens and its walls become flabby Hypertension

5. Although hypertension and atherosclerosis are closely linked, it is difficult to blame hypertension on any distinct anatomical pathology. • 90% of hypertensive people do not know their cause of it. Hypertension: Causes

6. Diet, obesity, heredity, race, and stress appear to be involved. • More women than men are hypertensive. • More blacks than whites are hypertensive. • A child of a hypertensive parent is 2X more likely to be hypertensive. • Higher risk if diet high in cholesterol, saturated fat, and sodium . • Obese people have a greater total length of blood vessels than in thinner individuals. • For each pound of fat, miles of additional blood vessels are required, making the heart work harder to pump blood over longer distances. Hypertension: Causes

7. Atherosclerosis – The narrowing of arteries from the inside out • The walls of the vessel thicken and then protrude into the vessel lumen. • It does not take much for the vessel to close completely • For some reason, the aorta and coronary arteries are the most affected. • Characterized by “fatty streaks” or gray to yellow lesions called atherosclerotic plaques Atherosclerosis

8. Initial event is damage to the tunica interna caused by: • Bloodborne chemicals such as cig- arette smoke, bacteria, or viruses • Physical factor such as a blow or chronic hypertension • Once a break has occurred, blood platelets cling to the injured site and initiate clotting to prevent blood loss. • Plaques grow slowly, through a series of injuries of injuries that heal, only to be ruptured again and again. Atherosclerosis

9. Arteriosclerosis– Any of a number of proliferative and degenerative changes in the arteries leading to their decreased elasticity. • End stage of the disease • As plaques hinder diffusion, cells of the arterial wall die and are replaced with scar tissue • Result: Increased rigidity of the vessels, which leads to hypertension and an increased risk of myocardial infarcts, strokes, and kidney failure. Arteriosclerosis

10. Coronary artery bypass surgery • The vessels removed from the legs or thoracic cavity are implanted in the heart to restore circulation • Balloon angioplasty • A catheter with a balloon packed into its tip is threaded through blood vessels to obstructed sites • When the catheter reaches the blockage, the balloon is inflated, and the fatty mass is compressed against the vessel wall • Only useful to clear a few very localized obstructions • A newer catheter device uses a laser beam to vaporize the arterial clogs • Cholesterol lowering drugs Treatment of Arteriosclerosis

11. Treatment of Arteriosclerosis: Bypass Surgery

12. Treatment of Arteriosclerosis: Balloon Angioplasty

13. These intravascular devices (catheters) are faster, cheaper, and much less risky than by pass surgery but: • They do nothing to treat the underlying disease • In time, new blockages occur in 30-50% of cases • Cholesterol lowering drugs were thought to wash the plaques off the walls. • They do work to some extent but are not tolerated by some patients because of their bad side effects. Treatment of Arteriosclerosis: Limitations

14. The Effects of Exercise on the Cardiovascular System • The heart becomes a more powerful pump. • The heart will hypertrophy (get larger) and its cardiac output will increase substantially. • The heart becomes more efficient. • Pulse rate and blood pressure decrease. • It clears fatty deposits from the blood vessel walls, helping to slow the progress of atherosclerosis.

15. Effect of Aging on the Cardiovascular System • The venous valves weaken (more varicose veins appear) • We all have progressive atherosclerosis • Gradual loss of elasticity in the blood vessels, which leads to hypertension

16. Coronary Artery Disease - Caused by the insidious filling of the blood vessels with fatty, calcified deposits. • Causes more than ½ of the deaths in those over the age of 65 • Most researchers feel that diet is the single most important contributing factor • Should eat less animal fat, cholesterol, and salt • Other recommendations: Exercise regularly and avoid stress and smoking Coronary Artery Disease