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CHAPTER 18 DISORDERS OF BLOOD FLOW AND BLOOD PRESSURE Essentials of Pathophysiology.

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Presentation on theme: "CHAPTER 18 DISORDERS OF BLOOD FLOW AND BLOOD PRESSURE Essentials of Pathophysiology."— Presentation transcript:

1 CHAPTER 18 DISORDERS OF BLOOD FLOW AND BLOOD PRESSURE Essentials of Pathophysiology

2 PRE-LECTURE QUIZ True/False F HDL is known as the “bad cholesterol.” T Most abdominal aneurysms are asymptomatic. F Essential (primary) hypertension is characterized by chronic elevation in blood pressure that results from some other disorder, such as kidney disease. F Orthostatic or postural hypotension is an abnormal rise in blood pressure that occurs when assuming the standing position from the supine position. T Venous insufficiency leads to tissue congestion and edema in the lower extremities.

3 PRE-LECTURE QUIZ  The __________ controls the transfer of molecules across the vascular wall, plays a role in platelet adhesion and blood clotting, and functions in the modulation of blood flow and vascular resistance.  __________, with its associated risk for the development of atherosclerosis, is a major cause of cardiovascular disease.  __________ phenomenon is a functional disorder caused by intense vasospasm of the arteries and arterioles in the fingers and, less often, in the toes.  __________ dissection is an acute, life-threatening condition that involves hemorrhage into the vessel wall with longitudinal tearing or separation of the vessel wall to form a blood-filled channel.  The body uses neural mechanisms and humoral mechanisms to effect the __________-term regulation of blood pressure, which occurs over minutes or hours and is intended to correct temporary imbalances in blood pressure. Endothelium Aortic Hyperlipidemia Raynaud Short

4 ARTERY STRUCTURE Arranged in tunics or coats Tunica intima: Endothelium Tunica media: smooth muscle Tunic adventitia: collagen and elastic fibers

5 ARTERY STRUCTURE Tunica intima: endothelium Tunica media: smooth muscle Tunica adventitia: collagen and elastic fibers

6 QUESTION Which vessel layer can expand to accommodate pressure changes? a. Tunica intima b. Tunica media c. Tunica adventitia d. Tunica externa

7 ANSWER b. Tunica media The tunica media is composed of smooth muscle, which can stretch/expand to accommodate changes in blood pressure. Is this answer arguable?

8 VASCULAR ENDOTHELIUM  Nutrients and O 2 pass into tissues  Wastes and CO 2 pass from tissues into blood  Creates compounds that cause vasodilation or vasoconstriction  Creates growth factors that can stimulate smooth muscle  Forms a smooth lining of the blood vessels that resists clot formation  Creates compounds to promote clot formation in injured areas

9 ATHEROSCLEROSIS  Lipids get into the vascular endothelium  White blood cells try to clear them away  foam cells  WBCs and vascular endothelium release growth factors that promote plaque formation  Plaques block the arteries

10 LIPOPROTEINS  The more protein, the higher the density  The more lipid, the lower the density

11 LIPOPROTEINS  The more protein, the higher the density  The more lipid, the lower the density  i.e. protein is heavier than lipids

12 QUESTION Tell whether the following statement is true or false. LDL is considered to be “good” cholesterol.

13 ANSWER False Rationale: LDL (low-density lipoprotein, which has more lipids and less protein) is the “bad” cholesterol. HDL (high-density lipoprotein) has more protein and less fat, and is considered “good” cholesterol.

14 LIPID TRANSPORT IN THE BODY  Dietary lipids absorbed as chylomicrons  Adipose and muscle cells take up lipids from chylomicrons  Chylomicron remnants are intermediate- density lipoproteins, IDL

15 LIPID TRANSPORT IN THE BODY (CONT.)  IDLs become low- density lipoproteins (“bad cholesterol”)  These can deliver fat to the liver and to other tissues  LDL receptors are necessary for the liver to take them up  Some LDLs are taken up by scavenger cells like macrophages

16 FATTY STREAKS AND ATHEROSCLEROTIC PLAQUES

17

18 ATHEROSCLEROSIS  Atherosclerosis develops because scavenger cells encounter the fatty deposits in the artery lining and  Try to destroy the fats by oxidizing them º Oxidized fats injure the endothelium º Clots form and release growth factors º Smooth muscle grows over the fatty core  Try to remove the fats by eating them  Become “foam cells” in the core of the plaque

19 LIPID TRANSPORT IN THE BODY  High-density lipoproteins (“good cholesterol”) are made in the liver  They go out to the peripheral tissues and pick up lipid  Then they carry it back to the liver

20 SCENARIO A man has several genetic defects in his lipoprotein receptors…  His liver lacks LDL receptors  His muscle cells lack receptors for the apoproteins on chylomicrons  His scavenger cells have extra LDL receptors Question:  Why might he develop atherosclerosis?

21 STABLE PLAQUES  Have thick fibrous caps  Partially block vessels  Do not tend to form clots or emboli

22 UNSTABLE PLAQUES  Have thin fibrous caps  Plaque can rupture and cause a clot to form  May completely block the artery  The clot may break free and become an embolus

23 QUESTION What immediate threat do unstable plaques present? a. Clot formation will increase pressure in the vessel. b. Plaque may lead to angina (chest pain). c. Clots may break loose and block blood flow to key organs. d. All of the above constitute immediate threats.

24 ANSWER c.Clots may break loose and block blood flow to key organs. Rationale: If a clot breaks loose, becoming an embolus, it may lodge in a blood vessel to the brain, heart, or lungs. When blood flow is significantly decreased or blocked altogether, the result is tissue death—in the examples here, stroke, heart attack, or pulmonary embolus. The other choices represent more long-term/chronic problems.

25 SCENARIO A woman complains of pain in her left leg.  Her foot is cool and pale  She reports that it is often red and warm when she is sitting down  The pain occurs when she is walking to church on Sundays  The skin on her left leg is shinier than on her right leg Question:  What could have caused all this? How?

26 ANEURYSMS  Wall of artery weakens and stretches  Risk of rupture and hemorrhage  Risk of clot formation

27 AORTIC ARCH ANEURYSM

28 CAROTID ARTERY ANEURYSM

29 DISCUSSION How would each of the following affect blood pressure?  Vasodilation  Decreased stretching of baroreceptors  Hypoxemia  Inhibiting angiotensin-converting enzyme  Beta blockers  Alpha-2 agonists  Calcium-channel blockers Lower resistance lowers BP Reflex raises BP Calls for more blood flow raises BP Blocks formation of Angiotesion II Lowers BP Slows HR Lowers BP Decreases Sympathetic response Lowers BP Decreases vascular resistance Lowers BP

30 VARICOSE VEINS

31 SCENARIO A woman complains of pain in her left leg…  Her foot is cool and pale  She reports that it is often red and warm when she is sitting down  The pain occurs when she is walking to church on Sundays  The skin on her left leg is shinier than on the right leg Question:  What could have caused all this? How?

32 ANEURYSMS  Wall of artery weakens and stretches  Risk of rupture and hemorrhage  Risk of clot formation


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