Chapter 05 Lecture Outline

Transcription

1 Chapter 05 Lecture Outline See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright 2016 McGraw-Hill Education. Permission required for reproduction or display. 1

2 Cardiovascular System: Heart and Blood Vessels 2

3 Points to ponder What are the functions of the cardiovascular system? What is the anatomy of the heart? Of blood vessels, such as veins and arteries? How is the heart beat regulated? What is blood pressure? What are common cardiovascular diseases and how might you prevent them? 3

4 5.1 Overview of the Cardiovascular System What is the cardiovascular system? It includes the heart and blood vessels. It brings nutrients to cells and helps get rid of wastes. Blood is refreshed in the lung, kidneys, intestine, and liver. Lymphatic vessels help this system by collecting excess fluid surrounding tissues and returning it to the cardiovascular system. 4

5 5.1 Overview of the Cardiovascular System What is the cardiovascular system? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CO 2 O 2 Respiratory System tissue cells Cardiovascular System food kidneys liver Figure 5.1 The cardiovascular system and homeostasis. Digestive System indigestible food residues (feces) Urinary System metabolic wastes (urine) 5

6 5.1 Overview of the Cardiovascular System What are the functions of the cardiovascular system? 1. Transport: oxygen, carbon dioxide and other wastes products, nutrients, and horomones 2. Protection: cells of the immune system are transported to help protect the body from infection 3. Regulation: maintain homeostasis of a variety of the body s conditions 6

7 5.2 The Types of Blood Vessels What is the main pathway of blood in the body? Heart arteries arterioles capillaries venules veins back to the heart 7

8 5.2 The Types of Blood Vessels Arteries and arterioles Arteries carry blood away from the heart. Their walls have 3 layers. Thin inner epithelium Thick smooth muscle layer Outer connective tissue Arterioles are small arteries that regulate blood pressure. 8

9 5.2 The Types of Blood Vessels Capillaries Microscopic vessels between arterioles and venules Made of one layer of epithelial tissue Form beds of vessels where exchange with body cells occurs Combined large surface area 9

10 5.2 The Types of Blood Vessels Capillaries Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. artery connective tissue arteriole v. a. blood flow elastic tissue endothelium precapillary sphincter smooth muscle arteriovenous shunt capillary bed valve venule blood flow vein v. = vein; a. = artery (left): Ed Reschke; (right): Biophoto Associates/Photo Researchers Figure 5.2 Structure of a capillary bed. 10

11 5.2 The Types of Blood Vessels Veins and venules Venules are small veins that receive blood from the capillaries. Venule and vein walls have 3 layers. Thin inner epithelium Thick smooth muscle layer Outer connective tissue Veins carry blood toward the heart. Veins that carry blood against gravity have valves to keep blood flowing toward the heart. 11

12 5.2 The Types of Blood Vessels How can you tell the difference between an artery and vein? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. artery connective tissue arteriole v. a. blood flow elastic tissue endothelium precapillary sphincter smooth muscle arteriovenous shunt valve blood flow venule vein v.=vein; a.=artery (left): Ed Reschke Figure 5.2 Structure of a capillary bed. 12

13 5.3 The Heart is a Double Pump Anatomy of the heart Large, muscular organ consisting of mostly cardiac tissue called the myocardium Surrounded by a sac called the pericardium Consists of 2 sides, right and left, separated by a septum Consists of 4 chambers: 2 atria and 2 ventricles 2 sets of valves: semilunar valves and atrioventricular valves (AV valves) Valves produce the lub and dub sounds of the heartbeat 13

14 5.3 The Heart is a Double Pump External anatomy of the heart Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. left subclavian artery left common carotid artery brachiocephalic artery superior vena cava aorta left pulmonary artery pulmonary trunk left pulmonary veins right pulmonary artery right pulmonary veins left atrium left cardiac vein right atrium right coronary artery left ventricle right ventricle left anterior descending coronary artery inferior vena cava apex Figure 5.3 The arteries and veins associated with the human heart. 14

15 5.3 The Heart is a Double Pump Internal anatomy of the heart Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. left subclavian artery left common carotid artery brachiocephalic artery superior vena cava aorta left pulmonary artery pulmonary trunk left pulmonary veins right pulmonary artery right pulmonary veins semilunar valve left atrium right atrium atrioventricular (bicuspid) valve atrioventricular (tricuspid) valve chordae tendineae papillary muscles right ventricle septum left ventricle inferior vena cava a. Figure 5.4a The heart is a double pump. 15

16 5.3 The Heart is a Double Pump How does blood flow through the heart? Inferior and superior vena cava (1) dump blood into the right atrium (2) Right ventricle (3) 2 pulmonary arteries (4) that lead to the lungs (5) where blood becomes oxygenated Pulmonary veins (6) bring blood from the lungs back to the left atrium (7) Left ventricle (8) is large and muscular to pump blood into the aorta (9) and to the rest of the body (10) Eventually blood will be pumped back to each vena cava (1) 16

17 5.3 The Heart is a Double Pump Visualizing blood flow through the heart Figure 5.4 The heart is a double pump. 17

18 5.3 The Heart is a Double Pump How do the structure of the vessels and heart match their functions? The left ventricle is much more muscular than the right ventricle because it must pump blood to the entire body. The arteries are more muscular than veins to withstand the higher pressure exerted on them. The veins have a thinner wall and a larger center to contain blood. 18

19 5.3 The Heart is a Double Pump How does the heartbeat occur? During systole, the atria contract together followed by the ventricles contracting together. This is followed by diastole, a rest phase, when the chambers relax. This cardiac cycle, or heartbeat, occurs 70 times/minute on average. 19

20 5.3 The Heart is a Double Pump What is the cardiac cycle? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pulmonary trunk aorta semilunar valves superior vena cava semilunar valves close ( dup ) aortic semilunar valve bicuspid valve right atrium left atrium right atrium a. left ventricle inferior vena cava c. right ventricle aorta pulmonary trunk d. atrioventricular (AV) valves close ( lub ) b. represents contraction d: Biophoto Associates/ Photo Researchers Figure 5.5 The stages of the cardiac cycle. 20

21 5.3 The Heart is a Double Pump How is the heartbeat controlled? Internal control: The SA node in the right atrium initiates the heartbeat and causes the atria to contract. This impulse reaches the AV node, also in the right atrium, to send a signal down the AV bundle and Purkinje fibers that causes ventricular contraction. These impulses travel between gap junctions at intercalated disks. 21

22 5.3 The Heart is a Double Pump How is the heartbeat controlled? External control: Heartbeat is also controlled by a cardiac center in the brain and hormones such as epinephrine and norepinephrine. 22

23 5.3 The Heart is a Double Pump Visualizing the heartbeat Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. SA node AV node branches of atrioventricular bundle Purkinje fibers a. Figure 5.6a An electrical signal pathway through the heart. 23

24 5.3 The Heart is a Double Pump Visualizing the gap junctions at the intercalated disks Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. gap junction b. Figure 5.4b The heart is a double pump. 24

25 5.3 The Heart is a Double Pump What is an electrocardiogram (ECG)? It is a record of the electrical changes in the heart muscle during a cardiac cycle. The atria produce an electrical current, called the P wave, when stimulated by the SA node. The contraction of the ventricles is the QRS complex. The recovery of the ventricles is called the T wave. Looking at these electrical changes allows doctors to detect abnormalities. 25

26 5.3 The Heart is a Double Pump What does a normal ECG look like? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. R P T SA node Q AV node branches of atrioventricular bundle b. Normal ECG S b: Ed Reschke Purkinje fibers a. Figure 5.6a-b An electrical signal pathway through the heart. 26

27 5.4 Features of the Cardiovascular System What is blood pressure? It is the pressure against a blood vessel wall, usually measured in an artery of the arm. The highest pressure, called the systolic pressure, is during blood ejection from the heart. The lowest pressure, the diastolic pressure, occurs when the ventricles relax. Average blood pressure is recorded at about 120/80 mmhg (systolic/diastolic). Reminder: this is controlled by the arterioles. 27

28 5.4 Features of the Cardiovascular System What is blood pressure? Figure 5.7 Sphygmomanometers measure blood pressure. 28

29 5.4 Features of the Cardiovascular System How is blood pressure categorized? 29

30 5.4 Features of the Cardiovascular System What is important about blood flow? Blood flow is under the highest pressure in the arteries but remember the thick, muscular walls. Blood flow is slower in the capillaries which is important to allow time for exchange between cells. Blood pressure is minimal in the veins and venules but blood flow increases. 30

31 5.4 Features of the Cardiovascular System Relative magnitude What is important about blood flow? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. arteries arterioles capillaries venules veins blood pressure total cross-sectional area of vessels velocity Blood flow (starting from heart) Figure 5.8 Blood velocity and pressure in the blood vessels. 31

32 5.4 Features of the Cardiovascular System If blood pressure is so low in the veins, why does the blood flow increase? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. to heart to heart They have help. 1. Skeletal muscle contraction 2. Breathing 3. Valves Figure 5.9 The skeletal muscle pump. a. Contracted skeletal muscle pushes blood past open valve. b. Closed valve prevents backward flow of blood. 32

33 5.5 Two Cardiovascular Pathways What are the 2 cardiovascular pathways Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. in the body? jugular vein (also subclavian vein from arms) CO 2 head and arms O 2 carotid artery (also subclavian artery to arms) Pulmonary circuit the right side of the heart that brings blood from the body to the heart and the lungs pulmonary artery superior vena cava CO 2 O 2 O 2 CO 2 lungs pulmonary vein aorta heart Systemic circuit the left side of the heart that brings blood to the entire body to deliver nutrients and rid it of wastes inferior vena cava hepatic vein hepatic portal vein renal vein iliac vein liver kidneys digestive tract intestinal artery renal artery iliac artery Figure 5.10 Overview of the cardiovascular system. CO 2 trunk and legs O 2 33

34 5.5 Two Cardiovascular Pathways Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. common carotid artery internal jugular vein superior vena cava external jugular vein subclavian artery subclavian vein inferior vena cava renal artery abdominal aorta mesenteric vein common iliac vein renal vein inferior mesenteric artery common iliac artery femoral artery femoral vein great sphenoid vein Figure 5.11 The major arteries and veins of the systemic circuit. 34

35 5.5 Two Cardiovascular Pathways The heart s blood supply: Coronary circulation There are small coronary arteries that supply the heart. They are separate from the systemic and pulmonary pathways of the body. 35

36 5.5 Two Cardiovascular Pathways What is the hepatic portal system? It is a system that brings amino acid- and glucoserich blood from the digestive tract to the liver. The liver synthesizes blood proteins and stores the glucose as glycogen. The liver also plays a role in purifying blood from the digestive tract. Finally, the blood will return to the heart via the inferior vena cava. 36

37 5.6 Exchange at the Capillaries Exchange at the capillary beds is primarily a result of osmotic and blood pressure Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. from heart Arterial End Blood pressure is higher than osmotic pressure. Net pressure out. water oxygen amino acids Tissue Fluid glucose carbon dioxide wastes Venous End Osmotic pressure is higher than blood pressure. Net pressure in. water to heart salt plasma protein arteriole smooth muscle fiber osmotic pressure blood pressure venule Figure 5.12 The movement of solutes in a capillary bed. 37

38 5.6 Exchange at the Capillaries Exchange at the capillaries Lymphatic capillary beds lie alongside capillary beds. When lymphatic capillaries take up excess fluid it becomes lymph. Lymph returns to the cardiovascular veins in the chest. Precapillary sphincters can shut down a blood capillary, and blood then flows through the shunt. 38

39 5.6 Exchange at the Capillaries Exchange at the capillaries Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. arteriole tissue cells lymphatic capillary blood capillary lymphatic duct venule Figure 5.13 Interaction of lymphatic and capillary beds. 39

40 5.7 Cardiovascular Disorders Why should we care about cardiovascular disease? Cardiovascular disease (CVD) is the most common cause of death in the Western world. 40

41 5.7 Cardiovascular Disorders Disorders of the blood vessels Hypertension/high blood pressure Atherosclerosis Stroke Heart attack Aneurysm 41

42 5.7 Cardiovascular Disorders Hypertension High blood pressure results when blood moves through vessels at a rate higher than normal, often due to arterial plaque. 140/90 mmhg is considered hypertension. It is a silent killer because there are few symptoms. It can lead to a heart attack, stroke, or kidney failure. 42

43 5.7 Cardiovascular Disorders Atherosclerosis It is a build up of plaque in blood vessels. Plaque that is stationary is called a thrombus, and an embolus when it detaches and can move to distant sites. It is associated with a stroke, heart attack, and aneurysm. 43

44 5.7 Cardiovascular Disorders Atherosclerosis coronary artery Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ulceration lumen of vessel fat cholesterol crystals atherosclerotic plaque Biophoto Associates/Photo Researchers Figure 5B Coronary arteries and plaque. 44

45 5.7 Cardiovascular Disorders Stroke A stroke is also known as a cerebrovascular accident (CVA). It usually occurs when a cranial artery is blocked or bursts. Part of the brain dies dues to lack of oxygen. Symptoms may include numbness of hands or face, difficulty speaking, and inability to see in one eye. 45

46 5.7 Cardiovascular Disorders Heart attack A heart attack is also known as a myocardial infarction (MI). Part of the heart dies due to lack of oxygen. It can begin with angina pectoris, a pain that radiates down the left arm due to a blockage of a coronary artery. 46

47 5.7 Cardiovascular Disorders Aneurysm It is a ballooning of a blood vessel. Atherosclerosis and hypertension can weaken a vessel and cause ballooning. The most commonly affected is the abdominal artery or the arteries leading to the brain. 47

48 5.7 Cardiovascular Disorders How are disorders of the blood vessels treated? Dissolving blood clots t-pa is a drug that dissolves clots 48

49 5.7 Cardiovascular Disorders How are disorders of the blood vessels treated? Treating clogged arteries Bypass surgery: usually a vein from the leg is taken and used to bypass a clogged artery Stents: wire mesh cylinder inserted into a clogged artery to hold it open Angioplasty: a tube with a balloon is inserted into the clogged area and the balloon is then inflated to open the vessel A stent and angioplasty may be used in combination 49

50 Treatments for Atherosclerotic Plaque in Coronary Arteries 50

51 5.7 Cardiovascular Disorders Disorders of the heart and its treatment Disorders Heart failure is when the heart no longer pumps properly. Treatments Left ventricular assist device (LVAD) Heart transplant either natural or artificial 51

52 5.7 Cardiovascular Disorders Disorders of the heart and its treatment Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. replacement heart wireless energytransfer system external wireless driver Figure 5.15 An artificial heart. internal controller external battery pack (right): Courtesy SynCardia Systems, Inc. rechargeable internal battery photograph of artificial heart 52

53 5.7 Cardiovascular Disorders Cardiovascular Disease Prevention Preventable risk factors include: use of tobacco products. drug and alcohol abuse. obesity and a sedentary lifestyle. poor diet. stress. poor dental hygiene. 53