Chapter 15 Circulation Of Blood PDF

Circulation of Blood Chapter 15 Copyright © 2017, Elsevier Inc. All Rights Reserved. 1 Learning Objectives Lesson 15.1: Circulation of Blood 1. 2. 3. Describe the structure and function of each major type of blood vessel: artery, vein, and capillary. List the major disorders of blood vessels a...

Circulation of Blood Chapter 15 Copyright © 2017, Elsevier Inc. All Rights Reserved. 1 Learning Objectives Lesson 15.1: Circulation of Blood 1. 2. 3. Describe the structure and function of each major type of blood vessel: artery, vein, and capillary. List the major disorders of blood vessels and explain how they develop. Trace the path of blood through the systemic, pulmonary, portal, and fetal circulations. Copyright © 2017, Elsevier Inc. All Rights Reserved. 2 Learning Objectives Lesson 15.1: Circulation of Blood (Cont.) 4. 5. 6. 7. Define hemodynamics, and identify and discuss the factors involved in the generation of blood pressure and how they relate to each other. Define pulse and locate the major pulse points on the body. Define hypertension and its associated risk factors and complications. Explain what is meant by the term circulatory shock and describe the major types. Copyright © 2017, Elsevier Inc. All Rights Reserved. 3 Blood Vessels  Types ➢ ➢ ➢ Arteries: Carry blood away from the heart and toward capillaries Veins: Carry blood toward the heart and away from capillaries Capillaries: Carry blood from the arterioles to the venules Copyright © 2017, Elsevier Inc. All Rights Reserved. 4 Structure of Blood Vessels  Arteries ➢ ➢ ➢  Tunica intima: Inner layer of endothelial cells Tunica media: Smooth muscle, thick in arteries; some elastic tissue; important in blood pressure regulation Tunica externa: Outer layer of fibrous connective elastic tissue Capillaries: Microscopic vessels ➢ Only one layer: The tunica intima Copyright © 2017, Elsevier Inc. All Rights Reserved. 5 Structure of Veins    Tunica intima: Inner layer; valves prevent retrograde movement of blood Tunica media: Smooth muscle; thin in veins Tunica externa: Heavy layer of fibrous connective tissue in many veins Copyright © 2017, Elsevier Inc. All Rights Reserved. 6 Artery and Vein Copyright © 2017, Elsevier Inc. All Rights Reserved. 7 Blood Vessels: Functions    Arteries: Distribute nutrients, gases, etc., carried in the blood by way of high pressure; assist in maintaining the arterial blood pressure; serve as blood reservoirs Capillaries: Serve as exchange vessels for nutrients, wastes, and fluids Veins: Collect blood for return to the heart; low-pressure flow of blood (compared with arteries) Copyright © 2017, Elsevier Inc. All Rights Reserved. 8 Capillary Exchange Copyright © 2017, Elsevier Inc. All Rights Reserved. 9 Disorders of Blood Vessels  Disorders of arteries: Arteries must withstand high pressure and remain free of blockage ➢ Arteriosclerosis: Hardening of arteries caused by calcification of fatty deposits on arterial walls • • ➢ Reduces flow of blood, possibly causing ischemia that may progress to necrosis (or gangrene) May be corrected by vasodilators (vessel-relaxing drugs) or angioplasty (mechanical widening of vessels), or surgical replacement Atherosclerosis: Lipids and other matter block arteries Copyright © 2017, Elsevier Inc. All Rights Reserved. 10 Atherosclerosis Copyright © 2017, Elsevier Inc. All Rights Reserved. 11 Balloon Angioplasty Copyright © 2017, Elsevier Inc. All Rights Reserved. 12 Disorders of Arteries  Aneurysm: Abnormal widening of arterial wall ➢ ➢ ➢ Promotes formation of thrombi that may obstruct blood flow to vital tissues Arterial walls may burst, resulting in lifethreatening hemorrhaging Cerebrovascular accident (CVA) or stroke: Ischemia of brain tissue caused by embolism or hemorrhage Copyright © 2017, Elsevier Inc. All Rights Reserved. 13 Disorders of Veins  Veins are low-pressure vessels ➢ Varicose veins (varices): Enlarged veins in which blood pools • • ➢ Hemorrhoids are varicose veins in the rectum Treatments include supporting affected veins and surgical removal of veins Thrombophlebitis: Vein inflammation (phlebitis) accompanied by clot (thrombus) formation; may result in fatal pulmonary embolism Copyright © 2017, Elsevier Inc. All Rights Reserved. 14 Varicose Veins Copyright © 2017, Elsevier Inc. All Rights Reserved. 15 Circulation of Blood  Systemic and pulmonary circulation ➢ ➢ Blood circulation: Refers to the flow of blood through all the vessels, which are arranged in a complete circuit or circular pattern Systemic circulation • • Carries blood throughout the body Path goes from left ventricle through aorta, smaller arteries, arterioles, capillaries, venules, venae cavae, to right atrium Copyright © 2017, Elsevier Inc. All Rights Reserved. 16 Blood Flow in the Circulatory System Copyright © 2017, Elsevier Inc. All Rights Reserved. 17 Pulmonary and Hepatic Portal Circulation  Pulmonary circulation ➢ ➢ ➢  Carries blood to and from the lungs Arteries deliver deoxygenated blood to the lungs for gas exchange Path goes from right ventricle through pulmonary arteries, lungs, pulmonary veins, to left atrium Hepatic portal circulation ➢ ➢ ➢ ➢ Unique blood route through the liver Vein (hepatic portal vein) exists between two capillary beds Assists with homeostasis of blood glucose levels Stores glycogen and detoxifies the blood Copyright © 2017, Elsevier Inc. All Rights Reserved. 18 Hepatic Portal Circulation Copyright © 2017, Elsevier Inc. All Rights Reserved. 19 Fetal Circulation    Refers to circulation before birth Modifications required for fetus to efficiently secure oxygen and nutrients from the maternal blood Unique structures include the placenta, umbilical arteries and vein, ductus venosus, ductus arteriosus, and foramen ovale Copyright © 2017, Elsevier Inc. All Rights Reserved. 20 Fetal Circulation (Cont.) Copyright © 2017, Elsevier Inc. All Rights Reserved. 21 Changes to Fetal Circulation at Birth     Baby’s specialized fetal blood vessels must stop working When newborn first breathes air, the pressure exerted closes off those vessels and the foramen ovale If the foramen ovale fails to close, ventricular septal defect (VSD) occurs, creating a lack of oxygen Resulting bluish tint is called cyanosis Copyright © 2017, Elsevier Inc. All Rights Reserved. 22 Blood Pressure  Defining blood pressure ➢ ➢ ➢ “Push” or force of blood in the blood vessels Exists in all blood vessels: Highest in arteries, lowest in veins Blood pressure gradient: Causes blood to circulate; liquids can flow only from areas of high pressure to areas of low pressure • • Low or nonexistent blood pressure gradient is fatal if not reversed Hypertension (HTN; high blood pressure) can cause a blood vessel to rupture Copyright © 2017, Elsevier Inc. All Rights Reserved. 23 Pressure Gradients in Blood Flow Copyright © 2017, Elsevier Inc. All Rights Reserved. 24 Factors That Influence Blood Pressure    Blood volume: The larger the volume, the more pressure is exerted on vessel walls Strength of heart contractions: Affect cardiac output; stronger heartbeat increases pressure; weaker beat decreases it Heart rate: Increased rate increases pressure; decreased rate decreases pressure Copyright © 2017, Elsevier Inc. All Rights Reserved. 25 Blood Viscosity and Resistance to Flow   Blood viscosity (thickness): Less-than-normal viscosity decreases pressure; greater-thannormal viscosity increases pressure Resistance to blood flow (peripheral resistance): Affected by many factors, including the vasomotor mechanism (vessel muscle contraction and relaxation) Copyright © 2017, Elsevier Inc. All Rights Reserved. 26 Vasomotor Mechanism Copyright © 2017, Elsevier Inc. All Rights Reserved. 27 Fluctuations in Arterial Blood Pressure    Blood pressure varies within normal range from time to time Central venous pressure: Influences pressure in large peripheral veins Venous return of blood to the heart depends on five mechanisms ➢ ➢ ➢ ➢ ➢ A strongly beating heart An adequate arterial blood pressure Valves in the veins Pumping action of skeletal muscles as they contract Changing pressures in the chest cavity caused by breathing Copyright © 2017, Elsevier Inc. All Rights Reserved. 28 Pulse   Definition: Alternate expansion and recoil of the blood vessel wall Nine major pulse points named after arteries over which they are felt Copyright © 2017, Elsevier Inc. All Rights Reserved. 29 Pulse Points Copyright © 2017, Elsevier Inc. All Rights Reserved. 30 Hypertension (HTN)     Occurs when blood pressure exceeds 140/90 mm Hg Ninety percent of HTN cases are primary essential (idiopathic); secondary HTN can be caused by kidney disease or other causes Many risk factors for HTN, including genetics, age, stress, obesity, and more Untreated HTN may contribute to heart disease, kidney failure, and stroke Copyright © 2017, Elsevier Inc. All Rights Reserved. 31 Classification of Hypertension (HTN) Copyright © 2017, Elsevier Inc. All Rights Reserved. 32 Circulatory Shock  Failure of the circulatory system to deliver oxygen to the tissues adequately, resulting in cell impairment ➢ Cardiogenic shock: Caused by heart failure Copyright © 2017, Elsevier Inc. All Rights Reserved. 33 Hypovolemic Shock   Drop in blood volume that causes blood pressure (and blood flow) to drop Often caused by hemorrhage or loss of interstitial fluid, causing blood plasma to drain out of the vessels Copyright © 2017, Elsevier Inc. All Rights Reserved. 34 Neurogenic Shock   Caused by nerve condition that relaxes (dilates) blood vessels and thus reduces blood flow Occurs when sympathetic stimulation is disrupted Copyright © 2017, Elsevier Inc. All Rights Reserved. 35 Anaphylactic Shock   Results from an acute allergic reaction called anaphylaxis Causes the same kind of blood vessel dilation that occurs in neurogenic shock Copyright © 2017, Elsevier Inc. All Rights Reserved. 36 Septic Shock   Results from complications of septicemia (toxins in blood resulting from infection) Toxins dilate blood vessels, inducing shock Copyright © 2017, Elsevier Inc. All Rights Reserved. 37 Questions? Copyright © 2017, Elsevier Inc. All Rights Reserved. 38