Circulation Chapter 37 Part 2
37.7 Pressure, Transport, and Flow Distribution Contracting ventricles put pressure on the blood, forcing it through a series of vessels Arteries carry blood from ventricles to arterioles Arterioles control blood distribution to capillaries Capillaries exchange substances Venules collect blood from capillaries Veins deliver blood back to heart
Human Blood Vessels
Fig. 37-17a, p. 648
outer coat smooth muscle basement membrane endothelium Artery elastic tissue elastic tissue Fig. 37-17a, p. 648
Fig. 37-17b, p. 648
outer coat smooth muscle rings over elastic tissue basement membrane endothelium Arteriole Fig. 37-17b, p. 648
Fig. 37-17c, p. 648
basement membrane endothelium Capillary (venules have a similar structure) Fig. 37-17c, p. 648
Fig. 37-17d, p. 648
outer coat smooth muscle, elastic fibers basement membrane endothelium Vein valve Fig. 37-17d, p. 648
Blood Pressure Blood pressure The pressure exerted by blood on the walls of blood vessels Highest in arteries, then declines through circuit Rate of blood flow depends on the difference in blood pressure between two points, and resistance to flow
Blood Pressure in the Systolic Circuit
arteries capillaries veins arterioles venules Fig. 37-18, p. 648
Blood Flow Thick, elastic arteries smooth out variations in blood pressure during the cardiac cycle Arterioles respond to signals from the autonomic and nervous systems, and to chemical signals, to direct blood flow to different parts of the body
Distribution of Cardiac Output in a Resting Person
100% lungs heart s right half heart s left half liver 6% digestive tract 21% kidneys 20% skeletal muscle 15% brain 13% skin 9% bone 5% cardiac muscle 3% all other regions 8% Fig. 37-19, p. 649
Controlling Blood Pressure Blood pressure depends on total blood volume, how much blood the ventricles pump (cardiac output), and whether arterioles are constricted or dilated Receptors in the aorta and carotid arteries monitor blood pressure and send signals to the medulla, which regulates cardiac output and arteriole diameter
Measuring Blood Pressure
Animation: Measuring blood pressure
37.8 Diffusion at Capillaries, Then Back to the Heart Capillary A cylinder of endothelial cells, one cell thick Capillary beds are diffusion zones, where blood exchanges substances with interstitial fluid Hydrostatic pressure moves materials out (ultrafiltration) Osmotic pressure moves water in (capillary reabsorption)
Fluid Movement at a Capillary Bed
blood to venule blood from arteriole high pressure causes outward flow A cells of tissue inward-directed osmotic movement B Fig. 37-21 (a-b), p. 650
Venous Pressure Venules deliver blood from capillaries to veins Veins deliver blood to the heart Large-diameter, blood volume reservoirs Valves help prevent backflow Amount of blood in veins varies with activity level
Venous Valve Action
Fig. 37-22a, p. 651
venous valve Fig. 37-22a, p. 651
Fig. 37-22b, p. 651
blood flow to heart valve open valve closed Fig. 37-22b, p. 651
Fig. 37-22c, p. 651
valve closed valve closed Fig. 37-22c, p. 651
37.7-37.8 Key Concepts Blood Vessel Structure and Function The heart pumps blood rhythmically, on its own Adjustments at arterioles regulate how blood volume is distributed among tissues Exchange of gases, wastes, and nutrients between the blood and tissues takes place at capillaries
37.9 Blood and Cardiovascular Disorders Red blood cell disorders Anemias, beta-thalassemias, polycythemia White blood cell disorders Infectious mononucleosis, leukemias, lymphomas Clotting disorders Hemophilia, thrombus, embolus
Blood and Cardiovascular Disorders Atherosclerosis Buildup of lipids in the arterial wall that narrows the lumen, may rupture and trigger heart attack
Fig. 37-23a, p. 652
wall of artery, cross-section unobstructed lumen of a normal artery Fig. 37-23a, p. 652
Fig. 37-23b, p. 652
atherosclerotic plaque blood clot sticking to plaque narrowed lumen Fig. 37-23b, p. 652
Clogged Coronary Arteries
coronary artery Fig. 37-24a, p. 653
aorta coronary artery blockage location of a shunt made of a section taken from one of the patient s other blood vessels Fig. 37-24b, p. 653
Blood and Cardiovascular Disorders Hypertension a silent killer Chronic blood pressure above 140/90 High blood pressure and atherosclerosis increase the risk of heart attack and stroke
Blood and Cardiovascular Disorders Arrhythmias abnormal heart rhythms EKGs record electrical activity of cardiac cycle
one normal heartbeat 0 0.2 0.4 0.6 0.8 a time (seconds) b c bradycardia (here, 46 beats per minute) tachycardia (here, 136 beats per minute) ventricular fibrillation d Fig. 37-25, p. 653
Risk Factors Cardiovascular disorders are the leading cause of death in the United States Risk factors Tobacco smoking, family history, hypertension, high cholesterol, diabetes mellitus, obesity, age, physical inactivity, gender
37.9 Key Concepts When the System Breaks Down Cardiovascular problems include clogged blood vessels or abnormal heart rhythms Some problems have a genetic basis; most are related to age or life-style
37.10 Interactions With the Lymphatic System Vessels and organs of the lymphatic system interact closely with the circulatory system Lymph vascular system Lymph capillaries and vessels that collect water and solutes from interstitial fluid and deliver them to the circulatory system
Three Functions of the Lymph Vascular System Returns fluids and plasma proteins that leak out of capillaries to the circulatory system Delivers fats absorbed from the small intestine to the blood Transports cellular debris, pathogens, and foreign cells to lymph nodes
Lymphoid Organs and Tissues Lymph nodes Organs that filter lymph before it enters blood and identify pathogens Tonsils in throat and adenoids in nasal cavity Respond to inhaled pathogens
Lymphoid Organs and Tissues Spleen Filters pathogens and worn out blood cells from blood Thymus gland Matures T lymphocytes essential to the immune system
Components of the Lymphatic System
Fig. 37-26a, p. 654
Tonsils Defense against bacteria and other foreign agents Right Lymphatic Duct Drains right upper portion of the body Thymus Gland Site where certain white blood cells acquire means to chemically recognize specific foreign invaders Thoracic Duct Drains most of the body Spleen Major site of antibody production; disposal site for old red blood cells and foreign debris; site of red blood cell formation in the embryo Some Lymph Vessels Return excess interstitial fluid and reclaimable solutes to the blood Some Lymph Nodes Filter bacteria and many other agents of disease from lymph Bone Marrow Marrow in some bones is production site for infectionfighting blood cells (as well as red blood cells and platelets) Fig. 37-26a, p. 654
Fig. 37-26b, p. 654
lymph capillary interstitial fluid flaplike valve made of overlapping cells at tip of lymph capillary capillary bed Fig. 37-26b, p. 654
Fig. 37-26c, p. 654
lymph trickles past organized arrays of lymphocytes valve (prevents backflow) Fig. 37-26c, p. 654
Animation: Human lymphatic system
Animation: Lymph vascular system
37.10 Key Concepts Links With the Lymphatic System A lymph vascular system delivers excess fluid that collects in tissues to the blood Lymphoid organs cleanse blood of infectious agents and cellular debris
Animation: Capillary forces
Animation: Examples of ECGs
Animation: Vein function
Animation: Vessel anatomy
ABC video: Pollution and Women s Health
ABC video: A new medicine for stroke victims
ABC video: Second-Chance Heart
ABC video: Heart Healthy
Video: And then my heart stood still