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Circulatory System B Circulation/Transport capillaries -actual site of exchange General venules & veins two major transport systems in body: – bring blood from capillaries back to heart A. The Circulatory System B. Lymphatic System B. The Lymphatic Sysem an open system that returns excess materials circulatory system works in conjunction with in the tissue spaces back to the blood lymphatic system fluid = lymph ! they are directly connected to each other no dedicated pump; muscle contractions A. Circulatory (cardiovascular) System move lymph along circulatory system consists of “plumbing” and lymphatic vessels move lymph in one “pumps” & circulating fluid direction; lymph does not circulate pump = the heart fluid = blood blood flows in closed system of vessels over 60,000 miles of vessels (mainly capillaries) >arteries ! capillaries ! veins heart< arteries & arterioles – take blood away from heart to capillaries Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 1 Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 2 The Circulatory System (Cardiovascular System) 4. maintain fluid and electrolyte balances in tissues and cells major connection between external and internal environment: 5. maintain acid/base balances in tissues and cells everything going in or out of body must go 6. help regulate temperature homeostasis transfers excess heat from core to skin for removal through the circulatory system to get to where its going C. Protective Functions: more than 60,000 miles of blood vessels with a pump 7. Clotting and Inflammation prevent excessive that beats 100,000 times each day fluid loss and limit the spread of infection General Functions of Circulatory System: 8. Circulating cells and chemicals actively seek out and remove pathogens from the body A. Transport = “immune system” B. Homeostasis C. Protection A. Transport functions: 1. Pick up food and oxygen from digestive and respiratory systems and deliver them to cells 2. pick up wastes and carbon dioxide from cells and deliver to kidneys and lungs 3. Transport hormones & other chemicals, enzymes etc throughout the body B. Homeostasis functions: Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 3 Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 4 The Heart – Anatomy lower border of heart (=apex) lies on diaphragm we are more aware of our heart than most other internal organs heart is enclosed in its own sac, = pericardium (=pericardial sac)(parietal pericardium) Some ancient Chinese, Egyptian, Greek and Roman scholars correctly composed of tough fibrous outer layer and inner surmised that the heart is a pump for filling vessels with blood serous membrane Aristotle however thought the heart was the seat of emotion and a source of heat to aid digestion: outer surface of heart is also covered with serous excited ! heart beats faster membrane (= visceral pericardium) “heartache” of grief (=epicardium) continuous with the pericardium his thoughts predominated for over 2000 years before its true nature reemerged between the 2 membranes is pericardial fluid !lubrication the heart is one of first organ systems to appear in pericarditis = inflammation of pericardium, developing embryo membranes become dry, each heartbeat becomes painful th ! heart is beating by 4 week wall of heart: study of heart = cardiology epicardium = visceral pericardium no machine works as long or as hard as your heart thin & transparent serous tissue beats: >100,000 x’s/day > 30 Million times each year myocardium = cardiac muscle cell > 3 Billion times in a lifetime to pump > 1 Million most of heart barrels of blood branching, interlacing contractile tissue heart is about size and shape of closed fist acts as single unit (gap junctions) endocardium = delicate layer of endothelial cells heart lies behind sternum in mediastinum, continuous with inner lining of blood vessels broad superior border of heart = base [endocarditis] Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 5 Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 6 Heart Chambers Heart Valves interior of heart is subdivided into 4 chambers: There are also 4 one-way valves that direct flow of blood through the heart in one direction: atria = two upper chambers with auricles 2 Atrioventricular (AV) valves smaller, thinner, weaker bicuspid (Mitral) valve ventricles = two lower chambers - separates left atrium and ventricle - consists of two flaps of tissues larger, thicker, stronger left ventricle much larger and thicker than tricuspid valve right ventricle - separates right atrium and ventricle - consists of three flaps of tissues left ventricle is at apex of heart both held in place by chordae tendinae Heart Vessels attached to papillary muscles There are 4 major vessels attached to heart: ! prevent backflow (eversion) keeps valves pointed in direction of flow 2 arteries (take blood away from heart): 2 Semilunar valves aorta - from left ventricle pulmonary trunk at beginning of arteries leaving the ventricles - from right ventricle aortic SL valve 2 veins (bring blood back to heart): at beginning of aorta pulmonary SL valve vena cava (superior & inferior) at beginning of pulmonary trunk - to right atrium pulmonary veins (4 in humans) - to left atrium Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 7 Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 8 Blood Vessels b. Tunica Media blood flows in closed system of vessels middle, made mainly of smooth muscle with some over 60,000 miles of vessels (mainly capillaries) elastic tissue and collagen fibers >arteries ! capillaries ! veins strengthens vessel walls ! prevent high pressure from rupturing them heart< allows vasodilation and vasoconstriction arteries & arterioles – take blood away from heart to capillaries usually the thickest layer, especially in arteries capillaries -actual site of exchange c. Tunica Interna (=T. Intima) venules & veins inner endothelium – bring blood from capillaries back to heart exposed to blood Histology of Vessels when damaged or inflamed induce platelets or walls of arteries and veins consist of three layers: WBC’s to adhere a. Tunica Externa b. Tunica Media ! may lead to plaque buildup and atherosclerosis c. Tunica Interna aneurysm = a weak point in arterial wall forms a. Tunica Externa (= T. adventitia) Is a bulging sac that may rupture or put pressure on nearby brain tissue, vessels or other passageways. outer loose connective tissue usually due to degeneration of the tunica media, atherosclerosis or hypertension anchors the vessel and provides passage for small nerves, lymphatic vessels and smaller blood Most common in abdominal aorta, renal arteries and circle of Willis vessels Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 9 Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 10 Types of Blood Vessels ~70% of all blood is in veins & venules ~60% in veins, ~10% in venules 1. Arteries & Arterioles low pressure: built to withstand the greatest pressure of the 12 – 8 mmHg venules 6 – 1 mmHg veins system larger veins near 0 !strong resilient walls, !thick layers of connective tissues many of the medium veins, especially in limbs !more muscular than veins have = 1 way valves arteries and arterioles typically contain ~25% of 3. Capillaries: all blood in circulation 15% in arteries; 10% in arterioles actual site of exchange of materials pressure is variable ! the rest is just pumps and plumbing MAP ~ 93 varies from 100 – 40 mmHg most organs receive blood from >1 arterial branch consist of only a single layer of squamous provides alternate pathways epithelium= endothelial layer (=tunica intima) 2. Veins & Venules arranged into capillary beds = functional units of circulatory system generally have a greater diameter than arteries but thinner walls, flaccid capillaries are extremely abundant in almost every ! more compliant tissue of the body three layer are all thinner than in arteries ! most of the 62,000 miles of blood vessels is tunica adventitia is thickest of three capillaries but not as elastic as arteries only 5% of blood at any one time is in capillaries little smooth muscle Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 11 Human Anatomy & Physiology: Circulatory System, Ziser Lecture Notes, 2013.11 12 Circuits of Bloodflow Anatomy of Circulatory System arteries, capillaries and veins are arranged into two Major Arteries and Veins circuits: Pulmonary Circuit: Arteries pulmonary a. pulmonary: heart ! lungs ! heart rt ventricle! pulmonary arteries (trunk)!lungs!pulmonary Veins pulmonary v. veins!left atrium Systemic Circuit: Arteries aorta systemic: heart ! rest of body ! heart ascending aorta rt & lft coronary a. left ventricle!aorta!body!vena cava!rt atrium aortic arch brachiocephalic a. common carotid a. heart is a double pump internal carotid a. oxygen deficient blood in pulmonary artery and vena cava external carotid a. ! usually blue on models subclavian a. axillary a. brachial a. lft common carotid a. lft subclavian a descending aorta celiac trunk superior mesenteric a. renal a. gonadal a. inferior mesenteric a. common iliac a. internal iliac a. external iliac a. femoral a. Veins: superior vena cava coronary v. brachiocephalic v. jugular v. subclavian v. axillary v. brachial v. inferior vena cava hepatic v. hepatic portal v. superior mesenteric v. inferior mesenteric v. renal
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