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Chapter 13 Cardiovascular System 1 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction A. B. C. The cardiovascular system consists of the heart and vessels (arteries, capillaries and veins.) A functional cardiovascular system is vital for supplying oxygen and nutrients to tissues and removing wastes from them. Deoxygenated blood is carried by the pulmonary circuit to the lungs, while the systemic circuit sends oxygenated blood to all body cells. 2 Fig13.01 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The systemic circuit delivers oxygen to all body cells and carries away wastes. The pulmonary circuit eliminates carbon dioxide via the lungs and oxygenates the blood. Deoxygenated blood Oxygenated blood O2 O2 CO2 Oxygenated blood pumped to all body tissues via aorta O2 CO2 Deoxygenated blood pumped to lungs via pulmonary arteries CO2 CO2 CO2 O2 CO2 CO2 O2 O2 CO2 O2 Alveolus O2 Oxygenated blood returns to heart via pulmonary veins Deoxygenated blood returns to heart via venae cavae Left atrium Right atrium Left ventricle Right ventricle 3 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Structure of the Heart A. B. The heart is a hollow, cone-shaped, muscular pump within the thoracic cavity. Size and Location of the Heart 1. The average adult heart is 14 cm long and 9 cm wide. 2. The heart lies in the mediastinum under the sternum; its apex extends to the fifth intercostal space and the base lies beneath the second rib. 4 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Coverings of the Heart 1. The pericardium encloses the heart. 2. It is made of two layers: the outer, tough connective tissue fibrous pericardium surrounding a more delicate visceral pericardium (epicardium) that surrounds the heart. 5 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. At the base of the heart, the visceral pericardium folds back to become the parietal pericardium that lines the fibrous pericardium. 4. Between the parietal and visceral pericardia is a potential space (pericardial cavity) filled with serous fluid. 6 Fig13.02 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right lung Left lung Aorta Superior vena cava Pulmonary trunk Diaphragm Left auricle Cut edge of fibrous pericardium Right auricle Right atrium Cut edge of parietal pericardium Heart (covered by visceral pericardium) Left ventricle Right ventricle Pericardial cavity 7 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Wall of the Heart 1. The wall of the heart is composed of three distinct layers. 2. The outermost layer, the epicardium, is made up of connective tissue and epithelium, and houses blood and lymph capillaries along with coronary arteries. It is the same as the visceral pericardium. 8 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. The middle layer called myocardium consists of cardiac muscle and is the thickest layer of the heart wall. The inner endocardium is smooth and is made up of connective tissue and epithelium, and is continuous with the endothelium of major vessels joining the heart. a. The endocardium contains the Purkinje fibers. 9 Fig13.04 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pericardial cavity Parietal pericardium Fibrous pericardium Endocardium Myocardium Coronary blood vessel Epicardium (visceral pericardium) 10 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Heart Chambers and Valves 1. The heart has four internal chambers: two atria on top and two ventricles below. a. Atria receive blood returning to the heart and have thin walls and ear-like auricles projecting from their exterior. b. The thick-muscled ventricles pump blood to the body. 11 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. A septum divides the atrium and ventricle on each side. Each also has an atrioventricular (A-V) valve to ensure one way flow of blood. a. The right A-V valve (tricuspid) and left A-V valve (bicuspid or mitral valve) have cusps to which chordae tendinae attach. 12 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. b. Chordae tendinae are, in turn, attached to papillary muscles in the inner heart wall that contract during ventricular contraction to prevent the backflow of blood through the A-V valves. 13 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The superior and inferior vena cavae bring blood from the body to the right atrium. 4. The right ventricle has a thinner wall than does the left ventricle because it must pump blood only as far as the lungs, compared to the left ventricle pumping to the entire body. 14 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. At the base of the pulmonary trunk leading to the lungs is the pulmonary valve, which prevents a return flow of blood to the ventricle. 6. The left atrium receives blood from four pulmonary veins. Blood passes from the left atrium into the left ventricle through the mitral valve. 7. The left ventricle pumps blood into the entire body through the aorta, guarded by the aortic valve that prevents backflow of blood into the ventricle. 15 Fig13.05 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior vena cava Aortic valve Right pulmonary artery Right pulmonary veins Right atrium Opening of coronary sinus Tricuspid valve Right ventricle Inferior vena cava Aorta Left pulmonary artery Pulmonary trunk Left pulmonary veins Left atrium Mitral (bicuspid) valve Chordae tendineae Left ventricle Papillary muscle Interventricular septum CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Skeleton of the Heart 1. Rings of dense connective tissue surround the pulmonary trunk and aorta to provide attachments for the heart valves and fibers. 2. These tough rings prevent dilating of tissue in this area. 17 Fig13.06a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © The McGraw -Hill Companies,Inc./University of Michigan Biomedical Communications (a) Fig13.06b Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Opening of left coronary artery Tricuspid valve Mitral valve Fibrous skeleton (b) Posterior CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Path of Blood Through the Heart 1. Blood low in oxygen returns to the right atrium via the venae cavae and coronary sinus. 2. The right atrium contracts, forcing blood through the tricuspid valve into the right ventricle. 20 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The right ventricle contracts, closing the tricuspid valve, and forcing blood through the pulmonary valve into the pulmonary trunk and arteries. 4. The pulmonary arteries carry blood to the lungs where it can rid itself of excess carbon dioxide and pick up a new supply of oxygen. 21 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Freshly oxygenated blood is returned to the left atrium of the heart through the pulmonary veins. 6. The left atrium contracts, forcing blood through the left bicuspid valve into the left ventricle. 7. The left ventricle contracts, closing the bicuspid valve and forcing open the aortic valve as blood enters the aorta for distribution to the body. 22 Fig13.07 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Systemic capillaries Tissue cells CO2 Superior vena cava O2 Pulmonary artery Alveolus CO2 CO2 Alveolar capillaries O2 O2 Alveolar capillaries Alveolus Pulmonary veins Right atrium Tricuspid valve Pulmonary valve Right ventricle Inferior vena cava Left atrium Mitral valve Left ventricle Aortic valve Aorta CO2 Systemic capillaries O2 Tissue cells CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. H. Blood Supply to the Heart 1. The first branches off of the aorta, which carry freshly oxygenated blood, are the right and left coronary arteries that feed the heart muscle itself. 2. Branches of the coronary arteries feed many capillaries of the myocardium. 24 Fig13.08 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Aorta Part of aorta removed Aortic valve cusps Right coronary artery Opening of left coronary artery 25 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. The heart muscle requires a continuous supply of freshly oxygenated blood, so smaller branches of arteries often have anastomoses as alternate pathways for blood, should one pathway become blocked. Cardiac veins drain blood from the heart muscle and carry it to the coronary sinus, which empties into the right atrium. 26 Fig13.09a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Aorta Superior vena cava Left pulmonary artery Right pulmonary artery Pulmonary trunk Left pulmonary veins Right pulmonary veins Left auricle Left coronary artery Right auricle Great cardiac vein Anterior interventricular artery (left anterior descending artery) Right coronary artery Anterior cardiac vein Small cardiac vein Inferior vena cava Left ventricle Right ventricle (a) Apex of the heart Fig13.09b Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior vena cava Right pulmonary artery Aorta Left pulmonary artery Left pulmonary veins Right pulmona Left auricle Circumflex artery Left atrium Cardiac vein Right atrium Inferior vena cava Coronary sinus Middle cardiac vein Left ventricle Posterior interventricular artery Right ventricle (b) Apex of the heart CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Heart Actions A. The cardiac cycle consists of the atria beating in unison (atrial systole) followed by the contraction of both ventricles, (ventricular systole) then the entire heart relaxes for a brief moment (diastole). 29 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Cardiac Cycle 1. During the cardiac cycle, pressure within the heart chambers rises and falls with the contraction and relaxation of atria and ventricles. 2. When the atria fill, pressure in the atria is greater than that of the ventricles, which forces the A-V valves open. 30 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Pressure inside atria rises further as they contract, forcing the remaining blood into the ventricles. 4. When ventricles contract, pressure inside them increases sharply, causing A-V valves to close and the aortic and pulmonary valves to open. a. As the ventricles contract, papillary muscles contract, pulling on chordae tendinae and preventing the backflow of blood through the A-V valves. 31 Fig13.10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve closed Aortic valve closed Pulmonary valve open RA Aortic valve open LA Atrial systole Atrial diastole Tricuspid and mitral valves open (a) LV RV Ventricular diastole Tricuspid and mitral valves closed Ventricular systole (b) 32 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Heart Sounds 1. Heart sounds are due to vibrations in heart tissues as blood rapidly changes velocity within the heart. 2. Heart sounds can be described as a "lubb-dupp" sound. The first sound (lubb) occurs as ventricles contract and A-V valves are closing. 3. 4. The second sound (dupp) occurs as ventricles relax and aortic and pulmonary valves are closing. 33 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Cardiac Muscle Fibers 1. A mass of merging fibers that act as a unit is called a functional syncytium; one exists in the atria (atrial syncytium) and one in the ventricles (ventricular syncytium). 34 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Cardiac Conduction System 1. Specialized cardiac muscle tissue conducts impulses throughout the myocardium and comprises the cardiac conduction system. 2. A self-exciting mass of specialized cardiac muscle called the sinoatrial node (S-A node or pacemaker), located on the posterior right atrium, generates the impulses for the heartbeat. 35 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Impulses spread next to the atrial syncytium, it contracts, and impulses travel to the junctional fibers leading to the atrioventricular node (A-V node) located in the septum. a. Junctional fibers are small, allowing the atria to contract before the impulse spreads rapidly over the ventricles. 36 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Branches of the A-V bundle give rise to Purkinje fibers leading to papillary muscles; these fibers stimulate contraction of the papillary muscles at the same time the ventricles contract. 37 Fig13.11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Interatrial septum Left bundle branch SA node AV node AV bundle Right bundle branch Purkinje fibers Interventricular septum 38 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Electrocardiogram 1. An electrocardiogram (ECG) is a recording of the electrical changes that occur during a cardiac cycle. 2. The first wave, the P wave, corresponds to the depolarization of the atria. 3. The QRS complex corresponds to the depolarization of ventricles and hides the repolarization of atria. The T waves ends the ECG pattern and corresponds to ventricular repolarization. 4. 39 Fig13.14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) 1.0 R Millivolts .5 T P 0 Q –.5 S 0 (b) 200 400 Milliseconds 600 40 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Regulation of the Cardiac Cycle 1. The amount of blood pumped at any one time must adjust to the current needs of the body (more is needed during strenuous exercise). 2. The S-A node is innervated by branches of the sympathetic and parasympathetic divisions, so the CNS controls heart rate. a. Sympathetic impulses increase the speed of heart rate. b. Heart rate is decreased by parasympathetic impulses. 41 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The cardiac control center of the medulla oblongata maintains a balance between the sympathetic and parasympathetic divisions of the nervous system in response to messages from baroreceptors which detect changes in blood pressure. 4. Impulses from the cerebrum or hypothalamus may also influence heart rate, as do body temperature and the concentrations of certain ions. 42 Fig13.16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Receptor Sensory or afferent neuron Central Nervous System Motor or efferent neuron Effector (muscle or gland) (a) Carotid baroreceptors Carotid sinus Cerebrum (frontal section) Sensory fibers Common carotid artery Hypothalamus Aorta Medulla oblongata (transverse section) Cardiac center Aortic baroreceptors Fibers of parasympathetic vagus nerve SA node AV node Spinal cord (transverse sections) Fibers of sympathetic nerve Sympathetic trunk (b) 43 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Vessels A. B. The blood vessels (arteries, arterioles, capillaries, venules, and veins) form a closed tube that carries blood away from the heart, to the cells, and back again. Arteries and Arterioles 1. Arteries are strong, elastic vessels adapted for carrying high-pressure blood. 2. Arteries become smaller as they divide and give rise to arterioles. 44 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The wall of an artery consists of an endothelium, tunica media (smooth muscle), and tunica externa (connective tissue). 4. Arteries are capable of vasoconstriction as directed by the sympathetic impulses; when impulses are inhibited, vasodilation results. 45 Fig13.17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Artery Vein Lumen Valve Endothelium of tunica interna Connective tissue (elastic and collagenous fibers) Tunica media Tunica externa (a) (b) 46 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Capillaries 1. Capillaries are the smallest vessels, consisting only of a layer of endothelium through which substances are exchanged with tissue cells. 2. Capillary permeability varies from one tissue to the next, generally with more permeability in the liver, intestines, and certain glands, and less in muscle and considerably less in the brain (blood-brain barrier). 47 Fig13.19 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tissue fluid Endothelial cell Slit Tissue fluid Capillary 48 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The pattern of capillary density also varies from one body part to the next. a. Areas with a great deal of metabolic activity (leg muscles, for example) have higher densities of capillaries. 49 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Precapillary sphincters can regulate the amount of blood entering a capillary bed and are controlled by oxygen concentration in the area. a. If blood is needed elsewhere in the body, the capillary beds in less important areas are shut down. 50 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Exchanges in Capillaries a. Blood entering capillaries contains high concentrations of oxygen and nutrients that diffuse out of the capillary wall and into the tissues. b. Plasma proteins remain in the blood due to their large size. 51 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. c. d. e. Hydrostatic pressure drives the passage of fluids and very small molecules out of the capillary at this point. At the venule end, osmosis, due to the osmotic pressure of the blood, causes much of the tissue fluid to return to the bloodstream. Lymphatic vessels collect excess tissue fluid and return it to circulation. 52 Fig13.21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lymphatic capillary Blood flow from arteriole Outward force, including hydrostatic pressure 35 mm Hg Net outward pressure 11 mm Hg Inward force of osmotic pressure 24 mm Hg Net force at arteriolar end Outward force, including hydrostatic pressure = 35 mm Hg Inward force of osmotic pressure = 24 mm Hg Net outward pressure = 11 mm Hg Capillary Tissue cells Outward force, Net inward including pressure hydrostatic 8 mm Hg pressure Inward force of 16 mm Hg osmotic pressure 24 mm Hg Blood flow to venule Net force at venular end Outward force, including hydrostatic pressure = 16 mm Hg Inward force of osmotic pressure = 24 mm Hg Net inward pressure = 8 mm Hg 53 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Venules and Veins 1. Venules leading from capillaries merge to form veins that return blood to the heart. 2. Veins have the same three layers as arteries have and have a flap-like valve inside to prevent backflow of blood. 54 Fig13.23 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Toward heart (a) (b) 55 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Veins are thinner and less muscular than arteries; they do not carry high-pressure blood. b. Veins also function as blood reservoirs. 56 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Pressure A. Blood pressure is the force of blood against the inner walls of blood vessels anywhere in the cardiovascular system, although the term "blood pressure" usually refers to arterial pressure. 57 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. 2. Arterial Blood Pressure 1. Arterial blood pressure rises and falls following a pattern established by the cardiac cycle. a. During ventricular contraction, arterial pressure is at its highest (systolic pressure). b. When ventricles are relaxing, arterial pressure is at its lowest (diastolic pressure). The surge of blood that occurs with ventricular contraction can be felt at certain points in the body as a pulse. 58 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Factors that Influence Arterial Blood Pressure 1. Arterial pressure depends on heart action, blood volume, resistance to flow, and blood viscosity. 2. Heart Action a. Heart action is dependent upon stroke volume and heart rate (together called cardiac output); if cardiac output increases, so does blood pressure. 59 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Blood Volume a. Blood pressure is normally directly proportional to the volume of blood within the cardiovascular system. b. Blood volume varies with age, body size, and gender. 60 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Peripheral Resistance a. Friction between blood and the walls of blood vessels is a force called peripheral resistance. b. As peripheral resistance increases, such as during sympathetic constriction of blood vessels, blood pressure increases. 61 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Blood Viscosity a. The greater the viscosity (ease of flow) of blood, the greater its resistance to flowing, and the greater the blood pressure. 62 Fig13.25 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood volume increases Heart rate increases Stroke volume increases Blood pressure increases Blood viscosity increases Peripheral resistance increases 63 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Control of Blood Pressure 1. Blood pressure is determined by cardiac output and peripheral resistance. 2. 3. 4. The body maintains normal blood pressure by adjusting cardiac output and peripheral resistance. Frank-Starling law of the heart is the relationship between fiber length and force of contraction. Baroreceptors sense change in BP 64 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Cardiac output depends on stroke volume and heart rate, and a number of factors can affect these actions. a. The volume of blood that enters the right atrium is normally equal to the volume leaving the left ventricle. 65 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. b. c. If arterial pressure increases, the cardiac center of the medulla oblongata sends parasympathetic impulses to slow heart rate. If arterial pressure drops, the medulla oblongata sends sympathetic impulses to increase heart rate to adjust blood pressure. 66 Fig13.26 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cardiac output increases Blood pressure rises Baroreceptors in aortic arch and carotid sinuses are stimulated Sensory impulses to cardiac center Parasympathetic impulses to heart SA node inhibited Heart rate decreases Blood pressure returns toward normal 67 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. d. Other factors, such as emotional upset, exercise, and a rise in temperature can result in increased cardiac output and increased blood pressure. 68 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. The vasomotor center of the medulla oblongata can adjust the sympathetic impulses to smooth muscles in arteriole walls, adjusting blood pressure. a. Certain chemicals, such as carbon dioxide, oxygen, and hydrogen ions, can also affect peripheral resistance. 69 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Venous Blood Flow 1. Blood flow through the venous system is only partially the result of heart action and instead also depends on skeletal muscle contraction, breathing movements, and vasoconstriction of veins (venoconstriction). 70 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Contractions of skeletal muscle squeeze blood back up veins one valve at a time. b. Differences in thoracic and abdominal pressures draw blood back up the veins. 71 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Paths of Circulation A. The body’s blood vessels can be divided into a pulmonary circuit, including vessels carrying blood to the lungs and back, and a systemic circuit made up of vessels carrying blood from the heart to the rest of the body and back. 72 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Pulmonary Circuit 1. The pulmonary circuit is made up of vessels that convey blood from the right ventricle to the pulmonary arteries to the lungs, alveolar capillaries, and pulmonary veins leading from the lungs to the left atrium. 73 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Systemic Circuit 1. The systemic circuit includes the aorta and its branches leading to all body tissues as well as the system of veins returning blood to the right atrium. 74 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arterial System A. B. The aorta is the body’s largest artery. Principal Branches of the Aorta 1. The branches of the ascending aorta are the right and left coronary arteries that lead to heart muscle. 2. Principal branches of the aortic arch include the brachiocephalic, left common carotid, and left subclavian arteries. 75 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The descending aorta (thoracic aorta) gives rise to many small arteries to the thoracic wall and thoracic viscera. 4. The abdominal aorta gives off the following branches: celiac, superior mesenteric, suprarenal, renal, gonadal, inferior mesenteric, and common iliac arteries. 76 Fig13.27 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right common carotid a. Right subclavian a. Left common carotid a. Left subclavian a. Brachiocephalic a. Aortic arch Ascending aorta Left coronary a. Right coronary a. Abdominal aorta Left gastric a. Celiac a. Splenic a. Hepatic a. Right gastric a. Suprarenal a. Right renal a. Superior mesenteric a. Lumbar a. Gonadal a. Inferior mesenteric a. Middle sacral a. Right common iliac a. Left common iliac a. 77 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Arteries to the Head, Neck, and Brain 1. Arteries to the head, neck, and brain include branches of the subclavian and common carotid arteries. 2. The vertebral arteries supply the vertebrae and their associated ligaments and muscles. 78 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. In the cranial cavity, the vertebral arteries unite to form a basilar artery which ends as two posterior cerebral arteries. 4. The posterior cerebral arteries help form the cerebral arterial circle which provides alternate pathways through which blood can reach the brain. 79 Fig13.29 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior cerebral a. Anterior cerebral a. Posterior communicating a. Posterior cerebral a. Internal carotid a. Pituitary gland Basilar a . Basilar a . Vertebral a. Spinal cord 80 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. 6. 7. The thyrocervical arteries are short vessels that give off branches to various parts of the neck, shoulder, and back. The right and left common carotid arteries diverge into the external carotid and internal carotid arteries. Near the base of the internal carotid arteries are the carotid sinuses that contain baroreceptors to monitor blood pressure. 81 Fig13.28 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superficial temporal a. Posterior .auricular a. Anterior choroid a. .Basilar a .Occipital a Maxillary a. Internal .carotid a. External carotid a. Facial a. Carotid sinus Lingual a. Vertebral a. Superior thyroid a. Thyrocervical axis Common carotid a. Subclavian a.. Brachiocephalic a. 82 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Arteries to the Shoulder and Upper Limb 1. The subclavian artery continues into the arm where it becomes the axillary artery. 2. In the shoulder region, the axial artery becomes the brachial artery that, in turn, gives rise to the ulnar and radial arteries. 83 Fig13.30 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right common carotid a. Right subclavian a. Axillary a. Anterior circumflex a. Posterior circumflex a. Deep brachial a. Brachial a. Radial recurrent a. Radial a. Ulnar recurrent a. Ulnar a. Principal artery of thumb Deep volar arch a. Superficial volar arch a. Digital a. 84 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Arteries to the Thoracic and Abdominal Walls 1. Branches of the thoracic aorta and subclavian artery supply the thoracic wall with blood. (internal thoracic artery, anterior intercostal arteries and posterior intercostal arteries) 2. Branches of the abdominal aorta, as well as other arteries, supply the abdominal wall with blood. (internal thoracic, external iliac, phrenic and lumbar arteries). 85 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Arteries to the Pelvis and Lower Limb 1. At the pelvic brim, the abdominal aorta divides to form the common iliac arteries that supply the pelvic organs, gluteal area, and lower limbs. 86 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. The common iliac arteries divide into internal and external iliac arteries. a. Internal iliac arteries supply blood to pelvic muscles and visceral structures. b. External iliac arteries lead into the legs, where they become femoral, popliteal, anterior tibial, and posterior tibial arteries. 87 Fig13.31 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superficial temporal a. External carotid a. Internal carotid a. Vertebral a. Common carotid a. Subclavian a. Brachiocephalic a. Aorta Axillary a. Coronary a. Intercostal a. Suprarenal a. Deep brachial a. Brachial a. Celiac a. Renal a. Superior mesenteric a. Radial a. Lumbar a. Inferior mesenteric a. Common iliac a. Internal iliac a. Gonadal a. External iliac a. Ulnar a. Deep femoral a. Femoral a. Popliteal a. Anterior tibial a. Posterior tibial a. Fibular a. Dorsalis pedis a. 88 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Venous System A. B. Veins return blood to the heart after the exchange of substances has occurred in the tissues. Characteristics of Venous Pathways 1. Larger veins parallel the courses of arteries and are named accordingly; smaller veins take irregular pathways and are unnamed. 89 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Veins from the head and upper torso drain into the superior vena cava. 3. Veins from the lower body drain into the inferior vena cava. 4. The vena cavae merge to join the right atrium. 90 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Veins from the Head, Neck, and Brain 1. The jugular veins (internal & external) drain the head and unite with the subclavian veins to form the brachiocephalic veins. 91 Fig13.32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Venous Sinuses Superior ophthalmic v. Vertebral v. Right external jugular v. Right . subclavian v. Anterior facial v. Right internal jugular v. Right axillary v. Right brachiocephalic v. 92 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Veins from the Upper Limb and Shoulder 1. The upper limb is drained by superficial and deep veins. 2. The basilic and cephalic veins are major superficial veins. 3. The major deep veins include the radial, ulnar, brachial, and axillary veins. E. Veins from the Abdominal and Thoracic Walls 1.Tributaries of the brachiocephalic and azygos veins drain the abdominal and thoracic walls. 93 Fig13.33 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right internal jugular v. Right external jugular v. Right subclavian v. Right brachiocephalic v. Axillary v. Brachial vv. Cephalic v. Basilic v. Median cubital v. Radial vv. Superior vena cava Left brachiocephalic v. Ulnar vv. Dorsal arch v. 94 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Veins from the Abdominal Viscera 1. Blood draining from the intestines enters the hepatic portal system and flows to the liver first rather than into general circulation. 2. The liver can process the nutrients absorbed during digestion as well as remove bacteria. 95 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Hepatic veins drain the liver, gastric veins drain the stomach, superior mesenteric veins lead from the small intestine and colon, the splenic vein leaves the spleen and pancreas, and the inferior mesenteric vein carries blood from the lower intestinal area. 96 Fig13.34 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Liver Stomach Hepatic portal v. Left gastric v. Right gastric v. Gallbladder Spleen Pancreas Splenic v. Superior mesenteric v. Inferior mesenteric v. Small intestine Ascending colon Descending colon Rectum 97 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Veins from the Lower Limb and Pelvis 1. Deep and superficial veins drain the leg and pelvis. 2. The deep veins include the anterior and posterior tibial veins which unite into the popliteal vein and femoral vein (becomes the extrenal iliac vein); superficial veins include the small and great saphenous veins. 3. These veins all merge to empty into the common iliac veins. 98 Fig13.35 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superficial temporal v. External jugular v. Anterior facial v. Internal jugular v. Subclavian v. Right brachiocephalic v. Axillary v. Superior vena cava Azygos v. Cephalic v. Brachial vv. Hepatic v. Basilic v. Inferior vena cava Median cubital v. Renal v. Radial vv. Ascending lumbar v. Ulnar vv. Gonadal v. Common iliac v. Internal iliac v. External iliac v. Femoral v. Great saphenous v. Popliteal v. Posterior tibial vv. Small saphenous v. Anterior tibial vv. 99