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Biology 218 – Human Anatomy Session: FALL Section: 52999 Days / Time: Instructor: Lecture Outline MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Chapter 22 The Cardiovascular System: Vessels and Circulation Introduction There are two groups of blood vessels Pulmonary circuit Blood goes to and from the lungs Systemic circuit Blood goes to the rest of the body and back to the heart Blood goes to both circuits at the same time with each heartbeat Histological Organization of Blood Vessels The walls of the vessels consist of three layers Intima (innermost layer) Media (middle layer) Adventitia (outermost layer) The layered walls give the vessels tremendous strength Histological Organization of Blood Vessels Intima (innermost layer) Consists of two sublayers Endothelial lining Underlying layer of connective tissue Arteries consists of a thick layer of elastic fibers giving the lining a “wavy” appearance Histological Organization of Blood Vessels Media (middle layer) Consists of smooth muscle When stimulated by sympathetic nerves, the muscles contract resulting in vasoconstriction Relaxation of the smooth muscle results in vasodilation Histological Organization of Blood Vessels Adventitia (outermost layer) Forms a connective sheath around the vessel Composed of collagen fibers Anchors the blood vessels in position The walls of some vessels are too thick to obtain nutrients via diffusion so they have their own blood supply in vessels called vasa vasorum Histological Organization of Blood Vessels Distinguishing Arteries from Veins Most arteries and veins run parallel to each other Arteries carry blood away from the heart and veins carry blood toward the heart Walls of arteries are thicker than veins © 2012 Pearson Education, Inc. Page 1 of 11 582729776 Biology 218 – Human Anatomy Session: FALL Section: 52999 Days / Time: Instructor: Lecture Outline MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Arteries maintain their circular shape and veins typically collapse when cut Endothelial lining of an artery has pleated folds Histological Organization of Blood Vessels Arteries As blood leaves the heart, it travels through: Elastic arteries Muscular arteries Arterioles Capillaries Capillary beds Histological Organization of Blood Vessels Capillaries Walls are thin enough to permit exchange of gases between the blood and the interstitial fluid The diameter is about 8 microns A red blood cell diameter is also about 8 microns Fenestrated capillaries contain pores Histological Organization of Blood Vessels Capillaries (continued) There are four mechanisms regarding the passage of material across the walls of capillaries Material can diffuse across the endothelial lining Material can diffuse through gaps between adjacent cells of the lining Material can diffuse through pores Material can move via endocytosis Histological Organization of Blood Vessels Capillary Beds This is an interconnected network of capillaries The capillary bed consists of vessels connecting arterioles with venules There are precapillary sphincters involved in regulating blood flow through the capillaries Histological Organization of Blood Vessels Capillary Beds (continued) In areas such as the brain, heart, and stomach, a continuous, rich flow of blood is required In these areas, more than one artery supplies a specific area These arteries (collateral arteries) typically fuse forming an arterial anastomosis If one arteriole is blocked, the other one will supply blood to the capillary bed Histological Organization of Blood Vessels © 2012 Pearson Education, Inc. Page 2 of 11 582729776 Biology 218 – Human Anatomy Lecture Outline Session: FALL Section: 52999 Days / Time: Instructor: MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Capillary Beds (continued) In areas such as the joints or visceral organs, blood flow through some vessels may be hindered due to body movement In order to accommodate this, there must be a direct connection between arterioles and venules This direct connection is called an arteriovenous anastomosis Histological Organization of Blood Vessels Veins Veins collect blood from tissues and return the blood to the heart As blood leaves the tissue and travels to the heart, it travels through the following vessels: Capillary beds Capillaries Venules Medium-sized veins Large veins Histological Organization of Blood Vessels Blood in the veins returning to the heart from the lower extremities has to go against gravity To assist in this process, many veins have valves (venous valves) These valves compartmentalize the blood in the veins thus acting as one-way valves If the venous valves do not close properly, varicose veins may occur Histological Organization of Blood Vessels The total blood volume is distributed unevenly within the vessels of the body Arteries and capillaries contain 30–35% of the volume Veins contain 65–70% of the volume Veins are more distensible than arteries Based on blood pressure, a vein can expand about 8 times as much as a parallel artery Blood Vessel Distribution Blood vessels can be divided into two circuits Pulmonary circuit Composed of arteries and veins that transport blood between the heart and the lungs Arteries and veins travel relatively short distances Systemic circuit Composed of arteries and veins that transport oxygenated blood between the heart and all other tissues Arteries and veins travel longer distances Blood Vessel Distribution There are functional and structural differences between the vessels in the two circuits Blood pressure in the pulmonary circuit is lower than in the systemic circuit Walls of the pulmonary arteries are thinner than the walls of systemic arteries © 2012 Pearson Education, Inc. Page 3 of 11 582729776 Biology 218 – Human Anatomy Lecture Outline Session: FALL Section: 52999 Days / Time: Instructor: MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Blood Vessel Distribution Vessel Distribution Functional patterns of the pulmonary and systemic circuits The distribution of arteries and veins is the same on the left side of the body as it is on the right side of the body except for the venae cavae and the aorta A single vessel will have different names according to specific anatomical boundaries Arteries and veins often anastomose Blood Vessel Distribution The Pulmonary Circuit Blood leaves the heart by passing through the pulmonary valve Blood enters the pulmonary trunk Blood enters the left and right pulmonary arteries Blood arrives at the lungs to drop off carbon dioxide and pick up oxygen Blood returns to the heart via the pulmonary veins Blood enters the left atrium of the heart Blood Vessel Distribution The Systemic Circuit Blood leaves the heart by passing through the aortic valve Blood enters the ascending aorta and then the aortic arch and then it branches into: Brachiocephalic trunk (then the right common carotid and right subclavian arteries) Left common carotid artery Left subclavian artery Descending aorta Coronary arteries Blood Vessel Distribution The Systemic Circuit (continued) Ascending aorta Begins at the aortic valve Left and right coronary arteries branch off the base of the ascending aorta Aortic arch Forms an arch going toward the left and posterior side of the heart Branching off the aortic arch are three elastic arteries Blood Vessel Distribution The Systemic Circuit (continued) Branches of the aortic arch Brachiocephalic trunk gives rise to the right common carotid artery (supplies blood to the right side of the head and brain) and to the right subclavian artery (supplies blood to the right arm) Left common carotid artery (supplies blood to the left side of the head and brain) Left subclavian artery (supplies blood to the left arm) © 2012 Pearson Education, Inc. Page 4 of 11 582729776 Biology 218 – Human Anatomy Lecture Outline Session: FALL Section: 52999 Days / Time: Instructor: MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Blood Vessel Distribution The Systemic Circuit (continued) The subclavian arteries Give rise to the vertebral arteries Give rise to the axillary arteries Prior to forming the axillary arteries, the subclavians form three branches: Thyrocervical trunk (supplies muscles of the neck, head, and upper back) Internal thoracic artery (supplies the pericardium and anterior wall of the chest) Vertebral artery (supplies the brain and spinal cord) Blood Vessel Distribution The flow of blood from the subclavians Axillary artery Branches to form the humeral circumflex artery Brachial artery Branches to form the deep brachial artery Divides to form the radial and ulnar arteries Arteries anastomose at the wrist forming the superficial palmar arch and deep palmar arch Blood Vessel Distribution The Carotid Arteries The common carotids ascend the neck Divide to form the internal carotids and external carotids The carotid sinus is at the base of the internal carotid artery consisting of baroreceptors and chemoreceptors Blood Vessel Distribution The internal and external carotid arteries External carotids supply the neck and outside of the skull Internal carotids enter the skull to deliver blood to the brain Internal carotid branches to form: Ophthalmic artery (supplies the eyes) Anterior cerebral artery (supplies frontal and parietal lobes of the brain) Middle cerebral artery (supplies the midbrain and lateral surfaces of the brain) Blood Vessel Distribution Blood supply to the brain Blood in the vertebral arteries go to the brain via: Left and right vertebral arteries fuse to form the basilar artery Basilar artery branches many times in the area of the pons Basilar artery eventually forms the vessels of the cerebral arterial circle (circle of Willis) Blood in the internal carotid arteries goes to the brain via: Anastomosing with the cerebral arterial circle Blood Vessel Distribution © 2012 Pearson Education, Inc. Page 5 of 11 582729776 Biology 218 – Human Anatomy Session: FALL Section: 52999 Days / Time: Instructor: Lecture Outline MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. The Descending Aorta A continuation of the aortic arch Divided into thoracic aorta and abdominal aorta Blood Vessel Distribution The Thoracic Aorta Branches to form the following vessels: Bronchial arteries Pericardial arteries Mediastinal arteries Esophageal arteries Intercostal arteries Superior phrenic arteries Blood Vessel Distribution The Abdominal Aorta Branches to form the following vessels: Celiac trunk Superior mesenteric artery Inferior mesenteric artery Inferior phrenic arteries Suprarenal arteries Renal arteries Gonadal arteries Lumbar arteries Right and left common iliac arteries Blood Vessel Distribution The Celiac Trunk Branches to form the left gastric artery Supplies the stomach Branches to form the splenic artery Branches to form the left gastroepiploic artery to supply the stomach Branches to form the pancreatic arteries to supply the pancreas Blood Vessel Distribution The Celiac Trunk (continued) Branches to form the common hepatic artery The common hepatic artery branches to form: Hepatic artery proper to supply the liver Right gastric artery to supply the stomach Cystic artery to supply the gallbladder Gastroduodenal artery to supply the duodenum Blood Vessel Distribution © 2012 Pearson Education, Inc. Page 6 of 11 582729776 Biology 218 – Human Anatomy Session: FALL Section: 52999 Days / Time: Instructor: Lecture Outline MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Inferior Mesenteric Artery Branches to form the left colic and sigmoid arteries Supply the terminal portions of the large intestine Branches to form the rectal arteries Supply the rectum Blood Vessel Distribution Arteries of the Pelvis The common iliac arteries Branch to form the internal iliac artery Supplies the urinary bladder, walls of the pelvis, external genitalia, and the medial side of the thigh Branches to form the external iliac artery Supplies blood to the legs Blood Vessel Distribution Arteries of the Leg External iliac arteries form the: Femoral artery The femoral artery continues to form the popliteal artery, and then splits to form the anterior tibial artery and posterior tibial artery Deep femoral artery Blood Vessel Distribution Arteries of the Foot The anterior tibial artery forms the dorsalis pedis artery The posterior tibial artery forms the medial and lateral plantar arteries Blood Vessel Distribution Systemic Veins Veins collect blood from the body tissues and return it to the heart Blood returns to the heart from the lower extremities via the inferior vena cava to the right atrium Blood returns to the heart from the upper extremities via the superior vena cava to the right atrium Blood returns to the heart from the lungs via the pulmonary veins to the left atrium Blood Vessel Distribution Venous Return from the Cranium The superficial cerebral veins drain into: Superior and inferior sagittal sinuses Petrosal sinuses Occipital sinus Left and right transverse sinuses Straight sinus All of the venous sinuses drain into the internal jugular vein The internal jugular drains into the brachiocephalic veins © 2012 Pearson Education, Inc. Page 7 of 11 582729776 Biology 218 – Human Anatomy Session: FALL Section: 52999 Days / Time: Instructor: Lecture Outline MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Blood Vessel Distribution Venous Return from the Cranium (continued) The vertebral veins drain into the brachiocephalic veins Blood Vessel Distribution Venous Return from the Head Veins from the head converge to form the: Temporal vein Facial vein Maxillary veins The temporal and maxillary veins drain into the external jugular vein The facial vein drains into the internal jugular vein Blood Vessel Distribution Venous Return from the Neck Vessels in the neck drain into the external jugular vein The external jugular vein drains into the subclavian vein Blood Vessel Distribution Venous Return from the Upper Limb Blood returns to the heart from the hands in the following sequence: Digital veins Superficial and deep palmar veins The superficial palmar veins drain into the cephalic vein Subclavian vein Brachiocephalic vein Superior vena cava Right atrium Blood Vessel Distribution Venous Return from the Upper Limb Blood can also return to the heart from the hands in the following sequence: The superficial palmar veins drain into the cephalic vein Median cubital vein Basilic vein Axillary vein Subclavian vein Brachiocephalic vein Superior vena cava Right atrium © 2012 Pearson Education, Inc. Page 8 of 11 582729776 Biology 218 – Human Anatomy Lecture Outline Session: FALL Section: 52999 Days / Time: Instructor: MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Blood Vessel Distribution Venous Return from the Upper Limb Blood can also return to the heart from the hands in the following sequence: The superficial palmar veins drain into the basilic vein Axillary vein Subclavian vein Brachiocephalic vein Superior vena cava Right atrium Blood Vessel Distribution Venous Return from the Upper Limb Blood can also return to the heart from the hands in the following sequence: The deep palmar veins drain into the radial and ulnar vein Those veins will unite to form the brachial vein Axillary vein Subclavian vein Brachiocephalic vein Superior vena cava Right atrium Blood Vessel Distribution Venous Return from the Abdominal Area The following veins drain into the inferior vena cava or the superior vena cava, which drains into the right atrium Lumbar veins go superior and drain into the superior vena cava Gonadal veins: the right gonadal vein drains into the inferior vena cava, the left gonadal vein drains into the left renal vein and then into the inferior vena cava Hepatic veins drain into the inferior vena cava Blood Vessel Distribution Venous Return from the Lower Limb Blood leaves the foot and returns to the heart via the following veins Plantar veins Drain into the anterior tibial, posterior tibial, and fibular veins Popliteal vein Femoral vein Common iliac vein Inferior vena cava Right atrium Blood Vessel Distribution Venous Return from the Lower Limb Blood also leaves the foot and returns to the heart via the following veins Dorsal venous arch Great saphenous vein © 2012 Pearson Education, Inc. Page 9 of 11 582729776 Biology 218 – Human Anatomy Lecture Outline Session: FALL Section: 52999 Days / Time: Instructor: MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Femoral vein External iliac vein Common iliac vein Inferior vena cava Right atrium Blood Vessel Distribution Venous Return from the Hepatic Portal System Blood in the inferior mesenteric, splenic, and superior mesenteric veins drains into the hepatic portal system Liver sinusoids Hepatic veins Inferior vena cava Right atrium Cardiovascular Changes at Birth The fetal cardiovascular system differs from the adult cardiovascular system The fetal lungs are nonfunctional The fetal digestive system is nonfunctional All fetal nutritional and respiratory needs are provided by diffusion across the placenta Blood in the fetal internal iliacs enters the umbilical arteries Enters the umbilical cord Enters the placenta Cardiovascular Changes at Birth All fetal nutritional and respiratory needs are provided by diffusion across the placenta (continued) Blood leaves the placenta Enters the umbilical vein Enters the ductus venosus Enters the fetal liver Enters the inferior vena cava Enters the fetal right atrium Cardiovascular Changes at Birth All fetal nutritional and respiratory needs are provided by diffusion across the placenta (continued) Blood in the right atrium can pass through the heart via the following methods: Through the tricuspid valve to the right ventricle Through the foramen ovale to the left atrium From the pulmonary trunk through the ductus arteriosus to the aortic arch Cardiovascular Changes at Birth Upon birth: Smooth muscles of the ductus arteriosus contract forming the ligamentum arteriosum found in the adult heart © 2012 Pearson Education, Inc. Page 10 of 11 582729776 Biology 218 – Human Anatomy Lecture Outline Session: FALL Section: 52999 Days / Time: Instructor: MW 5:00 PM – 9:20 PM RIDDELL Adapted from Martini Human Anatomy 7th ed. Pressure in the left atrium increases, thus closing the valvular flap of the foramen ovale, forming the fossa ovalis found in the adult heart Aging and the Cardiovascular System Age-related changes in the cardiovascular system Blood changes Decreased hematocrit Thrombi and emboli form more easily Pooling of blood in veins of the leg Heart changes Reduced efficiency and elasticity Atherosclerosis of coronary vessels Scar tissue forms Blood vessel changes Loss of elasticity Calcium deposits damage vessel walls © 2012 Pearson Education, Inc. Page 11 of 11 582729776
