Chapter 13 Blood Vessels and Circulation-2.docx

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University at Buffalo
Exercise Science
ES 207
Scott Wersinger

Chapter 13: Blood Vessels and Circulation 13.1 Functions of the Circulatory System Blood vessels outside the heart are divided into 2 classes: 1. Pulmonary vessels: a. Transports blood from the RV  lungs  LA 2. Systematic vessels: a. Transports blood from LV  all parts of the body  RA Circulatory system = pulmonary vessels + systematic vessels 5 functions of circulatory system: 1. Carries blood 2. Exchanges nutrients, waste products, & gases with tissues 3. Transports substances 4. Helps regulate blood pressure 5. Directs blood flow to the tissues 13.2 General Features of Blood Vessel Structure 3 main types of blood vessels: 1. Arteries 2. Capillaries 3. Veins Arteries: carries blood away from the heart • Thick with a lot of elastic • High pressure • Usually oxygen-rich blood • Pumped from V’s of heart • Elastic arteries, muscular arteries, arterioles Figure 13.1 Blood Vessel Structure Capillaries: • Blood flows from arterioles  capillaries • Capillaries branch to form networks across tissue • Blow flow is regulated by smooth muscle cells, Precapillary sphincters • Simple squamous epithelium with a basement membrane • Very small and very thin • Cannot be seen with naked eye • RBC have to pass through 1 at a time because it is so small • Site of exchange between blood & tissue fluid Veins: carries blood towards the heart • Thin with less elastic than elastic • Usually oxygen-poor • Thinner walls with less elastic tissue & fewer smooth muscle cells • Starts at capillaries & proceeds toward the heart • Venules, small veins, medium-sized veins, large veins Tunics: 3 layers of the blood vessel wall (not in capillaries / venules) 1. Tunica intima: a. Innermost layer b. Simple squamous epithelium 2. Tunica media: a. Middle layer b. Smooth muscle with elastic fibers & collagen i. Helps maintain blood pressure ii. Helps blood flow in different conditions 3. Tunica adventitia a. Outermost layer b. Connective tissue that is dense c. Thicker in small-medium vein than muscular artery Figure 13.2 Photomicrograph of an Artery and a Vein Arteries -Elastic arteries: • Largest in diameter • Thickest walls • Stretch when ventricles pump blood into them • Ex: aorta, pulmonary trunk -Muscular arteries: • Medium-sized and small arteries • Thick in diameter • Smooth muscle cells • “Distributing arteries” o Can control blood flow to body regions -Arterioles: • Transport blood from small arteries  capillaries • Smallest arteries in which the 3 tunics can be identified • Adapted for vasodilation & vasoconstriction Vasoconstriction: contraction of smooth muscle in blood vessels • Decreased diameter of blood vessels Vasodilation: relaxation of smooth muscle in blood vessels • Increased diameter of blood vessels Capillaries • Blood flows from arterioles  capillaries • Branch to form networks • Blood flow regulated by Precapillary sphincters o Precapillary sphincters:  Smooth muscle cells  Location: origin of the branches  Helps direct where blood is going to go • Endothelium in capillary walls o Layer of simple squamous epithelium surrounded by loose connective tissue • Branch without changing diameter • Capillary network o Where O2 and CO2 are exchanged, where nutrients go *** Vaso vasorum: capillary where exchange occurs Figure 13.3 Capillary Network Veins • Blood flows from capillaries  veins, & venules  small veins • Venules: diameter slightly larger than capillaries o Endothelium resting on a delicate connective tissue layer • Small veins: slightly larger in diameter o All 3 tunics are present • Medium-sized: collect blood from small veins & deliver to large veins • Large: contain valves • Valves: allow blood to flow toward the heart, but not in the opposite direction o Consists of folds in the tunica intima forming 2 flaps that allow blood to flow toward the heart & not in opposite direction Figure 13.4 Valves 13.3 Blood Vessels of the Pulmonary Circulation Pulmonary circulation: system of blood vessels that carries blood from: • RV  lungs  RA Pulmonary trunk: pumps blood from RV  right & left pulmonary arteries towards lung • R & L pulmonary arteries: extend to right & left lungs o Carry oxygen-poor blood to the pulmonary capillaries in the lungs  Here, blood takes up oxygen & releases carbon dioxide Pulmonary veins: exit lungs & carries O2-rich blood  LA Figure 13.5 Blood Flow Through the Circulatory System 13.4 Blood Vessels of the Systematic Circulation: Arteries Systematic circulation: system of blood vessels • Carries blood from LV  heart  tissues of body  RA Figure 13.6 Major Arteries Aorta: large, elastic artery o Main trunk of systematic arterial system o Carries blood from LV  through thorax & abdomen • Ascending aorta: passes superiorly from LV • Aortic arch: Carries blood to head & upper limbs o 3 major arteries originate from here  1. Brachiocephalic artery  2. Left common carotid artery  3. Left subclavian artery • Descending aorta: extends through thorax & abdomen to pelvis o Thoracic aorta: extends through thorax to diaphragm o Abdominal aorta: extends from diaphragm  Extends from diaphragm divides into common iliac arteries o Common iliac arteries: point where descending aorta divides in 2 • Arterial aneurysm: localized dilation of an artery o Usually develops in response to trauma / congenital weakness of the artery wall • Aortic Aneurysm, CTA: Anterior o No symptoms until they pop o Under high pressure it pops o Abdomen fills with blood & circulation stops • R & L coronary arteries: arise from base of ascending aorta o Supply blood to the heart Figure 13.7 Branches of the Aorta Arteries of Head & Neck Branches of aortic arch: st • Brachiocephalic artery: 1 branch off aortic arch  Supplies blood to right side of head & neck o Left common carotid artery: 2 branch off aortic arch  Supplies blood to the left side of the head and neck o Left subclavian artery: 3 branch off aortic arch  Supplies blood to the left upper limb • Right common carotid artery: transports blood to right side of the head & neck • Right subclavian artery: transports blood to right upper limb Figure 13.8 Arteries of the Head and Neck Figure 13.9 Major Arteries of the Head & Thorax Carotid sinus: enlargement of the internal carotid artery • Contains baroreceptors Cerebral arterial artery: at the base of brain • Includes the vessels that supply blood to most of brain Middle cerebral artery: brain is highly vascularized for memory Figure 13.10 Cerebral Arterial Circle Circle of Willis: comes off carotid arteries • Doesn’t matter where blood comes in “roundabout” • Right & left internal carotids feed into it • Basilar artery feeds into it • Several blood vessels (esp. middle cerebral artery) feed out and supply right and left side of brain • Basilar artery comes off of it, which bifurcates to vertebral artery o Basilar artery: gives off branches that supply blood to the pons, cerebellum, and midbrain  What most of the blood supply to the brain goes through o Vertebral arteries: branch from the subclavian arties  Supplies blood to the spinal cord, vertebrae, muscles, & ligaments in neck Arteries of Upper Limbs Axillary arteries: • Continuation of subclavian • Supply blood deep in clavicle Brachial artery: • Continuation of axillary artery • Where blood pressure measurements are taken Ulnar artery: • Branch of brachial artery • Near elbow Radial artery: • Branch of brachial artery • Supply blood to forearm and hand • Where pulse is taken Figure 13.11 Arteries of the Upper Limb Thoracic Aorta and Its Branches Branches of thoracic aorta divide into 2 groups • Visceral arteries: supply thoracic organs o Supply esophagus, trachea, parietal pericardium, part of lung • Parietal arteries: supply the thoracic wall o Posterior intercostal arties: supply the intercostal muscles, vertebrae, spinal cord, and deep muscles of the back o Superior phrenic: supplies the diaphragm Internal thoracic arteries: branches of subclavian arteries • Descend along internal surface of anterior thoracic wall • Give rise to anterior intercostal arteries: o Branches that extend between ribs to supply anterior chest wall Abdominal Aorta and Its Branches Branches of abdominal aorta divide into 2 groups 1. Visceral arteries: divides into paired & unpaired branches • Unpaired branches 3 major o Celiac trunk arteries: • Supplies blood to stomach, pancreas, spleen, upper duodenum, liver • Splenic artery comes off of it, sending blood to spleen • Gastric: stomach o Superior mesenteric artery:  Supplies blood to small intestine, upper portion of large intestine / colon o Inferior mesenteric artery:  Supplied blood to remainder of large intestine / colon Figure 13.12 Major Arteries of the Abdomen and Pelvis • Paired branches 3 major ones o Renal arteries:  Supply blood to kidneys o Hepatic arteries:  Supply blood to liver o Testicular arteries:  Supply blood to testes o Ovarian arteries:  Supply blood to ovaries o Suprarenal arteries:  Supply adrenal glands 2. Parietal branches: supply diaphragm & abdominal wall • Inferior phrenic arteries: o Supply blood to diaphragm • Lumbar arteries: o Supply blood to lumbar vertebra & back muscles • Median sacral artery: o Supplies inferior vertebrae Arteries of the Pelvis Abdominal aorta divides at the 5 lumbar vertebra into 2 common iliac arteries • Common iliac arteries: o Branches from abdominal aorta o Divides into internal & external iliac arteries  External iliac arteries: • Division of common iliac artery • Supplies blood to lower limbs  Internal iliac arteries: • Division of common iliac • Supplies blood to pelvic area o Visceral branches: supplies urinary bladder, rectum, uterus, vagina o Parietal branches: supplies blood to walls and floor of pelvic, lumbar, gluteal, proximal thigh muscles, external genitalia Arteries of the Lower Limb No major branches • Femoral artery: o Supplies blood to thigh • Popliteal artery: o Supplies blood to knee • Anterior / Posterior tibial artery: o Supplies blood to leg and foot • Fibular artery (Peroneal artery): o Supplies blood to lateral leg & foot Figure 13.13 Arteries of the Lower Limb Femoral triangle: • Location superior & medial area of thigh • Margins are formed by inguinal ligament, medial margin, lateral margin • Passing through: o Femoral artery, vein, & nerve • Pulse in femoral artery can be detected here • Susceptible to serious traumatic injuries that result in hemorrhage and nerve damage 13.5 Blood Vessels of the Circulatory System: Veins Vena cava Superior vena cava: • Returns blood from head, neck, thorax, upper limbs ▯ RA of heart Inferior vena cava: • Returns blood from abdomen, pelvis, lower limbs ▯ RA of heart Figure 13.14 Major Veins Veins of the Head and Neck 1. External jugular veins: a. More superficial b. Drains blood from posterior head & neck c. Empties into subclavian veins 2. Internal jugular veins: a. Much larger & deeper b. Drains blood from brain & anterior head, face & neck c. Empty into subclavian veins d. Join subclavian veins on each side to form brachiocephalic veins Subclavian veins: form brachiocephalic veins Brachiocephalic veins: join to form superior vena cava Figure 13.15 Veins of the Head and Neck Only memorize • External jugular vein • Subclavian vein • Right braciocephalic vein • Internal jugular vein • Left braciocephalic vein • Inferior vena cava Veins of the Upper Limbs 2 groups  Deep & Superficial Deep veins: drain deep structures of upper limbs • Follow same course as arteries • Named for respective arteries • Ex: o Brachial veins: empty into axillary vein o Basilic veins o Median cubital vein Figure 13.16 Veins of the Upper Limb Veins of the Thorax 3 major veins return blood from the thorax  superior vena cava: • Right & Left brachiocephalic veins • Azygos vein Anterior intercostal veins: way blood drains from the anterior thoracic Internal thoracic veins: empty into the brachiocephalic veins Posterior intercostal veins: • Drain into the azygos vein on the right • Drain into hemiazygos or accessory hemiazygos on the left Figure 13.17 Veins of the Tho
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