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Blood Vessels
Lecture Unit 2
Question | Answer |
---|---|
Arteries | Transport blood away from the heart. Carry O2 rich blood in the systemic circuit. Carry O2 poor blood in the pulmonary circuit & umbilical arteries. |
Anastomosis | Union of 2 blood vessels. Ex. The 2 vertebral arteries fuse into the basilar artery. |
Capillaries | Location of gas and nutrient exchange between vessels & tissues. |
Veins | Transport blood towards the heart. Carry O2 poor blood in the systemic circuit. Carry O2 rich blood in the pulmonary circuit & umbilical vein. |
Vessel Tunics | Lumen, Tunica intima, Tunica media, Tunica externa |
Lumen | inner space of the vessel |
Tunica intima | Innermost layer. Simple squamous endothelium. Touches blood directly. Most intimate. |
Tunica media | Circularly arranged smooth muscle fibers. Location of vasodilation & vasoconstriction. |
Tunica externa | Outermost layer. Collagen & elastic fibers. |
Comparison of Vessel Structures | Arteries-Thickest tunica media. No valves. Capillaries-Only tunica intima. Allow rapid gas exchange. Veins-Thickest tunica externa. Smaller tunica media than arteries. Valves. |
Blood flow | Heart, Elastic artery, Muscular artery, Arteriole, Capillary, Venule, Medium vein, Large vein, Heart. |
Elastic Arteries | Largest Arteries. "Conducting arteries." Between heart & muscular arteries. High elastin content allows arteries to stretch & dampen surges & reduce bp resulting from contraction of heart. Aorta & its major branches-Brachiocephalic trunk, etc. |
Aortic Branches -exs of elastic arteries. 3 branch directly from aorta. | Brachiocephalic trunk-right common carotid art-right external & internal carotid arts. -right subclavian art-right vertebral & internal thoracic. Left common carotid artery-left external & internal carotids. Left subclavian-vertebral & internal thoracic. |
Muscular Arteries | "Distributing arteries"-body organs & tissues. Thick tunica media. Actively changes diameter of lumen to regulate amt of blood flow to the tissues. Most of named arteries in lab. exs. brachial, coronary, inferior mesenteric arteries, etc. |
Arterioles | Smallest arteries. Lead to the capillary beds. Diameter regulated by: Local tissue factors. Sympathetic nervous system. Vasoconstriction & vasodilation. |
Capillaries | Functional units of cardiovascular sys. Gas/nutrient/waste exchange between blood & tissues. Smallest vessels. Endothelium only. tunica intima. Simple squamous epithelium. 3 types: Continuous, fenestrated, sinusoid. |
Capillary bed | Network of capillaries that run throughout body tissues. Flow control: precapillary sphincter. Bypass: thoroughfare channel. |
Continuous Capillaries | Most common. Muscle, skin, thymus, lungs, & the CNS. |
Fenestrated | Have pores. Small intestine, most endocrine glands, kidneys. |
Sinusoid | Bone marrow (RBCs born-get into blood stream), spleen, liver (RBCs die-leave blood stream). Look messed up. |
Venules | Smallest veins. Primary location of diapedesis (WBCs leaving blood stream). Venules join to form veins. |
Veins | Return blood to the heart. Act as blood reservoir. Walls thinner than artery walls. Low blood pressure. Most contain valves-prevent backflow of blood. Skeletal muscle contractions help pump blood toward the heart. |
Hepatic Portal System | For digestion/absorption of nutrients. Know where blood drains from. Hepatic portal vein-liver. Gastric & gastro-omental-superior stomach. Splenic-spleen. Inferior & superior mesenteric-intestines. |
Varicose Veins | Dysfunctional valves lead to blood pooling in the superficial limb veins. Genetic predisposition, aging, or strain that inhibits venous return. Strains-obesity, pregnancy, or continuous standing. |
Hemorrhoids | Varicose veins of the anorectal region. caused by increased intraabdominal pressure. Bowel movement, childbirth. |
Fetal Circulation (Part 1) | Umbilical cord-2 arteries become medial umbilical ligaments after birth. 1 umbilical vein becomes round ligament of liver or ligamentum teres. Ductus venosus-diverts blood from liver. Becomes ligamenum venosum after birth. Directly to inferior vena cava. |
Fetal Circulation (Part 2) | Foramen Ovale-diverts blood from r atrium to left. Bypasses immature lungs. Becomes fossa ovalis. Ductus arteriosus-diverts blood from pulmonary trunk to aortic arch bypassing immature lungs. Becomes ligamentum arteriosum. |
Patent Ductus Arteriosis | Ductus arteriosus stays open after birth. If untreated, PDA can lead to right ventricle failure. Treated w/ prostaglandin-inhibitors or surgery. |
Blood Pressure | Sphygmomanometer. Systolic/diastolic. Average=120/80 (specifically refers to brachial artery)-lower further from heart. Hypertenstion=high blood pressure (140/90) |
Atherosclerosis (Part 1) | Linked to over 50% of all deaths in U.S. Progressive disease of the elastic & muscular arteries. Aorta & coronary arteries most affected. Atheroma (fatty plaque)-thickening of the tunica intima. Narrowing of arterial lumen. |
Atherosclerosis (Part 2) | Risk factors: genetics, sex, age, smoking, hypertension. Treatments: angioplasty, stents, coronary bypass surgery. Best=Prevention! healthy diet-watch cholesterol. dont smoke. monitor bp. |
Abdominal Aortic Aneurism (Like vericose veins. BP makes worse-explode & bleed out. Most common in abdomen). | Localized dilation of a blood vessel, specifically arteries. Most often caused by atherosclerosis. May be detected through abdominal palpation, x-ray, or ultrasound. Treated w/ artificial vascular prosthesis or stents inserted through the femoral artery. |
Cerebrovascular Accident | Stroke. Caused by blockage of a brain blood vessel. Thrombus-blood clot that forms w/i the brain blood vessel. Embolus-clot that formed in another blood vessel that migrates to the brain. Can lead to death of brain tissue. |