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ABDOMINAL VESSELS. I. Introduction/General Information A. Uses for ultrasound 1. Screening procedure for abdominal abnormalities 2. Localize/Characterize masses 3. Measurement, rate, direction of blood flow via Doppler .
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I. Introduction/General Information • A. Uses for ultrasound • 1. Screening procedure for abdominal abnormalities • 2. Localize/Characterize masses • 3. Measurement, rate, direction of blood flow via Doppler
General Information, continued … B. Heart: 1. CVT used on adults 2. Ultrasound used in utero • C. Abdominal vessels • 1. Abdominal aorta • a. Ultrasound can delineate contour, course & size
General Information, continued … b. Can evaluate entire course c. Used to diagnose, follow progress of aneurysms d. Can distinguish between normal and aneurysm aortic pulsations
Abdominal Vessels, continued … 2. Celiac axis (trunk, artery) a. First unpaired branch off abdominal aorta (~ L-1) b. Originates from ventral surface c. Gives rise to splenic, common hepatic, & left gastric arteries
Arteries of the Abdominal Aorta Figure 19.11
Abdominal Vessels, continued … 3. Superior Mesenteric Artery a. Second, unpaired branch of abdominal aorta b. Originates ~ lower L-1 body c. 1 – 2 cm below celiac axis d. Supplies small intestines, pancreas, omentum, ascending and transverse colon
Arteries of the Abdominal Aorta Figure 19.11
Abdominal Vessels, con’t… 4. Inferior Mesenteric Artery a. Arises just above the bifurcation of the aorta (~L-3/4) b. Last unpaired branch of aorta c. Supplies jejunum, descending and sigmoid colon, rectum
Distribution of the Superior and Inferior Mesenteric Arteries Figure 19.13
Abdominal Vessels, continued … 4. Renal arteries a. First major paired branches from aorta b. Arise opposite each other 1-2 cm below SMA (~L-2) c. Multiple renal arteries occur in 20% of patients
Renal Arteries Figure 19.11
Abdominal Vessels, continued … 5. Common Hepatic Artery a. Right branch of celiac a. b. Continues to GDA, then… 6. Proper Hepatic Artery a. Branches within liver b. Begin at ~porta hepatis
Abdominal Vessels, continued … 7. Inferior Vena Cava a. Formed at ~ L-5 b. by union of Common Iliac Veins c. Largest vein in body d. Dilation may be due to: 1. right-sided CHF 2. Portal hypertension
Major Veins of the Abdomen L-5 Figure 19.21
Abdominal Vessels, continued … 8. Veins of Portal Circulation a. SMV: joins with splenic vein 1. runs parallel to SMA 2. On right side of abdomen b. IMV: terminates in splenic vein c. Portal Vein: enters liver
Veins of the Hepatic Portal System Figure 19.23
Abdominal Vessels, continued … d. Renal Veins – run parallel to renal arteries
Major Veins of the Abdomen Figure 19.21
Veins of the Right Lower Limb and Pelvis e. Femoral Veins - run parallel to femoral arteries f. Popliteal Veins – run parallel to popliteal arteries Figure 19.24a
II. Detailed Anatomy • Arteries • 1. Size: • a. ~ 2.5 cm – 0.5 mm • b. inside diameter • c. Arbitrary designation • 2. Structure: 3 coats or tunics
Detailed Anatomy, con’t… • a. Tunica intima • 1. aka: tunica interna • 2. innermost layer • 3. = endothelium • 4. thin: 1 cell layer + basement membrane
Vascular Tunics: Tunica Intima Tunica Intima Artery Capillary Vein
Structure, Arteries, continued … b. Tunica media 1. thickest layer 2. smooth muscle & connective tissue (mostly elastic) 3. in lamina 4. fibers circularly arranged around lumen
Vascular Tunics: Tunica Media Tunica Media
Structure arteries, continued … c. Tunica externa 1. thinner than media 2. thicker than intima 3. white fibrous C. T. 4. A few smooth muscle fibers, arranged longitudinally
Vascular Tunics: Tunica Externa Tunica Externa
Arteries, continued … 3. Variability of arteries a. larger elastic arteries: 1. aorta, pulmonary, carotids 2. have thicker tunica intima 3. increased elastic tissue
Arteries, variability, continued … 4. very thick tunica media a. smooth muscle b. obscured by elastic tissue 5. tunica externa is a. thin but strong b. limits stretch
Structure, arteries, continued 6. Serve as “shock absorbers” a. expand & contract b. accommodate the pressure from pumping of the heart c. Maintain blood flow
Structure, arteries, continued 7. arteriosclerosis leads to: a. decreased elasticity b. increased blood pressure c. High B.P., aneurysm, rupture of vessels
Variability, Arteries, continued … b. Muscular arteries 1. farther from the heart 2. tunica media a. more smooth muscle b. Less elastic tissue c. controlled by ANS
Elastic vs. Muscular Arteries Elastic Artery Muscular Artery
Variability, Muscular Arteries, continued … 3. actively influence blood flow, pressure 4. ANS: a. triggers smooth muscle contraction b. Sympathetic and parasympathetic responses
Variability, arteries, continued … 5. have capacity to establish collateral circulation 6. Especially coronary arteries 7. contract when injured a. ANS reaction b. Prevents blood loss
Detailed anatomy, continued … • B. Arterioles: small arteries < 0.5 mm • 1. Lie close to capillary beds • 2. Muscular • 3. Primary function: regulate capillary blood flow • 4. Allows for exchange of materials between blood and tissues
Detailed anatomy, continued … • C. Capillaries (sinusoids) • 1. Size: 1 mm long x 10 micrometers diameter • 2. Structure • a. Wall: 1 cell layer thick (endothelium) • b. inner surface contacts blood
Blood Vessel Anatomy: Capillaries Capillary
Capillaries, continued … c. outer surface rests on basement membrane d. Beyond basement membrane: 1. loose connective tissue 2. contains tissue fluid ( = plasma outside of blood stream)
Capillaries, continued … • 3. Organization of capillaries: • a. Form vast, complex networks • b. Penetrate to reach most tissues • c. Pre-capillary sphincter: • 1. smooth muscle rings • 2. regulate blood flow between arterioles & capillary beds
Capillaries, continued … • d. Capillary beds: (~ 60,000 miles) • 1. Specialized for exchange of materials • 2. each pound of adipose tissue contains 200 miles of capillaries
Capillary Networks • Capillaries connect arterioles to venules • Blood flow is from the arterial to the venous vessels • Every millimeter of tissue has capillary blood supply
Blood Vessel Anatomy, con’t… • D. Venules • 1. Vessels closest to capillary beds • 2. carry deoxygenated blood • 3. Small venules: structurally similar to large capillaries • 4. Medium venules: contain a few circular muscle fibers • 5. Large venules: have a tunica externa
Blood Vessel Anatomy, con’t… • E. Veins • 1. Structure: same tunics, but not as distinct • a. Tunica media may be absent • b. Tunica externa: usually thickest • 1. Provides strength to outer wall • 2. Lots of smooth muscle fibers • 3. Less elastic tissue
Vascular Tunics: Veins Tunica Externa Tunica Media Tunica Interna
Veins, continued … • Valves: in veins carrying blood against gravity • a. Folds of tunica intima • b. Prevent backflow • c. Absent in venae cavae, pulmonary & portal veins
Valves in Veins Venous Valve
Valves, continued … • 2. Internal jugular veins have valves • a. are “upside down” • b. blood is flowing back to heart c. when heart contracts, pushes blood up into SVC • d. valves keep -O2 blood from going back up into brain
Valves Assisted by Skeletal Muscles • Skeletal muscle contraction, especially in the extremities, assists the flow of blood back to the heart • Varicose Veins…..