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BIOL 2304 Fall 2008Chapter 191 Chapter 19 – Vascular System.

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Presentation on theme: "BIOL 2304 Fall 2008Chapter 191 Chapter 19 – Vascular System."— Presentation transcript:

1 BIOL 2304 Fall 2008Chapter 191 Chapter 19 – Vascular System

2 BIOL 2304 Fall 2008Chapter 192 A. categories and general functions: 1. arteries - carry blood away from heart 2. capillaries - allow exchange of materials between blood and tissue fluid 3. veins - return blood to heart

3 BIOL 2304 Fall 2008Chapter 193

4 BIOL 2304 Fall 2008Chapter 194 B. wall structure most vessel walls have 3 layers lumen = space inside vessel 1. tunica intima / tunica interna endothelium – simple squamous e. subendothelial layer – loose c.t. (collagen)

5 BIOL 2304 Fall 2008Chapter tunica media a. smooth muscle - cells circularly arranged controlled by ANS and chemical factors constriction decreases blood flow and increases systemic blood pressure dilation increases blood flow and decreases systemic blood pressure b. elastic c.t.

6 BIOL 2304 Fall 2008Chapter tunica adventitia / tunica externa c.t. attaches vessel to surrounding structures vasa vasorum nourish outer part of vessel wall

7 BIOL 2304 Fall 2008Chapter 197 C. arteries 1. elastic (conducting) - large arteries near heart (aorta and major branches) * conduct blood to muscular arteries * low resistance * tunica media = circular elastin sheets with few smooth m. cells * recoil maintains blood pressure during diastole

8 BIOL 2304 Fall 2008Chapter muscular - middle-sized arteries, distal to elastic arteries * distal to elastic arteries * tunica media very thick; much smooth m. and some elastin * regulate blood flow to organs * have an internal and an external elastic lamina

9 BIOL 2304 Fall 2008Chapter arterioles - smallest arteries * tunica media contains smooth m. only * diameter controlled by ANS and chemical messengers * diameter determines blood flow and blood pressure

10 BIOL 2304 Fall 2008Chapter 1910 D. capillaries * wall consists of endothelium and basal lamina (no tunica media or externa) * 8 to 10  m in diameter * join and branch to form capillary beds * cells are joined at spots around perimeter by tight junctions and desmosomes * intercellular clefts are spaces between cells

11 BIOL 2304 Fall 2008Chapter types a. fenestrated capillaries (high permeability) * have fenestra (openings) in endothelial cells * some fenestra are covered by a membrane, others are not * also have intercellular clefts * found in small intestine, synovial joints, kidney

12 BIOL 2304 Fall 2008Chapter 1912 b. continuous capillaries * intercellular clefts but no fenestra * most common type c. sinusoids * wide, leaky capillaries, usually fenestrated * fewer cell junctions * allow passage of large particles * found in bone marrow, spleen, liver

13 BIOL 2304 Fall 2008Chapter 1913 d. low-permeability capillaries * complete tight junctions * no fenestra, no clefts * restricted transport vesicles * can transport specific molecules in or out * found in brain (blood-brain barrier)

14 BIOL 2304 Fall 2008Chapter capillary beds precapillary sphincter - smooth m. cell wrapped around origin of capillary * controls blood flow through capillaries * sphincter controlled by autoregulation * when sphincter is closed, blood is diverted to thoroughfare channel

15 BIOL 2304 Fall 2008Chapter 1915 E. veins have thinner walls than arteries for the same diameter (larger lumen) act as capacitance vessels - store extra blood (65%) low pressure tunica adventitia thicker than tunica media venous valves prevent backflow

16 BIOL 2304 Fall 2008Chapter 1916 F. vascular anastomosis occurs when vessels join midstream anastomoses provide alternate pathways (collateral channels)

17 BIOL 2304 Fall 2008Chapter 1917 G. circulatory routes 1. pulmonary circuit: right ventricle to lungs to left atrium * pressure supplied by right ventricle * low pressure system * takes low oxygen blood (75% saturated) to lungs and brings high oxygen (98% saturated) blood back to heart

18 BIOL 2304 Fall 2008Chapter 1918 right ventricle pulmonary semilunar valve pulmonary trunk left and right pulmonary arteries lobar arteries (3 R, 2 L) take blood to lung lobes pulmonary capillaries pulmonary veins (superior and inferior, L and R) left atrium

19 BIOL 2304 Fall 2008Chapter systemic circuit: left ventricle to body to right atrium * pressure supplied by left ventricle * high pressure system * takes O2 to tissues and removes CO2 * distributes nutrients from digestive tract to body * collects wastes and takes them to kidney for excretion

20 BIOL 2304 Fall 2008Chapter 1920 a. circulatory pathways of the brain (cerebral arterial circle, circle of Willis)

21 BIOL 2304 Fall 2008Chapter 1921 anterior communicating a. anterior cerebral a. internal carotid a. posterior communicating a. posterior cerebral a. basilar a. vertebral a.

22 BIOL 2304 Fall 2008Chapter 1922 cross section of neck:

23 BIOL 2304 Fall 2008Chapter 1923 b. hepatic portal circulation portal system = two capillary beds in series, joined by veins or arteries

24 BIOL 2304 Fall 2008Chapter 1924

25 BIOL 2304 Fall 2008Chapter 1925 capillaries of small intestine, part of large intestine and stomach superior mesenteric vein capillaries of spleen, stomach and pancreas splenic vein capillaries of distal large intestine and rectum inferior mesenteric vein

26 BIOL 2304 Fall 2008Chapter 1926 hepatic portal vein liver liver sinusoids hepatic veins inferior vena cava

27 BIOL 2304 Fall 2008Chapter 1927 c. fetal circulation placenta = organ formed from extra-embryonic membranes and endometrium to exchange materials between fetal and maternal blood the umbilical veins take high-oxygen and high-nutrient blood from the placenta to the fetus the umbilical arteries take low-oxygen, high-waste blood back to the placenta

28 umbilical vein from placenta fetal liver hepatic portal vein ductus venosus inferior vena cava right atrium foramen ovale left atrium right ventricle left ventricle pulmonary trunk ductus arteriosus aorta lungs internal iliac a. umbilical a. to placenta BIOL 2304 Fall 2008Chapter 1928

29 BIOL 2304 Fall 2008Chapter 1929 adaptations: 1) to bypass the fetal liver ductus venosus - allows some umbilical vein blood to go through the fetal liver but diverts most of it directly into the inferior vena cava 2) to bypass the non-functional fetal lungs foramen ovale – opening in interatrial septum that allows blood to go from the right atrium directly into the left atrium ductus arteriosus – vessel that connects pulmonary trunk and aorta

30 BIOL 2304 Fall 2008Chapter 1930


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