Chapter 21: The Cardiovascular System: Blood Vessels

1. Chapter 21: The Cardiovascular System: Blood Vessels • Heart  arteries  arterioles  capillaries  venules  veins  heart

3. Blood Vessel Anatomy • Arterial Blood System ______________ vessels- “air,” “to carry” • Types: • Elastic = conducting • muscular = distributing • Venous Blood System - _________________ vessels • Capillaries - ______________ vessels

4. Arteries- 3 tunics figure 21.1 • ____________________- lining of simple squamous epithelium = 1. ____________, closest to the lumen • 2. Basement membrane • 3. Internal elastic lamina • ________________- middle coat, usually thickest, elastic & circular smooth muscle • __________________- stretch without tearing • Innervated by sym NS for constriction/dilation • _____________________- outer, elastic & collagen

5. Vaso vasorum • “_______________________” • Larger blood vessels require oxygen and nutrients, to do so they are served by these types of blood vessels

8. Types of arteries • ________________–largest diameter • __________________ in tunica media • Walls ___________ compared to diameter • Help ______ blood while ventricles relax • Walls stretch to store ______________ • Conduct blood to more muscular arteries • Aorta, brachoiocephalic, common coratid, subclavian, vertebral, pulmonary, common iliac

10. Types of arteries (2) • _____________________- distribute to various parts of the body • Media- more smooth muscle, less elastic • Capable of > vasoconstriction/dilation • Examples: brachial artery, radial artery

11. Arterioles • Small artery • 10-100 μm in diameter • ________________________ • Similar to arteries but usually just a ring of endothelial cells surrounded by scattered smooth muscle fibers • ______________ – opposition to blood flow • Mainly friction between blood an inner walls • Arterioles can be dilated or constricted  called resistance vessels • _________________ can affect bp

12. Capillaries = microcirculation • Microscopic vessels, 4-10μm • connect arterioles to venules • Near almost every cell in the body • # vary w/metabolic activity of the tissue • _______________ – exchange of nutrients and waste between blood and tissue cells thru interstitial fluid • Walls= single cell layer thick & b.m. • ________________– emerges from arteriole & supplies 10-100 capillaries (capillary bed)

13. Capillaries (2) • __________________ – ring of smooth muscle at the junction of the arteriole with metarteriole • Control flow to capillary bed • __________________- bypasses the capillary bed

16. Types of capillaries, fig. 21.4 • _______________ – endothelial cells form continuous tube only interrupted by intercellular clefts (gaps) • Skeletal & smooth muscle, CT, lungs • __________ – “window,” have small pores • Kidneys, villi, choroid plexuses, endocrine glands • ____________ – wider than other cap, may have unusually large fenestrations • Incomplete or absent basement membrane • Liver, red bone marrow, spleen, some endocrine

19. Venule • ______________________ forming these small veins • Walls very porous • Many phagocytic WBC migrate from here • Few scattered smooth muscle cells • Larger venules more ____________ _______________________

20. Veins • 3 layers, interna & media much thinner than artery (less smooth muscle & elastic) • thickest layer - tunica externa = collagen & elastic fibers, lack external & internal elastic lamina • __________ to handle volume & pressure Δ yet not capable to withstand  pressure • have abundant __________ (esp. in limbs) • thin folds in the tunica interna form flaplike cusps projecting into the lumen towards the  • _________________________

26. Capillary exchange, fig 21.7 • 7% blood in systemic cap at any one time • Diffusion • _______________- plasma in vesicles are endocytosed by endothelial cells & exocytosed out other side • Insulin, Ab from mother to fetus • ________________- passive process, large # of ions, molecules particles move in same direction at rates > than w/diffusion • Filtration & resorption

27. Pressure driven movements • ________– fluid & solutes  interstitial fluid • ___________– FROM interstitial fluid  blood capillaries • 2 pressures accountable for filtration: • Blood hydrostatic pressure (BHP)- generated by pump action of heart • Interstitial fluid osmotic pressure • Main pressure accountable for reabsorption: • Blood colloid osmotic pressure (BCOP) • _____________________ (NFP) = balance of all of these pressures

28. Pressure driven movements (2) • __________________ – pressure due to water in plasma exerted against bv • Interstitial fluid hydrostatic pressure pushes fluid back into capillaries • Is close to zero • Difference in ________________ across due to plasma proteins too large to pass pores or fenestrations • BCOP force of these large proteins to pull IF into capillaries (remember- diffusion from  to )

30. Edema • __________________________________ • Interstitial fluid 30% > than normal • Causes of excess filtration: •  capillary blood pressure •  permeability of capillaries • Chemicals, bacterial, thermal, mechanical • Cause of inadequate reabsorption: •  concentration of plasma proteins • Liver disease, burns, malnutrition, kidney disease

31. Blood pressure • Hydrostatic pressure exerted by blood on walls of blood vessel • __________________________________ • __________________________________ • @ 110mmHg during systole drops to70mmHg during diastole • Systolic- highest pressure in arteries during systole • Diastolic- lowest arterial pressure during diastole • Pressure falls progressively as distant from L.V.

33. Mean arterial pressure • MAP = average bp in arteries • @1/3 between systolic & diastolic • MAP = diastolic bp +1/3(systolic-dia) •  CO   MAP •  blood volume   MAP • *Don’t forget, just as in the ventricles, blood flows from areas of high to low pressure

34. Resistance = opposition to flow • BF = DP/R • BP = CO x TPR (TPR=total peripheral resistance= all the vascular R offered by systemic bv) • Viscosity- thickness,  viscosity   resistance, flow • vessel length- longer vessel,  resistance • vessel diameter (1/ r4)-  lumen   resistance • Blood volume-  volume   pressure • CO = SV x HR • If CO, P as long as R is same

35. Systemic Vascular Resistance (SVR) and venous return • Arterioles control SVR bp & blood flow to particular areas by Δ diameter • Controlled by brainstem • ____________________: • Besides heart 2 mechanisms to pump blood: • _________________: valves open, muscle contraction pushes blood thru proximal valve and closes distal, muscle relax & close proximal • _________________:  pressure in thoracic   pressure in abdominal   volume from abdomen to Rt Atrium

37. Regulation of Blood pressure • CV center – input from higher brain regions & sensory receptors • Figure 21.12 • Neural • Baroreceptors – Δ pressure • Carotid sinus- for pressure in the brain • Aortic- regulate systemic pressure • Chemoreceptors – Δ O2, CO2, H + • acidosis   symp hormones, vasoconstriction • Hormonal control • Renal regulation, symp hormones, ANP, Angiotensin II

38. Hormonal regulation of bp • _______________________ (RAA)- blood volume falls or kidney blood flow, renin  angiontensin II   bp • Vasoconstriction • Stimulates release of aldosterone • ______________-  CO by  HR and force, also cause vasoconstriction • _______- released due to  blood volume •  urine output,  vasoconstriction • __________________________- released by ,  bp by vasodilation

43. Circulatory shock • Failure to deliver O2 and nutrients to meet metabolic need • Hypovolemic – low blood volume • Cardiogenic – poor heart function • Vascular – inappropriate vasodilation • Obstructive- obstruction to blood flow • See figure 21.16 – responses • Activation of RAA • ADH • Sympathetic hormones • Local vasodilators: K+, H+, lactic acid, NO

45. Shock: signs and symptoms • Systolic bp  90 • Resting HR  due to symp • Pulse weak and rapid, CO &  HR • Skin is cool, pale, clammy • Mental state altered •  urine production •  thirst •  pH due to acidosis • Nausea - impaired blood flow to GI tract

46. Disorders • _________________- a group of diseases characterized by thickening of artery walls and loss of elasticity • _____________- thin weakened section of the wall of artery or vein, bulges out • Graft or replace • _______- inflammation of vein, often in leg • CVA= cerebrovascular accident- destruction of brain tissue (infarction) resulting of obstruction or rupture of bv supplying brain

47. Atherosclerosis, LDL, and HDL • Atherosclerosis - a stage of arteriosclerosis involving fatty deposits or plaques (atheromas) inside the arterial walls, thus narrowing the arteries  • Plaques develop from due to excessive LDL (containing much cholesterol) accumulate in the inner layer of the artery wall • HDLs decrease amount of excessive cholesterol, transport it to liver for elimination

48. Hypertension • Silent killer- damage to bv, heart, brain, kidney before any noticable pain or symptoms • Major risk factor for both#1 cause of death = heart disease, & #3 = stroke • Lifestyle changes: lose weight, exercise, reduce salt intake, maintain proper electrolyte intake, don’t smoke, manage stress • Drug treatment- • ACE (angiotensin converting enzyme) inhibitors • beta blockers- inhibit renin • Vasodilators • Ca 2+ channel blockers- decrease heart rate