1. Ch 11 - Vascular System

2. The Vascular System Taking blood to the tissues and back  Arteries, Arterioles – away from heart  Capillaries – gas exchange  Venules, Veins – toward the heart

3. Figure 19.2 Large veins (capacitance vessels) Large lymphatic vessels Arteriovenous anastomosis Lymphatic capillary Postcapillary venule Sinusoid Metarteriole Terminal arteriole Arterioles (resistance vessels) Muscular arteries (distributing vessels) Elastic arteries (conducting vessels) Small veins (capacitance vessels) Lymph node Capillaries (exchange vessels) Precapillary sphincter Thoroughfare channel Lymphatic system Venous system Arterial system Heart

4. Three layers (tunics) 1.Tunic interna  Endothelium 2.Tunic media  Smooth muscle  Controlled by sympathetic nervous system 3.Tunic externa  Mostly fibrous connective tissue Blood Vessels: Anatomy

5. Tunica intima Tunica media Tunica adventitia

6. Differences Between Blood Vessels  Walls of arteries are the thickest  Lumens of veins are larger  Walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue

7. Table 19.1 (1 of 2)

8. Table 19.1 (2 of 2)

9. Arteries Carry blood away from the heart. Thick layer of smooth muscle. Pulse, pulse points.

11. Arterioles Smallest arteries Lead to capillary beds Control flow into capillary beds via vasodilation and vasoconstriction

12. Capillaries very thin walled microscopic blood vessels across which gases are exchanged.

14. Capillaries cont. So small that blood cells flow through single file. Made only of thin epithelium, so gases, nutrients, and wastes can diffuse in and out.

16. Capillaries In all tissues except for cartilage, epithelia, cornea and lens of eye

18. Venules

19. Veins Blood returns to the heart. Very low pressure, blood flows against gravity.

21. Veins cont. One way valves to prevent backflow. Squeezing of skeletal muscle pumps blood toward the heart.

22. Movement of Blood Through Vessels  Most arterial blood is pumped by the heart  Veins use the milking action of muscles to help move blood Figure 11.9

23. Varicose Veins

24. Capillary Beds Capillary beds consist of two types of vessels 1.Vascular shunt – directly connects an arteriole to a venule Figure 11.10 2. True capillaries – exchange vessels  Oxygen and nutrients cross to cells  Carbon dioxide and metabolic waste products cross into blood

25. Capillary Exchange  Substances exchanged due to concentration gradients  Oxygen and nutrients leave the blood  Carbon dioxide and other wastes leave the cells

26. Capillary Exchange: Mechanisms  Direct diffusion across plasma membranes  Endocytosis or exocytosis  Some capillaries have gaps (intercellular clefts)  Plasma membrane not joined by tight junctions  Fenestrations of some capillaries  Fenestrations = pores

27. Diffusion at Capillary Beds Figure 11.20

28. Figure 19.14 Relative cross- sectional area of different vessels of the vascular bed Total area (cm 2 ) of the vascular bed Velocity of blood flow (cm/s) Aorta Arteries Arterioles Capillaries Venules Veins Venae cavae

29. Hepatic Portal Circulation

30. The term “PORTAL” is used to refer to veins which carry blood to organs other than the heart. Materials absorbed into the blood in the digestive system are carried into veins which anastomose into a single hepatic portal vein which leads to the liver. There those materials are processed before the blood continues on to the heart.

31. Hepatic Portal Circulation Route Right Atrium Aorta Celiac Artery Digestive Organs Hepatic Portal Vein Liver Inferior Vena Cava Hepatic Veins

32. Circulation to the Fetus

33. Fetal Circulation Placenta Umbilical Vein Ductus Venosus Inferior Vena Cava Right Atrium Foramen Ovale Left Atrium Right Ventricle Pulmonary Truck Ductus Arteriosis Aorta

34. Ventricular Septal Defect Animation

35. Patent Ductus Arteriosus Ductus Arteriosus fails to close after birth. Blood flows from Aorta into Pulmonary Arteries due to higher pressure in Aorta. Effects vary with size of patent opening. –Small - no symptoms to physical underdevelopment & increased respiratory infection susceptibility. Heart murmurs common. –Large - may cause congestive heart failure.

36. Pulmonary Artery Aorta Patent Ductus Arteriosus

37. Pulse  Pulse – pressure wave of blood  Monitored at “pressure points” where pulse is easily palpated Figure 11.16

38. Blood Pressure  Measurements by health professionals are made on the pressure in large arteries  Systolic – pressure at the peak of ventricular contraction  Diastolic – pressure when ventricles relax  Pressure in blood vessels decreases as the distance away from the heart increases

39. Comparison of Blood Pressures in Different Vessels Figure 11.17

40. Measuring Arterial Blood Pressure Figure 11.18

41. Variations in Blood Pressure Human normal range is variable Normal  140–110 mm Hg systolic; varies with age  80–65 mm Hg diastolic Hypotension  Low systolic (below 100 mm HG)  Often no cause for concern  Orthostatic hypotension  Acute hypotension during shock

42. Hypertension  High systolic (above 140 mm HG)  High diasolic (above 90 mm Hg)  Can be dangerous, increases peripheral resistance. Strains heart and damages vessels.

43. Atherosclerosis – narrowing of a blood vessel by a thickening of the wall of the vessel. Arteriosclerosis – the end stage of the disease. The damaged area of the blood vessel hardens, frays, and ulcerates, encouraging thrombus formation.

44. Blood Pressure: Effects of Factors Temperature  Heat has a vasodilation effect  Cold has a vasoconstricting effect Chemicals  Various substances can cause increases or decreases Diet Neural factors  Autonomic nervous system adjustments (sympathetic division causes vasoconstriction) Renal factors  Regulation by altering blood volume  Renin – Hormonal released from kidney. Results in vasoconstriction and water retention.

45. Figure 19.9 Baroreceptors in carotid sinuses and aortic arch are stimulated. Baroreceptors in carotid sinuses and aortic arch are inhibited. Impulses from baroreceptors stimulate cardioinhibitory center (and inhibit cardioacceleratory center) and inhibit vasomotor center. Impulses from baroreceptors stimulate cardioacceleratory center (and inhibit cardioinhibitory center) and stimulate vasomotor center. CO and R return blood pressure to homeostatic range. CO and R return blood pressure to homeostatic range. Rate of vasomotor impulses allows vasodilation, causing R Vasomotor fibers stimulate vasoconstriction, causing R Sympathetic impulses to heart cause HR, contractility, and CO. Sympathetic impulses to heart cause HR, contractility, and CO. Stimulus: Blood pressure (arterial blood pressure falls below normal range). Stimulus: Blood pressure (arterial blood pressure rises above normal range). 3 2 1 5 4a 4b Homeostasis: Blood pressure in normal range 4b 3 2 1 5 4a

46. Figure 19.9 step 1 Stimulus: Blood pressure (arterial blood pressure falls below normal range). 1 Homeostasis: Blood pressure in normal range

47. Figure 19.9 step 2 Baroreceptors in carotid sinuses and aortic arch are inhibited. Stimulus: Blood pressure (arterial blood pressure falls below normal range). 2 1 Homeostasis: Blood pressure in normal range

48. Figure 19.9 step 3 Baroreceptors in carotid sinuses and aortic arch are inhibited. Impulses from baroreceptors stimulate cardioacceleratory center (and inhibit cardioinhibitory center) and stimulate vasomotor center. Stimulus: Blood pressure (arterial blood pressure falls below normal range). 2 3 1 Homeostasis: Blood pressure in normal range

49. Figure 19.9 step 4a Baroreceptors in carotid sinuses and aortic arch are inhibited. Impulses from baroreceptors stimulate cardioacceleratory center (and inhibit cardioinhibitory center) and stimulate vasomotor center. Sympathetic impulses to heart cause HR, contractility, and CO. Stimulus: Blood pressure (arterial blood pressure falls below normal range). 2 3 1 4a Homeostasis: Blood pressure in normal range

50. Figure 19.9 step 4b Baroreceptors in carotid sinuses and aortic arch are inhibited. Impulses from baroreceptors stimulate cardioacceleratory center (and inhibit cardioinhibitory center) and stimulate vasomotor center. Vasomotor fibers stimulate vasoconstriction, causing R Sympathetic impulses to heart cause HR, contractility, and CO. Stimulus: Blood pressure (arterial blood pressure falls below normal range). 2 3 1 4b 4a Homeostasis: Blood pressure in normal range

51. Figure 19.9 step 5 Baroreceptors in carotid sinuses and aortic arch are inhibited. Impulses from baroreceptors stimulate cardioacceleratory center (and inhibit cardioinhibitory center) and stimulate vasomotor center. CO and R return blood pressure to homeostatic range. Vasomotor fibers stimulate vasoconstriction, causing R Sympathetic impulses to heart cause HR, contractility, and CO. Stimulus: Blood pressure (arterial blood pressure falls below normal range). 2 3 1 4b 4a 5 Homeostasis: Blood pressure in normal range

52. Factors Determining Blood Pressure

53. Developmental Aspects of the Cardiovascular System  A simple “tube heart” develops in the embryo and pumps by the fourth week  The heart becomes a four-chambered organ by the end of seven weeks  Few structural changes occur after the seventh week