Unit II: Transport Cardiovascular System II

1. Unit II: TransportCardiovascular System II Chapter 18: pp 657-671 Chapter 17: pp 595-619

2. Cardiac Output (CO) 40 Maximum for trained athletes exercising at peak levels • Amount ejected by ventricle in 1 minute • Cardiac reserve: •  with fitness,  with disease 35 30 Normal range of cardiac output during heavy exercise 25 Cardiac output (L/min) 20 x = SV: 80 mL/beat CO: 6000 mL/min HR: 75 beats/min 15 10 5 Average resting cardiac output Some forms of heart failure 0

3. Cardiac Output (CO) Factors affecting stroke volume (SV) Factors affecting heart rate (HR) Peripheral blood flow Blood volume Muscular contractions ANS Hormones Body temperature ↑ contractility = ↓ ESV Venous return ↑ = ↑ SV ↑ Filling time = ↑ ESV Vasoconstriction EDV Vasodilation ANS Hormones Influences the efficiency of contractions ↑ afterload = ↓ pumping efficiency and ↑ESV ESV STROKE VOLUME (SV) = EDV – ESV HEART RATE (HR) CARDIAC OUTPUT (CO) = HR x SV

4. Heart Rate • Pulse: • infants have HR of 120 bpm or more • young adult females avg. 72 - 80 bpm • young adult males avg. 64 to 72 bpm • HR rises again in the elderly • Tachycardia: • stress, anxiety, drugs, heart disease or  body temp. • Bradycardia: • in sleep and endurance trained athletes Tachycardia Bradycardia 60 bpm 100 bpm Normal range of resting heart rates

5. Anatomy of Blood Vessels • Tunica interna: repels blood cells and platelets • simple squamous endothelium overlying a basement membrane • Tunica media: smooth muscle, collagen, elastic tissue • Tunica externa: loose connective tissue Artery Vein LM x 60 Vein The structure of the wall of a vein Endothelium Smooth muscle Tunica intima Tunica media Tunica externa

6. Arteries Conducting/Elastic Arteries • 3 Categories by Size: • Conducting (elastic) arteries • pulmonary, aorta & common carotid • Distributing (muscular) arteries • Brachial, femoral and splenic • Resistance (small) arteries • Arterioles Internal elastic layer Tunica intima Tunica media Tunica externa Distributing/Muscular Arteries Tunica externa Tunica media Tunica intima Arterioles Smooth muscle cells Endothelium Capillaries Endothelial cells Basal lamina

7. Large Veins Veins • thinner tunica media • 3 Categories by Size: • Small veins • venules • Mediumveins • Radial, ulnar veins • valves prevent backflow • Large veins • Vena cava, pulmonary, jugular Tunica externa Tunica media Tunica intima Medium-sized Veins Tunica externa Tunica media Tunica intima Venules Tunica externa Endothelium Capillaries Pores Endothelial cells Basal lamina

8. Capillaries • Smallest blood vessels • Only vessels that allow exchange of materials • Anatomy: • simple squamous endothelium with basement membrane • walls: 0.2-0.4 µm thick; lumen: 5-9 µm diameter Arteriole Reabsorption Predominates Venule KEY Filtration Predominates CHP (Capillary hydrostatic pressure) No Net Movement BCOP (Blood colloid osmotic pressure) 20.4 L/day 24 L/day NFP (Net filtration pressure) 25 25 25 18 25 35 mm mm mm mm mm mm Hg Hg Hg Hg Hg Hg NFP = +10 mm Hg NFP = –7 mm Hg NFP = 0 Capillary CHP > BCOP CHP = BCOP BCOP > CHP

9. Capillary Beds • Metarterioles • connect arterioles to capillaries • Thoroughfare channel • connect capillaries to venule • Perfusion • precapillary sphincter

10. Types of Capillaries Basal lamina Endothelial cell Basal lamina • Continuous – (4nm) • endothelial cells have tight junctions • Fenestrated – (20-100nm) • organs that require rapid absorption or filtration • Ex. kidneys, small intestine • Sinusoids – (30-40nm) Nucleus Endothelial cell Nucleus Gap between adjacent cells

11. Circulatory Routes • Most common route • heart  arteries  arterioles  capillaries  venules  veins  heart • Portal system • hypothalamus – pituitary • in kidneys • intestines – liver • Anastomoses • Arteriovenous anastomosis • Ears, fingers, toes, palms

12. Blood Pressure • Force that blood exerts against a vessel wall • Measured at brachial artery of arm • Systolic pressure and diastolic pressure • Normal value, young adult: 120/75 mm Hg

13. Blood Pressure • Importance of arterial elasticity • expansion and recoil maintains steady flow of blood throughout cardiac cycle, smoothes out pressure fluctuations and  stress on small arteries • BP rises with age: arteries less distensible

14. Blood Pressure Resistance to flow = 1 Flow = 1 Internal surface area = 1 • BP determined by: • cardiac output • blood volume • peripheral resistance • Blood viscosity • Vessel length • Vessel radius (vasomotion) Resistance to flow = 2 Internal surface area = 2 Flow = ½ Greatest resistance, slowest flow near surfaces Least resistance, greatest flow at center

15. Arteries R. Common carotid R. Subclavian Brachiocephalic trunk Axillary Aortic arch Ascending aorta Descending aorta Diaphragm Brachial Renal Common iliac Radial Ulnar Femoral

16. Veins External jugular Internal jugular Subclavian Brachiocephalic Axillary Superior vena cava Brachial Diaphragm Inferior vena cava Renal Radial Common iliac Ulnar Femoral

17. Fetal Development and Circulation • Fetus = from 8 weeks until birth • Fetal circulation • umbilical-placental circuit • circulatory shunts • ductus venosus • foramen ovale • ductus arteriosus

18. Blood Circulation Before Birth Foramen ovale Ductus arteriosus Aorta Placenta Pulmonary trunk Liver Inferior vena cava Umbilical vein Ductus venosus Umbilical cord Umbilical arteries