BIOL 2002C 1st Edition Exam 3 Study Guide Chapter 21 What are the 3 layers of blood vessels a Tunica intima interna innermost layer endothelium of simple squamous epithelium basement membrane loose connective tissue supports endothelium b Tunica Media smooth muscles elastic connective tissue c Tunica Adventitia externa outermost connective tissue primarily collagen but contains elastin fibers in large veins Compare laminar and turbulent blood flow Laminar fluid in the center of a blood vessel will move faster Turbulent any sudden change in vessel size flow direction or an obstruction usually plaque causes the production of turbulence which greatly increases resistance Define systolic and diastole pressures pulse pressure and MAP Systolic pressure in vessels when left ventricle contracts 110 mm Hg on average Diastolic pressure in vessels when ventricles relax 70 mm Hg on average Pulse pressure difference between systolic and diastolic pressures 40 mm Hg on average Mean arterial pressure MAP average arterial pressure which forces blood into tissues that takes account diastole lasts longer than systole MAP Diastolic pressure Pulse Pressure 3 MAP declines due to continual friction from blood vessel walls Pulse Pressure due to decreased recoil from initial blood surges as blood moves Explain what the equation F P1 P2 R means and what each of its terms means Blood flow volumes of blood flowing through a structure per unit time mL min Blood Pressure force per unit area exerted by blood on blood vessel wall mm Hg Blood Flow F Pressure difference P1 P2 Peripheral resistance R Blood flows from higher pressure to lower pressure P is high and R is low you ll get high blood flow R is more important for homeostasis because BP is fairly consistent If P increases blood flow increases because it is directly proportional If R increases blood flow decreases because it is inversely proportional What are the sources of resistance in blood vessels and what affect do these sources have on resistance and BP Resistance forces working against flow reflects the amount of friction blood encounters from vessel walls that tend to slow it down also sometimes called peripheral resistance PR Describes the relationship of viscosity and blood vessel length to blood flow Blood viscosity resistance of liquid to flow the greater the viscosity the harder it is to move molecules and keep them moving therefor the slower the flow Blood is 3 4 times more viscous than water Total Blood Vessel Length the longer the vessel length the greater the resistance the longer the vessel length the greater the resistance Blood viscosity and blood vessel length do not change much in adult good unless you gain lose fat affects blood vessel length or you have a blood disorder like polycythemia which would affect viscosity Explain how vessel diameter and vascular compliance affect blood pressure Blood Vessel Diameter since blood flowing against vessel walls encounter more friction decreasing diameter results in increasing resistance R 1 radius4 Vascular compliance tendency for blood vessel volume to increase as blood pressure increases venous compliance is larger than arterial compliance Describe the 3 mechanisms used to keep blood moving in veins Respiratory pump inhaling causes an abdominal pressure increase which squeezes veins forcing blood upward and valves prevent it from flowing back additionally chest pressure decreases so veins expand to improve entry of blood back into the heart Muscular pump valves contraction of skeletal muscles squeezes blood into veins upward valves prevent back flow Increasing vessel diameter Increasing vessel diameter decreases resistance List the percent distribution of blood in each of the systemic vessel types Veins 65 Arteries 15 Capillaries 5 Explain the relationship between cross sectional area of blood vessels and the velocity of blood flow Blood velocity is inversely related to total cross sectional area of each type of vessel it is lowest in capillaries arterioles and venules Explain the 4 types of diffusion across capillary walls a Direct Diffusion lipid soluble molecules like oxygen and carbon dioxide diffuse through the lipid bilayers of the endothelial cell membrane non polar hydrophobic substances b Pinocytosis Some larger molecules like proteins are transported by vesicles through pinocytosis it is active transport c Intercellular clefts narrow passageways small water soluble molecules like sugar and amino acids can diffuse through fluid filled capillary clefts d Fenestrations larger pathways windows permeability varies from high liver to low brain Define the hydrostatic and osmotic pressures that are exerted within capillaries Explain how the interaction of hydrostatic and osmotic pressures between capillaries and interstitial fluids leads to fluid leaving or entering capillaries Fig 21 36 Be able to calculate NFP given HP s and OP s and know how to interpret the NFP in terms of the direction fluids would move into or out of capillaries a Colloid Osmotic Pressure OP force caused by proteins like albumin in water which can t leave capillaries so tend to draw water toward them Constant osmotic pressure along capillary bed of 28 mm Hg in capillaries only 8 mm Hg in interstitial fluids Colloid osmotic pressure tends to draw fluids INTO capillaries b Hydrostatic pressure HP Capillary force exerted by blood against capillary wall o same as capillary BP o higher at arteriole end 30 mm Hg than venous 10 mm Hg Interstitial fluid pressure of fluids outside capillaries o minimal because fluid quickly removed by lymphatics 3 mm Hg HP tends to force fluids OUT of capillaries Net Filtration Pressure NFP HPc HPif OPc OPif outward inward 30 3 28 8 33 20 13 If NFP is POSITIVE fluid is driven out of the capillary if NFP is NEGATIVE fluid is drawn back into the capillary Autoregulation keeping blood pressure constant with priority to brain heart and kidneys Long term can involve angiogenesis for production of new blood vessels and enlargement of existing vessels Short term Metabolic vasodilation of arterioles serving capillary beds of needy tissues caused by decreasing levels of O2 or nutrients increasing waste products NO nitric oxide attaches to Hb in lungs and is released in tissues when O2 is unloaded to cause local vasodilation of capillaries What is the vasomotor center Fig 21 38 cluster of sympathetic neurons in medulla oblongata vasomotor nerve fibers innervate smooth muscle of small arteries and