Bio 202 1st Edition Lecture 6Outline of Current LectureI. Layers of Blood VesselsII. Types of ArteriesIII. CapillariesIV. VeinsV. Circulatory RoutesVI. HermodynamicVII. Perfusion PressureCurrent LectureI. Layers of Blood Vessels*Tunica = layer*Lumen = empty space (blood is allowed to pass through)*Artery = Spongy and more openTunica interna:- Lining blood vessel- Endothelial cells  help repel blood cells from sticking to vessel- Selective permeable Tunica Media:- Smooth muscle tissue- Thicker tunica media in arteries than veins Tunica Externa- Connective tissue serves as an anchorII. Types of ArteriesConducting artery (huge)- Big transport system- Close to the Heart- Noticeable nerve in the tunica mediaVasa Vasorum  blood vessel going to blood vessel to bring nutrients to keep tissue healthy Distributing artery (medium)- Less pressure, distributing to other arteries and tissues Arterioles (smallest)- Taking blood to smaller regions- Aneurysm  weak point in an artery or heart wall*Abdominal aorta, renal arteries, arterial cause at base of brainIII. Capillaries- Sphincters open = capillaries well perfuse (blood moving in)- Sphincters close = little to no blood flow occurs- 50-100 um- Angiogenesis – vessels form from existing small vessels- Causes of angiogenesis; wounding, local irritants, infections, cancer1. Continuous Capillary- Loc: blood brin barrier- Huge erythrocyte- Intercellular cleft: allow few, small molecules to pass through (ions, H20)- Tight junctions: do not let nutrients pass throught, affects permeability2. Fenestrated Capillary- Filtration pores- Loc: kidneys/small intestine- Kidneys filtration:cleaning up urine/blood- < Tight junctions here- Increase in permeability3. Sinusoid Capillary- Large intercellular cleft- A lot of space in between cells- Plasma in lumen- Filtration of RBC- Loc: liver, spleen (old RBC) bone marrow (new RBC)III. Veins- Great capacity for blood containment- Thinner walls than arteries- A lot muscle hereIV. Circulatory Routes- Simplest and most common ~ 1 capillary bed- Portal system ~ 2 capillary beds- Anastomosis: blood vessels mergeArteriovenusVenousArterial*Blood Flow  amount of blood flowing through an organ*Perfusion  flow per given volume or mass of tissue in a given timeAt rest, flow is constantV. Hermodynamic- Flow, pressure, resistance- Increased pressure = increased flow- Increased resistance = decreased flow- Blood pressure (BP)  pressure against walls- Pulse pressure  difference between systolic and diastolic pressure- Measure of stress exerted on small arteries by pressure surges generated by the heart VI. Perfusion Pressure- MAP – average BP- MAP – diastolic + 1/3 (pulse pressure)- Edema = fainting (not enough pressure to