BIO210Y5 Lecture Notes - Lecture 21: Vasoconstriction, Vasomotor, Hyperthyroidism
Document Summary
Conducting tubes (blood vessels - capillaries, arteries, veins) Carries blood from and to gas exchange areas in lungs. Blood leaving the circuit must complete a systemic circuit before re-entering pulmonary circuit. Continuous: water, small solutes and lipid-soluble material. Fenestrated: rapid exchange of water and large solutes (peptides) 1. there is a lot more blood volume that needs to be supported. 2. majority of the volume needs to be circulated against gravity. Vascular resistance: friction between blood and vessel walls; depends on diameter and length of vessel. Most resistance near boundaries/ surfaces of vessel. Reduce the diameter by half: resistance increases 16x. Velocity of blood flow inversely proportional to resistance. Blood flow is highest in aorta and lowest in the capillaries. Arterial pressure is higher during ventricular systole and lower during ventricular diastole (walls stretch and recoil) Blood pressure: peak systolic over peak diastolic. Filtration becomes negative near venules and resorption predominates. Resistance weaker in veins close to the heart (greater diameter)
