BIOL 208 Lecture Notes - Lecture 5: Vasomotor Center, Medulla Oblongata, Sympathetic Nervous System
Document Summary
Blood pressure: blood pressure is the force per unit area on the blood vessel walls, blood pressure is due to resistance. Blood viscosity - thickness of the blood (usually does not change) Ex: polycythemia = excessive rbcs = higher viscosity. Protein de ciency - lack of plasma proteins leads to a decrease in viscosity. Vessel lengths - longer the blood vessel = greater the resistance. Every pound of fat requires another 100 miles of vessels (usually vessel length doesn"t change much) Blood vessel diameter - this is where resistance is the greatest. Blood owing through a vessel is slowed by friction on the walls. The longer the blood vessel the lower the resistance (varies by the 4th power; 2 x 2 x 2 x 2 = 16: arterial bp - the elastic arteries are closest to the heart. At systole, blood is forced into these arteries at a high pressure (systolic pressure)
