Movement of Materials across a Capillary

Control of Circulation Systemic Control: mechanisms to regulate mean arterial pressure Local Control: mechanisms to regulate flow to individual organs (autoregulation)

 P r 4  q  For a given arterial pressure (i.e.  P = constant), blood flow to an organ or tissue is controlled by the vasomotor tone of the arteries and arterioles. from Tortora and Grabowski, 1992 vasoconstriction - inc. in vasomotor tone, dec. r vasodilation - dec. in vasomotor tone, inc. r

ParasympatheticSympathetic Autonomic Nervous System

aortic and carotid baroreceptors “pressure is high” CV center sends para- sympathetic signals via vagus nerve to SA node slows heart rate Decrease sympathetic signals: dec. ventricular con- tractility arterial vasodilation dec. in venous tone “pressure is low” CV center sends sympa- thetic signals to SA node via cardiac accelerator nerve increases heart rate Increase sympathetic signals: inc. ventric. contactility arterial vasoconstriction inc. in venous tone Input to cardiovascular center in medulla

Sample Questions Which statement about aerobic metabolism is correct: a) it occurs when oxygen is present, but can also take place when oxygen is absent b) it is responsible for generating only a small percentage of the potential energy in a glucose molecule c) all enzymes and substrates in this metabolic sequence are located inside mitochondria d) it occurs in all living animals, regardless of their evolutionary history As presented in lecture, tracheal respiration: a) relies on hemocyanin (not hemoglobin) to transport oxygen in the blood b) is a form of respiration that delivers air directly to metabolizing cells c) is found in all insects except those capable of flight d) is unique among animals in that the gas exchange requires active transport mechanisms This species has a high blood volume per unit body mass, generates only low blood pressures with its neurogenic heart, and possesses ostia that facilitate the movement of deoxygenated blood back into the heart. It is a: a) crayfishc) salamander b) squidd) tuna

More sample questions The small blip in the tracing indicated by the arrow is caused by: a) depolorization of the atriac) depolarization of the ventricles b) repolarization of the atriad) opening of the tricuspid valve At the point in the cardiac cycle indicated by the “x”: a) ventricular pressure is at its greatest value b) the ventricles are beginning to refill with blood c) the atria have already contracted to start the next cardiac cycle d) all of the heart valves are open