KINE 1P90 Lecture Notes - Lecture 10: Cardiac Output, Sympathetic Nervous System, Stroke Volume
The amount of blood pumper per minute. Cardiac output (co) calculated by: co = heart rate (hr) x stroke volume (sv) When your body shifts from a reclining to a standing position (at rest), sv immediately drops. This is an effect of gravity which causes blood to pool in the legs, reducing the volume of blood returning to the heart. At the same time hr increases in order to maintain the cardiac output. Hr is regulated through the balance of parasympathetic and sympathetic influence on the sa node. At rest, parasympathetic nerves will release acetylcholine (ach) Ach will bind to receptors on the sa node. Slow down the closure of k+ channels, more k+ will flow out causing hyperpolarization. Since resting potential is farther, it takes longer to reach threshold potential, resulting in slower hr. Ne binds to receptors on the sa node. Speed up rate of depolarization so threshold potential is reached faster causing more frequent action potentials.