BIOC34H3 Lecture Notes - Lecture 5: Atrioventricular Node, Medulla Oblongata, Cardiac Output
Document Summary
Lecture 5: regulation of cardiac output: heart rate and stroke volume: regulation of cardiac output (co): heart rate. The heart is innervated by branches of the sympathetic nervous system, and branches of the parasympathetic nervous system. Input from both of these can affect pacemaker potentials, the rate of electrical conduction through the heart and the strength of contraction (sympathetic only). Heart rate can also be altered by hormones - particularly adrenaline (epinephrine) and noradrenaline (norepinephrine) from the adrenal gland (we"ll look more at that when we come to blood pressure regulation). The major regulatory mechanisms for heart rate are input from the sympathetic and parasympathetic nervous systems (and circulating adrenaline and noradrenaline when present). Sympathetic fibres originate in the brainstem (the medulla oblongata), travel through the spinal cord and spinal ganglia and onwards to the heart. The sympathetic cardiac nerve innervates the heart in three places - the sa node, the av node and the contractile muscle of the myocardium.
