Ch 19B Cardiophysiology PDF
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Summary
This document provides an overview of cardiophysiology, including details on cardiac muscle fibers, functional differences, electrical events, conduction systems, heart rhythms, and regulation. It's a useful resource for students and those interested in the human heart.
Full Transcript
Cardiac Muscle Fibers Cardiomyocytes – Striated, contract via sliding filaments – Short, fat, branched & connected by intercalated discs – 1-2 nuclei – Numerous St0 -If mitochondria -lowsarcrevcul oplasmiumce – Simpler SR, larger T tubules n - use s N &miner - Allow to signals through HO pass cell a...
Cardiac Muscle Fibers Cardiomyocytes – Striated, contract via sliding filaments – Short, fat, branched & connected by intercalated discs – 1-2 nuclei – Numerous St0 -If mitochondria -lowsarcrevcul oplasmiumce – Simpler SR, larger T tubules n - use s N &miner - Allow to signals through HO pass cell another one Major Functional Differences Stimulation – Skeletal muscle used motor neurons – Cardiac muscle uses autorhythmic cells Contraction – Skeletal muscle contracted in motor units – Cardiac muscle contracts as a whole – functional syncytium Absolute refractory period – Skeletal muscle – 1-2 ms – Cardiac muscle – 200 ms Energy requirements – Skeletal muscle can use anaerobic respiration – Cardiac muscle requires O2 system Sympathet nervous heart the ↳ as give can the heart Parasympatheti ↑ As long you It need heart the system The the ATP does not nervous to under go cardiac cycle Electrical Events Heart depolarizes & contracts without nervous system stimulation heart – Does the nervous system affect the heart? doesn't Coordinated heartbeat occurs due to gap junctions and the cardiac conduction system – Autorhythmic cells (non-contractile) Don't need move Pacemaker cells leakbrane PermeableNa acetocholine can affect The but run Not a bas - ae E mi ↳ & L ce dum to adCle l channel e so have - setapacehard ac S it Stora resting A T depolarizing to depolarit Conduction System Heart Rhythms Sinus rhythm Arrhythmias – Abnormal rates Tachycardia, bradycardia – Ectopic focus Ex: Junctional rhythm – AV node Ex: Heart block Basic rhythm can be modified Electrocardiography Cardiac Cycle Cardiac Output Cardiac output – volume of blood pumped out by each ventricle in 1 minute – Product of stroke volume (SV) and heart rate (HR) – 70 ml X 75 beats/min = 5250 ml/min = 5.25 L/min CO = SV x HR Regulation Stroke volume – Contractility – Ca++ – Preload – stretch – Afterload – SL valves Heart rate – ANS – Chemical – hormones & ions
