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Heart - How it Works
Questions
| Question | Answer |
|---|---|
| What happens during Atrial Relaxation? | Blood ENTERS both Atria |
| What happens during Atrial Contraction? | Blood LEAVES both Atria |
| What happens during Ventricular Contraction? | Blood LEAVES Ventricles |
| What happens during Ventricular Relaxation? | Blood FILLS Ventricles |
| What is Diastole? | Atrial Contraction, Ventricular Relaxation |
| What is Systole? | Atrial Relaxation, Ventricular Contraction |
| What is happening during Systole? | AV Valves = CLOSED, SL Valves = OPEN - "LUB" |
| What is happening during Diastole? | AV Valves = OPEN; SL Valves = CLOSED - "DUB" |
| Where are AV Valves located? | between the Atria and Ventricles |
| Where are the SL Valves located? | between Ventricles and Arteries |
| What causes heart murmurs? | Valves not opening/closing properly - may be some regurgitation |
| What is the composition of Heart Valves? | Endothelium = Simple Squamous Epithelium |
| What is the function of AV Valves? | prevent Regurgitation into Atria |
| What is the function of SL Valves? | prevent Regurgitation into Ventricles |
| When is the "Lub" sound created? | AV Valves = CLOSED - Systole |
| When is the "Dub" sound created? | SL Valves = CLOSED - Diastole |
| What is the function of the Sinoatrial Node? | sets Contractile Pace for both Atria |
| Where is the Sinoatrial Node located? | Superior portion of RIGHT Atrium |
| What is the function of the Atrioventricular Node? | accepts Electrical Excitation from Atria |
| Where is the Atrioventricular Node located? | on LOWER Interatrial Septum |
| What is the function of the Atrioventricular Bundle (bundle of His)? | Spreads Excitation through Ventricular Walls via the conduction Myofibers (Purkinje Fibers) |
| Where is the Atrioventricular Bundle (Bundle of His) located? | on LOWER Interatrial Septum - connected to AV Node |
| What is the role of the Vagus nerve w/ regard to the heart? | Heart rate is SUPRESSED by the Parasympathetic Vagus nerve |
| What structures(s) are responsible for accelerating the Heart Rate? | Sympathetic Nerves ( T-1 --> T-5 ) |
| What effect would cutting the Vagus nerve have on the Heart? | would Increase the Heart Rate |
| How is coordination and control of the heart set? | Sinoatrial Node --> Atrioventricular Node --> Atrioventricular Bundle --> Myofibers --> Ventricular Walls = Heart Rate |
| What is an anatomical difference between AV and SL Valves? | the flaps of AV Valves are restrained by Chordae Tendineae |
| What structures control the Chordae Tendineae? | Papillary Muscles = extensions of Myocardium |
| What is the function of Chordae Tendineae? | restrain flaps of AV Valves |