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Conduction-Brown
Conduction: Microanatomy and Physiology
Question | Answer |
---|---|
The functional layers of the heart | Endocardium (inner lining of heart), Epicardium (Outer lining of the heart), Myocardium (heart muscle) |
Endocardium | In contact with blood, simple squamous (endothelium), Valves and Ct are outgrowths of endocardium |
Epicardium | Contains blood vessels, simple squamous (mesothelium), also the same thing as visceral pericardium |
Myocardium | Cardiac muscle |
Intercalated Discs allow for | Coordinated heart contractions, connect cytoplasm of each cell to the cytoplasm of neighbors |
Cardiac nuclei are located | centrally |
SA node is located in the | Right atria |
AV node is located in | Septal wall of the right atrium |
Purkinje cells appear as | slightly transparent, large diameter cardiac myocytes in the endocardium |
Mesothelial lining | A serious layer that releases fluid to keep the heart from adhering to parietal pericardium |
Annulus fibrosis | A fibrous skeleton of connective tissue that insulates ventricles from the atria. Only depolarization from the AV node penetrates |
___initiate the contraction of the heart | Action potentials |
Three areas of the heart that have automaticity (spontaneous depolarization) | SA node, AV node, (some)Purkinje fibers |
"Phase 4" is also known as the | Slow diastolic depolarization |
Outflow of potassium (Ik) is involved in | Repolarization |
"Funny channel" (If) is a | inward sodium current when SA node cells have gone down to -60mV (resting minimum potential) |
"Phase 4" is due to which ion current | If or funny channel which is an influx of sodium |
Calcium channels opening cause | An influx of calcium which cause a rapid depolarization |
Norepinephrine binding to Beta1 on the SA node causes | Increase the function of If (funny channel) which increases rate of diastolic depolarization (Sympathetics) |
M receptors binding with Acetylcholine in the SA node causes | Increase in the potassium channel which decreases rate of diastolic depolarization (Parasympathetics) |
Conduction rate in SA node | .05 m/s |
Conduction rate in atria | 1 m/s |
Conduction rate in AV node | .01-.05 m/s |
AV nodal conduction is dependent on on voltage-gated _____ channels | Ltype-Calcium |
Speed of conduction in Purkinje fibers | 4-5 m/s |