MindMap Gallery Cardiac electrophysiology and physiological characteristics
This is a mind map about myocardial electrophysiology, which mainly includes transmembrane potential and current, Physiological characteristics, etc. Welcome to like and collect!
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
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Cardiac electrophysiology and physiological characteristics
Transmembrane potential and current
Working cells (ventricular myocytes)
0,1,2,3,4, period
① Resting potential: Inward rectifier potassium channel (Ik1) (high permeability to K when polarized)
②Stage 0: sodium inward current (INa) → fast channel, which can be blocked by tetrodotoxin, but myocardial cells have low sensitivity to it
③Phase 1: Instantaneous outward current (Ito) → K outflow
④Phase 2 (platform period)
Slow, long duration→ventricular myocyte action potential duration and effective refractory period are long
inward current
1) L-type calcium current (ICa-L): Main
2) Slowly inactivated INa
outward current
1) Inwardly rectifying potassium current (Ik1) → depolarization of the membrane leads to reduced permeability to K (impeding K outflow during the plateau phase)
2) Gradually strengthening delayed rectifier potassium current (Ik): late dominant
In the early stage, Ca2 influx is balanced with K outflux.
⑤3rd period: Ik gradually increases, Ik1
⑥Phase 4: Sodium pump (sodium-potassium pump) → sodium goes out, potassium goes in, Na-Ca2 exchanger → 3Na goes in, 1Ca2 goes out
Autonomic cells (sinoatrial node cells)
Issue 0, Issue 3, Issue 4
①Maximum repolarization potential: Ik1 channel less →-70mv
②Stage 0: ICa-L→slow depolarization→slow responding cells
③No phase 1 and 2: lack of Ito channel
④Phase 3: Repolarization → delayed rectifier potassium current Ik
⑤4 stages of automatic depolarization
a. Progressive attenuation of delayed rectifier potassium current Ik: Mainly
b. Progressive enhanced If:Na influx
c.ICa-T: Rapidly decaying inward current
Autonomic cells (Purkinje cells)
0,1,2,3,4, period
Stages 0, 1, 2, and 3 are the same as ventricular myocytes
4th phase automatic depolarization
If Enhancement: Main
Ik weakens
Physiological properties
(1) Excitability
1. Periodic changes in excitability
2. Influencing factors
① Resting potential or maximum repolarization potential
②Threshold potential level
③Ion channel status of sodium channel or L-type calcium channel
(2) Conductivity
Influencing factors
(1) Structural factors
① Large cell diameter → small resistance → large current and large conduction speed
②Number of gap connections
(2) Physiological factors
①The speed and amplitude of depolarization in period 0
②Membrane potential level (threshold potential level and resting potential)
③Excitability of the membrane adjacent to the unexcited area (3 points of excitability)
(3) Self-discipline
Influencing factors
①4 periods of automatic depolarization speed
②Maximum repolarization potential level
③Threshold potential level: Extracellular Ca2 increases (reduces permeability to Na) → threshold potential shifts upward (more difficult to activate)
(4) Shrinkage
Features
① Synchronous shrinkage (all or no shrinkage): intercalary disc → gap connection → rapid propagation
② No tetanic contraction occurs: long effective refractory period → alternating contraction and contraction
③Excitation-contraction coupling is highly dependent on Ca2 influx