Cardiac Muscle Physiology Faisal Mohammed MD Ph D
- Slides: 23
Cardiac Muscle Physiology Faisal Mohammed, MD, Ph. D 1
Objectives: By The end of this lecture students should be able to: n Distinguish the cardiac muscle cell microstructure n Describe cardiac muscle action potential n Point out the functional importance of the action potential n Outline the intracellular calcium homeostasis 2
Wall of the heart Cardiac Muscle Cells
Permeability Changes and Ionic Fluxes During an Action Potential (skeletal Muscle) 7
1 0 2 3 4
The Action Potential in Skeletal and Cardiac Muscle Figure 20. 15
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Functional importance of Cardiac action potential n The decrease in conductance (permeability) of potassium at phase 0 and 1 of the cardiac action potential contributes to the maintenance of depolarization in phase 2 (plateau) n The long absolute refractory period prevent the occurrence of tetanus (maintained contraction without a period of relaxation) in the cardiac muscle. n Skeletal muscle action potential is short that allows tetanus to occur
(inactivation gate) h Gate (activation gate) m Gate Activation gates open when the membrane potential becomes less negative and the inactivation gates close when the potential becomes less negative. The activation gate is fast but the inactivation is slow responding
PHASE 0 OF THE FAST FIBER ACTION POTENTIAL Na+ m A -90 mv m m B h -65 mv h Na+ m C 0 mv Chemical Gradient Electrical Gradient D h m +20 mv h Na+ E m +30 mv h 16
The importance of calcium influx through the slow voltage gated calcium channels 18
Mechanism of Cardiac Muscle Excitation, Contraction & Relaxation
Intracellular Calcium Homeostasis… 1 20
Intracellular Calcium Homeostasis… 2 21
Cardiac Muscle action potential Vs. Skeletal Muscle Ø Phase 0 –Depolarization phase (Na+ influx) Ø Phase 1 partial repolarization (Not in skeletal) Ø Phase 2 Plateau (~ depolarization not in skeletal) slow calcium channels Ø Phase 3 fast repolarization phase (K+ repolarization() Ø Phase 4 resting membrane potential 22
Thank You 23
- Faisal mohammed
- Name the tissue type
- Function of muscle tissue
- Comparison of skeletal cardiac and smooth muscle
- Heart muscles are
- Smooth muscle under the microscope
- All or none law
- Biceps brachii and biceps femoris
- Properties of cardiac muscle
- Basement membrane
- Simple cardiac cycle flow chart
- Cardiac muscle
- Cardiac muscle histology labeled
- Cardiac muscle tissue
- Cardiac muscle mitochondria
- Cardiac output
- Lateral head tricep
- Transverse tubule
- Glycolysis in cardiac muscle
- What is a tissue?
- Slide
- Skeletal muscle longitudinal section labeled
- Cardiac muscle
- Cardiac muscle