Properties of myocardium of animals Rhythmicity The cardiac muscles have an inherent ability to generate their own impulses spontaneously at regular intervals known as rhythmicity without the influence of nerves and hormones,. This property can be demonstrated by coronary perfusion of the isolated mammalian heart using Ringer’s solution. Contractility Contraction of cardiac muscle differs from other […]

Action potential in cardiac muscle Cardiac muscle has an inherent property of generating its own action potentials rhythmically, independent of nerve stimulation. This occurs in the peacemaker cells of the S.A. node, which depolarizes faster than any other parts of the heart. The onset of action potential in cardiac muscle is slower but prolonged than

Electro chemical changes during action potential in heart Spike potential (over shoot) Spike potential (over shoot) is the steep change in the negativity of the cell from – 90 mV to more positivity of + 40 mV in the membrane potential due to rapid increase in the permeability of the Na+ ions to the interior of the cell.

Channels system of cell membrane of heart Na – K leakage channels and Voltage gated Na channels and K channels are the Channels system of cell membrane of heart. Na – K leakage channels These channels are 100 times more permeable to K+ ions than Na+ ions and are exceedingly important in determining the level of normal

Events of action Potential in heart The action potential is caused by a sequence of changes or events occurring in the membrane permeability to Na+ and K+ ions. When an excitable cell is stimulated the cell membrane permits the inflow of Na+ ions into the cell to generate the action potential. Action potential is the rapid changes in

Basic mechanism of membrane potential in animals Three major factors cause the membrane potential- Differential permeability of the membrane to diffusion of ions, The Na+ – K+ electrogenic pump and Trapping of negatively charged anions inside the cell. Differential permeability of the membrane to diffusion of ions During resting state the cell membrane is 50 to100 times

Conduction system of heart in animals The specialized excitatory and conduction fibres show feeble contractions only because of very few contractile fibres, but they conduct impulses very rapidly through out the heart. In mammals, S.A. node (Sino auricular node) is the specialized structure of the cardiac muscle located at the junction of the right atrium

Heart and cardiac muscles of animals Heart Heart is situated in the middle mediastinal space. It has two anterior chambers, the atria and two posterior chambers, the ventricles. The heart is separated into left and right sides by a septum. The atria and ventricles communicate with each other through the atrio-ventricular orifices, which are guarded