Desmosomes
Allow force to pull on adjacent cells
Autorhythmic cells
control heart rate
Pacemaker potential
Unstable membrane potential, drifts towards 0
Contractile cells
smaller than skeletal muscle
-1 nucleus per cell, shorten in response to stimulus
Septum
separates left and right sides of heart so they function independently
Valves
prevent backwards flow of blood
Atrioventricular Valves (AV)
between atria and ventricles
Chordae Tendineae
Connects valve to ventricle
-connected to papillary muscles for stability
Right Side Tricuspid Valve (RST)
3 flaps
Left Side Bicuspid or Mitral Valve
2 flaps
Semilunar valves
b/w ventricles and arteries
Pulmonary Circuit
Heart to lungs and back
Oxygen poor blood leaves–> oxygen rich returns
Systemic Circuit
Heart to body and back
Oxygen rich blood leaves–>oxygen poor returns
Starling law of the heart
Heart pumps out all the blood that is returned to it
Inotropic Agent
Chemical that affects contractility
Contractility
Controlled by nervous and endocrine systems
Positive Inotropic Effect
Increases contractility
Negative Inotropic Effect
Decreases contractility
Plateau
- Complete opening of Ca channels, closing of some K channels
Autorhythmic cells action potential
Na-Ca Exchanger (NCX)
Exports Ca from cell after contraction
Graded Contraction
Force is proportional to # of formed crossbridges
-How much Ca is bound to troponin
Cardiac Refractory Period
Much longer than in skeletal muscle
-ensures that heart relaxes (fills with blood) and contracts (sends blood away)
Pericardium
Sac made of connective tissue that encases the heart
-filled w/ fluid for lubrication
Fibrous and Serous