action potential in muscles is very brief

depolarisation=++++

calcium channels are located in the sarcoplasmic reticulum

calcium is recycled between two compartments. the sarcoplasmic retuiculum - cytoplasm - combine to cause contraction which is then taken back up into stores to cause relaxation. the difference between cardiac and skeletal muscle is that there is no electronic signal required for skeletal muscle to contract

each T tubule is sandwhiched between the sarcoplasmic reticulum

the heart contains pacemaker cells which are specilised muscle cells in the myocardium which set the hearts rythm the pacemaker potentials depolarise toi thresholds

sino atrial node - sets rythm of heart from pacemaker cells the electrical signal is then propegated across the atrium and ventricles where it is then made into a mechanical stimulus

all cells in the heart have the ability to set their own rate of contraction which is a protective mechanism of the heart which means if a xconduction block occurs the rest of the heart can still set its own rythm the heart is different to skeletal muscle as it sets its own rythm and action potentials and has its own conduction pathway to the ventricles from the atrium to cause contraction

Ca is the key driver of heart contraction

• dentify, orientate and name the bones of the pectoral girdle and upper limb