Systole heart beats—is cued by messages from the brain, reflecting the brain's responses to conditions of the body, such as pain, emotional stress, level of activity, and to ambient conditions including external temperature, time of day, etc. Electrical systole opens voltage-gated sodium, potassium and calcium channels in cells of myocardium tissue. Subsequently, a rise in intracellular calcium triggers the interaction of actin and myosin in the presence of ATP which generates mechanical force in the cells in the form of muscular contraction, or mechanical systole. The contractions generate intra-ventricular pressure, which is increased until it exceeds the external, residual pressures in
Human Tissue Authority Human Tissue Authority The Human Tissue Authority (HTA) is an executive non-departmental public body of the Department of Health of the United Kingdom. It regulates the removal, storage, use and disposal of human bodies, organs and tissue for a number of scheduled purposes such as research, transplantation, and education and training. It was created by the Human Tissue Act 2004 and came into being on 1 April 2005 and its statutory functions began on 1 April 2006. The authority was originally chaired by Baroness Hayman followed, in 2006, by Shirley Harrison, from January 2010-2018 by Baroness Diana Warwick and since