Mortis

E. C. Bate-Smith and T. N. Mortis, Food Science, Cambridge University Press, U.K., 1952. 

Rigor ll a muscle condition in which muscle fibers, depleted of ATP and phosphocreatine, develop a state of extreme rigidity and cannot be easily extended. (In death, this state is called rigor mortis, the rigor of death.) From what you have learned about muscle contraction, explain the state of rigor in molecular terms. 

Mortis, M L, and M A Slutgess Tctra/ierfeoi Lett, 34, 42 T1993 ... 

If intracellular levels of ATP drop (eg, after death), ATP is not available to bind the S-1 head (step 4 above), actin does not dissociate, and relaxation (step 5) does not occur. This is the explanation for r or mortis, the stiffening of the body that occurs after death. 

A decrease in the concentration of ATP in the sarcoplasm (eg, by excessive usage during the cycle of con-traction-relaxation or by diminished formation, such as might occur in ischemia) has two major effects (1) The Ca ATPase (Ca + pump) in the sarcoplasmic reticulum ceases to maintain the low concentration of Ca + in the sarcoplasm. Thus, the Interaction of the myosin heads with F-actin is promoted. (2) The ATP-depen-dent detachment of myosin heads from F-actin cannot occur, and rigidity (contracmre) sets in. The condition of rigor mortis, following death, is an extension of these events. 

Sancta Maria, Mater Dei, ora pro nobis peccatoribus, nunc et in hora mortis nostrae. ... 

In the absence of ATP, myosin crossbridges are unable to release the actin. As a result, the sarcomeres, and therefore the muscle, remain contracted. This phenomenon is referred to as rigor mortis. Following death, the concentration of intracellular calcium increases. This calcium allows the... 

Tenderness. The contractile state of the muscle after rigor mortis is a major factor in meat tenderness, which is affected by post-mortem conditions creating differences in tenderness. Ageing of fresh pork can be used to improve tenderness. The process is based on a continuous weakening of the structural elements by different endogenous muscle peptidases along with an improved palatability (Taylor et al., 1995). 

Wygrecka, M., Morty, R.E., Markart, P., Kanse, S.M., Andreasen, P.A., Wind, T., Guenther, A., and Klaus, T.P. (2007) Plasminogen activator inhibitor-1 (PAI-1) is an inhibitor of factor VILactivating protease in patients with acute respiratory distress syndrome. J. Biol. Chem., 10.1074/jbc.M610748200, published online ahead of print. 

Postmortem findings include dark-tarry blood discharge from body orifices, absence of rigor mortis, hemorrhage of the mucous membranes, bloating, and rapid decomposition of the carcass. 

The fact that cardiovascular diseases occupy first place as causa mortis in civilized countries continues to influence strongly research in the field of bioactive pyridazine derivatives also, as shown by the enormous number of patents and papers dealing with pyridazines useful as cardiovascular drugs which have appeared within the period covered by this review. 

Postmortem examination in fatal cases has shown immediate onset of extreme rigor mortis in the muscles of the thighs and legs, edema and intraalveolar hemorrhage in the lungs, cerebral edema, and liver and kidney damage. The risk of serious intoxication is increased during hot weather. ... 

How We Become a Stiff When a higher vertebrate dies, its muscles stiffen as they are deprived of ATP, a state called rigor mortis. Explain the molecular basis of the rigor state. 

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