I thin the nurse knows that Whites have the highest incidence of cystic fibrosis. Whites have the highest incidence of cystic fibrosis . Cystic Fibrosis is a disease in which a mutated gene causes a thick and sticky mucus to be produced, resulting in mucus build up in the lungs and digestive tract. Before puberty, boys are affected more with asthma than girls. Female African Americans have the highest mortality rates for Asthma than all ethnic/gender groups. Whites on the other hand have the highest incidence of (COPD), even though higher rates of smoking occur in other ethnic groups..
Answer:
C. tetanic contractions might occur, which would stop the heart's pumping action.
Explanation:
The absolute refractory period of the cardiac muscle action potential refers to the time interval when the voltage gated sodium channels are inactivated. The absolute refractory period lasts ~180 msec. The action potential lasts 200-220 msec.
The refractory period of cardiac muscle is dramatically longer than that of skeletal muscle. This prevents tetanus from occurring and ensures that each contraction is followed by enough time to allow the heart chamber to refill with blood before the next contraction.
In order words, It is important for the cardiac muscle cells to have a longer refractory period, because if they were short like the skeletal muscles, the heart could enter tetanic contraction/summation which is when muscle is stimulated so rapidly that it does not have a chance to relax at all between stimuli.
PDK1 (pyruvate dehydrogenase kinase 1) is an enzyme which inactivates the pyruvate dehydrogenase by phosphorylating it using an ATP molecule<span>.
</span><span>PDK1 (phosphoinositide-dependent protein kinase-1) acts by catalyzing the phosphorylation of Thr-229 (threonine at position 229 in pyruvate dehydrogenase).
This phosphorylation is </span><span>synergistic</span> with the phosphorylation of C-terminal Thr-389, but this one is not done by the PDK1.
