<span>Many of those who were found to have died prematurely were making lifestyle choices that were deleterious to their health. They were doing things that caused their bodies to degrade at a rate that was faster than it should have been, and leading to premature death. In addition, this was at a rate much greater than mere chance, with almost one-half (48%) of those dying prematurely having these characteristics.</span>
Opposing or antagonist muscles are the muscles that do the opposite of the muscle that is working. For example, when a person performs a bicep curl, the elbow flexes as the bicep shortens. The opposing muscle group in this case is the triceps, which lengthen or elongate in order to allow this movement at the elbow.
Answer:
A. epinephrine
Explanation:
Bronchial constriction usually involves the tightening of the smooth muscles which surrounds the tube-like bronchial airways. This occurs via extra mucus production, spasming of smooth muscles, or swelling/inflammation of layers within bronchi or bronchioles. Bronchial constriction typically results in symptoms of wheezing, coughing and shortness of breath.
This can be treated via the use of the hormone epinephrine, a bronchiodilator. For some cases like asthma, epinephrine in small aerosolized (inhaled) doses can lead to the <em>temporary</em> relief of symptoms. Epinephrine acts by making bronchial tubes wider to allow the passage of air.
In the body, smooth muscle cells in the veins, arteries and heart are under the control of epinephrine receptors called β2 receptors. Epinephrine binding to the receptor triggers a cell signalling cascade that activates β2 receptors to dilate smooth muscle in the lungs.
Here's how-
- Calcium is essential to mediating muscle cell signalling and thus contraction
- in the lungs, epinepherine-β2 receptor binding leads to enzyme activation (adenylyl cyclase)
- conversion of the energy molecule ATP to the secondary messenger molecule cyclic AMP.
- cAMP inhibits the activity of the enzyme <em>myosin light chain kinase </em>(MLCK) in smooth muscle
- ∴ the enzyme remains inactive and the muscles relax
<em>Summary:</em><em> epinephrine → muscle relaxation →</em><em> bronchial dilation (reduced diameter) </em><em>→ decreased respiratory distress → easier breathing.</em>
This is true. Severe allergic reaction can result in anaphalactic shock and death.
<span>b. It is an important source of fuel for sprints and bouts of high-intensity exercise.</span>