Cell Signalling and Transduction
Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

Because nitric oxide breaks down quickly and thus cannot travel far
Because nitric oxide cannot cross cell membranes and enter the blood
None of these
Because other body tissues use a different signaling molecule

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Cell Signalling and Transduction
Which of the following is true about a hydrophilic signaling molecule?

Its receptor is located in the cytosol of the target cell
Since it can enter the cell, it directly affects some specific cell process
It is a steroid
It might trigger a signal cascade that causes some effect in a cell

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Cell Signalling and Transduction
In the signal transduction mechanism known as protein phosphorylation

phosphorylated proteins act with enzymes to trigger the signal cascade
All of these
receptor kinases play a key role in triggering the signal cascade
the signaling molecule binds to a surface receptor

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Cell Signalling and Transduction
Nitroglycerin has long been administered to human patients suffering from chronic chest pain (angina). This medication works because it

mimics the action of signal receptors
interferes with chemical cascades that trigger contraction of heart muscle
breaks down into nitric oxide, which increases blood flow to the heart
is broken down into hormones that affect the heart

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

never enter the blood of humans
are hydrophilic and so cannot penetrate the plasma membrane
are made in one location of the body but have their effects some distance away
bind to cell surface receptors to trigger chemical cascades

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