Page 1668 - Saunders Comprehensive Review For NCLEX-RN

decreasing blood volume, and thus decreasing BP.
8. Decreases in blood volume result in increased
antidiuretic hormone release; this promotes an
increase in blood volume and therefore BP.
9. Renin, a potent vasoconstrictor, causes the BP to
increase.
10. Renin converts angiotensinogen to angiotensin I;
angiotensin I is then converted to angiotensin II in the
lungs.
11. Angiotensin II stimulates the release of aldosterone,
which promotes water and sodium retention by the
kidneys; this action increases blood volume and BP.

N. The vascular system

1. Arteries are vessels through which the blood passes
away from the heart to various parts of the body; they
convey highly oxygenated blood from the left side of
heart to the tissues.
2. Arterioles control the blood flow into the capillaries.
3. Capillaries allow the exchange of fluid and nutrients
between the blood and the interstitial spaces.
4. Venules receive blood from the capillary bed and
move blood into the veins.
5. Veins transport deoxygenated blood from the tissues
back to the right heart and then to the lungs for
oxygenation.
6. Valves help return blood to the heart against the force
of gravity.
7. The lymphatics drain the tissues and return the tissue
fluid to the blood.
II. Diagnostic Tests and Procedures (refer to Chapter 10 for further information
on laboratory reference levels)

A. Cardiac markers

1. Troponin
a. Troponin is composed of 3 proteins—
troponin C, cardiac troponin I, and
cardiac troponin T.
b. Troponin I especially has a high affinity
for myocardial injury; it rises within 3
hours and persists for up to 7 to 10
days.
c. Normal values are low, with troponin I
being less than 0.35 ng/mL (less than
0.35 mcg/L) and troponin T being less
than 0.1 ng/mL (less than 0.1 mcg/L);
thus, any rise can indicate myocardial

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