Download Suggested Answers for Case Study, Chapter 23, Disorders of Blood

Suggested Answers for Case Study, Porth
Chapter 23, Disorders of Blood Pressure Regulation
1.
The reason for the high incidence of hypertension among African Americans
is not entirely clear. Salt sensitivity, or the increase of blood pressure in
response to a high sodium diet, has been speculated. This condition is thought
to involve an impaired renal sodium transport mechanism. Increased
vasomotor tone and abnormal endothelium-dependent vasodilation are other
possibilities for the prevalence of hypertension among African Americans.
Barriers to care are noteworthy in this population. There are frequently
financial considerations, difficulties in accessing health care, or long wait
times for treatment. Furthermore, health education materials may not be
culturally sensitive and fail to address the high rate of salt sensitivity,
smoking, and obesity among African Americans.
2.
An elevated systolic pressure, even in the absence of diastolic hypertension,
carries with it a high risk for cardiovascular disease. Increased systole is
associated with left ventricular hypertrophy, increased myocardial demand for
oxygen, and subsequent heart failure. An absolute or relative decrease in
diastolic pressure limits coronary perfusion. Finally, a widened pulse pressure
damages arterial tissues and predisposes an individual to atherosclerosis and
aneurysm formation.
3.
Diuretics reduce blood pressure by increasing renal secretion of sodium and
water. They reduce cardiac output and, with prolonged use, decrease
peripheral vascular resistance. ACE inhibitors limit the activity of ACE in
converting angiotensin I to angiotensin II. As a result, less circulating
angiotension II is available to trigger aldosterone secretion and
vasoconstriction. ACE inhibitors also inhibit bradykinin degradation and
stimulate the production of prostaglandins that have a vasodilating effect.