Writing III – Acid-Base Balance
Congestive heart failure (CHF) is caused by the inability of the heart to fill correctly, eject blood completely, or a combination of the two, which results in a decrease in cardiac output. Chronic hypertension (CH) is a constantly elevated blood pressure. Peripheral vascular disease (PVD) causes a restriction in blood circulation due to atherosclerosis, fatty deposits on the inner linings of the arteries that cause a blockage of blood flow; arteriosclerosis, loss of elasticity in the arteries themselves; or both. Restricted peripheral blood flow causes an increase in blood pressure because the heart would have to pump with more force to maintain proper cardiac output. Hypertension strains the filtration membranes of the glomeruli in the kidneys. After prolonged hypertension, the filtration membrane can be damaged, decreasing the filtration ability in the kidneys, and allowing proteins and other large molecules to enter the filtrate. Congestive heart failure and peripheral vascular disease result in decreased blood flow to the kidneys, decreasing the glomerular filtration rate (GFR). Both damaged filtration membranes and decreased blood flow through the kidneys result in decreased filtration and decreased GFR. Eventually, any kidney under this sort of strain will require dialysis or kidney replacement.
Congestive heart failure causes decreased cardiac output by decreasing the volume of blood ejected from the heart. The resulting decreased blood flow to the lungs also decreases gas exchange in the alveoli. Decreased gas exchange can result in inadequately oxygenated blood. Incomplete ejection of blood during ventricular contraction can cause mitral valve prolapsed, allowing blood to backflow into the left atrium, which increases pressure in pulmonary veins, causing pulmonary edema. Excess fluid in the alveoli due to edema disrupts normal gas exchange in the lungs, causing shortness of breath. Peripheral vascular...
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