Resorption in bones
Bone breakdown (Osteoclasts doing their work!). Primary intake.
Reabsorption
Moves substances (water, solutes) from filtrate back into bloodstream
Purpose of diuretics
Inhibit reabsorption of sodium and water from the body in different parts of the nephron.
Functions of the kidneys
-Maintenance fluid balance
-Maintenance of acid-base balance
-Excretion of metabolic wastes
Secondary functions of kindeys
-Erythropoietin
-Renin (secreted by juxtaglomerular cells)
-Calcitriol
Nephron
Smallest functional unit of the kidneys
Renal medulla
Pyramids in the kidney
renal cortex
Outermost part of the kidneys
Order of fluid through a nephron
- Afferent arteriole
- Bowman’s capsule
- Efferent arteriole
- Proximal convoluted tubule
- descending limb of nephron loop
- Ascending limb of nephron loop
- Distal convoluted tubule
- Collecting duct
Resorption
Moving water and solutes from fluid inside renal tubules back into bloodstream
Secretion
Process of moving waste products and excess ions from blood in the peritubular capillaries into tubular fluid to be excreted
Excretion
filtering blood and selectively removing metabolic wastes, excess water, and toxins to create urine
Filtration
1st step in urine formation. Blood cleaned inside glomerulus.
Preload (Filling pressure)
Amount of blood volume that fills the ventricles in diastole (relaxation) phase of cardiac cycle
After load (Peripheral vascular resistance)
Pressure ventricles must work against to open valves so blood can leave ventricles
Loops diuretics
Location: Ascending limb of loop of Henle
Mechanism: Inhibits Na, Cl, H2O reabsorption.
Indication: Tx of edema d/t HF, hepatic disease, renal disease, HTN.
AE: Hypokalemia, dehydration, hyperglycemia, electrolyte depletion.
Nursing implications: Monitor K, daily weight, I/O
Thiazide Diuretics
Hydrochlorothiazide (HCTZ)
Site: Distal convoluted tubule
Mechanisms: Blocks Na, K, Cl reabsorption. Results in H2O loss. Direct relaxation of the arterioles, decreases preload, decreases after load, decreases BP
Indications: HTN, CHF, liver disease
AE: hypokalemia, hyponatremia, possible hyperglycemia.
Nursing implications: Encourage K foods, monitor BP and electrolytes.
Aldosterone
Secreted by adrenal gland, action on distal CT and collecting duct; Increases sodium and H2O reabsorption increasing BP, excretion of K.
Potassium-sparing diuretics
Spironolactone
Site: DCT and collecting ducts
Mechanism: Aldosterone antagonist, retains K, blocks reabsorption of Na and H2O.
Indications: HTN, edema r/t renal or liver dz. Counteract K loss by other diuretics.
AE: Hyperkalemia
Nursing implications: Avoid K supplements, monitor arrhythmias.
Osmotic diuretics
Mannitol
Site: PCT and descending loop of Henle.
Mechanisms: increased osmotic pressure pulls H2O into renal tubules ; Inhibits tubules reabsorption of H2O and solutes. Rapid diuresis.
Indications: Increase intracranial pressure (cerebral edema), edema
AE: Pulmonary congestion
Nursing implications: Rapid infusion can lead to profound diuresis, monitor electrolytes.
