Final Exam 356

How do alterations in carbon dioxide influence acid-base states?

Carbon dioxide (CO2) levels are controlled by the lungs. Hyperventilation reduces the CO2 concentration (and therefore the H+ concentration) of the blood, causing respiratory alkalosis. Hypoventilation increases the CO2 concentration (and the H+ concentration), causing respiratory acidosis. In hypoventilation, the CO2 is essentially retained, causing arterial blood to become acidotic. In hyperventilation, the CO2 is "blown off" at a quick rate, resulting in alkalosis.

1. What causes isotonic imbalance?

Changes in the isotonic (normal) sodium and water balances of the body can be caused by a gain or loss of extracellular fluid (ECF). They can also be the result of changes in or sodium that alters the normal 0.9% salt solution of the body fluids. Hypertonic imbalances result when water is lost or sodium gained.

How does an increase in capillary hydrostatic pressure cause edema?

Hydrostatic pressure: Mechanical force of water pushing against cellular membrane. In vascular system, the blood pressure acts like hydrostatic pressure pushing water outside of the capillary system. Fluid is pushed out from the capillary into the interstitial space Hydrostatic pressure increases as a result of venous obstruction or salt and water retention. Venous obstruction causes hydrostatic pressure to increase behind the obstruction, pushing fluid out of the capillaries and into the interstitial spaces, thereby causing edema.

What is the most prominent electrocardiogram (ECG) change associated with hyperkalemia? With hypokalemia?

Hyperkalemia causes decreased cardiac conduction and more rapid repolarization of heart muscle. In mild states of hyperkalemia, the more rapid repolarization is reflected in the ECG as narrow and taller T waves with a shortened QT interval. Severe hyperkalemia depresses the ST segment, prolongs the PR interval, and widens the QRS complex as a result of decreased conduction velocity. The cardiac effects of hypokalemia are related to changes in membrane excitability. Because potassium contributes to the repolarization phase of the action potential, hypokalemia delays ventricular repolarization. The characteristic changes in the ECG reflect delayed repolarization. For instance, the amplitude of the T wave is decreased, the amplitude of the U wave is increased, and the ST segment is dep

What are some causes of hypernatremia?

Hypernatremia is a result of serum sodium levels exceeding 145 mEq/L. Causes include loss of free water while body sodium remains near normal (isovolemic) and when there is increased total body water and a greater increase in total body sodium resulting in hypervolemia resulting from the infusion of hypertonic saline solutions, or oversecretion of adrenocorticotropic hormone (ACTH) or aldosterone (hypervolemic).

In a urine analysis test, we shouldn't have these following substances:

Normal urine should not have protein, glucose or leukocytes.

How does a decrease in capillary oncotic pressure cause edema?

Oncotic pressure: pulls water into the capillary. Lost or diminished plasma albumin production contributes to decreased plasma oncotic pressure. The decreased oncotic attraction of fluid within the capillaries causes capillary fluid to move into the interstitial space, resulting in edema. Plasma albumin is a protein that keeps fluid in the intravascular space, limiting movement into the interstitial space, which causes the edema.

Diuretics and types

block Na re-absorption in the nepherons and send more Na to the urine--> water follows sodium May cause loss of Mg. K, P, Ca, bicarb Types of diuretics: Osmotic diuretics • Loop diuretic • Thiazides • Potassium sparing

Furosemide/lasix

blocks reabsorption of NaCl in loop of henle cause loss of Na K Cl diuretic side effects: Dehydration, hypotension, potassium loss (arrhythmia) Digoxin toxicity with hypokalemia!!!!

What are the 3 cause of renal failure?

1. Prerenal Cause: decrease perfusion (hypotension, renal arteries structual problems) 2. Intrarenal Cause: direct nepheron damage (nephrotoxic drugs) 3. Postrenel Cause: obstruction of urine flow (UTI, Calculi, tumors)

What are the 6 major functions of the renal system?

1. Fluid and electrolyte balance 2. Acid-base balance 3. Excretion of bio-active substances (hormone, foreign substances, drugs) 4. Regulation of Arterial Blood 5. Regulation of red blood cells production 6. Regulation of vitamin D production /vitmation activation occurs in the kidney

How can you not have a deficiency in total body potassium and still have hypokalemia?

ECF hypokalemia can develop without loss of total body potassium. For example, potassium shifts into the cells during respiratory or metabolic acidosis or after administration of insulin. In alkalosis, potassium shifts into the cell in exchange for hydrogen ions to maintain plasma acid- base balance. Insulin also promotes cellular uptake of potassium, causing an ECF potassium deficit. Keep in mind when measuring potassium, the index measures serum potassium. This does not include the potassium that has shifted into the cells.

Explain Factors effecting glomerulars filteration rate? How is filteration rate determined? How is GFR regulated?

Factors effecting GFR: ----->>>Capillary filtration pressure: >>Colloidal osmotic pressure >>Capillary permeability Average GFR: 125ml/min (only 1 ml of the 125 ml is excreted as urine) Average urine output is 60ml but 30 is minimal. 180 liters of filtrate a day How GFR is regulated: constriction and relaxation of afferent and efferent arterioles >>Sensitive to vasoactive hormones (Angiotensin II)

What two chemicals are altered in metabolic acid-base disturbances?

Most acid-base imbalances are caused by alterations in hydrogen ion (H+) concentrations and bicarbonate ion (HCO3). Too much hydrogen and not enough bicarbonate result in metabolic acidosis. An abundance of bicarbonate and too little hydrogen result in metabolic alkalosis.

What role does potassium play in the body? What metabolic dysfunctions occur in potassium deficiency? In potassium excess?

Potassium facilitates glycogen deposition in the liver and skeletal muscles. It maintains the resting membrane potentials of cells, which is important for normal nerve conduction; cardiac rhythm; and skeletal, smooth, and cardiac muscle contraction. In hypokalemia (potassium deficiency): (1) carbohydrate metabolism is affected because insulin secretion is depressed and muscle and liver glycogen synthesis is reduced; (2) metabolic alkalosis can occur because, as potassium moves from the intracellular fluid (ICF) to the ECF, hydrogen ions move into the cells to maintain cation balance; (3) polyuria and volume depletion can occur because decreased potassium levels impair renal function, resulting in a decreased ability of the kidneys to respond to ADH and to concentrate urine; and (4) skeletal, smooth, and cardiac muscle weakness and cardiac dysrhythmias can occur because low potassium levels decrease neuromuscular and cardiac excitability. In hyperkalemia (potassium excess): (1) skeletal, smooth, and cardiac muscle excitability is increased; (2) cardiac dysrhythmias such as heart block and cardiac arrest can occur; (3) metabolic acidosis can occur as potassium moves from the ECF into the cells and intracellular hydrogen ions move out of the cells and into the ECF; and (4) renal function is affected, resulting in fluid retention and oliguria.

Tubular Reabsorption -proximal tubule

Proximal Tubule: • 65% of reabsorption of water and electrolytes Na+, K+,Cl-, bicarbonate (HCO3-) • Highly permeable to water uses osmotic gradient • If blood glucose levels are high osmotic gradient will allow glucose spilled into urine - Secretion of H+ and medications

What is the difference between compensation and correction of acid-base disturbances?

Renal and respiratory adjustments to primary changes in pH are known as compensation. The respiratory system compensates for changes in pH by increasing or decreasing the concentration of carbon dioxide (carbonic acid) by changing ventilation. The renal system compensates by producing more acidic or more alkaline urine. The values for PaCO2 and bicarbonate will vary from normal levels in an attempt to maintain a ratio of 20:1. Correction occurs when the values for both components of the buffer pair (carbonic acid and bicarbonate) return to normal levels.

What is the most severe complication of hyponatremia?

The most life-threatening consequence is cerebral edema and increased intracranial pressure. Neurologic changes include lethargy, confusion, apprehension, seizures, and coma.

What forces promote net filtration?

The net filtration of fluid, or the movement of water back and forth across capillary membranes, is controlled by capillary and interstitial hydrostatic and oncotic pressures (Starling forces). Forces favoring movement of water from capillaries to interstitium are relative increases in capillary hydrostatic pressure and decreases in intravascular oncotic pressure. Forces favoring movement of water from the interstitium into the vascular compartment are relative increases in capillary oncotic pressure and interstitial hydrostatic pressure.

Kidney Functions Lab Test: Uric Acid BUN Creatinine

Uric Acid: 0.18-0.48mmol/L -Production of purine metabolism -High levels can cause gout and kidneys stones Urea (BUN-blood urea nitrogen) 8-21 mg/dl -protein metabolism -usually correspond with decrease in GFR Creatinine 0.8-1.3 mg/dl -production of muscle metabolism (elevation indicates loss of renal function) GFR: 115-125 ml/min Below 60 is renal failure

What hormones regulate salt and water balance?

Water balance is regulated primarily by antidiuretic hormone (ADH). When the serum osmolarity is elevated, ADH is released by the posterior pituitary gland and causes water to be reabsorbed into the blood from the distal tubules and collecting ducts of the kidneys. Serum sodium level is regulated primarily by aldosterone from the adrenal cortex, which causes the kidneys to reabsorb both sodium and water when the extracellular fluid level or the sodium level is low. In addition, antidiuretic hormones are released in response to an increase in blood volume or blood pressure and act to increase sodium and water excretion.

What are aquaporins?

Water moves freely by diffusion through the lipid bilayer in cell membrane through aquaporins, a family of water channel proteins that provide permeability to water.