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20 Cards in this Set

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Potassium is the main intracellular cation. TRUE/FALSE
TRUE. About 98% of the body K+ is intracellular, largely the result of the sodium potassium pump.
Deficiency results in neuromuscular dysfunction. An excess causes myocardial dysfunction.
The plasma level of K+ is much lower than that of sodium. TRUE/FALSE
TRUE.
List 4 key factors that maintain plasma potassium levels.
1. Dietary intake
2. Renal filtration
3. Serum pH
4. Effects of insulin and epinephrine
What effect does Aldosterone have on lumonal Na+?
It stimulates the sodium potassium ATPase pump and facilitates passage of sodium through the luminal membrane Na+ channels, particularly in the cortical collecting ducts.
How is Aldosterone linked to potassium?
Aldosterone also increases the permeability of the tubular membrane to potassium.
What else stimulates Aldosterone?
It increases with low blood pressure and low plasma sodium. High plasma levels of potassium, will directly stimulate adrenal cortical cells to produce aldosterone.
What is the association between plasma potassium and serum pH?
Plasma K+ concentration also changes with serum pH. If pH decreases(the H+ increases), H+ tends to enter the body cells in exchange for K+, and plasma K+ increases. When blood pH increases H+ decreases, H+ tends to leave cells and enter the bloodstream, to partly compensate for the alkalosis.
Alkalosis itself tends to enhance renal potassium secretion with subsequent excretion in place of H+ secretion. TRUE/FALSE
TRUE.
What other hormones might stimulate the entry of potassium into cells?
Insulin/Epinephrine/and Aldosterone.
A diabetic patient may become hypokalemic with overvigorrous treatment with insulin, so potassium levels must be watched.
K+ leaves muscle cells during exercise. Epinephrine also released during exercise helps reverse this outflow, increasing K+ entry especially into muscle cells.
Diuretics that prevent water reuptake at the renal tubular level also prevent the uptake of sodium and potassium, because the latter, for osmotic reasons, will tend to maintain their concentrations in the increased amount of tubular water. TRUE/FALSE
TRUE.
Thus, increased excretion of water and sodium, but not potassium, occur with the use of aldosterone inhibitors.
What is the difference between aldosterone and ADH regarding potassium secretion?
Aldosterone stimulates K+ secretion largely in the cortical end of the collecting duct and is not very active in the more distal medullary end of the collecting duct. ADH, acts largely on the medullary end of the collecting duct.
What is primary hyperaldosteronism?
Here, plasma K+ levels drop, because aldosterone stimulates potassium secretion in the distal tubule.
What is secondary hyperaldosteronism?
This may be secondary to increased renin production from reduced GFR, potassium loss may be minimal.
Low GFR means low fluid flow rate through the renal tubules; low fluid flow rate results in greater time for (sodium and) water reabsorption, and a greater concentration of K+ in the tubular fluid; increased K+ concentration in the tubular fluid decreases the gradient for potassium secretion into the tubular fluid.
Chloride is an important anion(negative ion) in the maintenance of fluid and electrolyte balance and is an important component in gastric juice. TRUE/FALSE
TRUE.
What is the relationship between chloride and bicarbonate?
Cl- concentration in general follows reciprocally changes in bicarbonate ion., since some anion is necessary to fill in the gaps of altered bicarbonate conc. and Cl- is the most common extracellular anion.
What is the Chloride shift?
1. when CO2 enters the RBC in peripheral tissues, it rapidly changes to H+ and HCO3- under the influence of carbonic anhydrase.
2. The H+ ion combines with Hg, but HCO3- leaves the cell in exchange for Cl-.
3. Within the lung, the Cl- shifts out of the red cell(when O2 combines with Hg and H+ is released tp combine with HCO3- and form CO2 for exhalation.
The more bicarbonate that is reabsorbed with sodium, the less chloride that can be reabsorbed with sodium, for reasons of ionic balance. TRUE/FALSE
TRUE. Acidosis favors Na+ and HCO3- reabsorption and chloride excretion(hypochloremia) except in hyperchloremic acidosis, where there is a defect in the renal tubules ability to secrete H+.
Discuss this equation:
Co2 + H2O---HCO3- +H+
CO2 may be considered a weak acid which is constantly being generated by the body. Being a gas, CO2 is dealt with through the lungs.
acids such as lactic, phosphoric and sulfuric and ketone bodies cannot be released by respiration. The kidneys do this.
Can unbound(raw) H+ filter through the glomeruli?
No. Raw H+ does not filter significantly through the glomeruli because most of it is bound to proteins, rather than floating free in the plasma. However, binding to plasma proteins usually does not impair tubular secretion of H+.
H+ is secreted by the renal tubules through CO2, which passes much more readily than H+ from the bloodstream into the renal tubule cells. TRUE/FALSE
TRUE.