45 Questions
What determines the chemical behavior of an atom?
The number of electrons in the outer orbits
What makes an atom stable?
Balanced force among the particles in the nucleus
Which particle determines the atomic number of an atom?
Protons in the nucleus
What causes an atom to become unstable and radioactive?
Presence of excess neutrons or protons
What is the effect of bombarding an atom with a neutron?
Atomic weight increases, atomic number remains the same
Which particles can be electrically charged electrolytes?
Ions and atoms
What predominantly constitutes plasma in terms of ions?
Na+ and Cl- ions
What affects the concentration of electrolytes in plasma and interstitial fluid?
Osmotic activity depending on the number of particles (ions) in a solution
How do cells prevent Na+ and Cl- diffusion?
Actively extrude Na+, passively allow K+ to enter
What determines the pH of a solution?
The relative number of H+ and OH- ions
What do acids yield?
H+ ions
What do bases take up?
H+ ions
What do strong acids readily give up?
H+ ions
What do weak bases less readily accept?
H+ ions
What do substances that regulate pH by neutralizing excess H+ ions act as?
Buffers
What is the primary function of water in the body?
Maintain osmolarity equilibrium between compartments
What is the main extra-cellular cation?
Na+
Which hormone is secreted by the posterior pituitary under the influence of nervous impulses originating in the supraoptic nucleus of the hypothalamus?
ADH
What is the formula for calculating osmolarity of plasma or ECF?
Osmolality (mOsmol/kg) = 2(Na+ + K+) + glucose + urea level (mmoI/L)
What is the main intracellular cation?
K+
What is the normal daily intake of sodium?
1 mmoL/kg
Which hormone absorbs water through the reabsorption of sodium?
Aldosterone
What causes hyponatremia (sodium and water deficiency)?
Abnormal GIT loss
What regulates water loss in the body?
Kidneys only
What is necessary for the regulation of body temperature?
Insensible water loss
What is the clinical picture of water excess?
Increased urine volume and body weight
What does water deficit result in?
Increase in osmoreceptors and decreased ADH production
What is the primary physiological regulatory mechanism for adjusting to changes in acid or base levels?
Respiratory mechanisms
What is the most important buffer system for maintaining constant pH levels?
Bicarbonate : carbonic acid ratio
Which condition is characterized by a base deficit or acid excess other than carbonic acid?
Metabolic acidosis
What is the primary compensatory mechanism for metabolic acidosis?
Increased respiratory activity
What causes metabolic alkalosis?
Excessive GI loss
How is metabolic alkalosis managed?
Fluid and electrolyte replacement
What is associated with a rise in pH and results from hypoxia and inadequate renal compensation?
Respiratory acidosis
What causes respiratory acidosis?
Respiratory depression
Which of the following is a clinical manifestation of hypokalaemia?
Paralytic ileus and cardiac arrhythmias
What is the treatment for hypernatraemia?
Diuretics, fluid replacement, and correction of underlying cause
What is the essential function of potassium (K+)?
Intracellular cation, excitability of nerve and muscle, and action of the heart
What are the clinical manifestations of hypercalcaemia?
Increased cell excitability (muscles and nerves) and cardiac arrhythmias
What causes hyperkalemia?
Renal failure, acidosis, and diabetics with reduced insulin secretion
What is the treatment for hypokalemia?
Diuretics, fluid replacement, and correction of underlying cause
What are the clinical manifestations of hypernatraemia?
Normal or decreased water intake, hyperosmolarity, and dehydration
What causes decreased extracellular fluid volume (ECF) in infants?
Decreased intake, vomiting, gastrointestinal fistulas, and severe diarrhea
What are the hazards of hypokalemia?
Decreased nerve and muscle excitability and paralytic ileus
What is the clinical picture of hypokalemia?
Vague symptoms, paralytic ileus, cardiac arrhythmias, and ECG changes
Study Notes
- Decreased Extracellular Fluid Volume (ECF) in infants: sunken eyes, depressed fontanels, dry coated tongue, dry wrinkled skin with lax subcutaneous tissues, collapsed skin veins, hypovolaemia causing tachycardia, orthostatic hypotension, shock, decreased Central Venous Pressure (CVP), and oliguria with no thirst.
- Clinical picture of increased ECF volume: slight puffiness of the face, total body edema, weight gain, hypertension, ascites.
- Treatment for decreased ECF volume: pre-operative replacement with normal saline or Ringer's lactate, treatment of the cause, and replacement of observed loss with saline.
- Hypernatraemia (high sodium level) causes: excessive saline transfusion in the early postoperative period, increased sodium reabsorption due to aldosterone, cortisone, or estrogen, inability to excrete sodium load due to severe illness or starvation, and abnormal renal retention of sodium due to renal, heart, or liver failure.
- Clinical picture of hypernatraemia: normal or decreased water intake, hyperosmolarity, dehydration, increased urine output, irritability, confusion, and seizures.
- Treatment for hypernatraemia: diuretics, fluid replacement, and correction of underlying cause.
- Essential functions of potassium (K+): intracellular cation, excitability of nerve and muscle, and action of the heart.
- Factors affecting K+ distribution: acid-base balance, insulin, cellular breakdown, and osmolality.
- Hypokalaemia (low potassium level) causes: decreased intake, vomiting, gastrointestinal fistulas, severe diarrhea, diuretics, alkalosis, and hormones.
- Hazards of hypokalemia: decreased nerve and muscle excitability, increased risk of supra-ventricular arrhythmias, increased risk of hepatic coma, and polyuria.
- Clinical picture of hypokalemia: vague symptoms, paralytic ileus, cardiac arrhythmias, muscular paresis, and ECG changes.
- Management of hypokalemia: estimation of K+ deficit, safe repletion, and monitoring of electrolyte levels.
- Potassium solutions used: 40 mEq/L K+ in glucose 5% or saline, and Darrow's solution.
- Causes of hyperkalemia: renal failure, acidosis, and diabetics with reduced insulin secretion.
- Clinical picture of hyperkalemia: increased cell excitability (muscles and nerves), cardiac arrhythmias, bradycardia, hypotension, and arrest.
- Treatment for hyperkalemia: calcium gluconate, alkalosis, glucose and insulin infusion, ion exchange resins, and dialysis.
- Factors affecting blood calcium level: parathormone, calcitonin, vitamin D, and phytic acid.
- Hypercalcaemia: usually due to a parathyroid tumor, and treatment involves removal of the tumor.
- Hypocalcaemia: seen in hypoparathyroidism as a complication of thyroidectomy, and after massive blood transfusion containing CPDA, and treatment involves calcium and vitamin D supplements.
- Magnesium (Mg++): intracellular cation, essential for muscle and nerve function, and electrolyte balance.
- Magnesium deficiency: occurs in prolonged GI losses, cirrhosis, and prolonged IV therapy, and symptoms include muscle weakness, tremors, and cardiac arrhythmias.
- Treatment for magnesium deficiency: magnesium supplements and addressing the underlying cause.
Test your knowledge about the cell membrane and capillary pressure with this quiz. Learn about the roles of plasma proteins, colloid pressure, and hydrostatic pressure in fluid movement, as well as the permeability of the cell membrane to different substances.
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