3. Dehydration (isotonic, hypotonic, hypertonic). Classification of the disorders of water balance (primary and secondary forms) Flashcards
Isotonic dehydration: Starting point
- Proportional loss of water + saline and other osmotically active molecules
- EC ↓; IC ↔
Isotonic dehydration: Compensation stage
- Water intake increases: Polydipsia
- Urine excretion decreases: Oliguria
Isotonic dehydration: Consequence stage
- Isotonic dehydration → Hypotonic dehydration
- Isotonic dehydration due to diarrhoea
- Exsiccosis: Condition that results from excessive loss of water
Hypotonic dehydration
Primary loss of saline
Hypotonic dehydration: Starting point
- Loss of water and saline simultaneously
- As a result of isotonic dehydration, there is compensation through polydypsia and oliguria
- Results in hypotonia and hyponatraemia
Hypotonic dehydration: Compensation stage
Water transport from EC → IC
Hypotonic dehydration: Consequence
- EC↓; IC↑
- Hemolysis/Swelling of cell
Hypertonic dehydration
Primary loss of water
Hypertonic dehydration: Starting point
- Water uptake ↓ / Loss of water
- Hypernatraemia → Decreased EC, hyperosmosis
Hypertonic dehydration: Compensation
Water transport from the IC → EC
(Not completely effective)
Hypertonic dehydration: Consequence
- EC ↓; IC↓
- Results in global/total dehydration
Draw the diagram showing the primary form of water balance disorders - Immediate changes in water balance
Dehydration: Following isotonic and isoionic changes
Cause: Increased Na-loss
- Plasma ↓
- Digestive juice ↓
- Chronic RF
- Addison’s disease
Hyperhydration: Following isotonic and isoionic changes
Cause: Increased Na-retention
- Acute RF
- “Salt poisoning”
- Hyperaldosteronism:
- Primary: Adrenal hyperfunction
- Secondary: Adrenal hyperfunction, liver failure
