ILA 2 Water and Salt Blance Flashcards
(30 cards)
How much water is there in the body? What is the distribution of the water?
42L
28L- Intracellular
14L- Extracellular
What % of the Bodies sodium is exchangable?
Where is the rest found?
70%
other 30% in bone crystal
How much of the total body sodium is found in the ECF and ICF respectively?
50% and 5%
What does Osmolality mean?
Concentration of solution expressed as solute particles per kg
What is Osmolarity defenition?
Concentration of solution expressed as solute per particles per L
What is Oncotic pressure?
Pressure exerted by plasma protein on capillary wall
What determines the balance of total extraceullar water?
Hydrostatic BP and interstitial colloidal oncotic pressure
Which part of the Capillary has higher hydrostatic pressure? What does this result in?
Arteriole end
Forces plasma and nutrients out of the capillaries
What happens to the ICF fluid when there is a drop in blood volume? Why?
Falls
Interstitial fluid moves into capillaries causing a reduction in gradient between IF and ICF causing water to leave cells and causing them to shrink
What happens when you have a low number of ALbumin?
Decreased oncotic pressure less water enter plasma in capillaries can cause excess fluid in interstitial space
What can Hypoalbuminaemia be a result of? (6)
Liver failure
Heart failure
Kidney damage
Protein losing enteropathy
Malnutrition
Inflammation throughout body
What are the 5 key routes of water loss?
Urine
Faeces
Sweat
Breath
Vomiting
What gland released ADH?
Pituitary gland
How is water conserved in the Nephron of the Kidney?
Descending loop- impermeable to NaCl and Permeable to water
Ascending loop- permeable to NaCl and impermeable to water
Water reabsorbed into Distal Convoluted tubule and collecting duct from interstital space
How does ADH work?
binds to receptors on collecting duct membrane
produces cAMP which activates protein kinase and phosphorylates proteins increasing rate of vesicles containing aquaporins fusing with membrane
What is thirst stimulated by? (2)
Increase in plasma osmolarity
Angiotensin 2
What happens in the kidney when renal blood flow is reduced? What is converted into what?
Juxtaglomerular cells convert prorenin into renin
Renin then converts angiotensinogen into agniotensin 1
ACE then converts angiotensin 1 into angiotensin 2
What 5 things does the release of angiotensin 2 stimulate?
- Increase in sympathetic activity
- Na+ and Cl- reabsorption, water retention
- Aldosterone secretion
- Vasoconstriction
- ADH secretion
What is the function of Aldosterone?
Increase Na+ and Cl- reabsorption, retain water and excrete K+
What does Na+ balance determine in the ECF? (2)
Blood volume and blood pressure
What 3 things occur when there is an excess of fluid?
Water moves into ICF
Stops stimulation of hypothalamus
Inhibits ADH in posterior pituitary gland, increasing urine volume
What can excess water consumption result in? Why?
Cells swelling up
Hyponatremia (low Na+ in blood)
What happens if there is excess fluid in the brain? What can this result in?
Cerebral oedema
Affects brain stem and CNS function causing seizures unconsciousness or coma
What is the name for too much fluid in the brain?
Hydrocephalus
