Flashcards in Renal System 2 Deck (37):
7 functions of the kidneys?
1. Regulation of water and electrolyte balance
2. Regulation of arterial pressure
3. Excretion of metabolic waste products
4. Regulation blood pH
5. Regulation of erythrocyte production
6. Regulation of hormone production
7. Regulating blood glucose levels
Symptoms when things go wrong in the kidneys?
High blood pressure
Shortness of breath
Are the kidneys linked to homeostasis?
Yes (eg blood pressure, water and electrolyte balance, pH, waste product removal
The movement of water through a selectively permeable membrane from an area of lower solute concentration (high water concentration) to an area of higher solute concentration (low water concentration)
What is osmotic pressure?
The pressure required to prevent net water movement (aka applied pressure)
What is osmolarity?
A measure of the osmotic pressure exerted by a solution across a perfect semi-permeable membrane compared to pure water
What is osmolarity dependent on?
The number of particles in solution (but independent of the nature of the particles)- is basically concentration
What is hyperosmotic?
A solution with a higher osmolarity than another (300mm NaCl vs 300mm urea)
What is an isosmotic solution?
Two solutions with the same osmolarity (150mm/NaCl vs 300mm urea)
What is hyposmotic?
A solution with a lower osmolarity than another (150mm urea vs 150mm NaCl)
What does tonicity take into account?
The concentration of a solute and the ability of the particle to cross a semi-permeable membrane (NaCl- low permeability)
What is hypertonicity?
When a solution with a higher POsm than another, and water will leave causing shrinkage
What is isotonicity?
Two solutions with the same POsm, so no net water movement
What is hypotonicity?
A solution with a lower POsm than another. Water will move into the cell causing swelling
What are the mechanisms of dehydration?
1. Excessive loss of water from ECF
2. ECF osmotic pressure rises
3. Cells lose water to ECF by osmosis, cells shrink
What are the mechanisms of hypotonic hydration?
1. Excessive water enters the ECF
2. ECF osmotic pressure falls
3. Water moves into cells by osmosis, cells swell
5 reasons to maintain osmolarity?
1. Setting membrane potential
2. Generating electrical activity in nerve and muscle
3. Initiation of muscle contraction
4. Providing energy for the uptake of nutrients and the expulsion of waste products
5. Generation of intercellular signalling cascades
Body mass composition of a female?
Body mass composition of a male?
In a 70kg male, describe in litre, the amount of fluid, that is extracellular fluid, that's plasma
60% fluid = 42L
1/3 of this is extracellular= 14L
20% of this is plasma= 2.8 L
What percentage of the blood is plasma?
55% (so 2.8 L of plasma in 5L of blood)
Amount of fluid that's intracellular fluid?
Percentage of extracellular fluid that's interstitial fluid?
80% (20% plasma)
Composition of average intake of water?
Composition of average water output per day?
What chemicals have high extracellular concentrations in the body?
What ion has a high intracellular Concentration in the body?
How much fluid enters the renal tubules per day?
180L of fluid (32 times blood volume)
In an adult, the entire extracellular fluid volume is filtered how many times per day?
How much extracellular fluid is reabsorbed per day?
On average, how much urine is produced per day?
Although the kidney constitutes only a small percentage of the mass of the body, what cardiac output does it receive at rest?
20-25% (so, a lot of blood flow)
Equation for excretion?
Excretion= filtration + secretion - reabsorption
Steps of urine production?
1. Filtration from blood into nephron
2. Tubular reabsorption from tubular fluid into blood
3. Tubular secretion from blood into tubular fluid
What is the glomerular filtration rate?
125ml/min (25% of total RPF)= 180L/day
What does glomerular filtration have a similar solute concentration to?
Plasma (glucose, electrolytes)