Basic renal processes Flashcards
Explain the process of urine formation
Plasma is filtered from the glomerular capillaries into Bowman’s space. This process is termed glomerular filtration, and the filtrate is called the glomerular filtrate.
It is cell-free, and except for larger proteins, contains all the substances in virtually the same concentrations as in plasma. This type of filtrate is called ultra-filtrate.
The fluid then passes through the tubules.
What is tubular reabsorption and secretion?
Tubular reabsorption - when the direction of movement is from the tubular lumen to the peritubular capillaries.
Tubular secretion - when the direction of movement is from the peritubular capillaries to the tubular lumen.
Is glucose completely reabsorbed or excreted?
Glucose is completely reabsorbed
Is albumin and globulins found in the glomerular filtrate?
No, plasma proteins are not found in the filtrate of healthy kidneys.
What forces are involved in filtration?
The blood in the glomerulus creates a glomerular hydrostatic pressure which forces fluid out of the glomerular capillaries and into Bowman’s space.
The fluid in the glomerular capsule produces a hydrostatic pressure which pushes fluid out of the glomerular capsule and back into the glomerulus.
There are no proteins in the filtrate and so it is all in the glomerular capillaries. There is therefore a pressure drawing water into the glomerulus, this is known as osmotic pressure.
Net filtration pressure = glomerular hydrostatic pressure - bowman’s capsule hydrostatic pressure - osmotic pressure opposing filtration
Which nutrients are completely reabsorbed and which are excreted completely?
100% of glucose is reabsorbed
99.5 % of sodium is reabsorbed
99% of water is reabsorbed
44% of urea is reabsorbed
What is GFR and eGFR?
The volume of fluid that is filtered from the glomeruli into Bowman’s space per unit of time is known as GFR. E is for estimated.
In a 70kg person, the GFR averages 180L a day (125l/min).
The total volume of plasma in the circulatory system is approximately 3L., it follows the kidney filter the entire plasma about 60 times a day.
What is the concept of renal clearance?
