Reabsorption and Secretion Flashcards
Through what mechanism are most molecules reabsorbed from the tubules?
Tm mechanism
How can the secretion of molecules into the urine be controlled?
Via the number of channels available on the membrane
Where does most of sodium reabsorption take place in the kidney?
Brush border of Proximal tubule (high number of channels)
How is sodium transported across the membrane in the kidneys?
Active transport via sodium channels
How does Chlorine get transported across the membrane in the kidneys?
The active transport of sodium creates an electrical gradient that allows chlorine to passively diffuse through?
How is water transported out of the tubule?
The movement of the molecules out of the tubules creates an osmotic pressure that draws water out.
How are potassium, calcium and urea transported out of the tubules?
The water leaving the tubules creates a high concentration of molecules therefore allowing them to passively diffuses out along their concentration gradient.
What two things does the rate of reabsorption be affected by for non actively absorbed molecules depend on?
The volume of water removed as that will determine the concentration gradient
The permeability of the tissue (number of channels)
To what two substances is the tubular membrane impermeable to?
Mannitol and inulin
What three types of channels do sodium and glucose use to be transported across the membrane?
Active Transporter
SGLT- sodium dependant glucose transporter
GLUT facilitated diffusion transporter
Where and how are molecules secreted into the tubules?
Proximal tubule via Tm secretory mechanism
What are the levels for hyper and hypokalaemia?
Hyper- >5.5mmol/L (leads to VF and death)
Hypo- >3.5mmol/L (arrhythmias and death)
Via what hormone is potassium secretion into the tubules controlled by?
Aldosterone
