Urinary System Flashcards
What is filtration and where does it take place in the kidney?
Through semipermeable walls of the glomerulus and glomerular capsule
Blood comes from the afferent arteriole and goes to the capillaries of the glomerulus.
Water passes through, some are absorbed later
The fluid filtered from the bloodstream into the glomerular capsule is now filtrate
It’s composition is adjusted through other parts of the renal tubule and is similar to the composition of plasma
Contains glucose, amino acids, H2O
Large proteins don’t escape neither do blood cells
What are some of the constituents in the glomerular filtrate?
Water
Mineral salts
Amino acids
Ketoacids
Glucose
Hormones
Urea
Why does filtration happen?
Difference between blood pressure in the glomerulus and the pressure of the filtrate in the glomerular capsule
What is reabsorption in the kidney and where does it take place?
Na+ from glomerular filtrate from PCT goes into blood capillaries
Na+ already in lining
Goes out of tube by active transport into the blood
Less Na+ in the epithelial lining mor Na+ in the lumen
This set up a concentration gradient
Co-transport of Na+, plus a ‘’friend’’ either amino acids or glucose into the lining
Now both in the lining
In descending loop of Henle, there is active transport of salts (NaCl) using ATP in the lining of LoH
High concentration of NaCl outside causing there to be osmosis of H2O in the filtrate from the lumen in the blood
In descending (1st part) same as LoH
In ascending (2nd part) same as collecting duct
Filtrate is very dilute
H20 is high
H20 has to leave to balance out the gradient
When in interstitial space, it goes into the blood
All that’s left is urine
What is the main function of the collecting ducts?
Reabsorb as much water as necessary to meet the body’s needs
What happens during secretion in the kidney and why does it happen?
Occurs as blood flows through the glomerulus
Substances not required may not be entirely filtered out the blood because of the short time they remain in the glomerulus or because they are too big to pass through
