Urine Formation & Tubular Secretion Flashcards
Define: glomerular filtration
Non-selective, passive process in which fluid passes from the blood into the glomerular capsule → part of the renal tubule
Once in the capsule, what is the fluid then called and what is its composition? (2)
- Filtrate
2. Blood plasma without proteins
Define: oliguria
Abnormally low output (100-400mL/day)
Define: anuria
Excessively low urine production (less than 100mL/day)
When does tubular reabsorption begin?
As soon as the filtrate enters the proximal convoluted tubule
How are tubule cells “transporters”?
Take up needed substances from the filtrate and pass them out
How is most reabsorption of substances done by?
Active transport
Define: active transport
Transport which requires cellular energy
What do the kidneys depend on to move substances?
Active transport so that substances can move AGAINST the concentration gradient → low concentration to high concentration instead
Define: passive transport
Movement of molecular substances across a cell membranes without the need for any cellular energy input
List and briefly describe the 3 main nitrogen waste products. (3)
- Urea - formed by the liver as an end product of protein breakdown when amino acids are used to produce energy
- Uric acid - released when nucleic acids are metabolized
- Creatinine - associated with creatine metabolism in muscle tissues
Where are the nitrogenous wastes held until voided?
In the filtrate
Where does most absorption occur in the kidneys?
Proximal convoluted tubules
What is tubular secretion important for?
Getting rid of substances that aren’t already in the filtrate
List the 3 substances that depend on tubular secretion to move into the filtrate. (3)
- Hydrogen ions
- Potassium ions
- Creatinine
