Lectures 17, 18 Flashcards
What are the problems of the terrestrial environment when the animals evolved to come on land?
. There is hardly any salt
. You are at risk of drying out
. It is not way to get rid of waste if Thrace to conserve water
What animals excrete waste in the form of ammonia?
Fish- ammonotelic animals (aquatic invertebrates and most bony fish)
not a prob because it diffuses into the water
The excrete 1g of nitrogen in the form of ammonia how much water would you need?
0.5l
How much water in needed to excrete 1g of nitrogen in the form of urea?
0.05l
How much water is needed to excrete 1g of nitrogen in the form of uric acid?
0.001
What animals excrete nitrogen in the form of urea?
Ureotelic animals- mammals, most amphibians and cartilaginous fish
What animals excrete water in the form of uric acid?
Uricotelic animals- birds, insects, non-avian reptiles
In the glomerulus what percentage of blood is filtered into the Bowen’s capsule?
20%
What is the podocytes?
are part of Bowman’s capsule and wrap around the capillaries
Where does most of the reabsorption in the tubule takes place?
Proximal convoluted tubule
What percent of Chlorine, sodium, potassium, amino acids, HCO3-and glucose do you reabsorb?
Chlorine: 67 Sodium: 67 Potassium: 65 Amino acids: 100 Glucose: 100 HCO3-: 90
What do the epithelial cells building the proximal tubule contain?
Microvilli to exchange the absorptive SA
What does Na+/K+ ATPase do?
Generates a chemical gradient for sodium ions. Will constantly pump sodium out of the cell in exchange for potassium- this requires energy
The gradient for sodium ions causes by the sodium/potassium ATPase is used for what?
To co-transport other substances into the cells at the luminal membrane
What happens to drugs in the body?
They are imported into the proximal tubule cells through suites of transporters in the interstitial membrane (so drugs are taken into the tubule system/ the filtrate
What does the descending limb of the loop of henle contain?
Water channels (aquaporins) but it is impermeable to salts
What does the ascending limb of the loop of henle contain?
Salt transporters (NKCC)but it is impermeable to water
What are the principal cells in the collecting duct responsible for?
Water absorption