Renal Physiology II Flashcards
What are the two different types of nephron?
Cortical nephrons and Juxtamedullary nephrons
What type of nephron has a glomerulus further away from the corticomedullary junction?
cortical nephrons
Where does the vast majority of water and solute reabsorption occur?
In the proximal convoluted tubule
What are the 3 different ways solutes/ water are reabsorbed in the PCT?
Primary activate transport, e.g ATPase/ Na+ pump
Secondary active transport e.g following an electrochemical gradient
Simple diffusion
What are some adaptations of PCT cells to allow for reabsorption?
They have a brush border which increases their surface area and mitochondria which gives them energy for active transport
What are the two different types of cell found in the collecting duct?
Principal cells and intercalated cells
What is the renal threshold?
the reasorptive capacity of the kidneys
What are the two ways that water can be reabsorbed?
Paracellularly (through tight junctions between cells) or transcellularly ( through cells via special channels)
How does the counter-current multiplier system work?
Ions are actively pumped out of the ascending limb making the medulla salty
this means that water passively moves out of the descending limb
These are the all absorbed by the peritubular capillaries
How does reabsorption work in the PCT?
Sodium is actively pumped out of the Tubular cells and Potassium is actively pumped into the tubular cells
High intracellular potassium means that potassium diffuses out
This causes sodium to then re-enter the tubular cell carrying amino acids and glucose
How does passive diffusion work in the PCT?
Water follows the movement of ions glucose etc via osmotic diffusion
What limb of the loop of henle is impermeable to water?
The ascending limb
How do ions get moved out of the ascending loop of henle?
Na+ gets pumped into the interstitium, then Cl- follows down the electrochemical gradient
creates a hypertonic environment in the interstitial fluid
What does the DCT and collecting duct control
excretion of water and electrolytes
What area is the site of K+ excretion and NaCl absorption?
DCT and collecting duct
What substance is completely reabsorbed in the PCT?
Glucose
It is co-transported with sodium
When would glucose be excreted in the urine?
When the plasma load exceeds the reabsorptive capacity called the renal threshold
What percentage of filtered urea is exreted?
around 40%
What is the effecr of ADH on the kidney tubules?
It increases water reabsorption in the DCT and collecting duct
What part of the adrenal gland produces aldosterone?
It is produced and secreted in the zona glomerulosa
in response to the RAAS system
What is the effect of aldosterone on kidney tubules?
It activates transcription and synthesis of new Na+ channels, new K+ channels and new Na+/ K+ pumps
What is ANP released in response to and what is its effect?
It is released in response to increased atrial stretch
and it increases excretion of Na+ to decrease blood pressure
What produces BNP and what it is in response to?
It is produced by CNS neurones in response to higher BP and blood volume
Where is urodilatin produced and what is it produced in response to?
It is produced in distal tubular epithelial cells and it dilates the afferent arteriole to increase GFR
What is the function of PTH?
It enhances the apical Ca2+ function
mediated by cAMP
What is the function of PTH?
It enhances the apical Ca2+ function
mediated by cAMP
What is the by-product of protein metabolism in birds?
Uric acid
What is the name of the glands in birds that do the majority of Cl- and Na+ excretion
Salt glands
What is secondary active transport?
When they follow the electrochemical gradient of the cell
What occurs in the ascending loop of henle?
Sodium is actively pumped out, Cl- then follows via the electrochemical gradient
Where can all the aquaporins be found?
1 in the PCT
2 in the apical membrane of the DCT
3, 4 in the basolateral membrane of the DCT/ collecting duct
