Flashcards in Renal Deck (107)
How does the R kidney positioning differ from the L?
The R kidney is located slightly lower d/t displacement by the liver.
What are the three major functions of the kidney?
Differentiate between hydrostatic and oncotic pressures.
Hydrostatic pressure refers to the pushing of fluids against the vessel walls from within the vasculature and within the interstitial space.
Osmotic pressure refers to the pulling force exerted on the vessel walls from within the vasculature and within the interstitial space
What is thirst triggered by?
Increased concentration of extracellular fluid (increased osmolality)
Decreased circulating blood volume
The amount of fluid excreted in the urine is controlled primarily by which hormones?
Natriuretic Peptides (ANP and BNP)
Where is ADH synthesized and released?
Synthesized in the hypothalmus
Released by the posterior pituitary gland
What factors increase the release of ADH?
-Increased osmolality of the extracellular fluid
-Decreased circulating fluid volume
How does ADH impact the concentration of filtrate in the collecting duct (and DCT)?
ADH stimulates the epithelial cells in the collecting duct to produce aquaporins causing water to be reabsorbed from the filtrate to the capillaries.
This happens via osmosis d/t the increased concentration of solutes (increased osmolality) in the capillary vs. the decreased concentration (hypotonic solution) present in the renal tubules.
Where is aldosterone synthesized and released from?
What are the main stimuli for aldosterone release? (2)
1. Angiotensin II (AII)- from RAAS, activated by decreased circulating blood volume
2. Increased concentration of K ions in the plasma
How does aldosterone impact the concentration of the filtrate in the collecting duct? (3)
1. Stimulates the Na-K pump
2. Opens Na channels (increased Na in the blood pulls water into the vascular=increased blood volume)
3. Open K channels (K moves into filtrate)
What hormones opposed the action of aldosterone?
When are ANP and BNP release?
ANP is released with the atrial cells are overstretched signaling an excess of volume.
BNP is released by the ventricles when EDV is elevated indicating an excess of volume (HF)
How do natriuretic peptides oppose the action of aldosterone?
ANP opposes AII. Promote fluid excretion by nautriuresis (moving Na into the urine so that water follows=decreased blood volume)
How many nephrons are there per kidney?
Traces the flow of filtrate through the kidney.
Glomerulus to PCT to LoH to DCT to collecting duct
What are the general functions of the glomerulus?
The capillary net that filters plasma, making ultrafiltrate that is called tubular fluid once it enters the PCT
What are the general functions of the PCT?
Has cuboidal epithelial cells with brush border villus membrane to increase surface area and is the main site of reabsorption of water, lytes and nutrients (isotonic filtrate)
What is the general function of the thin descending Loop of Henle?
Impermeable to solutes but permeable to water. Concentrates fluid as well as diffuses water out. (hypertonic filtrate)
What is the general function of the thick ascending Loop of Henle?
Impermeable to water but has NaK2Cl active transporters that reabsorb more solutes and dilute the tubular fluid. (Hypotonic) Sets up and maintains interstitial concentration gradient
What is the general function of the DCT?
Electrolyte modifications. Sense concentraiton of Na and Cl via villi and signals juxtaglomerular cells via PGE to release renin. Aldosterone acts on late distal tubule principle cells.
What is the general function of the collecting ducts?
Site of free water reabsorption through water channels ( aquaporins)controlled by ADH.
Important to acid-base balance; allow H secretion and bicarb secretion when necessary
What are the functions of the kidney?(5)
1. Remove toxins/waste from the body
2. Maintain proper H2O and electrolyte balance of blood (excrete H20 and lytes, secrete renin)
3. Maintain proper pH of blood (usually excrete H and create bicarb)
4. Secrete EPO
5. Activate vit D (vital to Ca absorption)
What is filtration?
The movement of substances out of the blood into the filtrate. Glomerulus into the PCT.
What is reabsorption?
The return of substances from filtrate now present in the tubular fluid back into the blood.
What is secretion?
The movement of substances out of peritubular blood via kidney tubule cells in tubular fluid.
What is the vasa recta?
Capillaries located around the LoH; absorb interstitial fluid without excessive removal of interstitial solute.
What is the renal corpuscle?
Glomerulus and Bowman's space
What is the kidney's release of renin stimulated by (RAAS stimulation)?
Decreased fluid volume