osmoregulation and secretion Flashcards
what is an osmoconformer?
An osmoconformer is isotonic to its environment
An example is a shark which lives in a salty environment. In order to be isotonic they hold onto high levels of urea, and their tissues can handle this.
What is an osmoregulaors
Osmoregulators osmoregulate and the needs are different
slide 29. What does the efferent arteriole supply in the juxtamedullary nephron? Cortical Nephron?
Juxtamedullary (vasa recta)
Cortical (peritubular capillaries
slide 32. What is within filtrate? What is the glomerular capsule continuous with? How are the capillaries within the glomerulus? Is glomerular filtration passive or active? What else helps filter based on size?
salts, amino acids, glucose, vitamins, waste, small molecules
continous with renal tubule (very first portion of renal tubule is the proximal tubule)
porous capillaries (fenestrated). allows solute rich but protein free fluid to enter the glomerular space
passive
capillary pores and collagen fibers prevent the exiting of formed elements, glycoproteins (based on charge) and albumin
What are the four portions of the renal tubule
Proximal tubule, thin descending limb of nephron loop, thick ascending limb of the nephron loop (gets thicker half-way up), distal tubule
proximal and distal describe the tubule’s relationship to the renal corpusal (consists of the glomerulus and the bowman’s capsule)
slide 34. Describe the portions of the renal tubule (histology, mitochondria, overall function). Proimal , nephron loop (made of ascending and descending loops, there are also thin and think segments)
Proximal. Longest has prominent vilii, which promotes secretion and absorption. Cuboidal epithelial cells. Has large mitochondria
Thin descending limb of nephron loop. simple squamous. low metabolic activity but high water reabsorption.
Thick ascending limb of the nephron loop. cuboidal epithelia. High conc. of mitochondria because of thick cells. Uses active transport thus high metabolic activity.
Distal tubule. cuboidal epithelia. the distal tubule is confined to the renal cortex and marks the end of the nephron
slides 38 and 39. How is the counter current multiplier achieved?
1) NaCl actively pumped out of the ascending limb
2) higher conc. of NaCl in the interstitial fluid draws water out of the descending limb (osmosis thru aquaporins)
3) loss of water concentrates salt in the bottom of the loop
4) high concentration of salt grants the ability for it to be pumped out
slide 40. Urea recycling relevance and steps?
Both the counter current multiplier and urea recycling help to generate the osmotic gradient. The vasa recta helps maintain it.
1) entrance of urea through the beginning portion of the ascending limb in the nepron loop
2) filtrate moves through the collecting duct on the cortical side and water gets reabsorbed. which concentrates the urine
3) as we get deeper into the collecting duct, the urea concentrates and leaves the collecting duct passively
slides 41 and 42. Producing concentrated urine. Do we do this when we are hydrated or dehydrated? Why?
We do this when we are dehydrated to conserve water. Dehydration is associated with high blood osmolarity, so releasing ADH (prevents secretion of water- diuresis) allows water to get back into the blood
1) in the initial part of the kidney, there is no osmotic gradient. so no water movement
2)ADH secreted, aquaporins are upregulated
3) With ADH, the concentrated medullary interstitial fluid creates a gradient for water reabsorption from the filtrate in the medullary collecting duct
4) deeper in the medulla, interstitial fluid is more conc. and even more water gets to leave the collecting duct before it exits out in the piss
counter current exchange. What is it? What structure is involved. Describewhat happens during movement up and down? Is the osmolarity of the medulla affected?
The counter current exchange helps to maintian the gradient made by the counter current multiplier.
It involves the vasa recta (vasa recta is only permeable to water and solutes) and how blood flows in opposite directions when it ascends and descends. So we are dealing with the capillaries around the nephron loop. Counter current multiplier (nephron loop) counter current exchange (capillaries)
As the plasma from the efferent arteriole descends, solutes move in and water moves out.
As the plasma ascends the vasa recta, solutes move out into the interstitial fluid and water moves in.
