L6-kidneys and diuretics

what are the key structures of the renal system 

list the 5 roles of the kidney 

• regulation of water,slats and acid-base balance 

• removal or metaboic waste 

• removal of foreign chemicals 

• gluconeogenesis ( formation of glucose )

• production of homromes and enzymes e.g. erythropoetin,renin,activates vitamin d 

whata re the key stuctures that ake up the anatomy of the kidney 

what are the three key functions of the nephron

1. glomerular filtration 

2. tubular secretion 

3. tubular reabsorption 

what are features of the glomerulus/bowmans capsule that allow effective filtration 

• good blood supply with high surface area 

• fenestrated blood vessles allows substances to move in and out 

• podecyte cells with extensions called pedicles which wrap around blood vessles within the glomerulus 

• basementwhat is membrane

what is glomerular filtration rate + how is it regulated 

its the volume of fluid filtered from the glomeruli to bowmans space per unit time and it can be regulated by adjusting blood pressure within the glomerulus 

what is diuresis

it is the increased production and passage of urine by the kidneys 

describe the control of glomerular filtration and water and salt retention 

1. when theres increased diuresis ( increased sodium and water loss dues to loss of urine ) the plasma volume decreases 

2. this leads to a decreases in blood pressure 

3. this also leads to a decrease in  renal sympathetic nerve activity which causes an increase in the constriction of the afferent renal arterioles 

4. both of these thigs leads to an overall reduced glomerular filtration pressure and a decreased glomerular filtration rate 

5. so a decrease in sodium and water excretion 

how do diuretics work in the kidney

they affect how the nephron retains water and salt 

what part of the nephron does carbonic anhydrase inhibitors work on 

the proximal convoluted tubule- this is where carbonic anhydrase functions 

where in the nephron does osmotic diuretics work 

it works on any water permeable part of the nephron 

so the proximal convoluted tubule, descending loop of Henle and the collecting duct

explain how osmotic diuretics work e.g. mannitol

• they enter the nephron through filtration 

• and they effect osmosis so effect how much water is retianed or lost 

• mannitol enters the tubule fluid  and increases the osmolarity of the fluid 

• the means it decreases the concnetration of water in the tubule fluid 

• so theres less drive for water to leave the tubule fluid as concnetration gradient has decreased and more water is excreted 

what are the theraputic uses of osmotic diuretics e.g. mannitol 

describe sodium reabsorption in the proximal convoluted tubule 

• sodium moves into the tubule cells through sodium and hydrogen ion counter transporters 

• when inside the tubule cells it can be moved from there into the interstitial space and then blood through sodium/potassium atpase pumps 

describe the secretion/production of H+ in the proximal convoluted tubule 

• inside the tubule cells carbonic anhydrase produces carbonic acid from h2o and co2

• this carbonic acid breaks down into H+ and HCO3 

• the hydrogen ion produced from this drives the sodium/hydrogen ion counter transporter 

• and the carbonate ion /HCO3 is reabsorbed which helps the body control acid base balance 

explain how carbonic anhydrase inhibitors work e.g. acetazolamide

• acetazolamide works by inhibiting carbonic anhydrase 

• this means there will no longer be hydogen ions in the tubule cells of the proximal conveluted tubule 

• this means the sodium/hydrogen ion counter transporter cant function and there isnt rebsoption of sodium ions 

• due to this there isnt reabsoption of water and more water is retained in the tubules and its excreted 

• theres also a loss of carbonate ions whic effects the regulation of acid -base 

• as theres still loss of carbonate from the filtrate it causes mild plasma acidosis as theres no carbonate but theres still hydrogen ions and in the urine theres alkalosis as theres a loss of hydrogen ions but still carbonate ions from the filtrate 

• 
  

describe the therapeutic uses of acetazolamide/carbonic anhydrase inhibitors+ why are they seen as weak diuretics