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The kidney and omsoregulation (XI. 3) - Coggle Diagram
The kidney and omsoregulation (XI. 3)
Malpighian tubule
Malpighian tubules are tubules that originate from the intestines
Ions and uric acid are transported inside the lumen of the tubules
In arthropods, nitrogen wastes are secreted with uric acid
The tubules empty their contents in tne guts and uric acid is secreted
Arthropods have a circulating fluid called hemolymph
Renal artery & vein blood
They also contain excretory wastes such as urea
Renal vein contains deoxygenated blood with constant concentrations of ions due to osmoregulation
Renal artery contains toxins and other molecules that haven't been fully metabolised
The renal vein also contains proteins, since the kidney doesn't filter them
Structure of the glomerulus
Fenestrations between the cells of the capillary walls allow fluid to escape, but not blood cells
Basement membrane prevents proteins to be filtered thanks to their size and negative charge
The glomerular flitrate contains approximately the same quantity of solutes as the blood, excepts for proteins
Podocytes wrap around the capillaries and leave tiny gaps that prevents small molecules to be filtered out of blood
The pressure in the glomerulus is very high
Those substances that make it through all three barriers make up the glomerular filtrate
Proximal convoluted tube
Glucose is moved out the tube witn co-transporter proteins that use Na+ ions flowing down the conc. gradient
Water, through osmosis, also flows outside the tube
Sodium ions are moved through active transport from the filtrate to the outside
The glomerular filtrate flows directly into the proximal convoluted tube
Loop of Henle
The descending wall is permeable to water, but not to Na+,
In the ascending limb, sodium ions are pumped out, its walls are impermeable to water so the conc. gradient outside increases
It creates a gradient of solute concentration in the medulla
Water flows out the descending limb into the interstitial fluid where the conc. is higher
Functions of ADH
The walls of the distal convoluted tubule have a low permeability to water
A large volume of dilute urine is produced
If the solute concentration of the blood is too low,little water is reabsorbed
If the solute conc. is too high, the hypothalamus detects this and causes the pituitary gland to secrete antidiuretic hormone (ADH)
Once the filtrate exits the loop of Henle, it is hypotonic
ADH makes the wall of the distal convoluted tubule more permeable, increasing water reabsorption
The kidney therefore produces a small volume of concentrated urine
Nitrogenous waste in animals
Terrestrial organisms convert ammonia intio less toxic urea/uric acid
Marine organisms release ammonia directly in their environement