11.3 The Kidney Flashcards
What are osmoregulators?
Many animals are known as osmoregulators because they maintain a constant internal solute concentration, even when living in marine environments with very different osmolarities.
What are osmoconformers?
Animals whose internal solute concentration tends to be the same as the concentration of solutes in the environment.
How to insects carry out osmoregulation?
Arthropods have a circulating fluid, known as hemolymph, that combines the characteristics of tissue fluid and blood. Osmoregulation is a form of homeostasis whereby the concentration of hemolymph, or blood in the case of animals with closed circulation systems, is kept within a certain range.
Animals need to get rid of nitrogenous waste. In animals it is usually in the form of urea but in insects the waste product is usually in the form of uric acid.
Insects have tubes that branch off from their intestinal tract. These are known as the malpighian tubules. Cells lining the tubules actively transport ions and uric acid from the hemolymph into the lumen of the tubules. This draws water by osmosis from the hemolymph through the walls of the tubules into the lumen. Then tubules empty their contents into the gut. In the hind gut most of the water and salts are reabsorbed while the nitrogenous waste is excreted with the feces.
What are the mapighian tubules?
They are the branches off the intestinal tract of insects.
DRAW THE KIDNEY
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What is the difference between the blood in the real artery and the blood in the renal vein?
IN THE RENAL ARTERY
- Toxins are higher, these are substances that are ingested and absorbed but are not fully metabolised by the body.
- Urea and excretory waste products are higher.
- More water
- Excess salt absorbed from food in the gut.
IN THE RENAL VEIN
- Deoxygenated because the metabolic activity of the kidney requires oxygen.
- More carbon dioxide
- Less glucose
PLASMA PROTEINS ARE THE SAME
What is the order of the kidney filtration?
- GLOMERULUS (IN THE BOWMANS CAPSULE)
- PROXIMAL CONVOLUTED TUBULE
- ## LOOP OF HENLE (DESCENDING AND ASCENDING)
What happens in the glomerulus?
Blood in the capillaries is at high pressure in many of the tissues of the body and the pressure forces some of the plasma out through the capillary wall to form tissue fluid.
In the glomerulus the pressure in the capillaries is particularly high and the capillary wall is particularly permeable, so the volume of the fluid forced out is about 100 times greater than in other tissues. The fluid forced out is called glomerular filtrate. This is called ultra filtration because the big proteins do not leave so they are filtered according to size. Any with a relative molecular mass of less than 65000 can pass through.
STRUCTURE OF GLOMERULUS
Which particles can pass through the capillary walls in the glomerulus?
Any with a relative molecular mass of less than 65000.
What is the structure of the glomerulus?
The capillary entering the bowmans convoluted tubule is called the afferent arteriole. The blood vessels inside are then at a very high pressure, there are gaps in the walls of these capillaries called fenestrations these are about 100nm in diameter and allow fluid to escape but not blood cells. On the outer wall of these capillaries in the podocytes these form the inner wall of the bowmans capsule. These cells have extensions that wrap around the capillaries of the glomerulus and many short side branches called foot processes. Very narrow gaps between the foot processes help prevent small molecules from being filtered out of the blood in the glomerulus.
The basement membrane forms the inner wall of the bowmans capsule on the outside of the podocytes. It covers and supports the wall of the glomerulus and many short side branches called foot processes. Very narrow gaps between the foot processes help prevent small molecules from being filtered out of blood in the glomerulus.
What is the blood vessel entering the glomerulus called?
The afferent arteriole
What is the blood vessel leaving the glomerulus called?
The efferent arteriole
What are podocytes?
On the outer wall of these capillaries in the podocytes these form the inner wall of the bowmans capsule. These cells have extensions that wrap around the capillaries of the glomerulus and many short side branches called foot processes. Very narrow gaps between the foot processes help prevent small molecules from being filtered out of the blood in the glomerulus.
THEY PROVIDE SUPPORT
What is the role of the proximal convoluted tubule?
The glomerular filtrate flows into the proximal convoluted tubule. Most of the re-absorbtion happens here.
It all begins with the sodium potassium pump the the cells next to the tubule and the capillaries. The sodium potassium pump, by active transport, pumps sodium out and potassium in. Because sodium is pumped out it passes into the capillaries and is then taken away. The concentration then lowers so more diffuses in from the filtrate in the tubules, it comes through a sodium amino acid pump, which brings amino acids across as well. Because of the movement of ions the water will move by osmosis into the capillaries, and glucose also comes through a sodium glucose co transport protein. There is a K+ channel protein to stop the concentration of K+ building up as Na+ needs to be pumped out very quickly.
Cl- ions are actively transported across and then diffuse into the capillaries.
What are the peritubular capillaries?
These are the capillaries that go round the proximal convoluted tubules and the loop of henle, reabsorbing all the stuff.
