Excretion Flashcards
What is excretion?
The removal of metabolic waste products not needed by the body
Examples of excretory products
Urea, heat, excess salts, excess water, carbn dioxide
Difference between the renal vein and renal artery
The renal artery brings blood in while the renal vein removes blood
Function of the ureter
A tube that collects urine from the kidney to the bladder
Function of the bladder
A temporary storage unit for urine
Function of the utethra
A short tube that release urine
Explain assimilation
A process by which food molecules are absorbed in cells, such as trucks used in respiration for energy. The excess is converted to glycogen for storage in the liver when the liver cells are stimulates by insulin hormone. The insulin hormone produced by the pancreas is then transported through blood into the liver cells. In the liver cells, glucagon stimulates the liver cells convert stored glycogen back to glucose. Amino acids absorbed can be used to make proteins such as plasma protein.
Roles of the liver in relation to assimilation
-converts fatty acids to cholesterol
-converts fatty acids&glycerol to fats to store in the skin or around the body
-breaks down excess amino acids
-uses amino acids to make protein
Explain ultrafiltration
Capillaries in the glomerulus get narrower causing pressure to increase on the blood moving through them. This forces water, glucose,urea and salts in the blood out the Capillaries to the bowmans capsule making a filtrate.
Explain selective reabsorption
As the filtration passes through the proximal convoluted tubule, the water, salts and glucose are REABSORBED back in the capillaries. Glucose & salts are reabsorbed through active transport while water is reabsorbed through osmosis. The loop of henle is long and U-shaped to increase surface area. The descending part is more permeable to water while the ascending part is more permeable to salts.
What is the function of the Antidiuretic Hormone?
The presence of ADH on the walls of CD&DCT makes the membrane more permeable to water by creating a water potential gradient. Hence, more water will be reabsorbed back to the capillary via osmosis
What is meant by kidney failure?
This is whereby one or two kidneys cannot work on their own
What are the causes of kidney failure?
Diabetes
high blood pressure
kidney injuries
excessive dehydration
Explain what happens during kidney dialysis
Kidney dialysis is an artificial way of filtering toxins out of the blood. It imitates a real kidney. Unfiltered blood is taken from the artery then pumped into the dialysis machine and returned backto the vein of the arm. The machine consists of a partially permeable membrane to separate blood and dialysate. They flow in opposite directions for easy exchange of materials.
How does the dialysis machine work?
It has no urea allowing more urea to pass through the partially permeable membrane as it will have a high concentration gradient. Dialysate will have the same concentration of salts & water at the normal level of a patient, therefor there’s no concentration gradient between dialysate and blood so the patients salt & water won’t diffuse. This is done for 6/8 hours.
