Excretion Flashcards
What is excretion?
Removal of toxic substances from the body
What is egestion
The removal of faeces from the body
Waste product, carbon dioxide
In plants it is removed through diffusion out the stomata and in animals it is removed by the lungs.
Where is carbon dioxide made
Made in respiring cells via respiration, it’s removed via blood plasma in the lungs
Where is urea made?
In the liver cells, made by deamination removed in the kidneys (and skin)
What is deamination?
The break down of amino acids into carbohydrates and ammonia (very toxic)
What artery and vein goes to the liver
Hepatic artery, hepatic portal vein
What does the kidney do?
Filters the blood and removed excess materials and passes them to the bladder to be stored for excretion
Structure of kidney
Around the outside is the cortex
In the middle is the triangular medulla, in the centre us the pelvis
Ultrafiltration
The process of filtering the blood in the glomerulus. The small molecules are forced out because of high pressures where as large molecules (proteins) are too large and stays in the blood.
Selective Reabsorption
Happens in the proximal convoluted tubule (PCT) where ions and water still needed in the body is actively transported back into the blood stream
PCT adaptations
Lots of mitochondria for active transport and folded membrane for increased surface area
Loop of henle
80% of water is transported in the PCT but the rest is absorbed in the loop of henle if needed
ADH
Is a hormone which tells your collecting duct how much water you need to réabsorba depending on how much you sweat. This is called osmoregulagion.
What does urine contain?
water, urea and ions
