Excretion Flashcards
what is excretion?
the removal of metabolic waste from the body
what are the main excretory products?
carbon-dioxide from respiration, nitrogen containing compounds such as urea, other compounds such as bile pigments
Where does the blood flow in the hepatic artery?
From the heart to the liver carrying oxygenated blood
Where does blood flow in the hepatic portal vein?
From the digestive system to the liver carrying deoxygenated blood rich in products of digestion
Where does the hepatic vein take blood?
away from the liver
What is a sinusoid?
where oxygenated and deoxygenated blood mix to join together and form the hepatic vein, blood flowing along here comes into close contact with the liver cells
What are kupffer cells?
specialised macrophges which breakdown and recycle old blood cells
What are hepatpcytes?
liver cells that have a cuboidal shape with many microvilli on their surface
What is the bile canaliculi?
a chamber which joins to the bile duct that transports bile to the gall bladder
What does the enzyme catalase do in the liver?
converts hydrogen peroxide to oxygen and water
what does cytochrome P450 do in the liver?
breakdown drugs including cocaine and various medicinal drugs
How is alcohol broken down?
ethanol is broken down into ethanal by ethanol dehydrongenase. Ethanal is dehyrdogenated further by the same enzyme. This produces ethanoic acid. Ethanoate (acetate) is combined with coenzyme A to form acetyl coenzyme A
Why do we not excrete the whole of an amino acid molecule?
they contain a lot of energy
what processes occur during the formation of urea?
deamination and the ornithine cycle
what occurs during deamination?
the amino group is removed and ammonia is produced as well as keto acid
what is keto acid used fr?
respiration
what happens in the ornithine cycle?
ammonia is combined with carbon dioxide to produce urea. Ammonia and carbon dioxide combine with the amino acid ornithine to produce citrulline. This is converted to arginine by adding more ammonia. The arginine is re-converted to ornithine by the removal of urea
what is the function of the kidney?
to filter blood and remove excess ions/water to produce urine
what are the regions within the kidney?
outer region - cortex
inner region - medulla
centre - pelvis leading to ureter
what is ultrafiltration?
filtration of the blood at a molecular level under pressure
what are the three layers adapted to enable ultrafiltration?
the endothelium of the capillary, the basement membrane, the epithelial cells of the bowmans capsule
how is the endothelium of the capillary adapted?
there are narrow gaps between the endothelium cells of the capillary wall which substances to pass out
how is the basement membrane adapted?
consists of a fine mesh of collagen fibres and glycoproteins which prevent molecules larger then 69,000 molecular mass, from passing
how is the epithelial cells of the bowmans capsule adapted?
they have cells called podocytes which have projections called major processes. Each major process has minor processes that hold cells away from the endothelium of the capillary - ensuring there are gaps between the cells
