Excretion Flashcards
(26 cards)
excretion
the removal of metabolic waste from the body
excretory products
carbon dioxide from respiration, nitrogen-containing compounds (urea), other compounds (bile)
importance of excretion
to ensure they don’t build up to toxic level, altering pH, acting as inhibitors on enzyme activity and preventing normal metabolism
how liver stores sugar
in the form of glycogen in granules in the cytoplasm of hepatocytes, broken down when required
how toxins can be rendered harmless
oxidation, reduction, methylation or combination with another molecule
enzymes in liver cells that render toxins harmless
catalase- converts hydrogen peroxide –> oxygen + water
cytochrome P450- break down (metabolise) drugs, cause side effects of medicinal drugs, involved in other metabolic reactions (ETC)
detoxification of alcohol
ethanol broken down in hepatocytes to acetyl CoA + reduced NAD for respiration
what if the liver has to detoxify too much alcohol
uses up stores of NAD so not enough left for fatty acids –> converted back to lipids –> stored in hepatocytes –> ‘fatty liver’ and hepatitis/cirrhosis
osmoregulation
the control of water potential in the body by controlling the levels of salt and water- prevent water entering cells causing lysis/leaving causing crenation
how to assess kidney function
estimating the glomerular filtration rate (GFR)- a measure of how much fluid passes into the nephrons per minute (normal is 90-120cm3min-1)
causes of kidney failure
diabetes mellitus, heart disease, hypertension, infection
renal dialysis
waste products, excess fluid and mineral ions are removed from the blood by passing over a partially permeable dialysis membrane, allowing exchange of substances with the dialysis fluid
how renal dialysis maintains the correct concentrations of substances
in excess in the blood -> diffuses into dialysis fluid
if too low concentration -> diffuses into blood from fluid
metabolic waste
a substance produced in excess by the metabolic processes in the cells
ornithine cycle
a series of biochemical reactions that convert ammonia to urea
nephron
functional unit of the kidney
ultrafiltration
filtration of the blood at molecular level under pressure
ADH
a hormone that controls the permeability of the collecting duct walls
osmoreceptor
a sensory receptor that detects changes in water potential
glomerular filtration rate (GFR)
the rate at which fluid enters the nephrons
monoclonal antibodies
made from one type of cell- they are specific to one complementary molecule
what is renal dialysis
a mechanism used to artificially regulate the concentrations of solutes in the blood
Kupffer cells
specialised macrophages that move within sinusoids, breakdown and recycle old RBCs
single layer of live cells
remove or return substances to blood
