liver & excretion Flashcards
Define excretion
The removal of waste products from the body
What does excretion maintain?
Metabolism also homeostasis for helping to keep the levels of certain substances in the blood, roughly constant
Give an example of excretion (respiration)
Carbon dockside is a waste product of respiration too much in the blood is toxic, so it’s ready for the body by the lungs or gills which act as excretory organ
What organ breaks down excess amino acids
the liver
Why do amino acids need to be broken down and excreted?
Amino acids contain nitrogen in amino groups Nitrogenous substances can’t usually be stored by the body. This means excess amino acids can be damaging to the body therefore they must be used by the body (to make proteins) or broken down and excreted.
Explain the first step of how amino acids are broken down in the liver
deamination
The nitrogen containing amino groups are removed from any excess amino acids, forming ammonia and organic acids
Step two of the breakdown of amino acids
The organic acids can be respired to give ATP, or converted to carbohydrate and stored as glycogen
What happens to ammonia?
Ammonia is too toxic for mammals to excrete directly, so it’s combined with CO2 in the authorised cycle to create your urea
What happens to urea?
urea is released from the liver into the blood, the kidneys and filters the blood and remove the urea as urine, which is excreted from the body
What is detoxification?
The liver breaks down other harmful substances like alcohol, drugs, and unwanted hormones into less harmful compounds that can be excreted from the body
How is alcohol detoxified
Alcohol, a toxic substance that can damage cells is broken down by the liver into ethanal Which is broken down into a less harmful substance called acetic acid, Excess alcohol over a long period of time can lead to cirrhosis of the liver, This is when the cells of the liver die in score tissue blocks blood flow
describe the hepatic artery
Supplies to live with oxygenated blood from the heart of the liver has a good supply of oxygen for respiration
Describe the hepatic vein
Takes deoxygenated blood away from the liver
What’s the hepatic portal vein?
Brings blood from the duodenum and ileum(Parts of the small intestine)so it’s rich in the products of digestion. This means any interested, harmful substances are filled it out and broken down straight away
What’s the bile duct ?
Takes bile( a substance produced by the liver to emulsify fat )to the gallbladder to be stored
What are liver lobules
Cylindrical structure is made of cells called hepatocytes arranged in rows radiating out from the centre
What is the central vein?
Found in middle of each lobule, Connect the hepatic vein.
Many branches of the Hepatic artery, hepatic portal vein and bile duct are also connected to each lobule
What is sinusoids?
Capillaries that connect the hepatic artery and the hepatic portal vein to the Central vein
Describe the blood flow through the liver
blood runs through the sinusoids past the hepatocytes that remove harmful substances and oxygen from the blood the harmful substances are broken down by the hepatocytes it’s less harmful substances that renter the blood.
The blood runs to the central vein, and the central veins from all the lobules connect up form the hepatic vein
What are kupffer cells?
Also attach the walls of sinusoids, they move bacteria and breakdown old red blood cells
What’s the bile canaliculi ?
Tubes of bile secreted by hepatocytes, These tubes drain into the bile ducts, the bile ducts from all the lobules eventually connect up and leave the liver
what detects kidney failure
glomerular filtration rate(GFR)
what is glomerular filtration rate
the rate at which blood is filtered from the glomerulus into the bowman’s capsule, lower than normal =kidneys not working
what can kidney failure be abused by, how?
-kidney infections- cause inflammation (swelling),damage cells, interferes with bowman’s capsule (filtration) and reabsorption in other parts of nephrons
-high blood pressure- can damage glomeruli. blood in glomeruli is already under high pressure but. the capillaries can be damaged if the pressure gets too high, meaning larger moods like proteins can get through walls into urine
what are the problems caused by kidney failure
1)waste product build up
2)fluid accumulation (swelling)
2)unbalance of electrolytes(blood too acidic)
3)longer term kidney failure causes anaemia
what happens as a result of electrolyte imbalance
blood may become too acidic, imbalance of calcium and phosphate can lead to brittle bones. salt build up may cause more water retention
what are 2 treatments of kidney failure
1)renal dialysis
2)kidney transplant
what is renal dialysis
a patients blood is filtered
2 types of renal dialysis
HAEMODIALYSIS, PERITONEAL DIALYSIS
Explain haemodialysis
patients blood is passed through dialysis machine, blood flows on one side of a partially permeable membrane and dialysis fluid flows on the other side.
waste products and chess water and ions diffuse across the membrane into the dialysis fluid,removing them from the blood . blood cells and larger molecules like proteins are prevented from leaving the blood.
how long are each dialysis sessions, how many are needed?
3/5 hours, 2 to 3 sessions a week
why might patients start to feel increasingly unwell between dialysis sessions
waste products and fluid start to build up in their blood
explain peritoneal dialysis
- dialysis fluid is put through a tube that passes front he outside of a patients abdomen into their abdominal cavity. waste products diffuse out of the patients blood into the dialysis fluid across the peritoneum(the membrane lies the abdominal cavity). after some time the fluiddd is drained out via the tube.
where when and how many times is peritoneal dialysis carried out
at patients home, serval times a day or in one long overnight session.
problems with peritoneal dialysis
risk of infection around site of tube, no dialysis free days
explain kidney transplants
new kidney implanted into patients body to replace with damaged one
form a person istg the same blood/tissue type, often donated by living relative , or people who have recently died(organ donor)
disadvantages/advantages of kidney transplants
cheaper than dialysis, more conviniet than dialysis
major operation that’s risky, immune system may reject , drugs to suppress
what do pregnancy tests detect (draw out steps of pregnancy test in notes)
human chronic gonadotropin (hCG), only found in urine of pregnant women
