Excretion Flashcards
What is metabolism?
All the chemical reactions that happen in your cells
Why can’t waste products build up in the body?
They are toxic and would cause damage by affecting other metabolic reactions
What is excretion?
The removal of the waste products of metabolism from the body
What is broken down by the liver?
Excess amino acids
Why do excess amino acids need to be broken down?
Amino acids contain nitrogen and nitrogen can’t be stored in the body so they are broken down to prevent damage to the body
What occurs in deamination?
Nitrogen containing amino groups (-NH2) removed from excess amino acids - forming ammonia (NH3) and organic acids
Why can’t ammonia be excreted directly? How is it excreted?
It is too toxic to be excreted directly, so it is combined with CO2 in the ornithine cycle to create urea
Where in the body is ammonia combined with CO2 in the ornithine cycle?
The mitochondria of the liver cells
What is alcohol broken down into and where?
Ethanol is broken down by the liver into ethanal
What are the four substances broken down by the liver?
1)excess amino acids
2) alcohol
3) paracetamol
4) insulin
What part supplies the liver with oxygenated blood from the heart?
The hepatic artery
What part takes deoxygenated blood away from the liver?
The hepatic vein
What part brings blood from the small intestine, and why?
The hepatic portal vein - it is rich in the products of digestion (no harmful substances also)
Where does the bile duct take bile to?
The gallbladder to be stored
What is the liver made up of?
Liver lobules - cylindrical structures made of cells called hepatocytes
What is in the middle of each lobule in the liver?
Central vein that connects to the hepatic vein
What are sinusoids in the liver?
Capillaries in which blood runs through past hepatocytes that remove the harmful substances and oxygen
What are the two parts of the liver in which blood runs through that join at the sinusoid to the central vein?
The hepatic artery and the hepatic portal vein
What do kupffer cells do and where are they located?
They removed bacteria and breakdown old red blood cells - connected to the walls of the sinusoids
What do hepatocytes produce and where does this go?
They produce bile and secreted into the bile canaliculi which drains to the bile ducts
Under a light microscope, what does the central vein of the liver look like?
A large white circular shape
Under a light microscope, what do hepatocytes in the liver look like?
The largest mass with red nuclei
Under a light microscope, what do sinusoids in the liver look like?
Other white spaces that aren’t the central vein
What are the two main function of the kidney?
To excrete waste products and regulate water potential of the blood
Where does blood enter the kidney?
The renal artery
Upon entering the kidney, where does the blood go and what happens to it?
The blood passes through the capillaries and substances are filtered out of the blood
What is the name of the process where substances are filtered out of the blood in the kidneys?
Ultrafiltration
What is reabsorbed back into the blood from the kidney and why?
Glucose because it is useful
Where do the unwanted substances from ultrafiltration go?
Ureter and the bladder to be expelled as urine
Once the blood from the kidney has undergone ultrafiltration, where does it go?
Out the kidneys through the renal vein
Where does ultrafiltration take place?
The glomerulus that is looped inside the bowmans capsule
How do substances move from the capillary into the Bowman capsule?
High pressure forces liquid and small molecules out the blood
What are the names of the arterioles before and after the blood enters the glomerulus?
The afferent arterioles and the efferent arteriole
Once the substances have entered the Bowman capsule, what path do they travel down?
Through proximal convoluted tubule, the loop of henle and the distal convoluted tubule to the renal vein that heads to the ureter
Why can’t larger molecules pass through into the Bowman capsule?
They are too big to pass through the pores in the endothelium
What takes place as the filtrate flows along the PCT, loop of Henle and the DCT?
Selective reabsorption
What is reabsorbed by the PCT?
Useful solutes (glucose, amino acids and vitamins)
What is urine usually made up of?
Water, urea and hormones
What doesn’t urine usually contain?
Proteins, blood cells, glucose and amino acids
What does the cortex of a nephron look like under a light microscope?
A glomerulus surrounded by a white Bowman capsule which is surrounded by squamous epithelial cells
What are the long white lines on a nephron under a light microscope?
Loops of henle
