Unit 5 - Excretion, homeostasis and the liver Flashcards
Respiratory acidosis
Effect of lowered blood pH (excess CO2)
Why must nitrogenous compounds be removed from the body
This is because the body cannot store amino acids, but it would be toxic to excrete them
Deamination
Process by which potentially toxic NH2 group is removed from amino acids to produce keto acids and ammonia. The ammonia is then coverted into urea (less toxic)
Where is CO2 from respiring tissues excreted
Lungs
Where is water from respiration excreted
Lungs
Bladder
Skin
Where is urea from the kidney excreted
Bladder/ kidney
Where are poisons excreted
Liver
Bladder
Where are drugs excreted
Liver
Bladder
Where are bile pigments from liver reactions excreted
Rectum (bilirubin in faeces)
Excretion
Removing metabolic waste from the body
Hepatic Portal Vein
Carries blood loaded with the products of digestion straight from the intestine to the liver (75% of the blood)
Hepatic Artery
Supplies liver w/ oxygenated blood (25% of the blood)
Hepatic Vein
Connects to inferior vena cava and carries deoxygenated blood back to heart
Sinusoids
Run from central vein to portal triads. Mixing increases O2 content of the blood from hepatic portal vein
Kuppfer cells
Hepatic macrophages that move within sinusoids
Ingest foreign particles
Recycle old RBC’s
What do hepatocytes do
Relatively unspecialised to carry out many functions
Synthesise proteins (enzymes and hormones)
Transform and store carbs (glycogen)
Synthesise cholesterol and bile salts
Form bile and secrete into bile canaliculi
Absorb substances from blood and also secrete products
Shape of hepatocytes
Cuboidal w/ many microvilli (increases SA for contact w/ sinusoids)
Organelles in hepatocytes
Rough ER
Golgi Apparatus
Mitochondria
Vesicles
Role of the liver in excretion
Break down excess amino acids and haemoglobin
Detoxifies alcohol
Produces urea
Basic functional unit of liver
Lobule
Protein metabolism in the liver
Protein synthesis of plasma proteins
Deamination to form keto acid and NH2
Transamination to make new amino acids
Fate of keto acids
Kreb’s cycle (respration)
Portal triads
Hepatic Artery
Bile duct
Hepatic Portal Vein
Bile canaliculi
Drains bile from hepatacytes to bile duct
Where does deamination occur
In hepatocytes
Keto acid
An acid with a carboxylic acid group and a ketone group
Equation of deamination
Amino acid + oxygen —> keto acid + ammonia
Ornithine cycle
2NH3 + ornithine + CO2 (from respiration) —> H2O + urea (circulates in blood until filtered by kidney)
Detoxification of alcohol
Alcohol is broken down by hepatocytes by alcohol dehydrogenase to make ethanal which is further dehydrogenated by ethanal dehydrogenase to make ethanoate
NAD is needed to oxidise and breakdown fatty acids
Uses of ethanoate
Build up fatty acids
Cellular respiration
Pressures in the glomerulus
Hydrostatic pressure
Oncotic pressure
Capsular pressure
Calculating net pressure in the nephron
Hp - (Op + Cp)
Where does blood leave from the nephron
Efferent arteriole
Whats in the glomerular filtrate
Glucose Amino acids Ions (sodium, potassim, etc) Urea Water