5.1.2 Liver and Excretion Flashcards
Deamination
Amino Acid + Oxygen ->keto acid + ammonia
Keto Acid enters respiration to release energy
Ammonia enters the ornithine cycle to be converted into urea
Examples of Excretion
CO2: waste from respiration, excreted via the lungs
Nitrogenous Waste: urea, produced in the liver and excreted as urine via the kidneys
Bile Pigments: produced from the breakdown of haemoglobin in the liver and excreted as bile in the intestines (faeces)
Hepatic Artery
supplies liver with oxygenated blood from the heart
Hepatic Vein
Takes deoxygenated blood away from the liver
Hepatic Portal Vein
brings blood from the duodenum and ileum so that toxins can be filtered out and broken down here in the liver
Bile duct
takes bile produced by the liver to the gall bladder to be stored
carbohydrate metabolism
Hepatocytes are involved in the homeostatic control of glucose levels in the blood. When the blood glucose levels rise, insulin levels rise and stimulate hepatocytes to convert glucose into glycogen.
Detoxification
Level of toxins tend to increase. Apart from urea, many other metabolic pathways produce potentially poisonous substances. The liver is where most of these are detoxified.
Transamination
The conversion of one amino acid into another. This is important because the diet does not always contain the required balance of amino acids but transamination can resolve this issue
Excretion in kidneys
Blood enters kidney through renal artery and then passes through capillaries in cortex. When in capillaries, substances are filtered out of blood into tubules called ultrafiltration. Useful substances reabsorbed back into the blood called selective reabsorption. Remaining substances such as urea pass along tubules then along the ureter to the bladder to be expelled during urination. Filtered blood passed out of the kidney through the renal vein.
Selective Reabsorption
Occurs throughout the nephron after the renal capsule. When filtrate is first formed, it is hypotonic to the blood.
Most of this occurs in the PCT, cells lining tubule are adapted for the reabsorption of substances from the lumen, across them, into the blood capillaries around them.
85% reabsorbed
Causes of Kidney Failure
Diabetes
Hypertension
Genetics
Kidney stones
Main Problems with Kidney Failure
blood in urine proteins in urine selective reabsorption may stop urea and toxins may accumulate in the blood disrupted water/ion balance
Glomerular Filtration Rate (GFR)
Rate that substances are filtered out of the blood in the glomerulus into the renal capsule
below normal rate = kidneys not functioning
blood test measures conc of creatinine (a breakdown product from muscle cells)
Age, Gender and Fitness need to be taken into consideration
GFR readings
reading below 60 for 3+ months indicated severe chronic kidney disease
reading below 15 shows kidney failure