5.1.2 Excretion COMPLETE Flashcards
DEFINITION- Excretion
The removal of the waste products of metabolism from the body.
CO2 Transport
- CARBONIC ACID- Water and CO2 converted by carbonic anhydrase. Then dissociates into H+ and HCO3-
- CO2 also dissolves into the plasma forming carbonic acid
- CO2 also directly binds to haemoglobin forming CARBAMINOHAEMOGLOBIN
Effect of increasing CO2
Increased CO2 leads to more H+ ions increasing acidity. Proteins act as a buffer taking up H ions.
Medulla Oblongata detects increase in H ions and increases breathing rate.
Respiratory Acidosis
Medical Condition in which decreased ventilation causes increased blood CO2 conc. and decreased pH.
Caused by asthma, blockages of the airways and emphysema.
Functions of the Liver
CONTROL- blood sugar, lipids and amino acids
SYNTHESIS- plasma proteins, cholesterol, bile
STORAGE- vitamins A/D/B12, from, glycogen
DETOXIFICATION- Alcohol, Drugs
BREAKDOWN- Old RBC, hormones
Hepatic Artery
Moves from the Aorta to Liver, blood contains O2 for aerobic respiration.
Hepatic Portal Vein
From the small intestine to the liver, blood contains amino acids and glucose. Not connected to the heart
Hepatic Vein
From the liver to the vena cava, blood contains CO2 and waste products of respiration.
Bile Duct
From the liver to the gallbladder, containing the bile produced by hepatocytes
Liver Lobules
The lobule is formed by many hepatocytes
Branches of the hepatic artery and portal vein carry blood betweens rows and are called SINUSOIDS
The central vein is a branch of the hepatic vein.
Channels carry bile are called BILE CANALICULUS
KUPFFER CELLS line the sinusoids
Hepatocyte Structure
Lots of organelles such as mitochondria and ribosomes
Glycogen granules and fat droplets
Microvilli to increase SA
Kupffer Cell Structure
Specialised macrophages, engulf bacteria and breakdown RBC, product of the breakdown includes Bilirubin
Formation of Urea
- Deamination
2. The Ornithine Cycle
Deamination
Excess amino acids can’t be stored
The amino group is removed to form ammonia.
Keto Acids remain or their converted into fats for storage
The Ornithine Cycle
Produces urea from ammonia, as urea is less toxic and less soluble.
Dissolves in plasma to be excreted by kidneys
Uses ATP and CO2, takes place in the mitochondria
DEFINITION- Detoxification
Conversion of toxic molecules to less toxic molecules, e.g. catalase breaks down hydrogen peroxide into water and oxygen
Ethanol
A drug that depresses nerve activity, small lipid molecules that cross the plasma membrane via simple diffusion. Enters bloodstream quickly and is toxic
Detoxification of Alcohol
Broken down in the hepatocytes
Ethanol-> Ethanal (ethanol dehydrogenase)
Ethanal-> Ethanoate (ethanal dehydrogenase)
2H atoms are removed and combine with coenzyme NAD
Problem with alcohol and fatty acids
If too much alcohol theres not enough NAD to breakdown the fatty acids, so they’re converted back to lipids and stored in hepatocytes.
Liver disease
Scarring of the liver cells causing cell damage and liver failure.
Role of the Kidney
Remove waste products from the blood to produce urine, carried out by the nephrons
Nephrons
Blood enters through the renal artery, which branches into tiny arterioles called AFFERENT Arterioles and enter renal capsule. They divide into a complex called the GLOMERULUS. These merge into the EFFERENT arteriole which eventually become the Renal Vein
Ultrafiltration
The filtration on a micro scale, small molecules are filtered out of the blood and into the lumen of the nephron.
Adaptions for Ultrafiltration
BASEMENT MEMBRANE- acts as a filter, however blood cells and proteins are too big
DIAMETER OF BLOOD VESSELS- The Afferent arteriole has a wider diameter. Builds up hydrostatic pressure
PODOCYTES- Specialised cells with fingerlike projections that allow filtrate to pass beneath cells
CAPILLARY ENDOTHELIUM- Spaces between cells that fluid passes between
