Excretion

• function of the liver

  detoxification of alcohols

  lactic acid break down

  glycogen storage

  remove and filter waste products
• excretion

  removal of metabolic waste from the body
• what would happen if water levels were unmanaged

  increased water potential in the blood

  water moves into cells

  causes them to burst
• urea

  if it builds up in the blood it can poison cells
• co2

  if it builds up in the blood it can increase acidity and denature the binding sites of haemoglobin
• the hepatic artery and hepatic portal vein all flow towards the hepatic vein
• alcohol

  ethanol to ethanal

  NAD -> NADH

  this then breaks down fats in respiration causing fats to build up in the liver which can turn fatty liver into scar tissue
• amino acids

  cannot be stored

  deamination -> removes the -NH2 group

  as ammonia is highly toxic and soluble

  ornithine cycle -> series of metabolic reactions that turn NH2 into urea
• urea

  CO(NH2)2
• why do birds excrete guanine instead of urea

  ammonia is more toxic than guanine

  urea is more soluble in water

  guanine has a higher proportion of nitrogen
• label the diagram

  a -> hepatic vein as blood is flowing out of the liver

  b -> hepatic artery as blood is entering through a narrow vessel

  c -> hepatic portal vein as blood is entering through a branched vessel

  
• how do ornithine and citrulline move in and out of the mitochondria

  facilitated diffusion as they are not lipid soluble so they require channel proteins and the conversion between them in the mitochondria creates concentration gradients
• how is ammonia formed in the mitochondria

  deamination of an amino acid
• why is catalase activity regulated in the liver

  large quantities of hydrogen peroxide and high turnover number of catalase would mean vigorous reaction and lots of oxygen produced very quickly
• how is catalase activity managed in the liver

  isolation of catalase in peroxisomes

  released in small quantities

  cells can limit catalase expression

  this limits enzyme concentration
• anaerobic respiration in muscle cells

  glucose -> pyruvate -> lactate
• role of pyruvate in anaerobic respiration

  hydrogen acceptor
• how is damaged liver tissue different structurally

  large gaps between cells

  cell death has occurred

  no clear sinusoids present
• name these tissues

  w -> liver

  x -> pancreas

  y -> skeletal

  
• how can something be metabolic waste

  produced from the breakdown of something else which is then removed from the body
• name each letter

  n -> central vein

  o -> hepatocyte

  
• liver cells name

  hepatocytes

  many mitochondria

  large nuclei

  golgi apparatus
• histology of the liver

  arranged in lobules

  blood mixes in the sinusoids

  hepatic portal vein comes from the digestive system
• sinusoids

  spaces that are surrounded by hepatocytes
• Kupfer cells

  protect against disease by destroying pathogens by phagocytosis
• bile

  first secreted into the canaliculi

  passes through bile ducts to the gall bladder where it is stored
• structure of the kidney

  glomerulus capsule -> ultrafiltration

  proximal convoluted tubule -> selective reabsorption

  loop of Henle

  distal convoluted tubule

  collecting duct
• what gets reabsorbed in the kidney

  amino acids

  glucose

  water

  some mineral ions
• structure of the glomerulus

  afferent arteriole -> high hydrostatic pressure

  endothelium of capillaries -> pores and thin

  basement membrane -> mesh of collagen

  if under high pressure it can be damaged and let proteins and RBC through

  epithelium of renal capsule -> podocytes

  bowman's capsule -> network of capillaries
• what cannot move into the bowman's capsule

  proteins

  red blood cells

  white blood cells

  platelets

  -> they are all too big
• the podocytes are wrapped around the capillaries in the bowman's capsule to create a short diffusion distance
• if protein is found in urine

  kidney damage
• if glucose is found in urine

  type 1 diabetes
• re-absorption of glucose control

  active transport of Na+ from the cells of the PCT into the blood

  lowers the concentration of Na+ in the cells causing them to move in via facilitated diffusion

  through cotransporter proteins glucose and amino acids are also reabsorbed by the cells
• which CT is impermeable to salts

  PCT
• histology of the kidney

  renal artery and renal vein

  outer layer -> cortex

  middle layer -> medulla

  inner layer -> pelvis
• kidney cortex

  dark outer layer that contains many capillaries
• kidney medulla

  contains the nephrons
• kidney pelvis

  where urine collects before being transported to the ureter
• loop of henle maintaining sodium ion gradient

  mitochondria in the podocytes provides energy for active transport of Na+ out of the loop of henle and into the surrounding medulla tissue

  this lowers the water potential so water moves into the medulla via osmosis where it is then reabsorbed back into the blood

  then in the ascending limb some of the ions are reabsorbed by diffusion