excretion

• what is excretion


  the process of removing waste from the body
• waste products examples and where they come from

  C02 from respiration

  Bile from breakdown of haemoglobin

  Urea from breakdown of amino acids
• what is a hepatocyte

  liver cell
• what are sinasoids

  space around the hepatocytes, lined with flat cells.
• what cells are inside the sinasoids

  cells called rupffer cells - a type of macrophage
• what is the central vein

  Vein found at the centre of the liver. It receives the blood from the sinusoids and return it to circulation via the hepatic vein
• what is the portal vein

  a vein conveying blood to the liver - branched
• what is the hepatic artery

  carries oxygenated blood to the liver
• What is the bile duct?

  Duct that carries the bile secreted in the liver via bile canaliculi from the liver to the gall bladder
• What are bile canaliculi?


  small ducts between hepatocytes that collect bile produced by the hepatocytes
• function of hepatocytes

  store of glycogen

  transamination (making one amino acid from another)

  detoxification (breaks down toxins)

  deamination (removing an amine group and adding it to C02 forming urea)
• what is the orthine cycle

  cycle that produces urea
• what does OACAU (often alanna carries an umbrella) in the orthine cycle

  Ornithine

  Ammonia

  Cirtruline

  Arginine

  Urea
• Kidney structure: 3 layers

  renal pelvis, medulla, cortex
• What is ultrafiltration?

  filtering of the blood plasma
• what is selective reabsorption

  The uptake of specific molecules and ions from the glomerular filtrate in the nephron back into the bloodstream
• journey of blood through the nephron summery:

  afferent arteriole

  glomerulus/bowman's capsule

  efferent arteriole

  proximal convoluted tubule

  loop of henle

  distal convoluted tubule

  collecting duct
• efferent arteriole

  carries blood away from the glomerulus
• afferent arteriole

  carries blood to the glomerulus
• what happens in bowman's capsule/glomerulus

  substances diffuse through 3 layers via tissue fluid using osmosis: capillary layer, membrane, podocytes
• What is a podocyte?

  'Octopus like' structure, with extended arms (pesicels) that wrap around capillaries
• what happens in the proximal convoluted tubule?

  Selective reabsorbtion of glucose back into the blood happens here.
• how does selective reabsorption work with the lines brush boarder in the kidney

  - Na+ ions and glucose diffuse into the brush border cells via facilitated diffusion.

  - Na+ ions are actively transported out at the other end to maintain conc gradient

  - Na+ and Glucose move to other side and glucose diffuses out into blood
• Loop Of Henley Function

  - descending limb - water moves out via osmosis

  - at the bottom - filtrate now very concentrated

  - start of ascending limb slat diffuses out into blood

  - end of ascending limb salts have to be actively moved out bc an equilibrium has been reached
• what happens in distal convoluted tubule

  water, Na+, Cl- absorbed back into boood via diffusion - permeability varies with ADH levels
• what is osmoregulation

  The control of water balance using ADH
• mechanism of ADH action on water level balance

  1. Drop in blood water potential is detected by osmoreceptors in the hypothalamus.

  2. Hypothalamus releases ADH in to posterior pituitary gland.

  3. ADH released from posterior pituitary gland in to blood.

  4. ADH transported in blood.

  5. ADH binds to receptors on cell membrane in collecting duct, triggering the formation of cAMP

  6. cAMP causes vesicles in the cells lining collecting duct to fuse with cell surface membranes.

  7. Membranes of vesicles contain aquaporins which make it permeable to water.

  8. Water moves from the filtrate in to tissue fluid and returns to the capillaries
• what is the bodies response to too much water

  ADh levels drop, cAMP levels drop. water channels removed and enclosed in vesicles. Collecting duct becomes impermeable to water. body produces large amounts of dilute urine.
• medical uses of urine testing

  - mass spectrometry and gas chromatography (separates molecules out to be identified)

  - immunoassay (detects specific protein)
• how are monoclonal antibodies made

  - HCG injected into mouse

  - mouse B cells make antbodies

  - B cells removed + fused w. myeloma cells makes hybridoma cells

  - divides rapidly and antibodies collected
• kidney failure causes

  infection, increase Bp, Genetics
• kidney failure symptoms

  loss of ions balance

  build up of toxic urea - poison cells person

  high blood pressure - no water potential balance

  weakend bones - loss of Ca2+

  pain+ stifness in joints - protein in build up

  Anaemia- reduces production of red blood cells so tired
• what is glomerular filtration rate


  measure of the amount of creatine in the blood. (breakdown product of muscles)
• what is haemodialysis

  dialysis machine

  artificial bowman's capsule

  no operation, little infection risk

  but takes a long time and have to be in hospital
• what peritoneal dialysis

  inside body

  uses natural membrane

  can be done at home

  live a normal life

  takes a long time
• what is transplant (ad and dis)

  chance of rejection

  immunosuppressants

  lasts 9-10 years - then replaced