Excretion

• What size must molecules be to be detected in urine ? 


  Have a molecular mass of less that 69,000

  <69000
• what can damage to the hypothalamus cause ? 


  inability to detect water potential of blood hence fewer aquaporins inserted into the cell surface membrane of the collecting duct less water reabsorbed into the blood
• which part of the nephron is within the cortex ?

  glomerulus and bowman’s capsule
• what is there structural difference between alpha and beta glucose? 


  in alpha glucose H is above the ring
• What is the likely affect of sulthiame on the reabsorption of sodium ions in the pct 


  Less reabsorption as less H+ ions in pct (as enzyme carbonic anhydrase cannot catalyse the production of hydrogen carbonate which dissociates into H+ ions )

  Less facilitated diffusion of NA+ into cells

  So less active transport of na ions into blood

  
• what are so we structures of tubule cells

  mitochondria

  ribosomes

  Golgi apparatus
• compare the processes happening in the pct and duct 


  similarities

  • both use active transport
  • both use selective reabsorption
  • both use Na+ ions
  • differences
  • pct uses calcium ions
  • pct only involves ions in co transport no glucose and amino acids like the pct
• name and explain one symptom of a kidney disease that prevents the cells of the collecting duct responding to adH in the blood 


  • always thirty
  • fewer aquaporins in plasma membrane of collecting duct due to reduced ADH so less reabsorption of water
• Why are podocytes unable to undergo mitosis 


  Cannot differentiate and divide

  If it occured it would change the number of gaps and affect ultrafiltration

  Podocytes shave is irregular so cannot divide
• what features of adult stem cells make them suitable for regenration of tissues In the kidney 


  they are multimpotent ( can differentiate into different types of cells)

  unspecialised so can differentiate into kidney cells
• suggest why the presence of proteins in the urine indicates kidney damage ? 


  protein is too large of a molecule to fit though the urine

  it should remsin in the blood not enter urine
• what is a function of the dct 


  selective reabsorption
• does the dct or pct have a higher concentration or urea 


  dct because water is reabsorped earlier in the nephron
• which part of the nephron is directly affected by adH 


  the collecting duct
• What effect do salted crisps and boiled sweets have on urine production?

  They cause a smaller volume of urine production
• What effect do bread, milk, and chocolate have on urine production?

  They cause a higher volume of urine production
• Why do salted crisps and boiled sweets reduce urine production?

  They reduce water potential of the blood
• What components in salted crisps and boiled sweets affect urine production?

  High sugar and salt contents
• What do osmoreceptors in the hypothalamus detect?

  Changes in the water potential of the blood
• What is the result of osmoreceptors detecting changes in blood water potential?

  Increased release of ADH
• What is the effect of aquaporins in the collecting ducts?

  More water is reabsorbed
• What does ADH cause in the collecting ducts?

  Production of aquaporins for water reabsorption
• How do bread, milk, and chocolate affect blood water potential?

  They increase water potential of the blood
• What is the effect of increased water potential of the blood on ADH release?

  It causes reduced ADH release
• How do the effects of salted crisps and boiled sweets differ from those of bread, milk, and chocolate on urine production?

  Salted foods decrease urine, while others increase it
• describe how the endocrine and nervous systems work together to increase water reabsorption from the collecting duct.


  Answer

  • Osmoreceptors in the hypothalamus detect changle in water potential of the blood
  • The hypothalamus is part of the nervous system
  • Causes a release of Adh from the posterior pituitary from the adrenal cortex
  • AdH binds to receptors on the cell surface mambrsne3 of the collecting ducts cells
  • Causes the production of more aquaporins increasing the permeability of the collecting duct.
• What decreases a persons blood pressure

  if they produce more urine that’s a sign
• what are the advantages and disadvantage solidness transplant ? 


  advantages

  • do not need to constantly undergo dialysis
  • better quality of life
  • diet less limited
  • disadvantage
  • your body may reject the kidney
  • difficult to find a donor
  • have to take long term immunosuppressant drugs
• what is a non invasive method of testing for kidney cancer 


  test urine
• Describe features of the glomerulus and bowman’s capsule that allow them to perform their function properly 


  Answer

  • Both responsible to high pressur ultrafiltration
  • In the bowman’s capsule the afterant arteriole is wider than efferent creating a high presuure system
  • bowmans capsule made up of podocytes which has finger like projections creacting gaps allowing filtrate to pass through
  • Basement membrane made of collagen and glycoproteins forming a fine filter
• If the glomerulus and pct of a person becomes damaged what differences do you suggest you would see in the composition of that persons urine ? 


  larger proteins present

  blood cells present

  more water present