kidney

• Label the diagram

  Sinusoid diagram

  A) hepatocytes

  B) hepatic artery

  C) hepatic portal vein

  D) kupffer cell

  E) bile duct

  F) sinusoid

  G) central vein

  
• Label the diagram

  Mammalian urinary system

  A) kidney

  B) renal vein

  C) renal artery

  D) ureter

  E) urethra

  F) bladder

  
• Label diagram

  Nephron structure

  A) glomerulus

  B) bowman's capsule

  C) pct

  D) collecting duct

  E) afferent arteriole

  F) efferent arteriole

  G) loop of henle

  H) dct

  
• Describe the process of ultrafiltration

  Bowman's capsule

  High hydrostatic pressure in the glomerulus forces small molecules out

  • urea, water, glucose

  The basement membrane acts as a filter

  Blood and large molecules remain in capillary

  • protiens
• How are bowman's capsules adapted for ultrafiltration?

  • fenestrations between epithelial cells of capillaries
  • fluids can pass between and under the folded membrane of podocytes.
• compare the processes occurring in the proximal and distal convoluted tubules.

  Similarities:

  • both use active transport
  • both involve, co-transport
  • both involve selective reabsorption
  • both involve use of, sodium ions

  Differences:

  • DCT involves use of, calcium ions
  • (co-transport in) DCT involves ions only
  • PCT involves ions and glucose/amino acid molecules
• Similarities between ultrafiltration and the formation of tissue fluid

  • Small molecules are filtered out
  • Large molecules/proteins/ cells, remain in the blood
  • Both processes occur in capillaries
  • Many molecules (e.g. water, sugars, ions) are reabsorbed back into capillaries
  • High (hydrostatic) pressure in both processes
  • Hydrostatic pressure greater than oncotic pressure in both
• Differences between ultrafiltration and the formation of tissue fluid

  • Filtrate enters the Bowman’s capsule + PCT in the kidney, but tissue fluid bathes cells

  • Molecules not reabsorbed by capillaries form urine in the kidney, but molecules not reabsorbed from tissue fluid will enter cells/form lymph.

  • knot of capillaries in ultrafiltration but a network of capillaries in the formation of tissue fluid
• why do some foods affect urine production?

  Salty/sugary -

  • reduce water potential of blood (because of high sugar / salt content)
  • hypothalamus, detect change
  • increased release of ADH
  • increase of aquaporins in collecting duct so more water is reabsorbed

  bread/milk -

  • increase water potential
  • causes reduced ADH release
• Ultrafiltration (molecules from glomerulus to bowman's capsule)


  • The afferent arteriole wider than the efferent arteriole = high hydrostatic pressure
  • endothelium fenestrations allow molecules out
  • basement membrane = as a molecular sieve - separate on size
  • podocytes - another filtration barrier
• What passes into the bowman's capsule during ultrafiltration?

  • Water
  • Urea
  • Glucose
  • Amino Acids
  • Na+
  • Cl+
• What cannot pass into the bowman's capsule during ultrafiltration?

  • No plasma proteins
  • No blood cells
• What structures of the nephron are in the cortex space?

  • PCT
  • DCT
  • Glomerulus
  • Bowman's capsule
• What structure is in the medulla space?

  Loop of henle
• What happens in PCT and of what?

  Selective reabsorption of:

  100% = amino acids

  100% = glucose

  some water
• What is lost on the descending limb?

  Water by osmosis

  It is not permeable to ions
• What is lost in the ascending limb?

  Ions through active transport via carrier proteins:

  • Na+
  • K+
  • Cl-
• Features of an effective reabsorption surface:

  One cell thick = short diffusion distance

  Microvilli = increase SA

  Many mitochondria for sodium-potassium pumps
• How might kidney problems lead to arrhythmia?

  potassium ion imbalance may affect the frequency of nerve impulses from the sinoatrial node in the heart. 

  • This may lead to arrhythmia and cardiac arrest.
• Sulthiame is a drug that inhibits the enzyme carbonic anhydrase


  • (less reabsorption because) idea of fewer H+ ions in PCT cells
  • less / no, co-transport / facilitated diffusion, of Na+ ions, into cells / from lumen
  • less / no, active transport of Na+ ions into, blood

  
• Explain why peritoneal dialysis can use active transport and diffusion while haemodialysis relies on diffusion alone.

  • peritoneal wall is made up of living cells
  • produces ATP to carry out active transport
  • dialysis membranes, only allow diffusion / cannot do active
• Kidneys


  Main role is excretion of waste products, such as urea in the form of urine
• Kidney functionblood vessels 


  Blood enters through renal artery, waste products filtered out into nephrons, useful substances reabsorbed, filtered blood leaves through renal vein
• Ultrafiltration


  Process where waste products are filtered out of the blood as it passes through the capillaries and into the nephrons
• Glomerulus


  • Capillary bed found within the Bowman's Capsule of the Nephron
  • Blood arrives through afferent arteriole, leaves through efferent arteriole
  • Allows molecules less than 69,000 Mr to enter Bowman's capsule
• Selective reabsorption


  Process where useful substances such as amino acids, glucose, vitamins are reabsorbed back through the tubules
• Proximal convoluted tubule


  • 100% of glucose and amino acids reabsorbed
  • Large proportion of water and salts also reabsorbed
  • Cells have microvilli and many mitochondria to facilitate active transport
• Glucose and amino acid reabsorption


  Active transport by co-transporter proteins (Na+ needs to be reabsorbed at the same time)
• Loop of Henle


  Produces a low water potential in the medulla of the kidney by acting as a countercurrent multiplier
• Dehydration


  More water reabsorbed into the blood by osmosis from the loop of Henle, distal convoluted tubule and collecting duct, producing more concentrated urine
• Well hydrated


  Less water reabsorbed, producing more dilute urine
• Antidiuretic hormone (ADH)


  Makes walls of distal convoluted tubule and collecting duct more permeable to water, increasing water reabsorption
• ADH mechanism


  Binds to receptors, activates enzymes to produce cAMP, causes vesicles with aquaporins to fuse with plasma membrane
• Kidney failure


  Caused by kidney infections or high blood pressure, leads to build-up of toxic waste and fluid imbalance
• Treatments for kidney failure

  • Renal dialysis
  • Kidney transplant
• Haemodialysis


  Removes blood from the body, pumps it through a machine where it is run in countercurrent flow alongside dialysis fluid, separated by an artificial membrane
• Peritoneal dialysis


  Dialysis fluid is put into the body cavity so exchange can happen across the peritoneal membrane
• Kidney transplant


  Long term solution, patients need to wait a long time for a suitable donor of the same blood and tissue type, immunosuppressants still need to be taken to prevent rejection, usually a family member donor as only one kidney is required for survival
• Which kidney failure treatment doesn't use immunosupressants?

  Peritoneal