urinary system

• homeostasis definition


  maintaining constant internal environment (within set limits)
• what does homeostasis control

  temperature, salt concentration, water, proteins, fats, carbohydrates
• components of homeostatic system

  • receptors
  • control centre
  • effector
• homeostasis uses 


  negative feedback to prevent small changes from becoming big ones
• osmoreceptors detect changes in water concentrations
• osmoreceptors are found in the hypothalamus
• ADH (antidiuretic hormone) AKA vasopressin is released in response to increase in blood osmolarity
• new-born's store 80% water
• new-born's contain 80% water
• adult females contain 50% water
• adult males contain 60% water
• in average young male there is about 40 litres of water, with

  • 25 L in cells themselves (intracellular fluid)
  • 12 L in interstitial fluid
  • 3 L in plasma
• what is interstitial fluid?


  Fluid that surrounds and fills the spaces between cells in tissues.
• in the nephron reabsorption occurs 


  when actively move fluid from nephron back into the blood
• secretion in the nephron occurs when fluid moves from blood stream into tubular fluid of the nephron (to be excreted in the urine)
• osmosis is the movement of water

  through a selectively permeable membrane, from an area of lower solute concentration to an area of higher solute concentration
• hypertonic means


  lots of solute
• hypotonic means 


  less solute in solution
• water enters the body through

  food, ingested liquids and tissue catabolism
• water leaves through 


  lungs, skin, kidney, intestines
• urinary system

  labels

  A) adrenal gland

  B) liver

  C) right kidney

  D) ureter

  E) bladder

  F) renal artery

  G) renal vein

  H) left kidney

  I) urethra

  
• left kidney is higher than right because of the liver on the right
• internal structure of the kidney

  labels

  A) renal pyramids

  B) cortex

  C) medulla

  D) pelvis

  
• darker pink sections are so because they have higher salt concentration
• head of the nephron sits in the renal cortex, nephron loop dips into the medulla
• blood enters through afferent arteriole
• blood exits nephron through efferent arteriole
• efferent arteriole is smaller than afferent to increase blood pressure to force fluid out via filtration
• filtration driven by high blood pressure
• high pressure in the glomerulus forces fluid in to the Bowman's capsule
• lots of fluid and solutes are reabsorbed in the PCT, such as glucose
• descending loop of Henle is only permeable to water, not salt
• descending loop of Henle gets increasingly concentrated (salt), as water leaves and enters surrounding tissue
• ascending loop of Henle is permeable to salt, not water so salt diffuses out as it ascends
• at the thicker part of the ascending loop of Henle, salt is actively pumped out, creating a salt concentration gradient
• the thicker part of the ascending loop of Henle is thicker because it has bigger cells which are packed full of mitochondrion
• more reabsorption happens in the DCT
• permeability of the collecting duct can be altered so water can be reabsorbed from the collecting duct or not
• renal corpuscle is the glomerulus and the Bowman's capsule
• blood enters Bowman's capsule via afferent arteriole, hitting the capillary bed (glomerulus), blood leaves by efferent arteriole