homeostasis

• what is homeostasis?


  The ability of an organism to maintain a stable internal environment within a range
• what is an endotherm?

  An endotherm is an organism that generates heat internally to maintain a constant body temperature.
• what is negative feedback?


  a physiological factor changes a receptor detects it sending an signal to a corrective mechanism which allows a effector cause a change which will switch off when within limits
• where are beta and alpha cells found?


  Pancreas
• what are beta cells associated with?


  Insulin production
• what are alpha cells associated with?


  glucagon production
• what is glycogenesis?


  Glycogenesis is the process of converting glucose into glycogen for storage in the liver and muscles.
• what is glycogenolysis?


  Breakdown of glycogen into glucose.
• what is gluconeogenesis?


  The production of glucose from non-carbohydrate sources.
• why is it important that blood glucose concentration remains stable?


  maintains blood water potential and concentration of respiratory substrate
• factors that affect blood glucose concentration?


  amount of carbohydrates , rate of glycogenolysis and gluconeogenesis
• causes of type 1 and how it can be controlled?

  Autoimmune response. Insulin injections.
• causes of type 2 and how it can be controlled?


  Causes: Genetics, lifestyle factors. Control: Diet, exercise, medication.
• signs of diabetes?


  glucose in urine , sudden weight lost and blurred vision
• parts of the nephron?


  bowmans capsule , proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct.
• what blood vessels are associated with the nephron?

  renal artery , afferent arteriole , efferent arteriole , glomerulus
• how is glomerular filtrate formed?


  ultrafiltration in bowmans capsule

  high hydrostatic pressure forces out urea and small molecules NOT plasma proteins against gradient

  basement membrane acts as a filter along with podocytes
• how is bowmans capsule adapted to ultrafiltration?


  fenestrations between epithelial cells
• what is selective reabsorption? 


  useful molecules reabsorb from glomerular filtrate in the proximal convoluted tubule
• outline the transport processes in selective reabsorption?


  cotransport of sodium ions , active transport , diffusion
• how are cells in the proximal convoluted tubule adapted for reabsorption ?


  Microvilli for more surface area , more protein channel and carrier proteins , many mitochondria for atp