homeostasis

• What is homeostasis?

  Control of internal environment within restricted limits
• How does negative feedback contribute to homeostasis?

  It counteracts change to maintain a stable state
• What effect does positive feedback have on a system?

  It exaggerates change from the original condition
• What three components are essential for homeostatic control?

  • Receptors
  • Coordinators
  • Effectors
• What is the role of a coordinator in homeostasis?

  Transfers information between components
• What is the role of a receptor in homeostasis?

  Detects deviation from optimum conditions
• What is the role of an effector in homeostasis?

  Carries out a response to stimuli
• What factors influence blood glucose concentrations?

  Diet and exercise
• Where are the Islets of Langerhans located?

  Pancreas
• Which cells detect decreases in blood glucose and release glucagon?

  Alpha cells
• Which cells detect increases in blood glucose and release insulin?

  Beta cells
• How does insulin affect cells when it binds to its receptors?

  Increases cell permeability to glucose
• How do cells increase the number of channel proteins on their cell membrane in response to insulin?

  Via vesicles moving channel proteins to membrane
• How does insulin lower blood glucose concentration in the liver?

  Activates enzymes converting glucose to glycogen
• What is the process of converting glucose to glycogen called?

  Gluconeogenesis
• How does glucagon raise blood glucose concentration?

  Activates enzymes converting glycogen to glucose
• What is the name of the process that converts glycogen into glucose?

  Glycogenolysis
• What is the name of the process that converts glycerol and amino acids into glucose?

  Gluconeogenesis
• What effect does adrenaline have on blood glucose levels?

  Increases blood glucose levels
• What second messenger is involved in glycogenolysis when adrenaline or glucagon binds to liver cells?

  cAMP
• What enzyme does cAMP activate in the second messenger model?

  Protein kinase
• What is the role of adenylate cyclase in the second messenger model?

  Converts ATP into cAMP
• Which type of diabetes involves the immune system attacking beta cells?

  Type one
• What is a common treatment for type one diabetes?

  Insulin shots
• What are possible causes of type two diabetes?

  Pancreas not producing enough insulin
• What are the common treatments for type two diabetes?

  Limiting carbohydrate intake and exercising
• What are the two main functions of the kidneys?

  Filter blood and produce urine
• What is the role of the kidneys in osmoregulation?

  Controls water potential of blood
• What is the functional unit of the kidney?

  Nephron
• What is the glomerulus?

  Mass of capillaries in nephron
• Why does the efferent arteriole branch into capillaries surrounding the nephron structure?

  To ensure short diffusion distance
• What condition results from the body's inability to maintain blood glucose concentration?

  Diabetes
• What two processes are the nephrons responsible for?

  Blood filtration and urine production
• What is the driving force behind substances being forced out of the capillaries in the glomerulus?

  High hydrostatic pressure
• Why is there high hydrostatic pressure in the glomerulus?

  Efferent arteriole has smaller diameter
• What is the name for substances being forced out of capillaries due to high hydrostatic pressure?

  Ultrafiltration
• What three layers must substances pass through during ultrafiltration?

  Endothelium, basement membrane, podocytes
• What is the name given to the mixture of substances that enter Bowman's capsule?

  Glomerular filtrate
• What process occurs in the proximal convoluted tubule where useful substances are reabsorbed?

  Selective reabsorption
• In the proximal convoluted tubule, how are sodium ions transported into the blood?

  Actively transported from epithelial cell