hormonal control

• whats the difference between endocrine and exocrine glands

  endocrine gland is a group or cells specialised to secrete hormones directly into the bloodstream. whereas ; exocrine glands secrete enzymes through ducts into organs
• describe a mechanism by which a steroid hormone may work (3)

  • non polar so can pass through plasma membrane
  • binds to receptor in nucleus or cytoplasm
  • forms hormone-receptor complex which acts as a transcription factor
  • turns gene on/off
• describe the mechanism by which adrenaline works

  • binds to complementary receptor on plasma membrane
  • activates adenyl cyclase
  • catalyses formation of cAMP
  • which triggers protein kinases to phosphorylate other enzymes
  • which perform gluconeogenesis
• state and explain which hormones are produced by the adrenal cortex

  • aldosterone regulates salt concentration of blood
  • cortisol regulates the metabolism and blood pressure
  • androgens are male and female sex hormones
• state and explain hormones released from the adrenal medulla

  • noradrenaline : increases heart rate , widens pupils , vasoconstriction of blood towards the muscles , vasodilatation of airway passages
  • adrenaline : increases glycogenolysis
• describe the events that occur in a beta cell in the islets of langerhans when insulin is required (5)

  • glucose enters via glucose transporter
  • is converted into ATP by mitochondria
  • ATP sensitive K channels close causing depolarisation
  • voltage gated Ca2+ channels open
  • Ca2+ cause secretory vesicles containing insulin to be released by exocytosis
• whats the difference between diabetes 1 and diabetes 2

  • in type 1 beta cells do not produce insulin
  • in type 2 cells do not produce enough insulin or body cells do not respond properly
• diabetes 1 past , present and furture cures

  • pig insulin : religious concerns , expensive , caused allergic reactions
  • microorganisms : pure so less likely to cause allergies , cheaper and produced in larger quantities
  • organ donors : immunosuppressants can leave someone susceptible to infection , in high demand
  • stem cells : can be made by SCNT , reduced chance of rejection , may mutate , risk of tumour growth
• describe the fight or flight responses coordination

  • sympathetic NS send impulse to adrenal medulla to release adrenaline and noradrenaline
  • hypothalamus stimulated pituitary to release ACTH which activates adrenal cortex
• how is the HR controlled

  • in the cardiovascular centre in the medulla oblongata
  • motor neurones link the medulla to the SAN
• how is negative feedback used to control blood glucose concentration (6)

  • when too high : chemoreceptors in hypothalamus detect low blood glucose , Beta cells release insulin which stimulate glycogenesis , increase in respiration , glucose taken up by effector cells
  • when too low : chemoreceptors detect this and release glucagon from alpha cells in pancreas which stimulates gluconeogenesis , glycogenolysis and decrease in respiration
• where are chemoreceptors and baroreceptors located

  • carotid artery
  • carotid sinus
  • aorta
• how is the SAN involved in regulating heart rate

  • controls the frequency of waves of excitation