cell signalling

• cell signalling


  how cells communicate with each other using signal molecules (hormones, neurotransmitters). can be extracellular or intracellular
• cells can be stimulated by

  -chemicals- hormones, neurotransmitters

  -pressure

  -light

  -temperature

  -oxygen levels
• cells need to have many different types of complementary receptors on their surface because it means many different hormones can act on the same cell
• steroid hormones- hydrophobic/ non-polar


  -stress hormones

  -can pass through the bilayer

  -simple diffusion

  -receptors found on the inside of the cell
• proteins hormones- hydrophilic/ polar


  -can't pass through bilayer

  -too large and repelled by fatty acid tails

  -receptors are found on the outside of the cell
• drugs


  -block receptors- inhibit cell activity

  -unlock cell receptors- stimulate cell activity and trigger a response
• viruses


  -binds to receptors on plasma membrane on host cells
• morphine

  -used to relieve pain

  -body naturally releases endorphins to relieve pain symptoms

  -endorphins bind to opioid receptors in the brain to block pain signals

  -morphine binds to the same receptor- triggering a reduction in pain
• beta blockers

  -treat irregular heart beat, hypertension and heart failure

  -beta receptors in the heart muscle usually receive impulses that increase heart rate

  -beta blockers block beta receptors to reduce heart rate and blood pressure
• antihistamines

  -histamines released by cell damage causing inflammation in neighbouring cells by binding to receptors

  -antihistamines block histamine receptors to reduce inflammation and pain, redness and swelling
• botox

  -toxin from a bacteria

  -binds to receptors on plasma membranes of muscle cells

  -blocks binding of neurotransmitters which leads to the paralysis of the muscle

  -permanent relaxation prevents formation of wrinkles

  -lethal in large quantities
• thorazine

  -drug used to treat schizophrenia

  -disturbances in area of brain related to thought, perception, attention, motor behaviour and emotion

  -dopamine is a neurotransmitter

  -imbalances in dopamine levels are thought to lead to schizophrenia

  -thorazine blocks dopamine receptors
• insulins affects on liver cells

  -activates enzymes that change glucose molecules so that they can't leave the cell

  -activates hormones that convert glucose to glycogen

  -increases permeability of liver cells to glucose
• muscle cells and insulin


  -the binding of the insulin to the receptors on the plasma membrane increases the number of glucose channels for increased uptake