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Hormonal Communication

OCR A-level BiologyTopic 3 of 1219 lessons

Revision notes for Hormonal Communication in OCR Biology A (H420). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Endocrine GlandsEndocrine glands are made of groups of cells specialised to secrete chemicals called hormones directly into the blood.
  2. HormonesHormones are chemical messengers that carry information from one part of the body to another.
  3. The Adrenal GlandsThe adrenal glands are situated on top of each kidney.
  4. Adrenal CortexGlucocorticoids These include cortisol which is released in response to stress and low blood sugar concentration.
  5. Adrenal MedullaThe adrenal medulla produces adrenaline and noradrenaline in response to stimulation by the sympathetic nervous system.
  6. PancreasThe pancreas, located in the upper abdomen behind the stomach, is both an endocrine and exocrine gland.
  7. Blood glucose concentrationThe blood glucose concentration increases after a carbohydrate-rich meal.
  8. InsulinInsulin is produced by the beta cells of the islets of Langerhans in the pancreas.
  9. GlucagonInsulin and glucagon are antagonistic hormones.
  10. Mechanism of Insulin SecretionWhen the blood glucose concentration is normal, ATP-sensitive potassium channels are open.
  11. Diabetes MellitusThere are two types of diabetes in which the body cannot control the blood glucose concentration.
  12. The Fight or Flight ResponseWhen a mammal detects a threat, such as a predator, its body prepares either to fight or to run away.
  13. Coordinating Nervous and Hormonal ResponsesMammals have two communication systems that work together to coordinate responses: the nervous system and the endocrine (hormonal) system.
  14. Adrenaline and the Second Messenger ModelAdrenaline is a hormone made from an amino acid.
  15. The Cardiovascular Centre in the MedullaHeart muscle is myogenic: the sinoatrial node (SAN) generates impulses without any nervous stimulation.
  16. Control of Heart RateHeart rate is controlled so that the supply of blood matches the tissues' need for oxygen and glucose and for removal of carbon dioxide.
  17. BaroreceptorsBaroreceptors are pressure receptors that detect changes in blood pressure.
  18. ChemoreceptorsChemoreceptors detect chemical changes in the blood, mainly changes in pH caused by carbon dioxide concentration.
  19. Hormonal Control of Heart RateHeart rate is also controlled by hormones, especially during the fight or flight response.

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