Coordinated Response (chapter 5 of hormonal communication)

Question 1

Fight or Flight response

Answer 1

• When a potentially dangerous situations is sensed, the body automatically triggers a series of physical responses
• The threat is detected by the autonomic nervous system, then the hypothalamus communicates with the sympathetic nervous system and the adrenal-cortical system
• Sympathetic NS = uses neuronal pathways to initiate body reactions - impulses sent out to glands and smooth muscle, and tells the adrenal medulla to release adrenaline and noradrenaline into the bloodstream - leads to e.g. an increased heart rate. Overall, this is controlled by the hormones released by the pituitary gland in the brain - hypothalamus stimulates the pituitary gland to release ACTH, which travels in the bloodstream to the adrenal cortex. This leads to the activation of many hormones to prepare the body
• Adrenal-cortical system = uses hormones in the bloodstream

Question 2

Fight or Flight physical responses and purposes

Answer 2

• Heart rate increases - pump more oxygenated blood around the body
• Pupils dilate - take in as much light as possible for better vision
• Arterioles in skin constrict - more blood to major muscle groups, brain, heart and muscles of ventilation
• Blood glucose levels increase - increases respiration to provide energy for muscle contraction
• Smooth muscle of airways relaxes - allows more oxygen into lungs
• Non-essential systems shut down (i.e. digestion) - focuses resources on emergency functions
• Difficulty focusing on small tasks - brain solely focused on where the threat is coming from

Question 3

Action of adrenaline

Answer 3

1. The hormone adrenaline approaches a receptor site (this is because its hydrophilic therefore cannot pass through cell surface membranes)
2. Adrenaline fuses to receptor site, and in doing so activates an enzyme inside the membrane
3. The activated enzyme (adenylyl cyclase) converts ATP to cAMP (on the inner surface of the cell membrane in the cytoplasm), which acts as a second messenger that activates other enzymes (protein kinases - these phosphorylate, meaning they activate more enzymes) that, in turn, covert glycogen to glucose