feedback loops

• What are the two systems that regulate animal physiology?

  The endocrine and nervous systems
• What are hormones in animals?

  Chemical signals secreted into the circulatory system
• How do hormones communicate within the body?

  They reach all parts of the body but only target cells respond

  
• What do endocrine signals do?

  They are secreted into extracellular fluids and travel via the bloodstream

  
• What roles do hormones play in the body?

  They mediate responses to environmental stimuli and regulate growth, development, and reproduction

  
• Which glands are involved in hormone production in animals?

  • Thyroid gland
  • Pineal gland
  • Hypothalamus
  • Parathyroid glands
  • Pituitary gland
  • Adrenal glands
  • Ovaries (females)
  • Testes (males)
  • Pancreas

  
• What hormone is produced by the adrenal medulla?

  Epinephrine
• What is the effect of epinephrine on the body?

  It mediates the body's response to short-term stress
• How does epinephrine affect liver cells?

  It binds to receptors, triggering the release of glucose into the bloodstream
• What is the role of cAMP in the signaling pathway of epinephrine?

  It acts as a second messenger to activate enzymes

  
• What are the steps in the signaling pathway triggered by epinephrine?

  1. Epinephrine binds to G protein-coupled receptor
  2. Activation of G protein
  3. Activation of adenylyl cyclase
  4. Conversion of ATP to cAMP
  5. Activation of protein kinase A
  6. Breakdown of glycogen to glucose

  
• How can the same hormone have different effects on different target cells?

  Due to different receptors, signal transduction pathways, and proteins in target cells
• What is a negative feedback loop in hormonal signaling?

  A mechanism that prevents excessive pathway activity to achieve homeostasis

  
• What is an example of a positive feedback loop?

  Contractions during labor

  
• What is the role of insulin and glucagon in blood glucose regulation?

  • Insulin: Reduces blood glucose levels
  • Glucagon: Increases blood glucose levels

  
• What type of cells in the pancreas produce glucagon?

  Alpha cells
• What type of cells in the pancreas produce insulin?

  Beta cells
• What happens to blood glucose levels after eating?

  Blood glucose levels rise, prompting insulin release

  
• What happens to blood glucose levels when fasting?

  Blood glucose levels fall, prompting glucagon release

  
• Why is maintaining glucose homeostasis important?

  Because glucose is a major fuel for cell respiration

  
• What is hyperglycemia?

  Frequent or ongoing high blood sugar
• What is diabetes mellitus?

  An endocrine disorder caused by insulin deficiency or decreased response to insulin
• What is Type I diabetes mellitus?

  An autoimmune disorder where the immune system destroys pancreatic beta cells
• What is Type II diabetes mellitus?

  A condition involving insulin deficiency or reduced response of target cells
• What are examples of positive feedback mechanisms in biology?

  • Lactation in mammals
  • Onset of labor in childbirth
  • Ripening of fruit
  • Blood clotting

  
• How does oxytocin function in milk release during nursing?

  It stimulates further release of milk in response to suckling

  
• What is the role of antidiuretic hormone (ADH)?

  It enhances water reabsorption in the kidneys

  
• What are the two antagonistic hormones that regulate blood calcium levels?

  Parathyroid hormone (PTH) and calcitonin

  
• What happens when blood calcium levels fall?

  PTH is released to increase blood calcium levels

  
• What is the ideal blood calcium level in mammals?

  10 mg/100 mL
• What are the effects of too much calcium in the blood?

  It can weaken bones and create kidney stones
• What are the effects of too little calcium in the blood?

  It can cause skeletal muscles to contract convulsively
• What are the functions of parathyroid hormone (PTH)?

  • Increases blood Ca2+ levels
  • Releases Ca2+ from bone
  • Stimulates reabsorption of Ca2+ in kidneys
  • Activates vitamin D for intestinal uptake of Ca2+

  
• What are the functions of calcitonin?

  • Decreases blood Ca2+ levels
  • Stimulates Ca2+ deposition in bones
  • Promotes secretion by kidneys