Lecture 2

• What is homeostasis?

  Dynamic maintenance of physiological variables
• Why is homeostasis important?

  It keeps body conditions stable
• What are some essential physiological variables for survival?

  Glucose metabolism, blood flow, lung ventilation
• What is the difference between negative and positive feedback mechanisms?

  Negative feedback normalizes variables; positive feedback amplifies changes
• What can result from kidney damage?

  Loss of consciousness and brain damage
• How does blood glucose fluctuate after meals?

  It increases and then decreases
• What is the role of the kidneys in homeostasis?

  Regulate water balance and osmolarity
• What happens to plasma osmolarity with excessive salt intake?

  It increases, affecting blood volume
• What are the components needed to regulate a variable in homeostasis?

  • Receptor
  • Control centre
  • Effector
• What is negative feedback?

  Response that normalizes a variable to set-point
• What is positive feedback?

  Response that increases a variable, leading to instability
• How does the autonomic nervous system (ANS) regulate homeostasis?

  It regulates involuntary physiological processes
• Where are most neuronal control centres located?

  In the brain, specifically the hypothalamus
• What are the two divisions of the autonomic nervous system?

  Sympathetic and parasympathetic nervous systems
• What is the role of hormones in the endocrine system?

  Regulate distant organs through blood
• What is paracrine signaling?

  Local cellular signaling using paracrine factors
• What is permissiveness in hormone interactions?

  One hormone needs another to exert full effect
• What is synergism in hormone interactions?

  Multiple hormones produce the same effect
• What is antagonism in hormone interactions?

  One hormone represses the action of another
• What is the main treatment for hypothyroidism?

  Hormone replacement therapy (HRT)
• What are the bioengineering strategies for type I diabetes treatment?

  • Pancreatic transplants
  • Glucose-responsive insulin delivery systems
  • Immunoisolation of transplanted islets
• How is oxygen saturation in the blood measured?

  Using a pulse oximeter
• What should SpO2 levels be above?

  95%
• What are the steps in the scaffold-based tissue engineering approach for thyroid dysfunction?

  1. Obtain a donor thyroid gland
  2. Remove donor cells, leaving 3D structure
  3. Add stem cells and growth factors
  4. Implant into patient
• What is the role of the efferent pathway in homeostasis?

  It carries signals from control centre to effectors
• What is the role of receptors in homeostasis?

  They detect deviations in physiological variables
• What is the function of the control centre in homeostasis?

  Analyzes input and decides response
• What physiological processes does the endocrine system influence?

  Reproduction, development, metabolism, immune response
• What happens when blood glucose levels rise after a meal?

  Insulin is secreted to lower glucose
• What is the role of ligands in paracrine signaling?

  They diffuse into ECM and interact with receptors
• What is the significance of morphogens during embryonic development?

  They regulate growth and development
• What can result from failure to feedback in paracrine signaling?

  It can lead to disease
• What is the primary function of the sympathetic nervous system?

  Mobilizes the body during activity
• What is the primary function of the parasympathetic nervous system?

  Keeps energy expenditure low
• How do the sympathetic and parasympathetic systems interact?

  They have opposing effects on functions
• What is the role of the hypothalamus in homeostasis?

  Regulates temperature, osmolarity, and blood pressure
• What is the role of the pons in homeostasis?

  Regulates ventilation and other autonomic functions
• What is the role of the medulla in homeostasis?

  Regulates vital autonomic functions
• How does the endocrine system communicate with target tissues?

  Through hormone secretion into the blood
• What is the effect of cortisol on epinephrine?

  Cortisol increases the activity of epinephrine