🐅Animal Physiology Unit 1 – Animal Physiology: Intro to Homeostasis

Key Concepts

• Homeostasis maintains stable internal conditions necessary for proper functioning of cells, tissues, and organs
• Set points are the optimal levels for various physiological parameters (body temperature, blood glucose, pH)
• Negative feedback loops work to restore deviations from the set point back to the normal range
• Positive feedback loops amplify changes in a system until a new state is reached (blood clotting, childbirth)
• Sensors detect changes in the internal environment and send signals to the control center
• Effectors receive signals from the control center and produce a response to correct deviations
• Physiological parameters are kept within a narrow range to ensure optimal functioning of the body

Homeostatic Mechanisms

• Thermoregulation maintains body temperature within a narrow range
  • Hypothalamus acts as the control center to regulate heat production and loss
  • Effectors include sweat glands, blood vessels, and skeletal muscles
• Osmoregulation maintains proper water and electrolyte balance
  • Hypothalamus detects changes in blood osmolarity and stimulates thirst and antidiuretic hormone (ADH) release
  • Kidneys adjust water reabsorption in response to ADH levels
• Blood glucose regulation keeps blood sugar levels within a normal range
  • Pancreas secretes insulin and glucagon to lower or raise blood glucose, respectively
  • Liver stores excess glucose as glycogen and releases glucose when needed
• Acid-base balance maintains blood pH within a narrow range (7.35-7.45)
  • Respiratory system adjusts ventilation rate to regulate carbon dioxide levels
  • Kidneys excrete or reabsorb hydrogen ions and bicarbonate to maintain pH balance

Feedback Systems

• Negative feedback is the most common type of feedback in biological systems
  • Deviations from the set point trigger responses that oppose the change and restore homeostasis
  • Examples include thermoregulation, blood glucose regulation, and blood pressure control
• Positive feedback amplifies changes in a system until a new state is reached
  • Typically limited to a few physiological processes (blood clotting, childbirth, action potentials)
  • Blood clotting cascade amplifies the initial response to form a stable clot and prevent blood loss
• Feedforward control anticipates changes and initiates corrective actions before deviations occur
  • Allows for faster responses to environmental challenges (increased heart rate before exercise)
  • Often works in conjunction with feedback systems to maintain homeostasis

Regulatory Systems

• Nervous system provides rapid, short-term regulation of physiological processes
  • Sensory receptors detect changes and send signals to the central nervous system
  • Motor neurons innervate effectors and produce rapid responses (muscle contraction, gland secretion)
• Endocrine system provides slower, long-lasting regulation through hormones
  • Hormones are released into the bloodstream and act on target cells with specific receptors
  • Responses are typically slower but more sustained compared to nervous system regulation
• Immune system defends against pathogens and maintains internal homeostasis
  • Innate immunity provides non-specific, rapid responses to foreign invaders
  • Adaptive immunity develops specific responses to pathogens and provides long-term protection

Physiological Examples

• Cardiovascular system maintains blood pressure and tissue perfusion
  • Baroreceptors detect changes in blood pressure and send signals to the medulla oblongata
  • Autonomic nervous system adjusts heart rate, contractility, and blood vessel diameter to maintain blood pressure
• Respiratory system regulates gas exchange and blood pH
  • Chemoreceptors detect changes in blood oxygen, carbon dioxide, and pH levels
  • Medulla oblongata adjusts ventilation rate and depth to maintain proper gas exchange and pH balance
• Renal system regulates water, electrolyte, and acid-base balance
  • Nephrons filter blood and adjust reabsorption of water, ions, and nutrients based on body needs
  • Renin-angiotensin-aldosterone system (RAAS) regulates blood pressure and fluid balance
• Digestive system maintains nutrient and energy homeostasis
  • Hormones (ghrelin, leptin) regulate hunger and satiety to maintain energy balance
  • Pancreatic enzymes and bile aid in digestion and absorption of nutrients

Lab Work and Experiments

• In vitro experiments study homeostatic mechanisms in isolated cells, tissues, or organs
  • Patch-clamp technique measures ion channel activity in individual cells
  • Organ bath experiments assess the effects of hormones or drugs on tissue function
• In vivo experiments investigate homeostatic processes in living organisms
  • Telemetry devices monitor physiological parameters (heart rate, blood pressure) in freely moving animals
  • Transgenic animal models allow for the study of specific genes in homeostatic regulation
• Computer simulations and mathematical models help predict and analyze complex homeostatic systems
  • Hodgkin-Huxley model describes the generation and propagation of action potentials
  • Feedback control models simulate the behavior of physiological systems under various conditions

Real-World Applications

• Understanding homeostatic mechanisms informs the development of targeted therapies for diseases
  • Insulin therapy for diabetes mellitus restores blood glucose homeostasis
  • Diuretics help manage hypertension by promoting sodium and water excretion
• Wearable technology and remote monitoring devices track physiological parameters in real-time
  • Continuous glucose monitors help individuals with diabetes manage their blood sugar levels
  • Smartwatches measure heart rate, sleep patterns, and physical activity to promote health and wellness
• Environmental challenges and stressors can disrupt homeostasis and impact health
  • Heat stress and dehydration can lead to heat exhaustion or heat stroke
  • High-altitude exposure can cause hypoxia and altitude sickness due to low oxygen levels
• Homeostatic principles are applied in engineering and control systems
  • Thermostats maintain a stable temperature in buildings using feedback control
  • Autopilot systems in aircraft maintain steady flight by adjusting to changes in wind and turbulence

Review and Practice

• Summarize the key components of homeostatic systems (set point, sensors, control center, effectors)
• Compare and contrast negative and positive feedback loops, providing examples of each
• Explain how the nervous, endocrine, and immune systems contribute to homeostatic regulation
• Describe the homeostatic mechanisms involved in thermoregulation, osmoregulation, and blood glucose control
• Analyze the role of feedback systems in maintaining cardiovascular, respiratory, renal, and digestive homeostasis
• Discuss the importance of homeostatic principles in the development of targeted therapies and health monitoring devices
• Apply your understanding of homeostasis to explain how the body responds to environmental challenges (heat stress, high altitude)
• Create a concept map or flowchart illustrating the components and processes involved in a specific homeostatic mechanism (e.g., blood pressure regulation)