Lecture Notes: Control and Coordination (Chapter 15)

Introduction

• Topic: Control and coordination
• Focus: Understanding how different parts of the body work together to respond to various stimuli
• Importance: This is considered a tough chapter, so we'll take our time to understand it

Coordination

• Definition: Different parts of the body working together
• Examples:
  • Seeing a piece of cake:
    • Eyes detect the cake
    • Stomach growls in response
  • Facing a wolf:
    • Eyes and ears detect the wolf
    • Heart rate increases

Systems Involved in Coordination

Endocrine System

• Function: Transmit signals via hormones
• Key Components:
  • Endocrine glands: Release hormones
  • Target organs: Respond to hormones
• Examples from Chapter 14:
  • Pancreas (endocrine gland) releasing insulin and glucagon to the liver (target organ)
  • Posterior pituitary gland releasing ADH to the collecting duct
• Hormones:
  • Chemical signals that travel through the blood
  • Bind to cell surface membrane receptors on target organs
• Process:
  • Stimulus detected by receptors
  • Endocrine glands release hormones
  • Hormones travel via blood to target organs
  • Target organs respond accordingly
• Example: Seeing a dog
  • Adrenal gland releases adrenaline
  • Adrenaline travels in blood to cardiac cells
  • Heart rate increases

Nervous System

• Function: Transmit signals via neurons (nerve cells)
• Key Components:
  • Receptors: Detect stimulus
  • Neurons: Transmit electrical impulses (nerve impulses/action potentials)
  • Effectors: Respond to impulses
• Types of Neurons:
  • Sensory neurons
  • Interneurons
  • Motor neurons
• Process:
  • Stimulus detected by receptors
  • Electrical impulses sent along neurons
  • Effectors respond accordingly
• Comparison with Endocrine System:
  • Both systems send signals from one part of the body to another
  • Endocrine system uses chemical signals (hormones), slower, less ATP required
  • Nervous system uses electrical impulses, faster, more ATP required

Why Two Systems?

• Speed:
  • Nervous system: Faster (milliseconds)
  • Endocrine system: Slower (minutes)
• Energy Efficiency:
  • Nervous system: High ATP requirement
  • Endocrine system: Low ATP requirement
• Situational Use:
  • Endocrine system: Long-term processes (e.g., growth, puberty)
  • Nervous system: Immediate responses (e.g., catching a ball)

Conclusion

• Understanding the differences and roles of the endocrine and nervous systems is crucial for grasping how the body coordinates and controls its responses to stimuli.