Biology Class: Reflex Arc

Introduction

• Instructor: Miss Angler
• Focus of lesson: Understanding the reflex arc and its significance
• Importance: Quick response to stimuli for safety
• Note: Familiarity with nervous system structures is recommended

Reflex Arc Overview

• Reflex arc: Pathway of an impulse through the spinal cord
• Significance: Allows for quick response without brain intervention

Components of a Reflex Arc

1. Stimulus Detection

   • Experienced through skin, eyes, or ears
   • Example: Skin receptors detect heat from a hot stove

2. Sensory Neuron

   • Role: Transmits sensory information
   • Characteristics: Cell body off to the side; enters spinal cord via dorsal root

3. Interneuron (Connector Neuron)

   • Location: Gray matter of the spinal cord
   • Function: Makes the decision to respond
   • Example decision: Move hand away from the hot stove

4. Motor Neuron

   • Function: Carries decision from spinal cord to effector
   • Path: Exits via spinal root towards destination

5. Effector

   • Definition: Structure that carries out the response
   • Examples: Muscles (cause movement), glands

Reflex Actions

• Quick and protective responses like coughing, yawning, blinking
• Bypass the brain to enable fast reaction
• Examples of protective functions:
  • Coughing clears airway obstructions
  • Yawning increases oxygen intake
  • Blinking protects eyes from sudden threats

Exam Preparation

• Description: Be able to describe the reflex arc process
• Significance: Understand why reflex arcs are crucial for safety
• Drawing: Be prepared to draw and label a reflex arc

Terminology Recap

• Reflex Arc: Pathway of electrical impulse from receptor to effector
• Receptors: Specialized cells detecting external stimuli (pain, pressure, temperature)
• Sensory Neuron: Carries sensation to spinal cord
• Interneuron (Connector Neuron): Decision-making neuron in spinal cord
• Motor Neuron: Sends response to effector
• Effector: Muscle or gland that responds
• Reflex Actions: Quick actions like blinking, sneezing, coughing

Conclusion

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