Lecture on Nervous System and Pain - Crash Course Anatomy & Physiology
Jul 7, 2024
Lecture on Nervous System and Pain - Crash Course Anatomy & Physiology đź§
Introduction
Brain's Role: The brain is often seen as the central component of the nervous system, but it needs a support system to stay connected to the external world.
Importance of Sensory Input: Without constant external input, the brain can start to hallucinate and confuse internal thoughts with external reality.
Peripheral Nervous System
Function: Connects brain to physical world, enabling responses to stimuli.
Structure: Network that spans across the body, feeding information to the central nervous system (CNS) about temperature, touch, pain, etc.
Types of Receptors:
Thermoreceptors: Respond to temperature changes.
Photoreceptors: React to light.
Chemoreceptors: Detect chemicals.
Mechanoreceptors: Respond to pressure, touch, vibration.
Nociceptors: Special receptors for pain.
Importance of Pain
Function: Pain indicates stress, damage, or danger, prompting protective behavior.
Case Study: Ashlyn Blocker - a person with a genetic mutation causing insensitivity to pain, leading to dangerous situations unnoticed due to lack of pain.
Example Scenario: Stepping on a Tack
Process Breakdown:
Stimulus: Tack pierces the skin.
Reception: Mechano- and nociceptors detect stimulus.
Response: Immediate reflex in spinal cord to lift foot.
Perception: Brain interprets pain, leading to further action (e.g., removing tack).
Reflex Arc: Involves sensory reception, transmission to CNS, motor response to effector (muscles).
Types of Reflexes:
Intrinsic Reflexes: Inborn, immediate response (e.g., lifting foot from tack).
Learned Reflexes: Acquired from experience (e.g., dodging obstacles).
Neuronal Response
Action Potentials: Tac activates receptors, leading to sodium ion influx and action potentials that travel along neurons.
Signal Transmission: Signal moves through synapses via neurotransmitters.
Pathways: Sensory division collects data, central nervous system processes, motor division responds.
Brain Involvement
Integration in Spinal Cord: Initial reflex handled here to facilitate rapid response.
Higher Processing: Brain analyzes and gives meaning to the pain signal.
Somatosensory Cortex: Identifies and localizes pain.
Limbic System: Registers emotional response.
Frontal Cortex: Understands reason behind the pain.
Conclusion
Peripheral Nervous System: Critical for connecting the brain to the physical environment.
Reflex Arcs: Fundamental for rapid, protective responses without conscious thought.
Different Reflexes: Can be both innate and learned.