National Park Biology Unit 2: Nervous System

Overview

• Topic: Control and Communication in Biology
• Focus on the Nervous System
• Nervous System divided into:
  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)

Central Nervous System (CNS)

• Composed of the Brain and Spinal Cord
• Key components of the brain:
  • Medulla:
    • Located at the bottom of the brain/top of the spinal cord
    • Controls breathing and heart rate
    • Manages unconscious responses
  • Cerebellum:
    • Located at the back, side of the brain
    • Responsible for balance and muscular coordination
  • Cerebrum:
    • Wrinkled area at the top of the brain
    • Responsible for conscious thought, memory, reasoning, intelligence

Types of Neurons

• Sensory Neurons:
  • Relay electrical impulses from sense organs (e.g., skin, eyes)
• Interneurons:
  • Located in CNS (brain and spinal cord)
  • Connects sensory and motor neurons
• Motor Neurons:
  • Carry nerve impulses from CNS to effectors (muscles or glands)

Neural Pathway (SIM Order)

• Sensory Neuron → Interneuron → Motor Neuron
• Sense organs detect stimuli (light, sound, chemicals, touch)
• Stimuli trigger electrical signals sent via neurons

Reflex Actions

• Protect the body from harm (e.g., flinching, coughing, blinking)
• Rapid and automatic responses
• Reflex arc:
  • Bypasses the brain for speed
  • Travels through spinal cord
  • Follows sensory → interneuron → motor neuron pathway

Synapses

• Gaps between neurons
• Neurotransmitters:
  • Chemicals that transfer messages across synapses
  • Allow electrical impulses to pass from one neuron to another

Conclusion

• Nervous system overview completed
• Next topic will cover hormones in the continuation of the unit