Overview of the Nervous System and Neurons

Introduction

• Focus on Unit 2, Topic 3 of AP Psychology: Nervous System and Neuron.
• Nervous system: Body's primary information system for thoughts, voluntary and involuntary actions.
• Functions like a high-speed bullet train, sending signals rapidly throughout the body.

Structure of the Nervous System

Central Nervous System (CNS)

• Composed of the brain and spinal cord.
• Acts as the control center, giving orders to the body.

Peripheral Nervous System (PNS)

• Composed of nerves branching off from the brain and spine.
• Enables communication between CNS and the rest of the body.
• Divisions of PNS:
  • Sensory Division (Afferent Division): Conducts impulses from sensory stimuli to the CNS, informing the brain about internal and external environments.
    • Uses sensory receptors (e.g., eyes, ears, nose, tongue, skin).
  • Motor Division (Efferent Division): Sends signals from the CNS to muscles and glands, creating movement responses.
    • E.g., Moving hand off a hot burner.

Types of Nervous Systems

Somatic Nervous System

• Controls voluntary movements (e.g., biking, playing video games).

Autonomic Nervous System

• Controls involuntary activities (e.g., breathing, heart rate).
• Divisions of Autonomic Nervous System:
  • Sympathetic Division: Mobilizes body for action; fight or flight response.
  • Parasympathetic Division: Relaxes body; rest and digest state.

Neurons and Glial Cells

Neurons

• Basic functional units of the nervous system.
• Communicate via electrical impulses and chemical signals.
• Structure of a Neuron:
  • Soma (Cell Body): Houses nucleus and genetic material.
  • Dendrites: Receive chemical information from other neurons.
  • Axon: Transmits information away from the soma.
  • Axon Terminal: Where neurotransmitters are released into the synapse.
• Action Potential: Electrical impulse sent down the axon.

Glial Cells

• Most abundant cells in the nervous system.
• Support neurons through protection and nutrient supply.
• Schwann Cells: Produce myelin sheath covering axons, increasing speed and protecting axons.
• Nodes of Ranvier: Gaps in the myelin sheath aiding action potential.

Synapse and Neurotransmission

• Synapse: Meeting point between two neurons.
• Neurotransmitters: Released into the synaptic gap to relay information to the next neuron.

Conclusion

• Nervous system crucial for body function and communication.
• Upcoming content: Neurotransmitters and types of neurons.
• Encouragement to engage with additional resources and practice questions.