Nervous System Lecture Notes

Introduction

• Focus on organ systems enabling life, starting with the Nervous System.
• Nervous System allows behaviors and sentience.

Components of the Nervous System

• Central Nervous System (CNS): Brain and spinal cord, analyzes and interprets data.
• Peripheral Nervous System (PNS): Nerves outside the CNS, sends information to and from CNS.

Neurons

• Specialized cells in the nervous system.
• Structure: Dendrites (receive info), Axon (transmits signals), Myelin (insulation).
• Neurons form nerves, transmitting electrochemical signals.

Types of Neurons

• Afferent Neurons: Carry information to CNS.
  • Called sensory neurons in PNS; activated by external stimuli.
• Efferent Neurons: Carry information from CNS.
  • Called motor neurons in PNS; carry signals to muscles and organs.

Nervous System Divisions

• Somatic Nervous System: Controls voluntary actions.
• Autonomic Nervous System: Manages involuntary functions like heartbeat, digestion.
  • Sympathetic Division: Fight-or-flight response.
  • Parasympathetic Division: Rest and digest functions.

Reflex Loop

• Spinal cord can make decisions without brain involvement.
• Example: Reflex action when touching a hot stove.

Neuron Functionality

• Membrane Potential: Voltage difference across neuron membrane.
• Action Potential: Stimulus-induced rapid rise and fall of electrical potential.
  • Triggered by ion channel activity, leading to signal propagation.
  • Saltatory conduction: Signal jumps between Nodes of Ranvier, speeding transmission.

Synapse

• Connection between axon of one neuron and dendrite of another.
• Neurotransmitters pass signals across synapse.

Neuron Signal Transmission

• Involves sodium-potassium pump and ion channels.
• Resting potential maintained at -70 millivolts.
• Action potential involves influx of sodium ions, followed by potassium efflux.

Example: Eating Pizza

• Taste receptor neurons activated by pizza.
• Action potentials travel to the brain.
• Brain processes taste and sends commands to chew, swallow, etc.

Conclusion

• Review the functions of the nervous system in the processing and response to stimuli.
• Expect further episodes on digestion.

For questions or further review, refer to the table of contents or reach out via social media platforms.