Nervous and Endocrine Systems

Jul 17, 2024

Lecture: Nervous and Endocrine Systems

Introduction

  • Scenario: Sudden noise at night -> body’s response
  • Brain releases chemicals causing reactions (fight or flight)
  • Highlight: Psychological experiences are biological

The Neuron

  • Basic Parts:
    • Soma (Cell body): Life support (nucleus, DNA, mitochondria)
    • Dendrites: Receive messages from other cells
    • Axon: Transmits electrical impulses; sometimes covered with myelin sheath
      • Myelin sheath: Speeds up signal transmission; degradation causes diseases like multiple sclerosis

Neuron Function

  • Signals triggered by sensory input or neighboring neurons
  • Action Potential: Electrical charge traveling down the axon
  • Synapses: Contact points between neurons
    • Synaptic gap: Tiny space between neurons
  • Neurotransmitters: Chemical messengers that cross the synaptic gap
    • Reabsorbed by the releasing neuron (reuptake)

Types of Neurotransmitters

  • Over 100 kinds; can be excitatory or inhibitory
  • Excitatory: Increase likelihood of neuron firing
    • Example: Norepinephrine (alertness, arousal), Glutamate (memory)
  • Inhibitory: Decrease likelihood of neuron firing
    • Example: GABA, Serotonin (mood, hunger, sleep)
  • Dual-function: Can be excitatory or inhibitory
    • Examples: Acetylcholine (muscle action, memory), Dopamine (learning, movement, pleasure)

The Endocrine System

  • Hormones: Chemical messengers in the bloodstream
    • Affect mood, arousal, metabolism, immune system, growth, and reproduction
    • Operate slower than nervous system signals

Important Endocrine Glands

  • Adrenal Glands: Secrete adrenaline (fight or flight)
  • Pancreas: Secretes insulin and glucagon (regulate sugar absorption)
  • Thyroid and Parathyroid: Regulate metabolism and calcium levels
  • Sex Hormones: Estrogen and testosterone (produced by ovaries/testes)
  • Pituitary Gland: Master gland; releases growth hormone and oxytocin
    • Controlled by the hypothalamus

Feedback Loop

  • Interaction between nervous and endocrine systems
  • Example of response to a scare (feedback loop): Brain -> Hormone release -> Body response -> Brain calming down

Conclusion

  • Nervous and endocrine systems collaboratively control body responses
  • Upcoming topic: Deep dive into the brain’s components and functions