Sympathetic and Parasympathetic Nervous System

Sympathetic Nervous System

• Function: Prepares the body for "fight or flight" responses.
• Neurotransmitters:
  • Epinephrine (adrenaline)
  • Norepinephrine (noradrenaline): Increases alertness, arousal, and blood pressure.
• Receptors:
  • Alpha: Primarily cause vasoconstriction.
  • Beta: Increase heart rate and force of contraction (β1), cause bronchodilation (β2).
• Active State:
  • Increased heart rate and force of contraction
  • Bronchodilation
  • Pupil dilation
  • Increased blood flow to skeletal muscles
  • Decreased blood flow to digestive system
  • Increased blood glucose levels
  • Increased sweating
• Inactive State:
  • Normal resting heart rate
  • Normal bronchial tone
  • Normal pupil size
  • Balanced blood flow distribution
  • Normal digestive function
  • Stable blood glucose levels
  • Normal sweating

Parasympathetic Nervous System

• Function: Responsible for "rest and digest" functions.
• Neurotransmitter: Acetylcholine
• Receptors:
  • Muscarinic: Mediate parasympathetic effects (e.g., decreased heart rate, increased secretions).
  • Nicotinic: Involved in neuromuscular junction signaling and some CNS functions.
• Active State:
  • Decreased heart rate
  • Bronchioconstriction
  • Pupil constriction (miosis)
  • Increased digestive system activity
  • Increased salivation and urination
  • Decreased blood pressure
• Inactive State:
  • Normal resting heart rate
  • Normal bronchial tone
  • Normal pupil size
  • Balanced digestive function
  • Normal salivation and urination
  • Normal blood pressure

Other Receptors

• Opioid Receptors:
  • Location: Primarily in the brain and spinal cord.
  • Function: Modulate pain, reward, and addictive behaviors; influence autonomic functions.
• GABA Receptors:
  • Location: Ubiquitous in the brain and spinal cord.
  • Function: Inhibit neuronal activity, leading to calming effects, muscle relaxation, and reduced neuronal excitability.

Anticholinergic Substances

• Mechanism: Block acetylcholine, reducing parasympathetic nerve impulses.
• Effects: Drying of bodily fluids, smooth muscle relaxation, pupil dilation.
• Uses: Treat overactive bladder and Parkinson's disease.
• Note: Does not activate the sympathetic response; it reduces parasympathetic activity.

Sympathomimetic Substances

• Mechanism: Mimic the effects of the sympathetic nervous system.
• Effects: Increase heart rate, dilate airways, elevate blood pressure.
• Uses: Treat asthma, shock, and certain heart conditions.

This quiz covers the functions, neurotransmitters, and effects of the sympathetic and parasympathetic nervous systems. Understand how each system prepares the body for different states, such as 'fight or flight' vs. 'rest and digest'. Test your knowledge on the associated receptors and bodily responses.