The Nervous System and Drug Therapy

 Anatomy and Physiology of the Nervous System

Nervous system senses and interprets our surroundings and controls vital body functions.

Central nervous system (CNS) includes the brain and spinal cord; processes information received from the body.

Peripheral nervous system is nerves outside of the brain and spinal cord; brings signals to the CNS for interpretation.

Somatic nervous system controls intentional, voluntary movement.

Autonomic nervous system controls involuntary and automatic body functions.

  - Sympathetic nervous system uses adrenergic and some cholinergic receptors

  - Parasympathetic nervous system uses cholinergic receptors only.

• The brain is divided into sections:
• • Cerebrum – performs higher cognitive functions; thinking and memory
      - Cerebral cortex
  • Cerebellum – coordinate movement and balance
  • Pons, medulla, brain stem – regulate automatic and reflex functions
  • Thalamus, hypothalamus – middle of the brain; controls various functions, including hormone regulation and body temperature
  • Pituitary gland – helps regulate hormones and controls the growth cycle throughout life
• Cell structure along the border of the CNS is different from anywhere else in the body; oxygen, carbon dioxide, small molecules (glucose), and small lipid-soluble drugs pass easily from blood to CNS tissue. Large water-soluble molecules, drugs and most pathogens, do not easily enter the brain or spinal cord.
  
  

  Blood-brain barrier (BBB) protects the delicate tissue of the CNS from potentially harmful chemicals.

  Neurotransmitters are chemicals that carry signals from one nerve cell to the next. Chemicals are released from the end of one nerve and cross the synaptic cleft between nerve cells, and connect to receptors on the adjoining cell, passing the signal along.

  The core of many nervous system conditions is attributed to altered production, release, or metabolic breakdown of neurotransmitters. Most drugs for conditions like depression or psychiatric problems supplement, mimic, or block the actions of specific neurotransmitters.