Pharmacology: Part I

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Pharmacology Part I

• the physiology of drug action

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How the body communicates...

• Nervous system
• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)
• Somatic Nervous System
• Autonomic Nervous System (sympathetic
  para-sympathetic)
• Circulatory system
• Endocrine system
• Immune system

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Relative to this communication, drugs will
either...

• stimulate

• depress

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Psychoactive drugs target the nervous sytem

• Regulation of metabolic functions
• Control of muscular movement
• Receipt and processing of perceptual input
• Communication within and across systems
• Response by feedback mechanisms

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cognition
emotion
vital functions
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Key anatomical features

• reticular formation filter for incoming nerve
  impulses
• medulla oblongata vital center for breathing,
  heart rate, blood pressure, gastrointestinal
  function, etc.
• cerebellum center for motor coordination
• hypothalamus center for pleasure and pain
• cerebrum center for memory and other cognition

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Basic Function

• Convert stimuli into nerve impulses (receptor
  cells)
• Conduct nerve impulses towards the CNS (afferent
  neurons)
• Discriminate the impulses (thalamus subthalamus)

Stimulus
Impulse
Pathway (nerve)
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Basic Function

• Interpret the impulses
• Make a decision related to the impulses
• Dispatch a response to the end / effector organs
• Conduct messages to those effectors (efferent
  neurons)

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Nervous Tissue

• Capabilities -
• irritability / excitability
• conductivity
• Types of cells -
• neurons
• neuroglia (the glue cells)

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Nervous Tissue

• Neuron - structural and functional unit of the
  nervous system
• dendrites (receptors) transmit impulse towards
  the cell body
• axon (conductors) transmit impulse away from
  the cell body
• telodendria (end) transmit impulse across the
  synaptic cleft

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Neurotransmitters

• Excitatory
• acetylcholine
• epinephrine / norepinephrine
• dopamine
• serotonin

• Inhibitory
• gamma aminobutyric acid
• glycine
• endorphins

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Physiology of the Synapse
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Structurally specific drugs can and do interfere
with the process...
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The resultant drug effects...

• Activate
• stimulate
• irritate
• Inactivate
• depress -- inhibit
• block -- kill / destroy
• Substitute / Replace