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UPPERS DOWNER AND ALL AROUNDERS. Chapter 2 Part I. How Psychoactive Drugs Affect Us. Chapter 2 Focuses on the following: Why do we crave a drug? Why can’t we stop craving a drug. Chapter 2 will also examine the neurochemistry of craving and satiation. Look at different genetic factors

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How psychoactive drugs affect us
How Psychoactive Drugs Affect Us

  • Chapter 2 Focuses on the following:

  • Why do we crave a drug?

  • Why can’t we stop craving a drug.

  • Chapter 2 will also examine the neurochemistry of craving and satiation.

  • Look at different genetic factors

  • Look at the role of brain chemicals

  • Risk factors

How psychoactive drugs affect us1
How Psychoactive Drugs Affect Us

  • Factors that determine effects and abuse potential include:

    • Route of administration

    • Speed of transit to the brain

    • Affinity for nerve cells and neurotransmitters

Routes of drug administration and absorption 5 common ways that drugs enter the body
Routes of Drug Administration and Absorption.5 common ways that drugs enter the body

Routes of drug administration and absorption
Routes of Drug Administration and Absorption.

  • Inhaling:

    • Allows the vaporized drug to enter the lungs, the heart and then the brain in about 7-10 seconds (Most rapid)


  • Marijuana inhaling tent used by the Scythians, c. 500 B.C.

  • Man in India smokes ganja (marijuana) in a “chillum” pipe.

Routes of drug administration and absorption1
Routes of Drug Administration and Absorption.

  • Injecting (Intravenous):

    • Puts drugs directly into a vein

    • Put drugs into muscles or under skin

Routes of drug administration and absorption2
Routes of Drug Administration and Absorption

  • Snorting & Mucosal Exposure:

    • Drugs can be snorted and absorbed through capillaries in the nasal passages or placed on mucosal tissues in the gums, cheeks, or even rectum and absorbed.

  • Cocaine snorter’s nose showing how cocaine ate a hole through the nasal septum separating the nostrils.

Routes of drug administration and absorption3
Routes of Drug Administration and Absorption

  • Oral Ingestion:

  • Drug passes through the esophagus and stomach to the small intestine where it is absorbed by the capillaries lining the walls of the small intestine.

  • Hindu ascetic prepares marijuana for drinking.

Routes of drug administration and absorption4
Routes of Drug Administration and Absorption

Contact or Transdermal Absorption

Absorption through the skin is the slowest method of drug use. It often takes 1–2 days for effects to begin and the absorption can continue for about 7 days. Nicotine, fentanyl, and heart medications can also be absorbed this way

Skin creams & ointments absorbed through skin

Drug distribution
Drug Distribution

  • Drugs Circulate through the bloodstream to the rest of the body where they cause an effect, be ignored, be absorbed or be biotransformed

  • Distribution depends on the drug itself and on blood volume of the person (6-8 quarts in an adult, 3-4 in child)

  • Takes 10 to 15 seconds after entering the bloodstream and has the greatest effect on the brain and spinal cord

Drug distribution blood brain barrier
Drug Distribution: Blood-brain Barrier

  • The walls of the capillaries that form a protective shield around the nerves cells of the central nervous system (CNS) and guard against toxins, virus, and bacteria can be penetrated by psychoactive drugs

  • Penetration happens because psychoactive drugs are Fat-soulable and the brain and its barrier are fatty

  • Psychoactive drugs such as heroin, nicotine, alcohol and marijuana cross this barrier more easily than other substances.

  • Cocaine (water soluble) hitchhikes onto protein molecules to pass through blood-brain barrier.

  • It takes 1–2 years for the blood-brain barrier to develop fully in infants.

The nervous system
The Nervous System

  • Principle Target of Psychoactive drugs

  • Network of 100 billion nerve cells & 100 trillion connections

  • Nervous System is made up of the:

    • Central Nervous System

    • Peripheral Nervous System

The nervous system1
The Nervous System

  • Psychoactive drugs primarily affect the central nervous system. The two parts of the central nervous system are the brain and spinal cord.

  • The Central Nervous System

    • Includes the Brain and Spinal Cord

    • Is the message center, receiving, analyzing and responding to messages from the peripheral and autonomic nervous systems

    • Drugs alter the information sent from our environment,

    • Disrupts the processing (Thinking) of information

    • Disrupts the commands sent back to various parts of body

Peripheral nervous system
Peripheral Nervous System

  • Is divided further into two systems:

    • Autonomic Nervous System:

      • Controls involuntary functions such as circulation, digestion and respiration

      • Helps body respond to stress

      • Conserves the body’s resources and restores homeostasis

      • Many cells of the autonomic nervous system is located in the brain and spinal cord.

      • Psychoactive drugs that cross the brain-blood barrier can disrupt involuntary functions

Peripheral nervous system1
Peripheral Nervous System

  • Somatic Nervous System

    • Transmits sensory information from the skin, muscles & joints to the central nervous system (CNS),

    • Then transmits instructions from the CNS back to the skeletal muscles, allowing the body to respond

Old brain new brain
Old Brain – New Brain

  • Old Brain: Consist of the brain stem, cerebellum and mesocortex. Regulates physiologic functions. Experiences basic emotions & cravings. Imprints survival memories

  • New Brain: Consist of the neocortex and processes information from the old brain. Allows us to reason, speak, create and remember.

  • Craving is often located in the old brain and is a powerful primitive impulse that can override the rationality of the new brain.

Reward reinforcement center
Reward / Reinforcement Center

  • Part of the Old Brain that encourages a person to remember and repeat an action.

  • It is also affected by drugs and is thus responsible for craving

  • Drugs act on the reward pathway to trigger craving for euphoria or pain relief

  • AKA “mesolimbic dopaminergic reward pathway”

Reward reinforcement center nucleus accubens satiation center
Reward / Reinforcement Center Nucleus Accubens & Satiation Center

Necleus Accumbens

Small group of nerve cells call the “medial forebrain bundle”

Psychoactive drugs stimulate this area and the longer the use, the stronger the “do it again”

Satiation Center: keeps balance

  • When activated by drugs, the impact is so strong that it can imprint emotional memory of euphoria or pain relief more deeply than survival memories

  • Induce strong cravings

  • Connected with the physiologic regulatory center of body like heart rate and respiration


  • Nerve cells: Consisting of dendrites, the cell body, the axon and terminals transmit impulses by sending neurochemicals AKA “neurotransmitters” across the synaptic gap between the nerve cells or neurons

  • Messages travel in multiple directions but with purpose, enabling the senses to transmit messages to the brain that, in turn, send messages and commands back to the appropriate muscles, tissues, and organs. A single nerve cell can receive signals from hundreds, even thousands of other nerve cells.


  • They move holding sacs in one nerve cell, across the synaptic gap, slot into rector sites, trigger an impulse, and then move back to the sending cell.

  • The rapid signals are reflex reactions

  • Slower signals allow time for thought


  • The released neurotransmitters cross the synaptic gap and slot into receptor sites on the postsynaptic neuron, causing the retransmission of the message. The slotted neurotransmitters are then released and either metabolized in the synaptic gap or more likely reabsorbed through reuptake ports in the sending terminal, ready to be transmitted again. (p. 53)

Neurotransmitters receptors
Neurotransmitters & Receptors

  • Endorphins & enkephalins are the body’s own opiods or (Endogenous Opiods)

  • Exogenous opiods are external opiod drugs such as heroin and morphine

  • Psychoactive drugs cannot create sensations or feelings that don’t have a natural counterpart in the body

    • So psychoactive drugs duplicate or mimic the natural counterpart in the body to a higher degree

Major neurotransmitters
Major Neurotransmitters

  • Acetycholine

  • Norepinephrine

  • Epinephrine

  • Dopamine

  • Histamine

  • Serotonin

  • Enkephalins

  • Endorphins

  • Dynorphins

  • GABA

  • Glycine

  • Glutamic Acid (Glutamate, Glutamine)

  • Subtance PA

  • Anandamide

  • Corticotrophines (cortisone)

  • Nitric Oxide

  • 100 more have been discovered

Uppers downer and all arounders

If the cells senses too many neurotransmitters, then it closes down ports.If there is too few neurotransmitters, then the cell opens more ports

  • Cocaine forces the release of extra neurotransmitters, especially dopamine, epinephrine, and norepinephrine.

  • It then also blocks the reuptake ports so the neurotransmitters cannot be reabsorbed by the sending neuron thus causing excess stimulation of the user.

Heroin neurotransmitters
Heroin & Neurotransmitters closes down ports.

  • When heroin is taken, it slots into receptor sites on the edge of the pain-transmitting nerve cell, causing a reduction in the amount of substance “P” that gets across the gap.

  • The heroin also slots into receptor sites on the receiving neuron, blocking the substance “P” that gets through. When heroin or opioid use is discontinued, the pain returns unless that tissue or organ has been repaired. (p. 57)

Agonist antagonist
Agonist & Antagonist closes down ports.

  • Drugs disrupt neutral message transmission

    • Agonist are those drugs that enhance neutral signals mimic or facilitate the effects of neurotransmitters

    • Antagonist are those drugs that block neurotransmitters

Uppers downer and all arounders

  • Heroin will act like a second messenger and slot into the opiod (enkeohlin) receptors and block the release of Substance “P” neurotransmitters

  • Heroin can also slot into the Substance “P” receptor sites without causing pain.

  • Cocaine forces the release of norepinepherine & dopamine neurotransmitters by entering the presynaptic neurons causing an exaggerated effect

  • Ecstacy works this way with serotonin