Communication and Structure•Chemicals and the Body

Chemicals and the Body

• Agonists-Drugs that mimic a neurotransmitter.• Antagonists-Drugs that stop a neurotransmitter.

Chemicals and the Body

Psychoactive Drug: A drug capable of influencing perception, mood, cognition, or behavior.

Methods of getting a drug into the body:

Via Inhalation– Nasal Cavity– Lungs– Smoked

Via Injection– Subcutaneous– Intraparatineal– Intravenous– Intramuscular

Via Absorption– Skin– Mouth– Anal Cavity (intestines)

Via Ingestion

Fat/Water Soluble Distinction

Fat Soluble: • Stored-

– Bodies fat tissues– Fat deposits– Liver

• Storage methods make these substances potentially poisons.– Potential to build up to harmful levels in the body– Active in the brain because they bind to fats.

Water Soluble:• Not easily stored.• Used the moment they enter the body. • Unused material is flushed out.

Major CategoriesStimulants: Speed up activity in the CNS. Nicotine, Caffeine, Cocaine, Amphetamines Ritalin and Adderall

Depressants: Slow down activity in the CNS. Alcohol, Tranquilizers, Barbiturates Most Inhalants

Opiates: Relieve pain. Opium, Morphine, Heroin Methadone

Psychedelic drugs: Disrupt normal thought processes. Lysergic Acid Diethylamide (LSD), Mescaline (Peyote Cactus Buttons) Salvia Divinorum, Psilocybin (Mexican Magic Mushrooms), Marijuana (Tetra-Hydra-Cannibinol) Nutmeg, Thyme, Mace

Chemicals and the Body

Naloxone-– Counters Heroin.– Also counters the placebo effect.

Symptomatology

• Tolerance: Increased resistance to a drug’s effects accompanying continued use.

• Withdrawal Symptoms: Physical and psychological symptoms that occur when someone addicted to a drug stops taking it.

– Withdrawal from a depressant can kill you

– Withdrawal from an opiate will make you wish you were dead

Therapeutic Window

Defined: (Therapeutic Index) Comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxic effects.– Quantitatively, it is the ratio given by the dose required

to produce the toxic effect divided by the therapeutic dose

– Commonly used measure of therapeutic index is the lethal dose of a drug for 50% of the population divided by the effective dose for 50% of the population

TR = LD50 / ED50