Discussion 17 Flashcards
Psychopharmacology
study of how drugs affect the
nervous system and behaviour
Psychoactive drug
substance that acts to alter
mood, thought, or behaviour; is used to manage neuropsychological illness; and often is taken recreationally
Oral administration
Oral administration is easy and convenient but is nonetheless a
complex route. To reach the bloodstream, an ingested drug must first be absorbed through the lining of the stomach or small intestine. Drugs in liquid form are absorbed more readily. Drugs taken in solid form are not absorbed unless the stomach’s gastric juices can dissolve them. Some drugs may be destroyed or altered by enzymes in the gastrointestinal tract’s microbiome. Whether a drug is an acid or a base also influences its absorption more barriers that the drug must
pass (stomach/intestinal lining, bloodstream), slow acting
Inhalation
Drugs administered as gases
or aerosols penetrate the cell linings of the respiratory tract very easily
and are absorbed across these membranes into the bloodstream almost immediately after they are inhaled. Thus, they reach the bloodstream by circumventing the barriers in the digestive system or skin. When administered as a gas or in smoke, drugs like nicotine, cocaine, and tetrahydrocannabinol (THC), are similarly absorbed quick, less barriers than oraladministration, damage to lung tissue
Injection
Still fewer obstacles confront a drug destined for the brain if that
drug is injected directly into the bloodstream. And the fewest obstacles are encountered if a psychoactive drug is injected directly into the brain. This route of administration is normally carried out only by medical professionals in a sterile setting
Blood-brain barrier
The passage of drugs across capillaries in the brain is difficult because the blood–brain barrier, the tight junctions between the cells of blood vessels found in the brain, blocks passage of most water-soluble substances. The blood
brain barrier protects the brain’s ionic balance and denies many neurochemicals passage into the brain, where they can disrupt communication between neurons. It protects the brain from the effects
of many circulating hormones and from toxic and infectious substances
What are areas that are not protected by the blood-brain barrier
Areas that are not protected by the blood-brain barrier
Pineal gland entry of chemicals that affect day-night cycles
Pituitary gland: entry of chemicals that influence pituitary hormones
Area postrema: entry of toxic substances that induce vomiting
What are two ways molecules cross the blood brain barrier
- Small molecules, such as oxygen and carbon dioxide, and lipid
soluble molecules can pass through the endothelial membranes. - Complex molecules of glucose, amino acids, and other food components are carried across the membrane by active transport systems or ion pumps (transporter proteins specialized to convey a
particular substance)
How does the body eliminate drugs
After a drug is administered, the body begins to break it down through catabolism, a process that takes place in several areas of the body, including the kidneys, liver, and the intestines. The body excretes drugs and their
metabolites in urine, feces, sweat, breast milk, and exhaled air.
What is the problem with the excretion of drugs
some drugs end up in sewage plants which cannot get cleared by them and they end up back in the water ways negatable affecting both animals but also humans having very negative effects; male minnows attacking females
Drugs at the synapse
when we talk about drugs we talk about action at the synapse. Drug interactions are either mimicking or altering neurotransmitters. Drugs have a variety of impacts from synthesis of a neurotransmitter, we can impact essentially the whole process.. A drug will interact with postsynaptic receptor - ramp up or decrease its activity
Preventing reuptake of neurotransmitter and enzymatic breakdown
what are the major steps of neurotransmission
Synthesis of neurotransmitter in the som, axon, or terminal
Packaging and Storage of neurotransmitter in the vesicles
Release of the neurotransmitter from the terminal;s presynaptic membrane into the synapse
Receptor interaction in the postsynaptic membrane, as the neurotransmitter acts on an embedded receptor
a) inactivation by reuptake into the presynaptic terminal for reuse
OR
5. b) Inactivation by enzymatic degradation of excess neurotransmitter
What are two major effects drugs can have on the synapse
Agonists - increase neurotransmission
Antagonists: Decrease neurotransmission
Tolerance
decrease in a response to a drug with the passage of time. We do not always respond in the same manner to a give drug
what was the study that represented tolerance
Participants were given alcohol every day for 13 weeks–enough to keep them intoxicated. Prisoners incarcerated from drug use, asked for participation.
When the experiment behan all the participants increased their intake of alcohol
After 15-20 days of alcohol consumption blood alcohol levels fell, and the signs of intoxication fell too
what is metabolic tolerance
the number of enzymes needed to break
down alcohol in the liver, blood, and brain increases. As a result,
any alcohol consumed is metabolized more quickly, so blood
alcohol levels fall
what is cellular tolerance
brain cell activities adjust to minimize the
effects of alcohol in the blood. Cellular tolerance can help explain
why the behavioral signs of intoxication may be so low despite a
relatively high blood alcohol level
what is learned tolerance
explains a drop in outward signs of intoxication.
As people learn to cope with the demands of living under the
influence of alcohol, they may no longer appear intoxicated
sensitization
—increased responsiveness to
successive equal doses. sensitization is much more likely to develop with intermittent useMany drug therapies, including those for the psychiatric disorder schizophrenia, must be taken for several weeks before they
produce beneficial effects. Possibly sensitization underlies the
development of these beneficial effects. Sensitization is related to drug dependence. Before a person
becomes dependent on or addicted to a drug, he or she must be
sensitized by numerous experiences with the drug away from the home environment.Many drug therapies, including those for the psychiatric disorder
schizophrenia, must be taken for several weeks before they produce beneficial effects. Possibly sensitization underlies the development of these beneficial effects.
