WEEK 5 | DRUGS Flashcards
Define psychoactive drugs
substances that contain chemicals similar to those found naturally in our brains that later consciousness by changing chemical processes in neurons.
what is the site of action for psychoactive drugs
- Site of action on the CNS( central nervous system)
Define pharmacokinetics
refers to the movement of the drug through the body that involves absorption, distribution, metabolization and excretion
Define pharmacodynamics
refers to the mechanism of action of drugs
Types of drugs (4 in total)
1) Depressants: decreases activity of CNS. Initial high but followed by sleepiness, slower thinking, and impaired concentration.
- Examples: alcohol
2) Stimulants: increases activity of the CNS. Increases sense of alertness, well-being and energy.
- Examples: tobacco(nicotine), cocaine, caffeine
3) Opiates: sense of euphoria and decreased pain
- Examples: heroine, morphine, cocaine
4) Psychedelics: dramatically altered perception, mood and thoughts
- Examples: Marijuana, LSD, ecstasy
what is the meaning of sedative and hypnotic?
Meaning of sedative = calming
Meaning of hypnotic = sleep-induced
Define blood brain barrier
seal to separate body compartment
What is the blood brain barrier composed of?
Astrocytes
What makes up the blood brain barrier?
1) Glial tissues
2) Tight junctions of the brain capillary walls
3) Lack of pores
What is the only way drugs enter the brain?
Because of the blood brain barrier drugs cannot enter the brain unless they are lipid soluble enough to diffuse through the capillary walls and the glia.
What is the blood brain barrier compared to?
watchdog
What does the blood brain barrier provide?
Not only does it keep things out but it prevents neurotransmitters to leak out and get lost because the brain needs it.
Why is the blood brain barrier not found in the pituitary and the hypothalamus?
the hormones it secretes need to go into circulation and pass through the rest of the body.
Define solubility
refers to its ability to dissolve
What are the 2 types of solubility that are most significant for drugs?
1) Dissolve in water
2) Dissolve in lipids
Do drugs dissolve?
Drugs do not dissolve. For the most part, will not cross membranes and they will be eliminated from the gastrointestinal tract. Injected into the bloodstream they can remain and cause blockage.
Why is lipid solubility important to drugs?
Membranes have a lipid structure thus they are able to pass through them and diffuse to the other side.
Define and give an example of hydrophobic
- Refers to being “afraid of water” and an example is oil, rain runs off from a ducks back
Ionization
the process by which electrically neutral atoms are converted to charged atoms. Ex: NaCl becomes Na+ and Cl- . we say that table salt ionizes
How does ionization compare to drugs?
When drugs enter the extracellular fluid, they may ionize somewhat as they dissolved yielding a solution that contains both ionized and unionized portions of the drug. Since the ionized portion carries a charge, it has difficulty crossing the membrane because of equilibrium of charges.
What is a major factor of absorption?
How much of the drug was in its ionized form
Which drugs are hardest to absorb?
Water-soluble drugs because they ionize in bodily fluid and then cannot readily cross membranes
What case can a lipid-soluble drug not cross the membrane?
If they ionize, the ionized portion loses its lipid solubility