Chapter 6 Flashcards
What are psychoactive drugs?
substances that alter mood, thought, or behaviour, and used to manage neuropsychological illness
What do we call the way a drug inters and passes through the body to reach its target?
Route of Administration
Drugs injected into the bloodstream encounter the fewest barriers to the brain but must be ___________.
Hydrophilic
Drugs that are prepared for inhalation or intravenous injections are much cheaper per dose, why?
Because the amount required is a lot sale than what’s needed for an oral dose
Why is the passage of drugs across capillaries in the brain difficult?
Because of the blood-brain barrier
What does the blood-brain barrier do?
it protects the brains ionic balance and denies neurochemicals passage in the brain. It also protects the brain for circulating hormones and toxic substances
Capillaries are composed of a single layer of ___________ cells.
Endothelial cells
Explain how Endothelial cells differ from in the brain and the rest of the body
Endothelial cells in capillary walls in the body are not joined, so substances can pass through. But in the brain, they are fused to form tight junctions, so most molecules can’t squeeze between them
In brain capillaries, Astrocytes are attached to and cover most of the capillary wall, what exactly of they do here?
They provide a route for the exchange of food and waste between capillaries and the brains extracellular fluid
The _________ is a source of many hormones secreted into the blood, and their release is triggered by other ________ carried to the _________ by the blood
Pituitary; hormones; pituitary
The absence of a blood0brain barrier in the brainstems area allows toxic substances to enter from blood, how does our body react to this?
it triggers vomiting, so any ingested toxins in the stomach can come out
What does the brain need to for fuel, and what does it need to build proteins
Oxygen and glucose, and amino acids
What 2 ways do molecules cross the blood-brain barrier
1) Small molecules pass through the endothelial membranes (oxygen, carbon dioxide, lipid-soluble molecules)
2) Complex molecules are carried across the membrane by active transport systems or ion pumps (glucose, amino acids)
When a drug enters the blood stream, the body begins to break it down through ________.
Catabolism
Where does the body excrete drugs
urine, faces, sweat, breast milk, and exhaled air
How does the liver play a part in eliminating drugs
to convert certain lipid-soluable molecules into a water-soluble form
The liver houses a family of drug-catabolizing enzymes that break down different drugs into forms more easily excreted from the body, what is the drug?
Cytochrome P450 enzyme family
What is the difference between antagonist drugs and agonists drugs
Agonists increase neurotransmission, and antagonists decrease neurotransmission
All synapses on muscles are ___________, meaning they use ACh as their neurotransmitter
Cholinergic
What are 2 drugs that influence ACh release from the axon terminal, explain what happens
Black widow spider venom = acts as an agonist by promoting the release of excessive amounts of ACh
Botulinum toxin = found in canned goods, and acts as an antagonist by blocking ACh release. The effects can lat for weeks and even months (can cause death)
What happens when Botulinum toxin is injected into muscle?
It paralyzes the muscle, making it useful for blocking excessive and enduring muscular twitches.
Another word for Botulin is “botox,” commonly used for paralyzing facial muscles that cause wrinkling Nicotine
Nicotine acts as an agonist to stimulate ___________ receptors. Nicotines molecular structure is similar enough to that of _____ to allow nicotine to fit into ____ receptors’ binding sights.
Cholinergic; ACh; ACh
Early European explorers of South America discovered that the indigenous peoples living along the Amazon River killed small animals using arrowheads coated with curare prepared from the seeds of a plant. How were the indigenous not killed from ingesting curare?
Because curare cant pass from the gut into the body. This is why curare drugs have been synthesized
What is an agonist for the enzyme acetylcholinesterase
physostigmine (obtained from an African bean)
In small doses (because big doses disrupt movement and breathing), what can physostigmine be used to treat?
Myasthenia gravis, a condition of muscular weakness
Organophosphates bind to AChE, allowing ACh to build up to toxic levels, where has Organophosphates been used?
As chemical weapons
What are the 3 types of tolerance?
Metabolic tolerance, Cellular tolerance, and Learned tolerance
What is metabolic tolerance?
when the number of enzymes needed to break down alcohol increases
What is cellular tolerance?
where brain cell activities adjust to minimize the effects of alcohol in the blood
What is learned tolerance?
A drop of visible signs of intoxication, people learn how to handle it
What is sensitization?
the opposite of learned tolerance, its the increased reaction with continued drug use
