Chapter 6: How Drugs and Hormones Influence Behaviour Flashcards
(349 cards)
substances that act to alter mood, thought or behaviour; is used to manage neuropsychological illness, may be taken recreationally
psychoactive drugs
the way a drug enters and passes through the body to reach its target
route of administration
5 ways drugs can be administered
- orally
- inhaled into the lungs
- rectally in a suppository
- absorbed from patches applied to the skin or mucous membranes
- injected into the bloodstream, muscle, or brain
injecting a drug directly into the brain allows it to ___ because ___
act quickly in low doses; it encounters few barriers
taking drugs ___ is the safest, easiest and most convenient way to administer them
orally
drugs that are weak acids pass from the ___ into the ___
stomach; bloodstream
drugs that are weak bases pass from the ___ to the ___
intestines; bloodstream
drugs injected into ___ encounter more barriers than do drugs inhaled
muscle
drugs ___ encounter few barriers en route to the brain
inhaled into the lungs
drugs ___ encounter the fewest barriers to the brain but must be hydrophilic
injected into the bloodstream
drugs ___ are absorbed thru the skin and into the bloodstream
contained in adhesive patches
drugs in __ form are absorbed more readily, while drugs in ___ form are not absorbed unless the stomach’s gastric juices can dissolve them
liquid; solid
the drug is diluted by the approx. ___ of blood that circulate an adult body, and when it leaves the bloodstream, the body’s roughly ___ of extracellular fluid further dilute it
6 litres; 35 litres
with each obstacle eliminated en route to the brain, a drug’s dosage can be reduced by a factor of __
10
drugs that are prepared for ___ are much cheaper per dose because ___
inhalation or intravenous injection; the amount required is so much smaller than that needed for an effective oral dose
the body’s barriers to internal movement of drugs
- cell membranes
- capillary walls
- placenta
why is the passage of drugs across capillaries in the brain difficult?
the blood-brain barrier blocks passage of most water-soluble substances
___ can compromise the integrity of the blood-brain barrier, letting ___ through
injury or disease; pathogens
none of the brain’s neurons are farther than ___ from a capillary
50 micrometers
brain capillaries are composed of a single layer of ___
endothelial cells
how are endothelial cells in the body different from those in the brain?
- in the body endothelial cells in capillary walls are not fused, so substances can pass through the clefts between the cells
- in the brain, endothelial cell walls are fused to form tight junctions, so molecules of most substances cannot squeeze between them
endothelial cells of brain capillaries are surrounded by ___
the end feet of astrocytes attached to/covering most of the capillary wall
___ provide a route from the exchange of food/waste between capillaries + the brain’s extracellular fluid
astrocytes
3 barrier-free brain sites
- pineal gland
- pituitary gland
- area postrema