Pschiactric Disorders, Drug Addiction And Action Flashcards
What is an Antagonist?
They inhibit transmissions at synapse and block neurotransmitters
What is an Agonist?
They facilitate transmission at synapse, they increase or mimic neurotransmitters
Describe affinity and efficacy
If a drug has a high AFFINITY for a receptor it binds to it
If a drug has a high EFFICACY for a receptor it activates it
What is the relevance of the nucleus accbens?
Most drugs stimulate the release of dopamine
Drug-sustained bursts of dopamine-inhibits GABA-increased activity in nucleus accumbens
Give an example of a stimulant
Amphetamine (speed) stimulates dopamine synapse by increasing release of dopamine from presynaptic terminal
Give an example of a stimulant
Cocaine: blocks the reuptake of dopamine thus prolonging effects (accumulation of dopamine in the synaptic cleft)
What do stimulants do?
Increase in dopamine causes a widespread reduction of activity in the brain except the nucleus accumbens. Followed by a crash as the dopamine disappears it can’t be replaced quickly enough.
What is an opiate (with examples)
Morphine and heroin: increased relaxation and decreased pain sensitivity.
Mimic endorphins, it attaches to specific endorphin receptors. Inhibits GABA, thus increases dopamine. Also hindbrain area that usually releases norepinephrine
Reduces stress but also memory storage.
Describe marajuana
Contains cannabisoids, which bind to specific receptors
Inhibit GABA release, increase dopamine therefore you have a perception of heightened awareness.
Cannabisoid receptors are abundant in the hypothalamus, the feeding section of the brain, increased hunger ‘munchies’
Describe botolinium toxin (Botox)
It is a deadly neurotoxin released by decaying food. An antagonist which blocks release of acetylcholine at neuromuscular junctions which causes paralysis. Small doses are used to reduce muscle tremors and cosmetically.
Describe addiction
Drugs increase the ‘need’ for the substance even if the experience is not pleasant
Describe sensitisation of the nucleus accumbens
The nucleus accumbens becomes more sensitive to substances after repeated use; increased ability to release dopamine in response to the substance. Reduced sensitivity to other things.
Describe withdrawal
Cravings for the drug. Relapse causes increased sensitivity. User learns that drug relieves stress related to withdrawal and so craves it more during future withdrawal.
What is addiction?
Continued use of a substance when it interferes with your life
Describe alcohol effects.
Alcohol affects many areas of the brain-mostly inhibitory, it relaxes Brain activity and communication.
What types of alcoholism are there?
1) late onset (after 25) gradual, men=women, less severe (few relatives with alcoholism
2) early onset (before 25) rapid, men more than women, more severe (more relatives with alcoholism)
Why are people alcoholics?
Genetic influence: coding for increased risk taking, coding for increased stress response: more likely to relapse
Sons of alcoholic fathers:
1) high alcohol tolerance
2) greater decrease of stress when consuming
3) smaller amygdala (risk taking)
Describe depression (general)
Twice as common in women than men. (5%of adults)
Hereditary, not specifically for depression. More common for relatives of women with early onset depression.
Low serotonin turnover associated with aggression and depression. Implication of gene controing serotonin. Transporter protein, this controls the ability of an axon to reabsorb serotonin. (Short and long)
What is postpartum depression?
After giving birth. 20% of all women suffer, only 0.1% long lasting
What is bipolar depression?
Vary between mania and depression. Can be treated with lithium salt
Blocks synthesis of arachidonic acid
What is seasonal affective disorder (SAD)?
Usually associated with winter, common near poles, where there are long nights, (affects circadian rhythm) less severe than depression- can be treated with light therapy.
Describe schizophrenia
Means split mind-emotional v intellectual Some patients show inappropriate emotional expression detached from circumstances. Hallucinations, delusions, thought disorders- can be acute or chronic. Positive symptoms (additions): delusions etc Negative symptoms (absences): poor social interaction etc
What are problems with schizophrenia diagnosis?
Difficult to diagnose as often confused with other conditions. Difficult to pinpoint specific brain areas.
What are schizophrenia demographics?
More common in men than women, earlier onset in men. 1% of all population. Equal promotions in cultures and populations thus may have a genetic basis. Why has it evolved? May be a byproduct of language…?
What is the neurodevelopmental hypothesis?
Abnormalities in development of the nervous system before birth and in neonates.
1) infections, poor nutrition,
2) slight brain abnormalities
Larger ventricles, less space for brain cells (relate to age and Indiv diff)
Prefrontal cortex damage (working memory)
Smaller cell bodies in hippocampus (mem consolidation)
Less lateralisation (right plenum temorale larger, language deficit? Left handed)
How can drug abuse affect psychosis?
Drug abuse associated with excess dopamine which can cause psychosis. This is the dopamine hypothesis=excess activity in dopamine synapses, twice as many dopamine receptors but normal level of dopamine.
Dopamine inhibits glutamate- inhibits dopamine- angel dust- PCP
What are drugs?
Tend to imitate substances already present in our nervous system, particularly those that affect transmissions at the synapse.
Mainly from plants (eg nicotine from tobacco plants
Plant produces these to attract insects to avoid being eaten etc
Nervous system of many animals similar
