Class 12 Flashcards
What are Neurotransmitters?
Over 100 different NTs have been identified. Single neuron can produce many different NTs. NTs can interact with other NTs & hormones & body in many different ways. Same NT can have different roles in
different parts of body.
Neurotransmitters are released into one ________________, are ________-acting & produce ________-term response. ________________________ can affect groups of neurons, or effector cells with appropriate receptors. They can have a wide variety of actions across many targets far from release site.
• synapse
• fast
• short
• Neuromodulators (neurohormone)
What is a Neurotransmitter Agonist?
A NT agonist is a chemical that has the same effect on postsynaptic neuron as neurotransmitter does.
What is a Neurotransmitter Antagonist?
molecule that blocks effect of NT or its agonists. Are sometimes called blockers. Usually, transmitter must be inactivated, otherwise, it might “lock up” circuit that must respond frequently. NT may leak over to other synapses & interfere with their functions. Typically, transmitters are taken back into terminals by membrane proteins called transporters in process called reuptake. They are repackaged in vesicles & used again.
Dopamine in the CNS, dopamine functions as a _______ and ____________________.
• NT
• & neuromodulator.
Dopamine In the PNS, it has key roles in the ____________________ and ____________.
Immune system & kidneys
Dopamine Neural Functions Include?
PLEASURE & MOTIVATION PATHWAYS, for eg. frisson (emotional goosebumps that come from any aesthetic experience, especially music). All animals (including fruit flies) can be trained to repeat an action if it is consistently followed by an increase in dopamine levels.
REWARD-MOTIVATED BEHAVIOUR. Anticipation of most types of rewards increases level of dopamine in brain, & many addictive drugs increase dopamine release.
MOTOR CONTROL (e.g., dopamine reduction with aging causes increased rigidity). Midbrain areas including substantia nigra produce most of brain’s dopamine.
Dopaminergic axons project to many other brain regions & exert powerful effects on their targets.
(Dopamine and the Basal Ganglia) The basal ganglia are responsible for?
Initiating behaviours, but not for determining details of how they are carried out. BG determine which several possible behaviours occur by release of inhibition (disinhibition). While continuing to inhibit other motor systems that would generate competing behaviours.
When chosen response is successful & is followed by increase in dopamine activity, same response is easier to produce when similar situations arise.
Generally help in directing involuntary movements including postural proximal adjustments. This “background positioning” is necessary before fine, distal movements may take place.
(Dopamine and the Basal Ganglia) Parkinsons disease results from?
Loss of dopaminergic neurons in substantia nigra of brain stem.
Beyond age of 60, its most common neurodegenerative disorder after Alzheimer
Parkinson’s beyond age of 60, its most common neurodegenerative disorder after Alzheimer
characterized by movement disorders including?
- resting tremors when muscles are relaxed
- tremor stops when voluntary movement of body part begins; tremor usually occurs first in hands & is often one of first noticeable symptoms of disease
- difficulty initiating movement
- rigidity
- bradykinesia (slow movement)
- hypomimia (a reduction in facial expression)
- when confronted with strong stimuli such as serious threat, PD reactions can be vigorous
- soft & slurred speech
- festination: quickening & shortening of normal strides leading to fast- shuffling gait
- prescription of drugs that are dopamine antagonists, (also often used for schizophrenia) can often result in anhedonia, diminished ability to experience pleasure & slowed reactions
- drugs that are dopamine agonists (e.g., L-Dopa) can lead to impulsive behavior, such as compulsive gambling
What is Acetylcholine (ACh)?
main neurotransmitter of parasympathetic nervous system.Cholinergic drugs stimulate parasympathetic nervous system by copying action of ACh. Anticholinergics can treat variety of conditions, including urinary incontinence.
ACh is also NT at neuromuscular junctions. Chemicals that affect cholinergic systems can have very dangerous effects, ranging from paralysis to convulsions.
Botulinum toxin is a key ingredient of drug Botox. It’s neurotoxic protein produced by bacterium Clostridium botulinum.
Prevents release of ACh from axon terminals at neuromuscular junction thus preventing muscle contractions. This can be helpful in combatting both spasmodic torticollis & wrinkles.
What is Botulinum toxin?
Botulinum toxin is a key ingredient of drug Botox. It’s neurotoxic protein produced by bacterium Clostridium botulinum.
Prevents release of ACh from axon terminals at neuromuscular junction thus preventing muscle contractions. This can be helpful in combatting both spasmodic torticollis & wrinkles.
What are Endocannabinoids?
NTs & neuromodulators. These chemicals bind to
cannabinoid receptors throughout body.
Endocannabinoids, anandamide, & 2- AG are involved in multiple neural functions. Exogenous cannabinoids are found in cannabis (marijuana) plant.
CBD & THC are two well-known exogenous cannabinoids that mimic endocannabinoids.
THC is main psychoactive component of cannabis.
CBD, or cannabidiol is essential component of medical marijuana, derived directly from hemp plant, relative of marijuana, or manufactured in laboratory.
Research has indicated that cannabis reduces nausea & vomiting during chemotherapy & reduces chronic pain & muscle spasms.
T/F CBD causes a “high” by itself?
- False
CBD does not cause a “high” by itself.
CBD exhibits no effects indicative of any abuse or dependence potential…. To date, there is no evidence of public health related problems associated with use of pure CBD.”
CBD has been touted for management of a wide variety of health issues, including?
Several childhood epilepsy syndromes, anxiety, & insomnia. May inhibit inflammation.
Cannabis has various mental effects, which include?
euphoria, altered states of mind & sense of time, relaxation, & increase in appetite.
What is Endorphin (endogenous morphine)?
Opioid NT & neuromodulator produced & stored in pituitary gland. Also help block perception of pain & increase feelings of wellbeing. Are produced & stored in pituitary gland.
Common factors leading to release of endorphins are pain & stress.
Massage, meditation, laughter, & exercise are known to stimulate endorphin production & to elevate pain thresholds.
Chili peppers can also lead to enhanced secretion of endorphins; spicier the pepper, the more endorphins are secreted.
At least 20 types of endorphins have been found in humans.
Interact with opiate receptors in brain to reduce
perception of pain & act similarly to drugs such as morphine (major component of heroin) & codeine.
play a major role in brain’s inhibitory response to pain. Research shows massage, meditation, laughter & exercise may trigger endorphin release. Though they’re both part of brain’s reward system, endorphins are quickly released during specific act to alleviate pain & stress. In contrast, dopamine is released slowly & thought to be responsible for mood-boosting sensation you feel after activity.
Common factors leading to release of endorphins are?
pain & stress
Massage, meditation, laughter, & exercise are known to stimulate _________________________ & to elevate _________________________.
endorphin production & to elevate pain thresholds.
Endorphins Interact with opiate receptors in brain to?
reduce perception of pain & act similarly to drugs such as morphine (major component of heroin) & codeine.
Endorphins play a major role in?
The brain’s inhibitory response to pain.
What is Epinephrine (Adrenalin)?
Acts as Sympathetic Nervous System NT. It’s released as hormone via adrenal medulla.
Plays important role in body’s fight or flight response.
release into bloodstream causes increased blood pressure, heart rate, & glucose levels.
Chronic stress & certain health conditions can affect
body’s ability to produce or respond to adrenalin.
