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Neurology Questions
Brain Basics - Neurotransmitters and Neuromodulators
Question | Answer |
---|---|
What is the role of Acetylcholine (ACh)? | Used by neurons to cause voluntary muscles to contract, and other neurons to control the heartbeat. It may also be critical for normal attention, memory and sleep. |
What is myasthenia gravis? | A disease characterised by fatigue and muscle weakness. It is caused by antibodies that block one type of ACh receptor. |
Where are neurotransmitters synthesised? | Axon terminals |
What is the main treatment of Alzheimers | Drugs which inhibit acetylcholinesterase and increase ACh in the brain. (ACh releasing neurons die in Alzheimer's patients) |
What are Amino Acids? | Building blocks for proteins. Certain amino acids can also serve as neurotransmitters in the brain. |
Name 2 Amino Acid Neurotransmitters which inhibit the firing of neurons | glycine and gamma-aminobutyric acid (GABA) |
What is the activity of (GABA) increased by? | benzodiazepines (eg. valium) and by anticonvulsant drugs. |
Name 2 Amino Acid neurotransmitters which act as excitory signals | Glutamate and asparate |
What do N-methyl-d-asparate (NMDA) receptors do? | NMDA receptors have been implicated in activities ranging from learning and memory to development and specification of nerve contacts. Overstimulation of NMDA can cause nerve cell damage or cell death. This is what happens as a result of trauma or stroke |
What is NMDA activated by? | Glutamate and asparate |
What does the term catecholamines include? | The neurotransmitters dopamine and norepinephrine |
What are the 3 principle circuits in the brain dopamine is involved in? | The circuit that regulates movement, cognition and emotion, regulation of the endocrine system |
What is dopamine's role in the endocrine system? | Directs the hypothalamus to manufacture hormones and hold them in the pituitary gland for release into the bloodstream or to trigger the release of hormones held within cells in the pituitary gland |
If people with Parkinson's Disease had dopamine deficits in the brain, what sort of symptoms would be occurring? | Muscle tremors, rigidity and difficulty moving. |
What is levodopa | A substance from which dopamine is synthesised. It is an effective treatment for Parkinson's disease, allowing patients to walk and perform skilled movements more successfully |
Where is Serotonin found? | A neurotransmitter present in the brain and other tissues, particularly blood platelets and the lining of the digestive tract |
What does Serotonin do? | Serotonin has been identified as an important factor in sleep quality, mood, depression and anxiety. |
What does the drug fluoxetine do? | Alters Serotonin's action and relieves symptoms of depression and obsessive compulsive disorder |
What are peptides? | Short chains of amino acids that are linked together |
Where are peptides synthesised? | cell body |
Do peptides greatly outnumber the classical transmitters? | yes |
What does the word enkephalin literally mean? | "In the head" |
What is the first opiate peptide that was discovered? | enkephalin |
What is enkephalin and what does it do? | Enkephalin is an opiate peptide which resembles morphine (an opium derivative used medically to kill pain) |
What does the word endorphin mean | "endogenous morphine" |
What is the role of the naturally occurring opiod peptides? | They are released by brain neurons in times of stress to minimise pain and enhance adaptive behaviour |
Where is substance P found? | Some sensory nerves- tiny unmyelinated C fibres |
What is substance P and what does it do? | Substance P is a peptide which causes the sensation of burning pain. The active component in chilli peppers and capsaicin causes the release of substance P |
What are trophic factors? | Trophic factors are substances that are necessary for the development, function and survival of specific groups of neurons. |
Researches have found several small proteins in the brain which act as trophic factors. Describe their life (made, released etc.) | Made in brain cells, released locally in the brain, and bind to receptors expressed by specific neurons. |
While the nervous system uses neurotransmitters as its chemical signals, what does the endocrine system use? | Hormones |
Name various sources of hormones (Parts of the body) | Pancreas, kidneys, heart, adrenal glands, gonads (testis and ovaries), thyroid, parathyroid, thymus and even fat |
How does a large part of the endocrine system work? | By acting on the endocrine glands which controls the pituitary gland. The pituitary gland secretes factors into the blood that act on the endocrine glands to either increase or decrease hormone production |
What does the 'feedback loop' in the endocrine system involve? | Communication from the brain to the pituitary to an endocrine gland and back to the brain |
What is the endocrine system important for? | The activation and control of basic behavioural activities, such as sex; emotion; responses to stress; and eating, drinking, and the regulation of body functions, including growth reproduction, energy use and metabolism |
What does the way the brain respond to hormones indicate? | The brain is malleable and capable of responding to environmental signals |
The brain contains receptors for thyroid hormones and the six classes of steroid hormones. Name these six classes. | androgens, estrogens, progestins, glucorticoids, mineralocorticoids and vitamin-D |
Insulin, gherkin and leptin a what kind of hormones? | Metabolic |
What do hormones do in the brain? | Alter the production of gene products that participate in synaptic neurotransmission as well as affect the structure of brain cells |
What kind of hormone is the glucocorticoid cortisol? | Stress Hormone |
What is reproduction in females is a good example for? | A regular, cyclic process driven by circulating hormones and involving a feedback loop |
How does the hormonal reproduction cycle in females work (Detailed, with names of hormones) | GnRH is released which causes FSH and LH to be released which act on the ovary to stimulate ovulation and promote release of the ovarian hormones estradiol and progesterone. The increased estrogen then acts on the hypothalamus to decrease FSH and LH |
What is GnRH | gonadotropin-releasing hormone, a peptide that acts on cells in the pituitary |
What does FSH stand for | follicle-stimulating hormone |
Name the 'sex hormones' | Testosterone, oestrogen and progesterone |
What is sexual differentiation of the brain caused by? | Sex hormones acting in fatal and early postnatal life |
What are the molecules nitric oxide and carbon monoxide examples of? | Neurotransmitters which are gases |
Where are the 'gas neurotransmitters' stored/made and how do they go to adjacent neurons | They are made by enzymes as they are needed and released from neurons by diffusion. Rather than acting at receptor sites, they simply diffuse into adjacent neurons and act upon chemical targets, which may be enzymes |
What does nitric oxide do? | Governs erection in the penis, governs the relaxation that contributes to the normal movements of digestion in the intestine. It also is the major regulator of the intracellular messenger molecule cyclic GMP |
Protaglandis are a class of compounds made from lipids by an enzyme called what? | cyclooxygenase |
What are protaglandis and what do they do? | Prostaglandin are a class of compounds made from lipids by an enzyme called cyclooxyrgenase. These very small and short-lived molecules have various effects, including the induction of a fever and the generation of pain in response to inflammation |
How does the drug Aspirin work? | Reduces a fever and lowers pain by inhibiting the cyclooxyrgenase enzyme |
What are endocannabinoids and what do they do? | Membrane-derived messengers which control the release of neurotransmitters, usually by inhibiting them, and can also affect the immune system. They also play big role in control of behaviours. They increase in the brain under stressful situations |
What do 'second messengers' do? | Convey the chemical message of a neurotransmitter (The first message) from the cell membrane to the cell's internal biochemical machinery |
How long do 'second messengers' effects last for? | Their effects may last for a few milliseconds to as long as many minutes. They may also be responsible for long-term changes in the nervous system |
What is adenosine triphosphate (ATP) and where is it found? | The chemical source of energy in cells. It is present in all the cytoplasm of all cells |
What is cyclic monophosphate (cAMP) and how is it formed? | A second messenger inside the cell. It is made by an activated G protein causing the enzyme adnylyl cyclase to convert adenosine triphosphate (ATP) into cyclic monophosphate (cAMP) |
What does cyclic monophosphate (cAMP) do? | It does various things ranging from changes in the function of ion channels in the membrane to changes in the expression of genes in the nucleus |
What substances are thought to play a role in the manufacture and release of neurotransmitters and in intracellular movements and carbohydrate metabolism in the cerebrum, and also involved in growth and development processes? | Second Messengers |