epinephrine
(noun)
(adrenaline) an amino acid-derived hormone secreted by the adrenal gland in response to stress
Examples of epinephrine in the following topics:
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Epinephrine and Norepinephrine
- As a hormone and neurotransmitter, epinephrine acts on nearly all body tissues.
- Epinephrine acts by binding to a variety of adrenergic receptors.
- Epinephrine is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3.
- Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively.
- Kidney function is halted temporarily by epinephrine and norepinephrine.
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Hormonal Regulation of Stress
- The hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) are released by the adrenal medulla.
- Epinephrine and norepinephrine increase blood glucose levels by stimulating the liver and skeletal muscles to break down glycogen and by stimulating glucose release by liver cells.
- Epinephrine and norepinephrine are collectively called catecholamines.
- The body cannot sustain the bursts of energy mediated by epinephrine and norepinephrine for long times.
- When an animal feels threatened, epinephrine and norepinephrine released by the adrenal medulla prepare the body to fight a threat or flee from it by breaking down stores of glycogen, which provides an immediate boost of energy.
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Lipid-Derived, Amino Acid-Derived, and Peptide Hormones
- For example, cortisol has a half-life of 60 to 90 minutes, whereas epinephrine, an amino acid derived-hormone, has a half-life of approximately one minute.
- Examples of amino acid-derived hormones include epinephrine and norepinephrine, which are synthesized in the medulla of the adrenal glands, and thyroxine, which is produced by the thyroid gland.
- (a) The hormone epinephrine, which triggers the fight-or-flight response, is derived from the amino acid tyrosine.
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Humoral, Hormonal, and Neural Stimuli
- Recall that in a short-term stress response, the hormones epinephrine and norepinephrine are important for providing the bursts of energy required for the body to respond.
- Here, neuronal signaling from the sympathetic nervous system directly stimulates the adrenal medulla to release the hormones epinephrine and norepinephrine in response to stress.
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Adrenal Glands
- The adrenal medulla contains two types of secretory cells: one that produces epinephrine (adrenaline) and another that produces norepinephrine (noradrenaline).
- Epinephrine is the primary adrenal medulla hormone, accounting for 75 to 80 percent of its secretions.
- Epinephrine and norepinephrine increase heart rate, breathing rate, cardiac muscle contractions, blood pressure, and blood glucose levels.
- The release of epinephrine and norepinephrine is stimulated by neural impulses from the sympathetic nervous system.
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Hormone Functions
- Examples of endocrine glands include the adrenal glands, which produce hormones, such as epinephrine and norepinephrine that regulate responses to stress, and the thyroid gland, which produces thyroid hormones that regulate metabolic rates.
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Cell Signaling and Cellular Metabolism
- Also known as epinephrine, adrenaline is a hormone (produced by the adrenal gland attached to the kidney) that prepares the body for short-term emergencies.
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Plasma Membrane Hormone Receptors
- The amino acid-derived hormones epinephrine and norepinephrine bind to beta-adrenergic receptors on the plasma membrane of cells.
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Hypersensitivities
- If not treated with epinephrine to counter the blood pressure and breathing effects, this condition can be fatal.
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Autonomic Nervous System
- This is both because one preganglionic neuron synapses on multiple postganglionic neurons, amplifying the effect of the original synapse, and because the adrenal gland also releases norepinephrine (and the closely-related hormone epinephrine) into the blood stream.