norepinephrine

Examples of norepinephrine in the following topics:

• Epinephrine and Norepinephrine

  • Norepinephrine is a catecholamine with multiple roles.
  • Areas of the body that produce or are affected by norepinephrine are described as noradrenergic.
  • The actions of norepinephrine are carried out via the binding to adrenergic receptors.
  • Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively.
  • Kidney function is halted temporarily by epinephrine and norepinephrine.

• Neurodevelopmental Disorders: Mental Illnesses

  • Some research supports the "classic monoamine hypothesis," which suggests that depression is caused by a decrease in norepinephrine and serotonin neurotransmission.
  • One argument against this hypothesis is the fact that some antidepressant medications cause an increase in norepinephrine and serotonin release within a few hours of beginning treatment, but clinical results of these medications are not seen until weeks later.
  • For example, dopamine may also be decreased in depressed patients, or it may actually be an increase in norepinephrine and serotonin that causes the disease, and antidepressants force a feedback loop that decreases this release.
  • For example, monoamine oxidase inhibitors (MAO inhibitors) block the enzyme that degrades many neurotransmitters (including dopamine, serotonin, norepinephrine), resulting in increased neurotransmitter in the synaptic cleft.
  • Other types of drugs, such as norepinephrine-dopamine reuptake inhibitors and norepinephrine-serotonin reuptake inhibitors, are also used to treat depression.

• 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.

• 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.

• Adrenal Glands

  • The adrenal medulla contains two types of secretory cells: one that produces epinephrine (adrenaline) and another that produces norepinephrine (noradrenaline).
  • 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.

• Autonomic Nervous System

  • Postganglionic neurons then release norepinephrine onto target organs.
  • 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.
  • The physiological effects of this norepinephrine release include dilating the trachea and bronchi (making it easier for the animal to breathe), increasing heart rate, and moving blood from the skin to the heart, muscles, and brain (so the animal can think and run).

• 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.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • 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.

• Plasma Membrane Hormone Receptors

  • The amino acid-derived hormones epinephrine and norepinephrine bind to beta-adrenergic receptors on the plasma membrane of cells.