neurohormone
Học thuậtThân thiện
Definition
Noun: A neurohormone is a type of hormone that is produced and released by specialized nerve cells (neurons) directly into the bloodstream or surrounding fluid. Unlike neurotransmitters, which act across a tiny synaptic gap between two neurons, neurohormones are secreted to travel through the circulatory system to affect distant target cells or organs.
Examples
- Norepinephrine acts as both a neurotransmitter and a neurohormone. When released into the bloodstream from the adrenal medulla, it functions as a neurohormone to increase heart rate and blood pressure.
- Vasopressin, also known as antidiuretic hormone (ADH), is a neurohormone released from the pituitary gland that helps regulate water balance in the body.
- The release of the neurohormone oxytocin during childbirth stimulates uterine contractions.
Advanced Usage
- Neurohormonal: The adjective form describes processes or systems involving neurohormones.
- The body's response to stress involves a complex neurohormonal cascade.
- The term is often used in scientific contexts to distinguish the method of delivery (endocrine) from that of classical neurotransmitters (synaptic).
Variants and Related Words
- Neurohormonal (adjective): Pertaining to or involving neurohormones.
- Neurosecretion (noun): The process by which neurons release neurohormones. A neurohormone is a type of neurosecretory substance.
Synonyms
- Neurosecretory substance
- Neural hormone
Different Meanings / Clarifications
- Neurohormone vs. Neurotransmitter: This is a key distinction. Both are chemical messengers released by neurons. A neurotransmitter acts locally at a synapse between two neurons (e.g., dopamine in the brain). A neurohormone is released into the blood to have a more widespread, endocrine effect (e.g., vasopressin acting on the kidneys).
- Neurohormone vs. Hormone: All neurohormones are hormones, but not all hormones are neurohormones. A neurohormone is specifically secreted by neurons. Other hormones are secreted by dedicated endocrine glands (e.g., insulin from the pancreas, which is not a neurohormone).
Noun
- a hormone that is released by nerve impulses (e.g., norepinephrine or vasopressin)