a chemical that is produced in the body of a plant or animal, sometimes in very small quantities, and which, when transported (usually by the blood stream in animals) to the target site in another part of the organism, elicits a particular response.
http://medical-dictionary.thefreedictionary.com/Chemical+messenger
nucleus/cytosol. The strength of binding between a messenger and its receptor is known as __________. affinity. One of the striking features of second messengers is the ability to elicit a marked response on a target cell by small changes in the concentration of a chemical messenger. This phenomenon is known a(n) __________. signal amplification.
https://www.studyblue.com/notes/note/n/chp-5/deck/9764210
Injection of epinephrine into the blood stream will cause an increase of blood flow throughout the body. The relief is only temporary due to the short half-life of adrenaline; therefore, immediate hospitalization is required to ensure safety to the individual.
https://www1.udel.edu/chem/C465/senior/fall00/Performance1/epinephrine.htm.html
Epinephrine, more commonly known as adrenaline, is a hormone secreted by the medulla of the adrenal glands. Strong emotions such as fear or anger cause epinephrine to be released into the bloodstream, which causes an increase in heart rate, muscle strength, blood pressure, and sugar metabolism. This reaction, known as the Flight or Fight Response prepares the body for strenuous activity.
https://www1.udel.edu/chem/C465/senior/fall00/Performance1/epinephrine.htm.html
The ACTH chemical messengers, sent from the pituitary gland into the bloodstream, arrive at the adrenal cortical cells. When the splanchnic nerve in the hypothalamus fires, a signal is sent down the spinal cord directly to the adrenal gland.
http://learn.genetics.utah.edu/content/cells/fight_flight/
a chemical transmitter substance produced by cells of the body and transported by the bloodstream to the cells and organs on which it has a specific regulatory effect. adj., adj hormo´nal. Hormones act as chemical messengers to body organs, stimulating certain life processes and retarding others.
http://medical-dictionary.thefreedictionary.com/Chemical+messenger
Specifically, blood tests can help doctors: 1  Evaluate how well organs—such as the kidneys, liver, thyroid, and heart—are working. 2  Diagnose diseases and conditions such as cancer, HIV/AIDS, diabetes, anemia (uh-NEE-me-eh), and coronary heart disease. 3  Find out whether you have risk factors for heart disease.
https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/
1. (Biochemistry) a chemical substance produced in an endocrine gland and transported in the blood to a certain tissue, on which it exerts a specific effect. 2. (Biochemistry) an organic compound produced by a plant that is essential for growth. 3. (Biochemistry) any synthetic substance having the same effects.
http://www.thefreedictionary.com/Chemical+messenger
Blood tests are very common. When you have routine checkups, your doctor may recommend blood tests to see how your body is working. Many blood tests don't require any special preparations. For some, you may need to fast (not eat any food) for 8 to 12 hours before the test. Your doctor will let you know how to prepare for blood tests.
https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/
parathormone, parathyroid hormone - hormone synthesized and released into the blood stream by the parathyroid glands; regulates phosphorus and calcium in the body and functions in neuromuscular excitation and blood clotting.
http://www.thefreedictionary.com/Chemical+messenger
what blood stream messenger
Hormones are  blood stream messengers. Hormones are the bloodstream messenger.