Endocrine System Flashcards
(28 cards)
How does the Endocrine system help with body activity?
It releases mediators called hormones.
Hormone
(Hormon = to excite and get moving) is a mediator molecule that is released in one part of the body but regulates the activity of cells in other parts of the body.
How do hormones enter the body?
Through interstitial fluid and then the bloodstream.
How long does it take for a hormone to go into effect?
some in seconds/ most several minutes or more.
Target cells of the body?
virtually all types of cells
How many glands does the body contain?
Two
- Exocrine
- Endocrine
Exocrine Glands
(Outside) secrete their products into ducts that carry the secretions into body cavities, the luman of an organ, or outer surface of the body. includes, sweat, oil, mucus, digestive glands.
Endocrine Glands
(Within) Secrete their products (hormones) into the interstitial fluid surrounding the secretory cells rather than into ducts. Some of the most vascular tissues of the body. Include pituitary, thyroid, parathyroid, adrenal, and pineal glands.
Organs that secrete hormones?
hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta.
Endocrinology
The science and structure and function of the endocrine glands and the diagnosis and treatment of disorders of the endocrine system.
Hormones help regulate:
- Chemical composition & volume of internal environment.
- Metabolism & energy balance.
- Contraction of smooth and cardiac muscle fibers.
- Glandular secretions
- Some immune activites.
Also,
- Control growth and development
- regulate operation of reproductive systems
- help establish circadian rhythms.
What do hormones bind to?
Protein receptors
Hormone binding
Only target cells will have receptors that accept and recognize that hormone that is specific to that target.
How many receptors does a target cell have for hormones?
2000 - 100,000
Down-regulation
an affect present when too much hormones are present so the target-cell decreases.
Up-regulation
an effect present when too little hormones are present so the target cell increases.
Circulating hormones
Most endocrine hormones are circulating. They pass from the secretory cells that make them into interstitial fluid and then to the blood.
Local hormones
act locally on neighboring cells or on the same cell that secreted them without first entering the bloodstream.
Paracrines
local hormones that act on neighboring cells.
Autocrines
hormones that act on the same cell that secreted them.
How many classes can hormones be divided into?
Two
- lipids
- water soluble
Lipid-soluble Hormones - bound to transport proteins.
- Steroid hormones - derived from cholesterol.
- Thyroid hormones - made from iodine & amino acid tyrosine.
- Nitric oxide - both a hormone and neurotransmitter. by the enzyme nitric oxide synthase.
Water-soluble Hormones - circulate in blood in free form
- Amine hormones - made by decarbonizing amino acids.
- Peptide hormones or protein hormones/glycoprotein - amino acid polymers. Glyc = attached carbohydrates.
-eicosanoid hormones - derived from arachidonic acid
TWO MAJOR TYPES: prostaglandins, & leukotrienes.
Transport proteins
- make lipid-soluble hormones temporarily water-soluble which increases their solubility in blood
- help keep hormones in urine through filtering mechanisms in the kidneys of hormone molecules.
- Provide a ready reserve of hormone, already present in bloodstream.
