ENDOCRINOLOGY NOTES Flashcards
the study of hormones, the endocrine system, and their physiological role in the body
Endocrinology
secretes its products into the interstitial fluid and the blood
Endocrine Gland
a chemical messenger released from living cells that travels through the blood to target cells and induces a biological effect or response
Hormone
cells with receptors to specific hormones
only cells with specific receptor will react with a specific hormone
Target Cells
Hormone receptors
In or on the surface of the cell membrane: ___________________________
In the cell cytoplasm: _______________
In the cell nucleus: ________________
peptide and catecholamine hormones
steroid hormones;
thyroid hormones
may consist of a single cell or a group of cells that secrete substances into ducts (tubes), onto a surface, or into the blood in the absence of ducts
Glands
Two major types of glands
endocrine glands
exocrine glands
glands with ducts products pass out of the cell and away from the gland by means of ducts into a luminal area
Exocrine Glands
products are released from the cell, passed directly into the circulation, and are
carried by the blood to body tissues and eventually target cells
Endocrine Glands
interaction between secreted chemical messenger with a receptor on the same type of cell that synthesized it
Autocrine
interaction of a secreted chemical messenger with receptors on adjacent cells on the
same tissue
Paracrine
example of Autocrine
Example: insulin-like growth factor-I (IGF-I)
example of paracrine
Example: somatostatin secretion inhibits insulin secretion
expressed on surface of effector cell and interacts with target cell via direct cell-cell
contact
Juxtacrine
Example of juxtacrine
Example: cell adhesion proteins (laminin)
secretes own hormone that acts inside the same cell, regulating intracellular events
Intracrine
one organism releases a substance (pheromone) that causes a response in another
organism
Ectocrine
a chemical messenger produced by a ductless gland or tissue and carried in the blood to a target organ where it effects a change in cellular activity
Endocrine
Principal Functions of the Endocrine System
- maintenance of the internal environment in the body (homeostasis)
Examples: PTH and insulin - integration and regulation of growth and development
- control, maintenance, and instigation of sexual reproduction
Types of Hormones
- Peptide Hormones
- Steroid Hormones
- Amine Hormones
Derived from cholesterol which are rapidly mobilized
- Steroid Hormones
- Peptide Hormones
May contain ________________ (TRH: 3; GH: 200)
___________; no need for transport proteins
Synthesized in _________; stored in ________
Secretion: ___________
__________,_________half-life
3 to 200 amino acids
Water soluble
ribosomes; vesicles
exocytosis
fast acting; short
Hydrophobic/lipophilic; require specific transport proteins as carriers
- Steroid Hormones
- Steroid Hormones
Secretion: ___________________
___________; ______half-life
diffusion across cell membrane
slow-acting; longer half-life
(behave like peptides; cell surface receptors)
Catecholamines
(behave like steroids; nuclear receptors)
Thyroid hormones
behave like protein hormones because they circulate
unbound to protein, have a short half-life, and have a similar mechanism
of action
Catecholamines
have a long half-life, circulate bound to a carrier
protein, and have a mechanism of action similar to steroids
Thyroid hormones
- Substrate control
Example: glucose and insulin
- Nervous control
Example: adrenal medulla hormones
- Tropic hormones
Example: release of hormones by anterior pituitary to stimulate other glands (e.g., ACTH to adrenal cortex)
