Endocrine - scope of hormones Flashcards
What are the 2 body control systems which overlap and integrate at many levels?
The nervous system and the endocrine system
Define “hormone”.
A chemical mediator that is secreted by an endocrine tissue or gland into the blood, which transports it to its target cell.
What are the differences between endocrine and paracrine actions?
1- Endocrine = major hormones of human body and are released by the 7 classic endocrine glands
1-Paracrine = ‘factors’ released by numerous specialised tissues, NOT part of the classic endocrine system
2-Endocrine uses circulatory system to transport hormones
2-Paracrine uses extracellular fluid to transport hormones
3-Endocrine signalling acts on faraway cells
3-Paracrine signalling acts on nearby cells
What are neurohormones?
Hormone secreted by neurons into the blood
What are the 3 types of endocrine action?
- single gland releases multiple hormones (e.g. anterior pituitary gland)
- single hormone released by more than one endocrine gland (e.g. somatostatin)
- single hormone with more than one target cell (vasopressin)
What is a tropic hormone classified as?
A tropic hormone is one whose primary function is the regulation of HORMONE SECRETION by another endocrine gland. (e.g. thyroid-stimulating hormone - released by anterior pituitary gland and arrives at thyroid gland to release thyroid hormone)
What is a trophic hormone classified as?
A trophic hormone is one whose function is to stimulate and maintain its endocrine target tissue. (e.g. TSH stimulates thyroid gland, making cells larger and more numerous)
What are the 3 classifications of hormones?
Peptide
Amine
Steroid
What is a hydrophilic hormone and where is its receptor on its target cell?
A hydrophilic hormone is water soluble. As it is NOT lipophilic, it cannot pass through the lipid cell membrane of its target cell(s) and so the receptor must be on the cell surface (cascade effect)
E.g. peptides and amines
What is a lipophilic hormone and where is its receptor on its target cell?
A lipophilic hormone is lipid soluble. It can pass through the lipid cell membrane of its target cell and so its receptor will be (deep) inside the cell.
E.g. Steroids, thyroid hormone
What is hyposecretion of a hormone?
Secretion is too little
What is primary hyposecretion?
Primary hyposecretion is because of an abnormality in the gland.
What are some factors that may cause primary hyposecretion?
Genetic Dietary Chemical/Toxic Immunological Disease Iatrogenic Idiopathic
What is secondary secretion?
Endocrine gland is A-OK but is secreting too little hormone because of a problem with its tropic hormone
What is the typical treatment for hyposecretion?
Replacement therapy
