Endocrine System Flashcards
(95 cards)
What are steroids?
-A class of lipids
-Readily diffuse across the cell membrane
-the term steroid describes both hormones produced by the body and artificially produced medications that duplicate the action for the naturally occurring steroids
What is the structure of steroids?
-Main feature of steroids is the fused ring system of 3 cyclohexanes and one cyclopentane
-large number of carbon-hydrogens(make steroids non-polar
-variety of functional groups may be atttached
Fungus steroids
-ergosterols: same function as cholesterol in animals
-required to build and maintain membranes regulates membrane fluidity over the range of physiological temperatures
Plant steroids
-phytosterols: structural component of cell membrane
-brassinosteroids: numerous roles: pollen tube formation, cell expansion and elongation, vascular differentiation
Define cholesterol and its classification
-essential structural component fo mammalian cell membranes: membrane permeability and fluidity
-technically classified as a modified steroid(or a sterol: steroid alcohol)
Cholesterol is an important component for what
-the manufacture of bile acids, steroid hormones and vitamin D
How is cholesterol made?
-Obtained from the diet, and is synthesized in the body from carbohydrates,proteins, fat
How does cholesterol help regulate membrane fluidity?
-disturbs the close packing of the phospholipids
-reduces permeability to some solutes
What type of steroid acts as a hormone?
-sterone
What five groups are steroid hormones grouped in and why?
-steroid hormones are grouped by the receptors to which they bind
-glucocorticoids(corticosteroids)
-mineralocorticoids(corticosteroids)
-androgens(sex steroid)
-estrogens( sex steroid)
-progestins(sex steroid)
Define hormones and what they control
-signaling molecules secreted by a cell that can alter activities of any cell with receptors for it
-typically produced by one tissue and transported through the bloodstream to another tissue to alter its physiological activity
-involved with the control of: development and function of gonads, metabolism, inflammation, salt and water balance in body fluids, molting in insects and crustaceans(ecdysone)
Steroid hormones are… soluble
-lipid soluble
Define sex steroids:
-subset of sex hormones that produce sex differences or support reproduction; includes androgens, estrogens, and progestins
Define corticosteroids
-most medical ‘steroid’ drugs are corticosteroids(prednisone)
-synthesized from cholesterol within the adrenal cortex
Define anabolic steroids
-class of steroids the interact with androgen receptors to increase muscle and bone synthesis
-there are natural and synthetic anabolic steroids
-popular language steroids usually refers to anabolic steroids
What do anabolic steroids do?
-increase production of actin and myosin proteins, can then be incorporated into existing myofibrils and add to muscular strength
-block the effects of stress hormone cortisol on muscle tissue(cortisol contributes to muscle breakdown, decreases amin acid uptake by muscle and inhibits protein synthesis
-affect the number of cells that develop into fat storage cells by favoring cellular differentiation into muscle cells instead
The endocrine system has over 60 major hormones that control
-growth(HGH: human growth hormone)
-reproduction (LH:lutenizing hormone)
-sexual development (testosterone)
-use and storage of energy
The endocrine system works in parallel with the … to control …… along with maintaining….
-nervous system
-growth and maturation
-homeostasis
Endocrine system includes ….
-four major types of cell signaling
Hormones and local regulators are …
-group into 4 classes based on their chemical structure
Hormones are regulated by
-feedback pathways
Define hormones
-substances secreted by cells that control the activities of cells elsewhere in the body
-only specific target cells respond to a specific hormone
Tropic hormone
-a hormone that regulates hormone secretion by another endocrine gland
Classical endocrine signaling
-endocrine glands secrete hormones over a distance (endocrine cell —-hormone—transported through blood—-target cell—response)