Chapter 17 - Endocrine System

Front 1

Endocrine

Back 1

derived from greek words "endo" and "crino", meaning to separate within

Front 2

Endocrine System

Back 2

body's communication organ system; composed of glands that secrete chemical signals into the circulatory system

Front 3

Hormones

Back 3

secretory products of endocrine glands; means "to set into motion"; a chemical signal that
1)is produced in minute amounts by collections of cells
2)is secreted into the interstitial places
3)enters the circulatory system, where it is transported some distance, and
4)acts on specific tissues at another site in the body to influence the activity of those tissues in a specific fashion

Front 4

Amplitude-modulated signals

Back 4

signals that impact target tissues mainly by increases or decreases in the conc. of hormones in the body fluid; most endocrine hormones are this

Front 5

Frequency-modulated signals

Back 5

signals that vary in frequency but not in amplitude; exert their effect based on frequency of stimulus; common among neuronal signals

Front 6

Neurohoromone

Back 6

chemical signals that are secreted into the circulatory system by neurons;
function like hormones

Front 7

Intercellular chemical signals

Back 7

allow one cell to communicate with other cells

Front 8

Autocrine chemical signals

Back 8

type of intercellular chemical signal released by cells and have a local effect on the same cell type from which the chemical signals are released

Front 9

Paracrine chemical signals

Back 9

type of intercellular chemical signal released by cells and affect other cell types locally without being transported in the blood

Front 10

Pheromones

Back 10

specialized chemical signals that are secreted into the environment and modify the behavior and the physiology of other individuals

Front 11

Biological half-life

Back 11

the length of time it takes for half a dose of a substance to be eliminated from the circulatory system

Front 12

Factors by which the half-life of hormones is shortened

Back 12

1)Excretion
2)Metabolism
3)Active Transport
4)Conjugation

Front 13

Factors by which the half-life of hormones is lengthened

Back 13

1)bind reversibly with plasma proteins
2)some hormones are protected by their structure (i.e., carbohydrate complexes of glycoprotein hormones

Front 14

Conjugation

Back 14

accomplished when cells in the liver attach water-soluble molecules to the hormone, usually sulfate or glucuronic acid; "mark" molecules for excretion by the kidney and liver at a greater rate

Front 15

Receptor site

Back 15

the portion of each protein or glycoprotein molecule where a chemical signal binds on a receptor molecule

Front 16

Specificity

Back 16

the tendency for each type of chemical signal to bind to a specific type of receptor site, and not to others

Front 17

Down-regulation

Back 17

a phenomenon in which the number of receptors on a cell surface can rapidly decrease after exposure to certain chemical signals;
in general, tissues that exhibit this are adapted to respond to short-term increases in hormone conc. and tissues that respond to hormones maintained at constant levels normally do not exhibit this

Front 18

Up-regulation

Back 18

periodic increases in the sensitivity of some cells to certain hormones;
results from an increase in the rate of receptor molecule synthesis

Front 19

Membrane-bound receptors

Back 19

hormone molecule receptors that extend across the plasma membrane and have their receptor sites exposed to the outer surface of the plasma membrane;
initiates a response inside the cell

Front 20

Intracellular receptors

Back 20

receptors in the cytoplasm or in the nucleus of the cell; usually interact with lipid-soluble hormones

Front 21

G-protein

Back 21

complex receptor proteins of the plasma membrane that produce intracellular response through the action of a second-messenger; consists of three subunits: alpha, beta, and gamma

Front 22

Intracellular mediators

Back 22

ions or molecules that either enter the cell, or are synthesized in the cell, and regulate enzyme activities inside of the cell

Front 23

Adenylate cyclase

Back 23

an enzyme activated by G proteins; converts ATP to cAMP

Front 24

Protein kinases

Back 24

enzymes that regulate the activity of other enzymes by attaching phosphates to them; activated by cAMP

Front 25

Phosphorylation

Back 25

regulation of cellular activity by the attachment of phosphate ions;
increases or decreases the activity of the enzyme, depending on the specifc enzyme

Front 26

Cyclic guanine monophosphate (cGMP)

Back 26

an intracellular mediator molecule that is synthesized in response to a chemical signal binding with a membrane-bound receptor;
combine with specific enzymes in the cytoplasm of the cell and activates them, producing a response

Front 27

Guanylate cyclase

Back 27

an enzyme located at the inner surface of the plasma membrane that converts GTP to cGMP and two phosphates

Front 28

Cascade effect

Back 28

an amplification system that facilitates rapid hormonal response within a cell; results when a few mediator molecules activate several enzymes and each of the activated enzymes in turn activates several other enzymes that produce the final response