Endocrine System

What are Hormones?

chemical messengers that travel in the bloodstream to other tissues

Characteristics of Direct Signaling

short distance, cells communicate thru physical contact, gap junctions

Characteristics of Indirect Signaling

long distance, cells communicate thru chemical messengers, hormones or NTs

What are the 5 Types of Indirect Signaling?

autocrine, paracine, endocrine, neuronal, inter-individual

What is Autocrine Signaling?

when the signaling and target cell are the same

What is Paracrine Signaling?

when the signal diffuses to a nearby/adjacent target cell

What is Endocrine Signaling?

when signals travel to distant target cells via circulatory system

Characteristics of Exocrine Glands?

secrete substances thru ducts into external space

Examples of Exocrine Glands?

eccrine, salivary, mucosal

Characteristics of Endocrine Glands?

ductless, release hormones into extracellular fluid/circulatory system

Examples of Endocrine Glands?

pituitary, thyroid, adrenal

What are Secondary Endocrine Organs?

organs whose main functions are non-endocrine, but they also release hormones

What are 2 ways of regulating hormones?

one hormone produces multiple responses, multiple hormones regulate one response/physiological process

What are the 3 Classes of Hormones?

peptides, steroids, amines

Characteristics of Hydrophilic Messengers?

premade, secreted by exocytosis, dissolve in extracellular fluid, bind to transmembrane receptors

Characteristics of Hydrophobic Messengers?

made on demand, diffuse across membranes, bound by carrier proteins, bind to intracellular receptors

What are Protein/Peptide Messengers?

chains of AA, hydrophilic, soluble in aqueous soln, cant diffuse across plasma membrane

Steps Protein/Peptide Messengers

peptide dissolves in EC fluid, travels to target by diffusion or circ, binds to transmembrane proteins, initiates signal, rapid effect

How are Peptide Hormones synthesized?

in advance, by ribosomes, stored in vesicles, secreted by exocytosis

Why synthesize the entire peptide hormone chain?

quick response to stimuli, synthesize hormones all at once

Peptide synthesis process (cleavage)

prehormone inactive, cleavage, prohormone inactive, cleavage, hormone active

Characteristics of Amine Hormones?

NH2 group, endocrine hormones and NTs, hydrophilic except thyroid hormones

Where are Biogenic Amines derived from?

tryptophan, tyrosine, histidine

What are Tryptophan derivatives?

serotonin, melatonin

What are Tyrosine derivatives?

dopamine, epinephrine, thyroid hormones

What is a Histadine derivative?

histamine

Where are Steroid hormones derived from?

cholestrol

What are the 3 Classes of Steroid Hormones?

mineralocorticoids, glucocorticoids, reproductive hormones

Properties of Steroid Hormones?

hydrophobic, transported by carrier protein, travel thru blood vessels, bind to intracellular receptors, SLOW EFFECTS