endocrine system Flashcards
allow cells to communicate with each other to regulate body activities
-most are produced by a specific collection of cells or gland
chemical messenger
organ consisting of epithelial cells that specialized in secretion
gland
controlled release of chemicals from a cell
secretion
– secreted in a local area
-stimulates the cell that originally secreted it
autocrine
act locally on nearby cells
-secreted by one cell type in ECF and affect surrounding cells
paracrine
– secreted by neurons
- activate an adjacent cell, whether neuron, muscle cell or glandular cell
- secreted into synaptic cleft
- can be considered paracrine agents
neurotransmitters
– secreted into the bloodstream by certain glands and cells
-affect cells distant from source
endocrine
composed of – endocrine glands + endocrine cells (throughout the body)
endocrine system
– chemical messengers secreted into bloodstream, not into a duct
hormones
types of hormones
– nonpolar
-steroid, thyroid, fatty acid derivative (e.g. eicosanoids)
Lipid-soluble hormones
type of hormone
– polar
-protein, peptide, most amino acid derivative
water soluble hormones
• Circulate as free hormones (dissolve directly into blood and delivered to target tissue w/o attaching to binding proteins) because they can dissolve in blood
water soluble hormones
• Tend to diffuse from the walls of the capillaries more slowly (because they are big)
water soluble hormones
• Capillaries regulated by these hormones are usually fenestrated or very porous
water soluble hormones particularly protein
type of hormone that • Have short half-lives
water soluble