What are the chemical messengers secreted to target cells?

Hormones

What are the functions of the endocrine system?

Maintain internal environment, regulation of growth and development, control and instigation of sexual reproduction and development

What are the categories of hormones?

Peptides and proteins (polypeptides); amino acid derivatives; steroids (cholesterol based); fatty acid derivatives - eicosanoids

Which hormones are chains of amino acids that are water soluble and make up the largest number of hormones?

peptides

What are the types of amino acid based hormones?

tyrosine derivatives; tryptophan derivatives; glutamic acid

What are the tyrosine derivatives?

thyroid hormones (T₃ and T₄); catecholamines/adrenal medulla (epinephrine, norepinephrine)

What type of hormone is a derivative of cholesterol, consists of four covalently bonded rings, and is lipid soluble?

Steroids

What are examples of steroids?

glucocorticoids, mineralocorticoids, androgens, estrogens, progestogens

What are large groups of molecules derived from polyunsaturated fatty acids?

eicosanoids

What are the principal groups of eicosanoids?

prostaglandins, prostacyclins, leukotrienes, thromboxanes

What type of hormones diffuse through the plasma membrane, enter the nucleus, forms hormone-receptor complex, and then binds to transcription factors to chromosome to activate/inactivate genes?

lipid soluble steroids and thyroid hormones

What type of hormone action is: binds to receptor on cell surface, actives g-protein, actives adenylate cyclase, converts ATP to cAMP, cAMP actives protein kinases which produce the final effect?

peptides and water-soluble amines

Hormones circulate in the blood but only affect cells that have a receptor for that hormone. What are these cells called?

target cells

How to endocrine hormones signal cells?

travel via the bloodstream to target cells

How do neurohormones signal cells?

release via synapses and travel via the bloodstream

What do paracrine hormones act on?

adjacent cells

What do autocrine hormones act on?

released and act on the cell that secreted them

What do intracrine hormones act on?

within the cell that produces them

Endocrine action

the hormone is distributed in blood and binds to distant target cells

Paracrine action

the hormone acts locally by diffusing from its source to target cells in the neighborhood

Autocrine action

the hormone acts on the same cell that produced it

Unlike the nervous system, the endocrine system is ____________?

anatomically discontinuous

Humoral

in response to changing blood levels

Neural

in response to nerve fibers

Hormonal

in response to other hormones

What are the inputs to endocrine cells?

neuron, hormone, ion, organic nutrients

The concentration of hormone as seen by target cells is determined by?

rate of production, rate of delivery, rate of degradation and elimination

Up-regulation

insipidus

down-regulation

type II, melitus

Negative feedback occurs when?

a change in a physiological variable triggers a response that counteracts the initial fluctuation

Example of negative feedback

LH from pituitary stimulates the testes to produce testosterone which in turn feeds back and inhibits LH secretion

Example of positive feedback

LH stimulation of estrogen which stimulates LH surge at ovulation