Endocrine System

Chemical Messengers secreted into the blood or extracellular fluid by one cell that affect the functioning of other cells

That system that broadcasts its hormonal message to essentially all cells by secretion into blood and extracellular fluid…cells must bear a receptor for the hormone being broadcast in order to respond

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

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

The hormone acts on the same cell that produced it

A roundish organ that lies immediately beneath the hypothalamus, resting in depression of the base of the skull called the sella turcica

Anterior Pituitary: composed of cells that secrete protein hormones Posterior Pituitary: composed largely of axons of hypothalamic neurons, which extend downward as a large bundle behind anterior pituitary Stalk: portion of the posterior pituitary that suspends the anterior gland from the hypothalamus

target: liver, adipose tissue Promotes growth, control of protein, lipid, and carbohydrate metabolism

Target: thyroid gland Stimulates secretion of thyroid hormones

Target: adrenal gland Stimulates secretion of glucocorticoids

Target: Mammary a Gland Milk production

Target: ovary and testies Control of repro function

Target: Ovary and testies Control of repro function

Target: kidney Conservation of body water

Target: ovary and testies Stimulates milk ejection and uterine contractions

Melatonin: aids night activity in reptiles and amphibians

Thyroxin and triiodothyronine: growth, metabolism and cellular differentiation Calcitonin: minor role in decreasing blood calcium levels

Parathyroid Hormone: maintains blood calcium levels

May control stem cell production of lymphocytes

Glucocorticoids: promote gluconeogenesis, decrease inflammatory reaction, affect muscle tone, and excitability of nerves, affect fat and water metabolism, inherit cartilage growth and development Aldosterone: maintains proper levels of blood sodium and phosphorus Epinephrine: fight or flight reaction

Insulin: promotes movement of glucose into the cells Glucagon: promotes the breakdown of glycogen to glucose

Testis Ovaries Uterus Stomach Small intestines Kidney Liver

Proteins and peptides Generation of second messengers which alter activity of other molecules usually enzymes within the cell

Steroids and thyroid Hormones Alter transcriptional activity of responsive genes