Ch. 13 Endocrine System

Endocrine System  System consisting of cells, tissues, and organs “glands” that release substances called hormones into the internal environment of the body.

Gland Types  Endocrine - secretions go into the blood stream.  Exocrine - secretions go into ducts.  The endocrine system utilizes endocrine glands, not exocrine.

Homeostatic Functions  Regulate metabolic processes  Control rates of certain chemical reactions  Transport across cell membrane  Regulate water and electrolyte balance  Roles in reproduction, development, and growth

Hormone Action  Biochemical released by one cell to affect second cell(s)  Travels into extracellular fluid or by blood stream  Works only on specific target cell.  Watch animation from cd

Prostaglandin Action  Act locally  Affect the organ from which they are produced  Potent and rapidly activated, not stored

Control of Hormonal Secretions  Negative feedback system  Gland secretes a substance  Substance reaches a certain concentration  Endocrine gland becomes inhibited (turns off), which is a negative effect.  Due to inhibition, concentration of substance decreases.  Endocrine gland becomes uninhibited (turns on)

Control Sources  Hypothalamus controls pituitary  Pituitary stimulates other endocrine glands  receives constant information from cerebrospinal fluid.  info from neural connections in brain

Control Sources Continued  Brain controls some glands directly (adrenal medulla - sympathetic response)  Responds to internal environment (insulin production - blood glucose levels)

Diseases of the Endocrine System  Dwarfism - insufficient secretion of growth hormone during childhood.  Gigantism - oversecretion of growth hormone during childhood.

Diseases of the Endocrine System  Cretinism - underactive thyroid gland during infancy and childhood.  Graves diseases (hyperthyroidism) - overstimulation of the thyroid gland.  Goiter - an iodine deficiency causes thyroid to enlarge an function improperly

Diseases of the Endocrine System  Addison’s disease - adrenal cortex does not secrete hormones sufficiently causing a variety of electrolyte imbalances, low blood pressure, and increased skin pigmentation to name a few.  Cushing’s disease - caused by hypersecretion of cortisol (primarily). Causes high blood pressure, fluid retention and thin skin to name a few.