1. The Endocrine System

2. Introduction Second messenger system of the body
Hormones control several major processes
Reproduction
Growth and development
Mobilization of body defenses
Maintenance of much of homeostasis
Regulation of metabolism

4. Hormones Cells secrete hormones into extracellular fluids
Blood transfers hormones to target sites
These hormones regulate the activity of other cells
Steroid Hormones- derived from cholesterol, sex hormones, adrenal cortex hormones Ex. Estrogen, testosterone. Cortisol.
Nonsteroid Hormones- amines, proteins, peptides, glycoproteins, most hormones Ex. OT, FSH, TSH

6. Steroid Hormone Action
Diffuse through the plasma membrane of target cells
Enter the nucleus
Bind to a specific protein within the nucleus
Bind to specific sites on the cell’s DNA
Activate genes that result in synthesis of new proteins

8. Nonsteroid Hormones Hormone binds to a membrane receptor
Hormone does not enter the cell
Sets off a series of reactions that activates an enzyme
Catalyzes a reaction that produces a second messenger molecule
Oversees additional intracellular changes to promote a specific response

10. How are they Released

11. Major Glands

12. Pituitary Gland Size of a grape Hangs by a stalk from the hypothalamus
Protected by the sphenoid bone
Has two functional lobes
Anterior pituitary – glandular tissue
Posterior pituitary – nervous tissue

13. Anterior Pituitary Hormones
Growth Hormone (GH)- stimulates increase in size and rate of body cells, enhances movement of amino acids through membranes, promotes growth of long bones, secretion inhibited by somatostatin, secretion stimulated by growth hormone-releasing hormone
Prolactin (PRL)- sustains milk production after birth, amplifies effect of LH in males,
Thyroid Stimulating Hormone (TSH)- controls secretions of hormones from the thyroid gland,

14. Cont……..
Adrenocorticotropic Hormone- controls secretions of some hormones of adrenal cortex,
Follicle-Stimulating Hormone (FSH)- stimulates development of egg-containing follicles in ovaries, stimulates follicular cells to secrete estrogen, stimulates production of sperm cells, controlled by gonadotropin-releasing hormone
Luteinizing Hormone (LH)- promotes secretions of sex hormones, stimulates release of egg from ovary, promotes growth of long bones, controlled by gonadotropin-releasing

15. Posterior Pituitary Hormones
Antidiuretic Hormone (ADH)- causes kidneys to reduce water excretion, in high concentration, raises blood pressure, controlled by hypothalamus in response to changes in blood water concentration and blood volume
Oxytocin (OT)- stimulates uterine contractions, stimulates mammary glands to release milk, controlled by hypothalamus in response to stretch in uterine and vaginal walls and stimulation of breasts

16. Overview

17. Thyroid Hormones
Thyroxine (T4) and Triiodothyronine (T3)- increases rate of energy release from carbohydrates, increases rate of protein synthesis, accelerates growth, stimulates activity in the nervous system, controlled by TSH
Calcitonin- lowers blood calcium and phosphate ion concentrations by inhibiting release of calcium and phosphate from bones, increases rate at which calcium and phosphate are deposited in bones

18. Thyroid Disorders
General Hyperthyroidism high metabolic rate, hyperactivity, weight loss, protruding eyes
Cretinism- hypothyroidism in infants, leads to small stature and mental retardation
Myxedema- adult hypothyroidism, low metabolic rate, sluggishness

19. Parathyroid Hormone
PTH- increases blood calcium levels, decreases blood phosphate levels, stimulates bone resorption by osteoclasts, inhibits osteoblasts, stimulates kidneys to retain calcium and excrete phosphate, promotes calcium absorption into intestine
Disorders: Hyperparathyroidism- caused by tumor, fatigue, muscular weakness, altered mental functions, bone weakening. Hypoparathyroidism- caused by injury or removal of gland, muscle cramps, seizures, low blood calcium levels

20. Adrenal Hormones
Epinephrine and Norepinephrine- come from the medulla of the adrenal gland release controlled by sympathetic nervous system, increases heart rate and blood pressure, dilates respiratory airways, promotes breakdown of glycogen, activates reticular formation, increases metabolic rates
Cortex Hormomes: Aldosterone-increases blood volume and pressure by promoting conservation of sodium ions and water. Cortisol- decreases protein synthesis, increases fatty acid release, stimulates glucose synthesis from noncarbohydrates. Adrenal androgens- supplement sex hormones from the gonads, may be converted to estrogen

21. Pancreatic Hormones
Glucagon- stimulates liver to break down glycogen, stimulates liver to convert noncarbohydrates into glucose, stimulates break down of fats, controlled by blood glucose concentrations
Somatostatin- helps regulate carbohydrates
Insulin- promotes formation of glycogen from glucose, inhibits conversion of noncarbohydrates into glucose, enhances movement of glucose into adipose and muscle cells, decreases blood glucose concentrations, promotes transport of amino acids, enhances synthesis of proteins and fats, controlled by blood glucose concentrations

22. Others
Pineal Gland- secretes melatonin, regulates circadian rhythms, may control onset of puberty, helps regulate female reproductive
Thymus Gland- secretes thymosins, promotes development of certain lymphocytes
Reproductive Glands- ovaries secrete estrogen and progesterone, testes secrete testosterone, placenta secretes estrogen, progesterone, and gonadotropins

23. Life’s little Curves endocrine glands shrink
GH levels even out, muscular strength decreases
ADH levels increase due to slow break down
calcitonin levels decrease
PTH increases, osteoporosis risk increases
insulin resistance may develop
changes in melatonin secretion affect the body clock
thymosin production declines increasing risk of infections

25. References Jack Brown M.S. Biology
Shier,David, Jackie Butler, Ricki Lewis: Hole’s Human Anatomy and Physiology 10th edition: 2004: McGraw-Hill
Marieb, Elaine: Essentials of Human Anatomy and Physiology 7th edition. 2003: Pearson Education Inc: Benjamin Cummings pub.
Microsoft Encarta Encyclopedia 2004