Hypothalamus GHRH (+) GHIH ( - ) Pituitary Sleep Stress Exercise Limbic structures Metabolic signals Glucocorticoids GH somatotropin Direct effects mobilize fat insulin antagonist Indirect effects Somatomedins:IGF-1  protein synthesis  tissue growth  (-)(-) (-)(-)

Thyroid Hormones Include –Triiodothyronine or T 3 –Tetraiodothyronine or T 4 or thyroxine Transported in blood Bind with intracellular receptor molecules and initiate new protein synthesis Increase rate of glucose, fat, protein metabolism in many tissues thus increasing body temperature Normal growth of many tissues dependent on

Thyroid Hormone Hyposecretion and Hypersecretion Hypothyroidism –Decreased metabolic rate –Weight gain, reduced appetite –Dry and cold skin –Weak, flabby skeletal muscles, sluggish –Myxedema –Apathetic, somnolent –Coarse hair, rough dry skin –Decreased iodide uptake –Possible goiter Hyperthyroidism –Increased metabolic rate –Weight loss, increased appetite –Warm flushed skin –Weak muscles that exhibit tremors –Exophthalmos –Hyperactivity, insomnia –Soft smooth hair and skin –Increased iodide uptake –Almost always develops goiter

Parathyroid Glands Embedded in thyroid Secrete PTH –Increases blood calcium levels –Stimulates osteoclasts –Promotes calcium reabsorption by kidneys

Regulation of PTH Secretion

 Decreasing blood Calcium Parathyroids Parathyroid hormone KidneysBone Reabsorption of Calcium Dissolution of CaPO 4 crystals Increased blood Calcium Active Vitamin D Increased Calcium absorption in Small Intestine.

Adrenal Glands Functions as part of sympathetic nervous system Composed of medulla and cortex (3 layers) Hormones –Medulla secretes epinephrine and norepinephrine –Cortex secretes mineralocorticoids, glucocorticoids, androgens

Hormones of Adrenal Cortex Mineralocorticoids –Zona glomerulosa –Aldosterone produced in greatest amounts Increases rate of sodium reabsorption by kidneys increasing sodium blood levels (regulates water volume) Glucocorticoids –Zona fasciculata –Cortisol is major hormone Increases fat and protein breakdown, increases glucose synthesis, decreases inflammatory response Androgens –Zona reticularis –Converted to androgen and testosterone

 Blood Pressure  Chloride Ion Kidney Renin Lungs Angiotensin II Zona Glomerulosa Aldosterone Reabsorption of Na+ Excretion of K+ & H+  Blood Volume Vasoconstriction  Blood Pressure (+) (-)(-) (-)(-)  K+ (+).

Nonspecific Stress Higher Brain Centers Hypothalamus Zona Fasciculata Anterior Pituitary CRH ACTH Cortisol (-)(-) (-)(-) Gluconeogenesis Mobilization of fat stores  bone formation  immune system (+)

Pancreas Located along small intestine and stomach Exocrine gland –Produces pancreatic digestive juices Endocrine gland –Consists of pancreatic islets –Composed of Alpha cells secrete glucagon Beta cells secrete insulin Delta cells secrete somatostatin

Insulin and Glucagon Insulin Target tissues: liver, adipose tissue, muscle, and satiety center of hypothalamus Increases uptake of glucose and amino acids by cells Glucagon Target tissue is liver Causes breakdown of glycogen and fats for energy

Regulation of Insulin Secretion

Regulation of Blood Nutrient Levels After a Meal

Regulation of Blood Nutrient Levels During Exercise

Hormones of the Reproductive System Male: Testes Testosterone –Regulates production of sperm cells and development and maintenance of male reproductive organs and secondary sex characteristics Inhibin –Inhibits FSH secretion Female: Ovaries Estrogen and Progesterone –Uterine and mammary gland development and function, external genitalia structure, secondary sex characteristics, menstrual cycle Inhibin –Inhibits FSH secretion Relaxin –Increases flexibility of symphysis pubis

Pineal Body In epithalamus Produces –Melatonin Enhances sleep –Arginine vasotocin Regulates function of reproductive system in some animals

Effects of Aging on Endocrine System Gradual decrease in secretory activity of some glands –GH as people age –Melatonin –Thyroid hormones –Kidneys secrete less renin Familial tendency to develop type II diabetes

Diabetes Mellitus Results from inadequate secretion of insulin or inability of tissues to respond to insulin Types –Type I or IDDM (Insulin-dependent) Develops in young people –Type II or NIDDM (Non-insulin dependent) Develops in people older than More common