Hypothalamus

GHRH(+)

GHIH

(-)

Pituitary

SleepStressExercise

Limbicstructures

Metabolicsignals

Glucocorticoids

GHsomatotropin

Direct effects mobilize fat insulin antagonist

Indirect effects Somatomedins:IGF-1 protein synthesis tissue growth

(-)

(-)

Thyroid Hormones

• Include

– Triiodothyronine or T3

– Tetraiodothyronine or T4 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 bloodCalcium

Parathyroids

Parathyroid hormone

Kidneys Bone

Reabsorption of Calcium

Dissolution of CaPO4 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

ZonaGlomerulosa

Aldosterone

Reabsorption of Na+Excretion of K+ & H+ Blood Volume

Vasoconstriction Blood Pressure

(+) (-)

(-)

K+ (+)

.

Nonspecific StressHigher Brain

Centers

Hypothalamus

ZonaFasciculata

Anterior Pituitary

CRH

ACTH

Cortisol

(-)

(-)

GluconeogenesisMobilization 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 40-45

• More common