Endocrine System

1. Endocrine System By: Faith K.& Kennedy R.

2. Overview • Compared to other organs of the body, the organs of the Endocrine System are small and unimpressive. Indeed, to collect 1kg (about 2.2 pounds) of hormone-producing tissue, you would need to collect all the endocrine tissue from eight or nine adults! The Endocrine System also lacks the structural or anatomical continuity typical of most organ systems. Instead, bit and pieces of Endocrine tissue are tucked away in widely separated regions of the body. However, functionally the endocrine organs are impressive, and when their role in maintaining body homeostasis is considered, they are true giants.

3. Major Body organs

4. Pituitary gland • The neuroendocrine gland located beneath the brain that serves a variety of functions including regulation of the glands, thyroid, adrenal cortex, water balance, and lactation.

5. Thyroid gland • Often referred to as the body’s major metabolic hormone, is actually two active iodine-containing hormones, thyroxine or T4, and triiodothyronine T3. • It is also one of the largest of the body’s endocrine glands • It straddles the anterior trachea. • Thyroxine is the major hormone secreted by the thyroid follicles. • Most triiodothyronine is formed at the target tissues by conversion of thyroxine to triiodothyronine

6. Pineal gland • The pineal gland is a small cone shaped gland that hangs from the roof of the third ventricle of the brain. • Function: secretes melatonin ( makes you drowsy )

7. Parathyroid glands • Secrete parathyroid hormone PTH or Parathormone. Which is the most important regulator of homeostasis in the blood. • PTH stimulates osteoclasts to break down bone matrix and release calcium into the blood

8. Thymus • Produces a hormone called thymosinand others that appear to be essential for normal development of a special group of white blood cells and the immune response • Its large in infants and children and decreases in size throughout adulthood by old age it is composed of mostly of fibrous connective tissue and fat.

9. Adrenal Gland • Curve over top of kidneys and are bean shaped. • The adrenal cortex produces three major groups of steroid hormones which are collectively called Corticosteriods(Mineralocorticoids, Glucocorticoids, and sex hormones. • Mineralocorticoids= are important in regulating the mineral (salt) content of the blood (sodium and potassium ions) • Glucocorticoids= promote normal cell metabolism and help the body to resist long term stressors primarily by increasing blood Glucose levels

10. Ovaries • Producing female sex cells (Ova) • Also produce two groups of steroid hormones : estrogen and progesterone • Estrogen: responsible for developing sex characteristics in women • Progesterone: works with estrogen to bring about the menstrual cycle and during pregnancy it quiets the muscles of the uterus so that an implanted embryo will not be aborted and help prepare breast tissue for lactation .

11. Testes • Suspended in a sac, the scrotum, outside the pelvic cavity • In addition to sperm they also produce male sex hormones (Androgens) of which testosterone is the most important. • Testosterone: promotes the growth and maturation of the reproductive system organs to prepare the young man for reproduction and also causes secondary sex characteristics (facial hair, lower voice, heavy bones, and muscles)

12. Pancreas • Located close to the stomach in the abdominal cavity • It is a mixed gland. Which has both exocrine and endocrine portions. • Has pancreatic islets that produce insulin and glucagon