Pituitary Gland “The Master Gland”
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Pituitary Gland “The Master Gland” • 2 Functional Lobes *Anterior Lobe *Posterior Lobe • Interacts closely with the Nervous System through the hypothalamus. • Protected by what structure? Anterior Pituitary • Regulated through humoral stimulation from the hypothalamus. • Many of the hormones released are Trophic Hormones. Anterior Pituitary Hormones • GH – Somatotropin – promotes mitosis – Too much = Gigantism or Acromegaly – Too little = Dwarfism • PRL – Prolactin – promotes breast milk production during gestation and nursing – Hyperprolactinemia = can disrupt fertility and menstruation – Hypo-secretion = lack of milk production • ACTH - Adrenocorticotropic Hormone – promotes the adrenal gland to release its hormones – Hypersecretion = Cushing’s Syndrome – Hyposecretion = loss of cortisol release by adrenal glands Anterior Pituitary Hormones • TSH - Thyroid Stimulating Hormone – promotes the thyroid gland to release its hormones – Hyposecretion can lead to hyperactive thyroid – Hypersecretion can lead to hypoactive thyroid and production of a Goiter • GRN – Gonadotropin Releasing Hormone – promotes activity in gonads – Hyper- and hypo- secretion can both lead to infertility Too Much Growth Hormone • Acromegaly is caused by too much growth hormone AFTER puberty has completed. • Gigantism is caused by too much growth hormone during adolescence and puberty. Too Little Growth Hormone • The girl below is pictured with her father at the age of 5 years. • The man on the left is 25 years old. The man on the right is 22 years old. Abnormal TSH secretion Goiter formation due to inadequate iodine consumption. Posterior Pituitary Hormones • Oxytocin – stimulates labor contractions during delivery – Lack of oxytocin during labor and delivery requires administration of PITOCIN to prompt contractions. • ADH – Antidiuretic Hormone – prevents loss of water from kidneys to bladder during times of dehydration. – Diabetes insipidis – loss of too much water – Polydipsia – excessive thirst Thyroid Gland • Located in the anterior portion of the neck, just below the throat. • Releases hormones that act on the metabolic rate. *T3: triiodothyronine *T4: thyroxine • Calcitonin – maintains blood calcium levels Thyroid Gland • T3: triiodothyronine & T4: thyroxine – High levels of these hormones can increase metabolic rates – Low levels of these hormones can decrease metabolic rates • Calcitonin – Low levels can result osteoporosis and kidney stones since blood calcium is not being placed into the bones Parathyroid Gland • Located on the posterior surface of the Thyroid gland. • Parathyroid Hormone (PTH) Parathyroid Gland Parathyroid Hormone (PTH) • The MOST important regulator of blood calcium levels. • Low levels of PTH result in muscle spasms and heart palpitations • High levels of PTH result in osteoporosis, too much calcium is being taken from bones Adrenal Glands • Located on the superior aspect of each kidney • 2 functional parts * Cortex * Medulla Each part secretes a specific type of hormone. Adrenal Gland Divisions CORTEX MEDULLA • MINERALOCORTICOID • CORTICOSTEROIDS – controls fluid and – Controls sympathetic/ electrolyte balance parasympathetic – Example - aldosterone function • Produces sex hormones – Example – cortisol and epinephrine – Example – androgens and (adrenaline) progesterone Pancreas • Located in abdominal cavity behind stomach. • Produces hormones for the use and storage of glucose – Insulin – allows glucose to absorb into cells – Glucagon – removes stored glucose from liver and fat cells Pancreas Insulin – Too little – diabetes mellitis – inability to use sugar to make ATP – Too much – hypoglycemia – low blood sugar Glucagon – Too much – glucagonoma caused by tumor of pancreas leads to symptoms much like diabetes – Too little – chronic low blood sugar due to inability to release glucose from liver and fat cells Pineal Gland • Close to the optic nerve in the brain. • Produces Melatonin - sleep-wake cycles. Disorders of Pineal Gland • Decreased melatonin levels are associated with – Insomnia • Chronic Fatigue Syndrome – Panic Disorders – Depression • SAD – Seasonal Affective Disorder – Peptic ulcers Thymus Gland • Located behind the sternum. • Decreases in size as you age. • Produces Thymosin needed for the production of T- lymphocytes. T-cells are needed for protection against viral infections, fungal infections, and cancer development Thymus Gland • Both high and low levels of thymosin cause immune dysfunction. – Too little thymosin results in lack of immune response – Too much thymosin causes havoc for the immune system and it does not respond correctly Gonads: Ovaries and Testes • Hormone producing glands of the female and male reproductive systems. • Controls fertility, reproduction, and gestation. Testes produce testosterone Ovaries produce estrogen Other Hormone-Producing Organs/Tissues • Placenta • Skin • Stomach • Adipose/Fat • Intestines • Liver • Heart • Kidneys • Striated muscles • Uterus.