The Pituitary Gland The hypothalamus significantly influences the pituitary gland Posterior pituitary Hypothalamic releasing and inhibiting hormones are delivered to the anterior pituitary The hypothalamus makes and releases the hormones of the posterior pituitary
Pituitary (Hypophysis) • Posterior Pituitary – “neurohypophysis” • Anterior Pituitary – “adenohypophysis” Oxytocin Antidiuretic Hormone (ADH)
Anterior Pituitary – synthesizes 6 hormones. Growth Hormone (hGH) (also called Somatotropin) Adrenocorticotropic Hormone (ACTH) (also called corticotropin) Thyroid Stimulating Hormone (TSH) Follicle Stimulating Hormone (FSH) Luteinizing Hormone (LH) Prolactin (PRL)
hGH – is the primary hormone that regulates overall body growth, also important in general metabolism. ACTH – stimulates cortisol secretion from the adrenal cortex (the stress hormone!). Also promotes growth of adrenal cortex. TSH – stimulates secretion of thyroid hormone and the growth of the thyroid gland. Important regulator of metabolic activity in the body.
FSH – a) in females: stimulates growth and development of ovarian follicles, and promotes estrogen secretion. b) in males: it is required for sperm production. LH – a) in females: responsible for ovulation and for luteinization. Regulates estrogen and progesterone. b) in males: stimulates interstitial cells (in testes) to secrete testosterone. * called interstitial cell stimulating hormone (ICSH) PRL – enhances breast development and milk production in females.
Pituitary Gland has enormous impact on entire Body. 7ft 7in tall, died at age 22. • Adrenal disorders in Females: • Hirsutism (male hair) • Oligomenorrhea (infrequent menstruation) • Deepening of voice • Hypertrophy of clitoris (resemble penis) Thyroid Goiter.
Negative Feedback Loop of Hypothalmic-Adenohypophysis and the Thyroid Gland
Normal Growth • Growth hormone and other hormones • An adequate diet • Absence of stress • Genetics
Acetyl CoA Hydroxymethyl Glutaric Acid (HMG-CoA) Statin = HMG-CoA reductase inhibitors Mevolaonate Mevolaonate Pyrophosphate Isopentenyl Pyrophosphate Geranyl Pyrophosphate Famesyl Pyrophosphate Squalene Ubiquinone (CoQ10) Dolichol Cholesterol
Cholesterol Vitamin D Cortisone Glucocorticoids Mineralcorticoids Steroid Hormones (testosterone, estrogen, progesterone) Bile Salts
Growth Hormone • Severe hGH deficiency leads to dwarfism • Over secretion of hGH in children leads to gigantism • Over secretion of hGH in adults leads to acromegaly
The Hypothalamus-Pituitary-Adrenal Axis (HPA) The CortisolConnection
CRH = Corticotropin Releasing Hormone ACTH = Adrenocorticotropic Hormone The many functions of cortisol in the body:
Cortisol • Promotes gluconeogenesis • Breakdown of skeletal muscle proteins • Enhances lipolysis (prevents glucose use) • Permissive – needed for NE vasoconstriction • Suppresses the immune system • Response to stressors – protective?
Hyper-Cortisolism • Adrenal tumor that ↑ cortisol • Pituitary tumor that ↑ ACTH e.g., Cushing’s Disease ↑ glucose and ↓ protein Loss of muscle mass Characteristic fat deposits
Normal Hyper-Cortisolism "Moon" face, "Buffalo" hump Protruding abdomen High Blood Pressure Weakness, Acne, Backache Excessive thirst & urination Easy Bruising
Hypo-Cortisolism • Under secretion of adrenal steroid hormones • Autoimmune destruction of adrenal cortex e.g. Addison’s Disease ↓ glucose (hypoglycemia) Poor response to stress Lack of vasoconstriction (permissive NE action)
Symptoms and Clinical Signs Fatigue and muscle weakness. Low Blood Pressure (Orthostatic Hypotension). Headache, sweating, joint and muscle pains. Increased Melanocyte-Stimulating Hormone (MSH).