Endocrine system

• Action: regulation of glucose metabolism
• Pituitary gland is a ductless gland that has directly supply hormones to the blood circulation.
• Pituitary gland acts as a chemical messenger.
• Pituitary gland, also known as the master pituitary gland, has two parts: Adenohypophysis (Anterior Pituitary Gland) and Neurohypophysis (Posterior Pituitary).
• Adenohypophysis (Anterior Pituitary Gland) has three parts: Par Distalis, Pars Intermedia, and Pars Tuberalis.
• Neurohypophysis (Posterior Pituitary) has one part: Pars Nervosa.
• Pars Distalis of Adenohypophysis (Anterior Pituitary Gland) is acidophilic and secretes Prolactin (PRL) which targets the Mammary Gland and has the action of milk production in preparation of parturition and lactation.
• Pars Distalis of Adenohypophysis (Anterior Pituitary Gland) also secretes Somatotrophin (Growth Hormone/GH) which targets the Epiphyseal Plate (?) and has the action of stimulating growth.
• Pars Distalis of Adenohypophysis (Anterior Pituitary Gland) also secretes Adenocortotrophic Hormone (ACTH) which targets the Adrenal Gland and produces cortisol.
• Oxytocin acts by causing the contraction of myoepithelial cells during milk ejection and relaxing the pubic symphysis during parturition.
• Neurohypophysis (Posterior Pituitary Gland) contains Pars Nervosa which secretes Oxytocin.
• Insulin originates from Beta Cells and its target site/organ is liver, skeletal muscle, adipose tissue.
• Gonadocorticoids originate from Zona Reticularis and its target site/organ is stress hormone.
• Norepinephrine originates from Adrenal Glands (Chromophobe cell) and its target site/organ is blood pressure maintenance in times of stress.
• Adrenal Gland is a parenchymatous organ which has the same structure of kidney which has Cortex and Medulla.
• Glucagon originates from Alpha Cells and its target site/organ is liver, it helps glucose levels rise back up.
• Aldosterone acts by stimulating sodium reabsorption and potassium excretion.
• Action: stimulate testosterone to release by Leydig cells of testes.
• Epinephrine originates from Adrenal Glands (Chromophobe cell) and its target site/organ is vascular smooth muscle.
• Adrenal Cortex consists of 3 parts: Zona Glomerulosa, Zona Fasciculata, Zona Reticularis.
• Vasopressin/Antidiuretic Hormone originates from Neurohypophysis: Hypothalamus and its target site/organ is kidney.
• Cortisol (Endogenous Steroids) originates from Zona Fasciculata and its target site/organ is stress hormone.
• Vasopressin/Antidiuretic Hormone acts by decreasing water excretion and increasing water absorption in the collecting ducts.
• Oxytocin originates from Neurohypophysis: Pars Nervosa and its target site/organ is Mammary Gland (myoepithelial cells in the muscular layer) and Pubic symphysis.
• Aldosterone originates from Zona Glomerulosa and its target site/organ is kidney.
• Pars Distalis of Adenohypophysis (Anterior Pituitary Gland) also secretes Thyroid Stimulating Hormone (TSH) which targets the Thyroid and produces T3 and T4 which regulate basal metabolic rate (BMR).
• Pars Distalis of Adenohypophysis (Anterior Pituitary Gland) also secretes Follicle Stimulating Hormone (FSH) which targets the Ovary and stimulates follicular growth.
• Pars Distalis of Adenohypophysis (Anterior Pituitary Gland) also secretes Luteinizing Hormone (LH) which targets the Testes and stimulates testosterone to release by Leydig cells of testes.
• Pars Intermedia of Adenohypophysis (Anterior Pituitary Gland) secretes Proopiomelanocortin (POMC) which targets the Adrenal Gland and acts as a precursor of ACTH.
• Pars Tuberalis of Adenohypophysis (Anterior Pituitary Gland) secretes Luteinizing Hormone (LH) which targets the Testes and is secreted by both Pars Distalis and Tuberalis.