Endocrine Glands and Hormones Endocrine glands produce hormones and secrete them into the bloodstream. Ductless glands Hormones then travel through the bloodstream until they reach their target organ, which they affect in a highly specific manner. Hormones only affect the organ(s) that contain a specific receptor for that hormone; resulting in this highly specific response once a hormone binds to its target tissue.
Pituitary Gland Attached to the hypothalamus by the infundibulum Divided into two lobes: Anterior Lobe Glandular tissue Posterior Lobe Neural tissue
Anterior Pituitary 1 Hypothalamic neurons secrete releasing and inhibiting hormones into primary capillary plexus. 2 Hypothalamic hormones travel though hypophyseal portal veins to the anterior pituitary; where they stimulate or inhibit release of hormones from the anterior pituitary. 3 Anterior pituitary hormones are secreted into secondary capillaries.
Hypothalamic Control of Anterior Pituitary
Anterior Pituitary Hormones Trophic hormones stimulate hormone secretion in other glands: Growth Hormone (GH) Thyroid-stimulating hormones (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimlulating hormone (FSH) Luteinizing hormone(LH) Prolactin (PRL) Can cause hypertrophy of target organ at high concentrations.
Posterior Pituitary Hormones Anti-diuretic Hormone (ADH) Also known as vasopressin Acts upon kidney to promote water re-absorption Urine volume is decreased Oxytocin Stimulates smooth muscle contraction, especially during parturition (birthing process) Promotes milk let-down (milk ejection reflex) in females.
Adrenal GlandAdrenal Cortex Regulated by hormones Release hormones called corticosteroids Zona glomerulosa – secretes mineralcorticoids Regulate Na+ and K+ balance Aldosterone: Sodium and water retention; while excreting potassium Zona fasciculata – secretes glucocorticoids Regulate glucose metabolism and that of other organic molecules. Cortisol: stimulate glucose formation and inhibit utilization of glucose. Zona reticularis – secrete sex steroids Weak androgens like Dehydropepiandrosterone (DHEA)Adrenal medulla Regulated by neural innervation Secretes epinephrine and norepinepherine Cause sympathetic-like response Activate by stress (fight or flight response) “Girls From Russia Make Good Soup”
Pancreas The pancreas is both an endocrine and an exocrine gland. Endocrine cells are located in islets of Langerhans. Alpha cells secrete glucagon Beta cells secrete insulin
This is what we will see in lab today
Diabetes Mellitus Type I Diabetes Mellitus [insulin-dependent] “adolescent-onset diabetes” Caused by destruction of the beta cells. Lack of insulin secretion leads to extracellular hyperglycemia and increased lipolysis Ketonemia Diabetic ketoacidosis: a condition of insulin deficiency causing increased hepatic ketogenesis; occurs in Type I diabetes only. 10% of diabetic population Type II Diabetes Mellitus [non insulin-dependent] “maturity-onset diabetes” Insulin resistance (target cells do not respond normally) Normal or elevated [insulin] initially; relative insulin deficiency Most patients obese 90% of diabetic population