ENDOCRINE SYSTEM Works more slowly than nervous system, releasing hormones into the blood that can control virtually all body cells Works more slowly than nervous system, releasing hormones into the blood that can control virtually all body cells Works with nervous system to coordinate functions of all body systems Works with nervous system to coordinate functions of all body systems

Function of Hormones Help regulate: Help regulate: Chemical compositions and volume of internal environment (interstitial fluid) Chemical compositions and volume of internal environment (interstitial fluid) Metabolism and energy balance Metabolism and energy balance Contraction of smooth and cardiac muscle fibers Contraction of smooth and cardiac muscle fibers Some immune system activities Some immune system activities Control growth and development Control growth and development Regulate operation of reproductive system Regulate operation of reproductive system Help establish circadian rhythms Help establish circadian rhythms

Endocrine glands Endocrine glands Do not secrete products into ducts like exocrine glands Do not secrete products into ducts like exocrine glands Secrete their products (hormones) into the interstitial fluid surrounding the secretory cells, then diffuse from blood into the interstitial fluid where they interact with their target cells Secrete their products (hormones) into the interstitial fluid surrounding the secretory cells, then diffuse from blood into the interstitial fluid where they interact with their target cells Include pituitary, thyroid, parathyroid, adrenal, and pineal glands Include pituitary, thyroid, parathyroid, adrenal, and pineal glands

Hypothalamus Control Center for internal environment Regulates nervous and endocrine systems via 3 mechanisms: Direct neural control over adrenal medulla ADH and Oxytocin production Regulatory hormone production (RH and IH) controls pituitary gland directly and all other endocrine glands indirectly

Pineal gland small endocrine gland in the brain small endocrine gland in the brain shaped like a tiny pine cone shaped like a tiny pine cone located near the center of the brain, between the two hemispheres located near the center of the brain, between the two hemispheres produces melatonin, a hormone that may weakly modulate wake/sleep patterns. produces melatonin, a hormone that may weakly modulate wake/sleep patterns.

Pituitary Gland (= Hypophysis) Gross Anatomy: Infundibulum adenohypophysis (anterior) neurohypophysis (posterior) Gross Anatomy: Infundibulum adenohypophysis (anterior) neurohypophysis (posterior) Gross Anatomy: Gross Anatomy: Posterior: Storage shed for ADH and oxytocin both produced in hypothalamus Posterior: Storage shed for ADH and oxytocin both produced in hypothalamus Anterior:7 peptide hormones Anterior:7 peptide hormones Anterior:

Hypophyseal Portal System Portal system: two capillary networks in serial arrangement Portal system: two capillary networks in serial arrangement Named after their destination Named after their destination Portal veins: blood vessels that link two capillary networks Portal veins: blood vessels that link two capillary networks

Thyroid Gland n Anterior surface of trachea just inferior of thyroid cartilage (or Adam’s apple) n Two lobes connected by isthmus n Thyroid follicles and thyroid hormone n C cells and Calcitonin

Four Parathyroid Glands Located on posterior surface of thyroid (superior and inferior) Located on posterior surface of thyroid (superior and inferior) Parathyroid hormone (PTH) Parathyroid hormone (PTH) Function: antagonist to Calcitonin. Function: antagonist to Calcitonin.

Thymus Gland Inside thoracic cavity immediately posterior to sternum Largest just before puberty Thymosin (important for immune system)

Adrenal or Suprarenal Gland Cortex: aldosterone, cortisol, sex hormone Cortex: corticosteroid production aldosterone, cortisol, sex hormone Medulla: modified sympathetic ganglion adrenaline and noradrenaline Medulla: modified sympathetic ganglion adrenaline and noradrenaline

Pancreas Part of endocrine and Part of endocrine and digestive systems. (99% exocrine) Pancreatic islets Pancreatic islets or islets of Langerhans Pancreatic islets  cells: glucagon  cells: glucagon (stimulates liver to convert glycogen to glucose)  cells: insulin  cells: insulin (promotes movement of glucose through cell membrane)  cells: somatostatin  cells: somatostatin