The Endocrine System Ch 19 PDF

The Endocrine System Ch 19 Intro Cells of the nervous and endocrine system to monitor and adjust the bodies physiological mechanisms. The activities of the two systems are closely coordinated The Nervous system produces short term effects The Endocrine system produces long term effects Releases chem...

The Endocrine System Ch 19 Intro Cells of the nervous and endocrine system to monitor and adjust the bodies physiological mechanisms. The activities of the two systems are closely coordinated The Nervous system produces short term effects The Endocrine system produces long term effects Releases chemicals, hormone, that travel to target organs within the body Overview of the Endocrine System It includes all the endocrine cells and tissues that produce hormones. Endocrine cells are glandular secretory cells that release hormones directly into Interstitial Fluids, Lymph, or Blood. Hormones are chemical signals that stimulate specific cells or organs into action. They regulate the metabolic operations of target cells Organized into 3 categories: 1.Amino acid Derivatives: Small molecules that are structurally similar to AAs Ex. Thyroid Hormone 2. peptide Hormones: Largest group of hormones Composed of Chains of AAs Ex. Growth Hormone 3.Lipid Derivatives: Subdivided into 2 groups: 1. Eicosanoids: 2. Steroids: Structurally similar to cholesterol Ex. Sex Hormones Hormones influence cellular activity by changing the types, activities, or quantities of cytoplasmic enzymes. enzymes are responsible for all cellular activity and metabolism Each hormone has a target cell These are specific cells with receptors that bind the hormones Endocrine activity is triggered by: Humoral Stimulation- Changes to the extracellular fluid Hormonal Stimulation- Arrival or Removal of specific hormones Neural Stimulation- Arrival of neurotransmitters at the neuroglandular junction Most endocrine activity is regulated by Negative Feedback mechanisms Hypothalamus Provides the highest level of endocrine control Integrates the activates of the nervous and endocrine systems Regulates the functions of both the anterior and posterior lobe of the pituitary Controls the production in the anterior lobe by secreting regulatory hormones Acts through the hypophyseal portal system An interlinking system of capillaries between Links hypothalamus and ant. pituitary Pituitary Gland The anterior lobe of the pituitary gland, or adenohypophysis contains a variety of endocrine cells Has 3 regions: 1. Pars Distalis 2. Pars Tuberalis 3. Pars Intermedia The posterior pituitary, or neurohypophysis contains axons of hypothalamic neurons. , Thyroid Gland Located on the anterior surface of the trachea between the cricoid and thyroid cartilages Has 2 main lobes giving it a butterfly-like appearance Lobes joined by the isthmus Thyroid follicles manufacture, store, and secrete thyroid hormones Follicular cells (T thyrocytes) line the follicle These cells actively transport iodine The hormone thyroxine contains 4 Iodine atoms Parafollicular cells (C Thyrocytes) produce Calcitonin Regulate calcium Intake Thymus Lies just posterior to the sternum within the mediastinum of the thoracic cavity Produces many hormones that are important in maintaining immune defense Uniquely, reaches its maximum size just prior to puberty (40g) and decreases in size through adulthood ( at 50 y/o weighs 12g) Adrenal Glands Also called the suprarenal glands attach firmly to the superior border of the kidneys Each is divided structurally and functionally into two regions: 1. The cortex Subdivided into: 1. 2. 3. Outer Glomerulosa- Secretes Mineralocorticoids (Aldosterone) Middle Zona Fasciculata- Secretes Glucocorticoids (cortisol) Inner Zona Reticularis- Secretes Androgen 2. The medulla Contains two populations of secretory cells 1. 2. Secretes Epinephrin- adrenaline Secretes Norepinephrine Pancreas Both an exocrine and endocrine gland: The exocrine pancreases makes up 99% of pancreatic volume Secreted digestive enzymes The endocrine pancreas consists of small groups of endocrine cells scattered within the gland Groups of cells are called islets of Langerhans Contain 4 types of cell: Alpha Cells- Secrete glucagon Beta Cells- Secrete insulin Delta Cells- Secrete Somatostatin F Cells- Secrete pancreatic polypeptide Ovaries & Testis