Chapter 18 Endocrine Reading Notes - Chapter 18 Main...

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Chapter 18Main regulatory functions of the endocrine system (maintenance of homeostasis and normal physiological functioning):1) Metabolism: Nutrient utilization and energy production. Glucose breakdown/storage.2) Food intake and digestion: Hunger/fullness. 3) Tissue development4) Helps regulate blood pH, as well as ion levels in the blood5) Water balance through ion levels6) Heart rate and blood pressure change: Helps prepare body for physical activity7) Control of reproductive functions8) Uterine contractions and milk release9) Immune system functionPITUITARY GLAND AND HYPOTHALAMUSThe hypothalamus contributes to regulatory control of the pituitary glandHypothalamus: In the diencephalon of the brain. Major site of nervous system and endocrine system interaction. The hypothalamus is regulated by 1) Hormones2) Sensory information entering the central nervous system. 3) Emotions.Pituitary gland: Secretes seven hormones and twoneurohormones that regulate physiological activities. Locatedinferior to the hypothalamusHypothalamus regulates the secretory activity of the pituitarygland. In fact, the posterior pituitary is an extension of thehypothalamus. Infundibulum: Pituitary stalk. Connects the hypothalamus to the pituitary.Parts of the pituitary gland:1) The posterior pituitary: Hormones released from the posterior pituitary are called neuropeptidesor neurohormones because hormones released from the posterior pituitary are released from neurons rather than endocrine cells.2) Anterior pituitary:Derived from epithelial tissue and releases hormones rather than neurohormones. This is because anterior pituitary release is from endocrine cells rather than neurons.
THE POSTERIOR PITUITARYAnatomy: Cell bodies are in the hypothalamus. Axons terminals in the posterior pituitary. Secretory vesicles store neurohormone within posterior pituitary neurons until an action potentialfires Action potentials pass down the axon and results in exocytosis and the release of neurohormone. Neurohormones then enter the bloodstream and act on target cells.POSTERIOR PITUITARY HORMONESmoodle.rockyview.ab.ca1. Antidiuretic hormone (ADH):Function: ADH functions to maintain osmolality and blood volume within a normal range of values (the set point).Stimulus of release: Increased osmolarity in blood (high ion concentration or low water concentration). Synthesis: Made by neuronal cell bodies in the hypothalamus and stored in axon terminals within the posterior pituitary. Increased osmolarity in blood results in action potentials in ADH neurons. This causes increased release of ADH from the posterior pituitary into the bloodstream.Target Tissue:1) Kidneys: ADH reduces water loss through urine by retaining water in the body.

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