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Transcript
Chapter 9 The Endocrine System General Characteristics chemicals released by cells enter the bloodstream target specific cells/organs regulated by negative feedback goal is to preserve homeostasis Endocrine System Two types of glands in the body Exocrine - secrete products through a duct − sweat, oil, salivary glands Endocrine - release hormones into the blood or lymph − pituitary, pancreas, thyroid Hormones chemical substances secreted that regulate metabolic activity of cells Hormones amino acid-based − proteins − peptides − amines steroids − derived from cholesterol prostaglandins − derived from lipids Hormone Action change plasma membrane permeability or electrical state synthesis of proteins/enzymes activation or inactivation of enzymes stimulation of mitosis Hormone Action each hormone affects only target cells or organs specific protein receptors − internal receptors − plasma membrane Hormone Action internal receptors − diffuse through membrane − result in mRNA translation of new protein plasma membrane − bind to membrane receptor (protein) − produces a second messenger to effect changes Hormone Action What causes endocrine glands to release hormones? negative feedback mechanisms − − hormone secretion is triggered increase in hormone levels inhibit further release − example: low blood Ca2+ Endocrine Organs Pituitary Gland where? two functional lobes − − anterior pituitary: glandular posterior pituitary: nervous Pituitary Gland Anterior Pituitary releases hormones − − − two affect non-endocrine organs tropic hormones: stimulate other endocrine glands to secrete hormones all are proteins Non-endocrine Anterior Pituitary Hormones Growth hormone (GH) − growth of skeletal muscles and long bones pituitary dwarfism gigantism Prolactin (PRL) - (pro = for; lact = milk) − milk production Tropic Anterior Pituitary Hormones Adrenocorticotropic hormone (ACTH) − regulates cortex of adrenal gland Thyroid-stimulating hormone (TSH) − growth and activity of thyroid Gonadotropic Anterior Pituitary Hormones regulate hormonal activity of gonads (ovaries and testes) follicle-stimulating hormone (FSH) − ♀ stimulates follicle development in ovaries − ♂ stimulates sperm development in testes luteinizing hormone (LH) − ♀ triggers ovulation − ♂ stimulates testosterone production Anterior Pituitary & Hypothalamus hypothalamus controls anterior pituitary hypothalamic hormones released into blood of portal system − portal system = 2 capillary beds connected by veins Hypothalamus & Posterior Pituitary hormones − − oxytocin antidiuretic hormone (ADH) synthesized by neurosecretory cells − transport hormones down axons to posterior pituitary Posterior Pituitary technically not an endocrine gland − − oxytocin − does not make the hormones it releases stores hormones made by hypothalamus uterine contractions, milk ejection antidiuretic hormone (ADH) − inhibits urine production Lab Exercise 15: Spinal Cord & Nerves − − − cow spinal cord demo answer questions pg 126. complete Review Sheet pp 301-302. Exercise 16 − all activities Pituitary Gland Thyroid Gland Thyroid Gland hormones − − thyroid hormone calcitonin follicles − store sticky precursor to hormones Thyroid hormone T4 or thyroxine T3 or triiodothyronine both contain iodine control glucose oxidation rate goiter − enlargement of thyroid gland due to lack of iodine Calcitonin decreases blood calcium levels − how? PTH antagonist Parathyroid glands posterior surface of thyroid parathyroid hormone (PTH) − − regulates Ca2+ in blood negative feedback mechanism Calcitonin and PTH Calcitonin and PTH Adrenal Gland cortex − glandular medulla − neural Adrenal Cortex Corticosteroids − − − mineralcorticoids glucocorticoids sex hormones Adrenal Cortex Mineralcorticoids − regulate mineral or salt content of blood − aldosterone K+ and Na+ ions target organ: kidneys Adrenal Cortex Glucocorticoids − − − − cortisone cortisol increase blood glucose levels long term stressors sex hormones − − androgens estrogens Adrenal Medulla neural secretes catecholamines − − epinephrine (adrenaline) norepinephrine sympathetic nervous response = short term stressor glucocorticoids = long term stressor Pancreas A unique gland with both exocrine and endocrine functions − − Exocrine: produces enzymes for digestion Endocrine: produces hormones for blood glucose regulation Pancreas pancreatic islets insulin glucagon Pancreas high blood glucose stimulates beta cells to release insulin insulin increases cells ability to move glucose across cell membranes Pancreas glucagon − − insulin antagonist released by alpha cells low blood glucose stimulates release targets liver to break down glycogen to glucose