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Alexis Rice Summary Chapter 13Endocrine System: Collection of specialized cells, and tissues that secrete hormones.-Hormones have access to every cell-Each hormone acts only on specific cells (target cells)-Only specific cells have receptors for specific hormones -Endocrine control is slower than nervous system-Endocrine and nervous systems interactEndocrine Glands: Ductless organs that secrete hormones into blood, interstitial fluid, lymphHormones: - Chemical messengers secreted by endocrine glands-Circulate in the bloodstream-Act on specific cells in the bodySteroid Hormones: - Structurally related to cholesterol-Lipid soluble, chemically derived from cholesterol-Activate specific genes to produce specific proteins-Slower acting than non-steroid hormones; minutes to hoursNon-steroid Hormones: - Structurally relates to proteins-Lipid insoluble-Water soluble-Bind to receptors on target cell membranes -Work through intermediate mechanisms to activate existing enzymes-Faster action than steroid hormones; seconds to minutesNegative Feedback Loops of Hormones: -Many hormones participate in internal homeostatic control mechanisms-Negative feedback loop involving hormones includes the following:-Endocrine gland serves as the control center-Hormone is the pathway between the control center and the effectors -Target tissues or organ are effectorsHypothalamus: - Homeostatic control center of the brain-Links nervous system and endocrine system-Produces two hormones of its own-Monitors and controls hormone secretions of the pituitary glandPituitary Gland: - “Master” gland-Secretes eight different hormones that regulate other endocrine organs-Two lobes: posterior and anteriorPosterior Pituitary: - Connection to hypothalamus by neuroendocrine cells-Hormones made in hypothalamus, stored in posterior pituitary-Hormones (ADH and oxygen) made in cell bodies in hypothalamus are transported down axons to axon endings in posterior pituitaryPosterior pituitary hormones non-steroidal: -Antidiuretic hormone (ADH)-Conserves water in kidneys-Regulates water balance in body-Oxytocin-Causes uterine contractions during labor and milk ejection through neuroendocrine reflex.Anterior Pituitary:-Controlled by hypothalamus-Releasing and inhibiting hormones from hypothalamus travel to pituitary throughpituitary portal system -The release of each anterior pituitary hormone is controlled, at least partially, bythe hypothalamusAnterior Pituitary Hormones:-ACTH (adrenocorticotropic hormone)-Stimulates adrenal cortex to release glucocorticoids (cortisol)-TSH (thyroid-stimulating hormone)-Acts on thyroid gland, promoting release of thyroid hormones -FSH and LH (gonadotropins)-Stimulate growth, development, and function of ovaries and testes-Not produced until about age 10-13 (puberty)-Increase in production initiates sexual maturation and development at puberty-Prolactin-Stimulates development of mammary glands and milk production-Growth Hormone-Has widespread effects on body-Major effects on bone, muscle-Most of its growth-promoting effects occur during childhood and adolescencePituitary Disorders: Hypersecretion and Hyposecretion -Diabetes Insipidus-Hyposecretion of ADH results in inability to conserve water appropriatley-Causes excessive urination, dehydration, thirst -Gigantism-Hypersecretion of growth hormone in childhood -Acrosmegaly-Excessive growth hormone over a long period in adults-Pituitary Dwarfism-Hyposecretion of growth hormone over a long period in adultsPancreas Secretes Glucagon, Insulin, and Somatostatin:-Pancreas: has both exocrine and endocrine functions-Pancreatic hormones are involved in regulating blood glucose levels -Endocrine cells in Islets of Langerhans within the pancreas secrete the followingthree hormones: -Alpha cells: secrete glucagon-Beta cells: secrete insulin-Delta cells: secrete somatostatin-Glucagon-Raises blood sugar-Causes breakdown of glycogen to glucose in liver-Insulin-Lowers blood sugar-Promotes uptake of sugar by cells in liver, muscle, and adipose tissue-Promotes conversion of glucose into glycogen, proteins, fat-Somatostatin-Inhabits secretion of glucagon and insulin, regulates other hormonesAdrenal Glands:-Adrenal Cortex: outer layer-Adrenal medulla: inner layerAdrenal Cortex: Glucocorticoids and Mineralocorticoids-Glucocorticoids (Cortisol is an example)-Secretion mediated through hypothalamus pituitary secretions-Maintain blood glucose levels during prolonged fasting-Suppress inflammatory responses-Mineralocorticoids (Aldosterone is an example)-Regulate sodium, potassium, water balance-Act on kidneys, promoting sodium reabsorption and potassium excretionAdrenal Medulla: Epinephrine and Norepinephrine-Adrenal Medulla-Neuroendocrine organ -Secretion stimulated by-Sympathetic nervous system-Hormones: Nonsteroidal-Epinephrine and norepinephrine-Enhance function of sympathetic nervous system-(fight-or-flight response)Thyroid and Parathyroid Glands·Thyroid located just below larynx in neck·Parathyroid glands embedded in back of thyroid·Both thyroid and parathyroid involved in calcium balance·Thyroid also involved in regulating metabolismThyroid Gland: Thyroxine Speeds Cellular Metabolism-Secretion: mediated through hypothalamus pituitary secretions-Steroidal hormones-Thyroxine (T4) and Triiodothyronine (T3)-Both regulates production of ATP from glucose, affect metabolic rate-Calcitonin-Lowers blood calcium levels-Decreases rate of bone resorption by inhibiting osteoclasts-Stimulates uptake of calcium by bonesParathyroid Hormone (PTH) Controls Blood Calcium Levels-Secretion-Response to lowered blood calcium levels-Action-Removes calcium and phosphate from bone-Increases absorption of calcium by the digestive tract-Causes kidneys to retain calcium and excrete phosphate-Major regulator of blood calcium concentration in adultsTestes Produce Testosterone-Functions of testosterone and other androgens-Before birth – responsible for development of external male genitalia-At onset of puberty-Regulates development and normal functioning of sperm, male reproductive organs, and male sex drive.-Regulates development of male secondary sex charachteristics-Small amounts of androgens produced by adrenal glands in both sexesOvaries Produce Estrogen and Progesterone-Hormones: steroidal-Estrogen-Initiates development of secondary sex characteristics-Regulates menstrual cycle-Progesterone-Regulates menstrual cycleOther Glands and Organs Also Secrete Hormones-Thymus:


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OHIO BIOS 1030 - Summary Chapter 13

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