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Endocrine System. CHAPTER 13. Endocrine System Overview. Endocrine system Consists of ductless glands Secrete hormones directly into bloodstream Affect the function of specific body organs Regulates many intricate body functions. Pituitary Gland. Referred to as “master gland”
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Endocrine System CHAPTER 13
Endocrine System Overview • Endocrine system • Consists of ductless glands • Secrete hormones directly into bloodstream • Affect the function of specific body organs • Regulates many intricate body functions
Pituitary Gland • Referred to as “master gland” • Secretes hormones that control functions of other glands • Known as hypophysis • Has two distinct lobes with specific functions
Pituitary Gland • Anterior Pituitary Gland = Adenohypophysis • Secretes Growth Hormone (GH) • Also called Somatotropic Hormone (STH) • Regulates growth of bone, muscle, and other body tissues • Secretes Adrenocorticotropic Hormone (ACTH) • Stimulates normal growth and development of adrenal cortex and secretion of corticosteroids
Pituitary Gland • Anterior Pituitary Gland • Secretes Thyroid-Stimulating Hormone (TSH) • Promotes and maintains normal growth and development of the thyroid gland • Stimulates secretions of the thyroid hormones • Secretes Lactogenic Hormone (LTH) • Also called Prolactin • Promotes development of breasts during pregnancy • Stimulates secretion of milk from breasts after delivery of baby
Pituitary Gland • Anterior Pituitary Gland • Secretes Follicle-Stimulating Hormone (FSH) • Stimulates secretion of estrogen and production of eggs in the female ovaries • Stimulates production of sperm in the male testes • Secretes Luteinizing Hormone (LH) • Stimulates female ovulation and the secretion of testosterone in the male • Melanocyte-Stimulating Hormone (MSH) • Controls intensity of pigmentation in pigmented cells of the skin
Pituitary Gland • Posterior Pituitary Gland = Neurohypophysis • Secretes Antidiuretic Hormone (ADH) • Decreases excretion of large amounts of urine • Increases reabsorption of water by the renal tubules • Secretes Oxytocin (OT) • Stimulates contraction of the uterus during childbirth • Stimulates release of milk from the breasts of lactating women in response to the suckling reflex of the infant
Pineal Gland • Tiny, pinecone-shaped gland • Located behind dorsal aspect of midbrain region • Plays a part in supporting body’s biological clock • Regulation of patterns of eating, sleeping, and reproduction • Secretes melatonin • Induces sleep
Thyroid Gland • Located in front of the neck just below the larynx, on either side of the trachea • Consists of a right and left lobe
Thyroid Gland • Secretes Triiodothyronine (T3) • Helps regulate growth and development of body • Helps control metabolism and temperature • Secretes Thyroxine (T4) • Helps maintain normal body metabolism • Secretes Calcitonin • Helps regulate the level of calcium in the blood
Parathyroid Glands • Four tiny rounded bodies located on dorsal aspect of thyroid gland • Secrete Parathyroid Hormone (PTH) • Also known as parathormone • Regulates level of calcium in blood
Thymus • Single gland located in mediastinum near the middle of the chest, just beneath sternum • Large in fetus and infants, shrinks with age • Secretes thymosin and thymopoietin • Stimulates production of T cells that are involved in the immune response
Adrenal Glands • Two small glands, one positioned atop each kidney • Also known as suprarenal glands • Consists of an adrenal cortex and an adrenal medulla • Each has independent functions
Adrenal Glands • Adrenal cortex secretes corticosteroids • Mineralocorticoids • Regulate how mineral salts (electrolytes) are processed in the body • Glucocorticoids • Influence metabolism of carbohydrates, fats, and proteins in the body • Necessary for maintaining normal blood pressure • Have an anti-inflammatory effect on the body • Increase glucose available during “fight-or-flight” responses by the body
Adrenal Glands • Adrenal cortex secretes • Gonadocorticoids • Sex hormones secreted in small amounts • Contribute to secondary sex characteristics in males and females
Adrenal Glands • Adrenal medulla secretes catecholamines • Epinephrine = adrenaline • Sympathiomimetic agent • Increases heart rate and force of heart muscle contraction • Dilates bronchioles in the lungs • Decreases peristalsis in the intestines • Raises blood glucose levels by causing the liver to convert glycogen into glucose
Adrenal Glands • Adrenal medulla secretes • Norepinephrine = noradrenaline • Known as a sympathomimetic agent • Produces a vasoconstrictor effect on the blood vessels, thereby raising blood pressure
Pancreas • Elongated gland located in upper left quadrant of the abdomen • Behind the stomach • Extends horizontally across the body • Beginning at first part of small intestines and ending at edge of spleen
Pancreas • Islets of Langerhans secrete: • Glucagon • Increases blood glucose levels by stimulating liver to convert glycogen into glucose when blood sugar is extremely low • Insulin • Makes it possible for glucose to pass from blood through cell membranes to be used for energy • Promotes conversion of excess glucose into glycogen for storage in the liver for later use
Ovaries • Female sex glands = female gonads • Pair of almond shaped glands • Located in upper pelvic cavity, on either side of lateral wall of uterus • Near fimbriated ends of the fallopian tubes • Responsible for producing mature ova and releasing them at monthly intervals during ovulation
Ovaries • Hormones secreted by the ovaries • Estrogen • Promotes maturation of ovum in the ovary • Stimulates vascularization of uterine lining each month to prepare for implantation of a fertilized egg • Contributes to secondary sex characteristic changes in female with onset of puberty • Progesterone • Primarily responsible for changes within the uterus in anticipation of a fertilized ovum • Responsible for development of maternal placenta after implantation of a fertilized ovum
Testes • Testes = male gonads = testicles • Two small ovoid glands located in scrotum • Primary organs of male reproductive system • Responsible for production of sperm and secretion of androgens (male steroid hormones) • Secrete testosterone • Responsible for secondary sex characteristic changes that occur in male with onset of puberty • Responsible for maturation of sperm
PATHOLOGICAL CONDITIONS Pituitary Gland
Acromegaly • Pronounced • (ak-roh-MEG-ah-lee) • Defined • Chronic metabolic condition characterized by the gradual, noticeable enlargement and elongation of the bones of the face, jaw, and extremities, due to hypersecretion of the human growth hormone after puberty
Diabetes Insipidus • Pronounced • (dye-ah-BEE-teez in-SIP-ih-dus) • Defined • Deficiency in secretion of antidiuretic hormone (ADH) by posterior pituitary gland • Characterized by large amounts of urine and sodium being excreted from the body
Dwarfism • Pronounced • (DWARF-ism) • Defined • Generalized growth retardation of body due to deficiency of human growth hormone • Also known as congenital hypopituitarism or hypopituitarism
Gigantism • Pronounced • (JYE-gan-tizm) • Defined • Proportional overgrowth of body’s tissue due to hypersecretion of human growth hormone before puberty
Hypopituitarism • Pronounced • (high-poh-pih-TOO-ih-tah-rizm) • Defined • Complex syndrome resulting from absence or deficiency of pituitary hormone(s)
PATHOLOGICAL CONDITIONS Thyroid Gland
Cancer, Thyroid Gland • Pronounced • (CAN-sir, THIGH-royd gland) • Defined • Malignant tumor of the thyroid gland • Leads to dysfunction of gland and inadequate or excessive secretion of thyroid hormone
Goiter, Simple; Nontoxic • Pronounced • (GOY-ter simple; nontoxic) • Defined • Hyperplasia of thyroid gland • Results from a deficient amount of iodine in diet, required for synthesis of T3 and T4, thyroid hormones produced by the thyroid gland
Graves’ Disease (Hyperthyroidism) • Pronounced • (high-per-THIGH-royd-izm) • Defined • Hypertrophy of thyroid gland resulting in excessive secretion of thyroid hormone • Causes extremely high body metabolism, thus creating multisystem changes
Graves’ DiseaseHyperthyroidism • Three distinguishing characteristics • Hyperthyroidism • Thyroid gland enlargement (goiter) • Exophthalmia • Unnatural protruding of the eyes
Hypothyroidism • Pronounced • (high-poh-THIGH-royd-izm) • Defined • Condition in which there is a shortage of thyroid hormone causing an extremely low body metabolism due to a reduced usage of oxygen
Hypothyroidism • Most severe form known as myxedema • Water retention all over body in connective tissues • Person has puffy appearance and thick tongue • Reduced metabolic rate
Thyroiditis(Hashimoto’s) • Pronounced • (thigh-royd-EYE-tis) • (HASH-ee-moh-TOZ) • Defined • Chronic inflammation of the thyroid gland, leading to enlargement of the thyroid gland
Thyrotoxicosis(Thyroid Storm) • Pronounced • (thigh-roh-toks-ih-KOH-sis) • Defined • Acute, sometimes fatal, incident of overactivity of the thyroid gland resulting in excessive secretion of thyroid hormone
PATHOLOGICAL CONDITIONS Parathyroid Gland
Hyperparathyroidism(Hypercalcemia) • Pronounced • (high-per-pair-ah-THIGH-royd-izm) • (high-per-kal-SEE-mee-ah) • Defined • Overactivity of any one of the parathyroid glands • Leads to high levels of calcium in blood and low levels of calcium in bones
Hypoparathyroidism • Pronounced • (high-poh-pair-ah-THIGH-royd-izm) • Defined • Decreased production of parathyroid hormone resulting in hypocalcemia • Characterized by nerve and muscle weakness with muscle spasms or tetany
PATHOLOGICAL CONDITIONS Adrenal Glands
Addison’s Disease • Pronounced • (AD-ih-sons dih-ZEEZ) • Defined • Life-threatening disease process due to failure of the adrenal cortex to secrete adequate mineralocorticoids and glucocorticoids • Resulting from an autoimmune process, a neoplasm, an infection, or a hemorrhage in the gland
Conn’s Disease(Primary Aldosteronism) • Pronounced • (PRYE-mary al-doss-STAIR-ohn-izm) • Defined • Condition characterized by excretion of excessive amounts of aldosterone • Leads to an increased volume of blood and hypertension • Causes body to retain extra sodium and excrete extra potassium
Cushing’s Syndrome • Pronounced • (CUSH-ings SIN-drom) • Defined • Cluster of symptoms in the adrenal gland as a result of an excessive amount of cortisol or ACTH circulating in blood
Cushing’s Syndrome • Cushing’s Syndrome • Symptoms • Central obesity • Round “moon” face • Edema • Hypertension • Supraclavicular fat pads (buffalo hump) • Muscular weakness and wasting • Skin infection • Poor wound healing • Low potassium level • Emotional changes
Pheochromocytoma • Pronounced • (fee-oh-kroh-moh-sigh-TOH-mah) • Defined • Vascular tumor of adrenal medulla • Produces extra epinephrine and norepinephrine • Leads to persistent or intermittent hypertension and heart palpitations
Virilism • Pronounced • (VEER-il-izm) • Defined • Development of male secondary sex characteristics in the female due to the excessive secretion of adrenocortical androgens from the adrenal cortex
Virilism • Virilism • Symptoms • Excessive hair on the body and face (hirsutism) • Absence of menstruation • Deepening of the voice • Acne • Oily skin • Muscular hypertrophy • Atrophy of the breasts and uterus • Ovarian changes
PATHOLOGICAL CONDITIONS Pancreas
Diabetes Mellitus • Pronounced • (dye-ah-BEE-teez MELL-ih-tus) • Defined • Disorder of pancreas in which beta cells of islets of Langerhans of the pancreas fail to produce an adequate amount of insulin • Results in body’s inability to appropriately metabolize carbohydrates, fats, and proteins