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What are the major organs of the endocrine system?
- Pituitary gland
- Thyroid gland
- Parathyroid gland
- Pancreatic islets
- Adrenal glands
- Testes and Ovaries
Located on the underneath side of the brain. Small pea-sized gland divided into an anterior and posterior lobe. Both lobes are controlled by the hypothalamus in the brain.
What are the names and roles of the 7 hormones secreted by the anterior pituitary gland?
- Growth hormone (GH): promotes growth,
- stimulates cells to increase in size and divide.
- Thyroid stimulating hormone (TSH): regulates the function of the thyroid gland.
- Adrenocorticotropin hormone (ACTH): regulates the function of the adrenal cortex.
- Prolactin (PRL): stimulates milk production in the breast (pregnancy and birth).
- Follicle stimulating hormone (FSH): responsible for the development of ova in ovaries and sperm in testes, stimulates the ovary to secrete estrogen.
- Luteinizing hormone (LH): stimulates secretion of sex hormones in both males and females and plays a role in releasing ova in females.
- Melanocyte stimulating hormone (MSH): stimulates melanocytes to produce more melanin, darkening the skin.
What are the names and the role of the two hormones secreted by the posterior pituitary gland?
- Antidiuretic hormone (ADH), also known as vasopressin: promotes water reabsorption by the kidney tubules.
- Oxytocin: stimulates uterine contractions during labor and delivery, and after birth the release of milk from the mammary glands.
Anterior Pituitary Insufficiency
- Pituitary dwarfism
- Adult Growth Hormone Deficiency (AGHD)
Inadequate growth hormone.
Mentally bright but small and underdeveloped sexually.
All growth processes are retarded, teeth are late in erupting.
Replacement therapy with injections of growth hormone is currently used to treat children with this condition
Rare condition. Caused by damage to the pituitary gland
or the hypothalamus. Clinical features: changes to body composition such as increased body fat, reduced exercise capacity, impaired heart function, reduced muscle mass, abnormal lipid profile and atherosclerosis, decreased ability to concentrate.
- Adults at risk for AGHD are those with a history of pituitary surgery, previous tumor on the pituitary or hypothalamus, history of radiation to the head, and previously documented growth hormone deficiency in childhood
hypersecretion of growth hormone prior to puberty. Retards normal closure of bone seal. Decreased sexual development.
Mental development normal or retarded. Etiology - adenoma
Treatment - removal of adenoma, radiation to reduce the size of the tumor
Hypersecretion of growth hormone after puberty. Long bones no longer grow. Excessive growth of soft tissue, weight gain. Enlargement of the face with coarse facial features. Protrusion of the tongue. Curvature of the spine, kyphosis. Glucose intolerance and diabetes mellitus occurs.
Etiology: adenoma. Treatment: surgical removal, radiation, medication.
Hyposecretion of the posterior pituitary gland
- Diabetes insipidus
- Nephrogenic diabetes insipidus
Inadequate production of ADH by the hypothalamus
or failure of the pituitary gland to release ADH into
the bloodstream. H20 not reabsorbed by kidney, lost in the urine. Extreme thirst (polydipsia), excessive production of
diluted urine (polyuria). Treatment - the underlying cause of diabetes insipidus must be corrected. Vasopressin can be taken orally, by injection, or nasal spray to maintain normal urine output.
ADH levels are normal. Kidney fails to concentrate urine in response to ADH
Nephrogenic diabetes insipidus
Produces the hormones thyroxine (T4) and triiodothyronine (T3). These are produced in the thyroid gland from the mineral iodine.
Where in the thyroid gland are the hormones made?
In the follicles, microscopic sacs.
Secreted by the thyroid gland in response to hypercalcemia. Its action is the opposite of parathyroid hormone and stimulates the increased deposition of calcium into bone which lowers blood levels of calcium.
What are the effects of thyroxine?
- Stimulates GI activity
- Increases body temp
- Increases cellular metabolism
- Increases respiration
- Stimulated heart activity
Congenital thyroid deficiency in which T4 is not synthesized. T4 is essential to physical and mental development. Mental retardation and an abnormal, dwarfed stature. Etiology: error in fetal development if the thyroid gland fails to form or is nonfunctional, or may be endemic where the mother suffers from an inadequate iodine supply. A dwarf with a stocky stature and protruding abdomen.
Sexual organs do not develop. Face can be misshapen: broad, sunken nose, small eyes set far apart, puffy eyelids, short forehead, thick tongue protrudes from wide-open mouth, face is expressionless. The earlier this condition is diagnosed and treated with T4, the more optimistic is the prognosis. Hormonal therapy required.
An enlargement of the thyroid gland. Can be caused by hypoactivity or hyperactivity of the thyroid or a deficiency in iodine needed to synthesize thyroid hormones. The usual cause is insufficient iodine in the diet.
Types of goiter
Diffuse colloidal or nontoxic