Biology 3201 13.2 Endocrine glands (Thyroid & parathyroid glands)

Thyroid is butterfly shaped and is wrapped around the larynx.

Parathyroid glands are 4 clumps of cells imbedded in the thyroid.

When thyroxine levels are high hypothalamus does NOT produce TRH which causes thyroxine levels to drop. When thyroxin levels are low the hypothalmus produces TRH which causes thyroxin levels to rise and the cycle continues

Hyperthyroidism: cause Antibodies attach to TSH receptors on thyroid Thyroid is constantly producing Thyroxin

Hyperthyroidism: symptoms Increased metabolic rate Eat lots & lose weight Enlarged thyroid Muscle weakness Sweating & warm skin Bulged eyes

Hyperthyroidism: treatments Remove thyroid Thyroid blocking drugs Radioactive iodine causes death of overactive thyroid

Hypothyroidism Opposite of Hyperthyroidism Caused by a lack of iodine in diet and consequently lack of thyroxine production.

Hypothyroidism Symptoms Low metabolic activity Reduced tolerance to cold Decreased heart rate Weight gain but poor appetite. Decreased mental capacity Poor physical development

Parathyroid & Thyroid

Thyroid produces calcitonin Reduces Blood Ca levels Calcitonin increases rate of Ca deposits in bone increases Ca in urine Parathyroid produces PTH Increases Blood Ca levels PTH takes calcium from bone and puts in blood. Kidneys reabsorb more Ca Intestines absorb more Ca

Good Web Sites on Thyroid http://www.colorado.edu/eeb/web_resources/thyroid/ http://www.pathguy.com/lectures/thyroid.htm http://www.well-net.com/prevent/thyroiddisease-1.html http://www.endo.com.br/temas_hipertireoidismo_usa.htm http://www.ei.educ.ab.ca/sch/fhs/biology/bio30.html