Endocrine system L2
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Review hormone chart in lesson
please
When is the quantity of hGH at it’s highest?
Childhood and adolescence
What causes pituitary dwarfism?
Too little GH(growth hormone) during childhood
What causes gigantism?
Too much growth hormone during childhood
What does overproduction of GH cause in adults?
Acromegaly
What is acromegaly and what does it cause?
• Syndrome where the pituitary gland produces excess HGH after epiphyseal plate closure • Continued growth in lower jaw, hands, feet, nose
What is the thyroid?
Large gland located in neck, where it is attached to trachea just below the larynx
What is the parathyroid?
Four glands are embedded in the posterior surface of the thyroid gland
What allows the thyroid to function?
Requires iodine to produce thyroxine (T4) which contains four iodine atoms, and triiodothyronine (T3) which contains three iodine atoms
What does the thyroid do?
Increase metabolic rate, and stimulate all body cells to metabolize and use energy at faster rate
What is too little thyroxine called?
hypothyroidism
What are symptoms of hypothyroidism?
• cold, fatigue, dry skin, hair loss, weight gain, sleep a lot (myxedema in adults) • in children, leads to abnormal mental and physical development , growth retardation (cretinism)
What is too much thyroxine called?
Hyperthyroidism (grave’s disease)
What are symptoms of hyperthyroidism?
• jittery, weight loss, fast heart rate, feel warm, mood swings, hair loss, bulging eyes • treated by removing a portion of thyroid gland (surgically or chemically)
What happens if iodine is lacking in the diet?
A simple goiter develops • Use of iodized salt helps prevent simple goiters
What does iodine do?
Iodine is required to synthesize thyroxine • Swelling is due to the continued stimulation by TSH (no thyroxine made so negative feedback doesn’t work), causes increase in thyroid size in an attempt to make more thyroxine
What does calcitonin do?
Produced by thyroid – helps lower blood calcium level when it is too high
What is the main function of calcitonin?
• Primary effect is to bring about deposit of calcium in bones temporarily reduces activity and number of osteoclasts • When blood calcium is returned to normal, release of calcitonin inhibited
What is the function of the parathyroid?
Secretes parathyroid hormone (PTH) - raises blood calcium when low, and decreases the blood phosphate level
What does PTH do?
PTH acts by stimulating the activity of osteoclasts - releasing calcium from bone - stimulates reabsorption of calcium by kidneys and intestine