~Thyroid Gland~ Katie Brown Dena Livingstone Endocrine system: 3rd Quarter Project
anatomy • The thyroid is a butterfly-shaped organ that’s located in the front of the neck. It is controlled by the hypothalamus part of the brain. • It sits inferior to the “Adam’s apple” and anterior to the trachea. • It’s one of the larger endocrine glands • Contains 2 primary lobes (right & left) on either side of the trachea. • Between the 2 lobes is the isthmus • Covered in a tough fibrous capsule which protects it from other tissues/organs.
~Thyroid Gland~ Illustration Actual healthy thyroid gland
The Thyroid is hormonal… Chemical Description of the Thyroid • The Thyroid gland produces 2 main hormones: thyroid hormone & calcitonin • There are 2active iodine-containing thyroid hormones: • :Thyroxine (T4) - this type of hormone is produced and released by the thyroid follicles. It is a iodine-filled hormone. • Triiodothyronine (T3) • Formed at target tissues by conversion of T4 into T3 • Both these hormones are similar in that they are built from 2 linked tyrosine amino acids. Thyroxine has 4 bound iodine atoms, while triiodothyronine has 3. • Calcitonin • a hormone which decreases the levels of calcium and phosphate contained within in the blood stream • it also promotes/strengthens bone formation.
Molecular makeup • The thyroid gland is composed of numerous hollow structures called thyroid follicles - which contain colloidal material that help to form thyroid hormone (particularly thyroxine). • Also contained within the thyroid gland are the parafollicular cells, which produces calcitonin. • - these are located within the connective tissue in • between the follicles. • The Thyroid Gland is normally simple cuboidal epithelium. colloid follicle cell parafollicular cell
The thyroid is known to many people because of those who are obese, who tend to blame it on their glands! • However, the effect of the thyroid gland on weight is NOT that great!!! - Thyroid hormone regulates metabolism rate. People with normal functioning thyroids that take thyroid hormone for weight loss may end up losing little weight (muscle NOT fat) or gain weight due to hyperthyroidism.
Physiology • The function of the thyroid gland is to take iodine and turn it into thyroid hormones thyroxine (T4) and triiodothrynine (T3). • Thyroid cells are the only cells in the body that can absorb iodine. T4 and T3 are made by these cells combining iodine and the amino acid tyrosine. These hormones are then released into the bloodstream for transport, through which metabolism is controlled by converting oxygen/calories to energy. • Thyroid hormone controls the rate at which glucose is burned/oxidized and converted into body heat and chemical energy. It is also involved in normal tissue growth and development (chiefly in the reproductive and nervous system) (METABOLISM). • Calcitonin, another hormone produced by the thyroid gland, decreases blood calcium levels by having calcium deposited in the bones. • Every cell in our bodies depend on the thyroid gland for regulation of their metabolism.
C O N T I N U E D O N N E X T P A G E The Thyroid Gland and the Organs it Interacts With… • The Thyroid gland, a hormone producing gland, interacts with organs of various body systems. • The thyroid hormones it produces are needed for regular tissue growth/development within these location. • These hormones are metabolic hormones that help produce body heat and chemical energy. • Some organs that interact with the thyroid are gland are: • The parathyroids: miniscule glandular tissues located on the posterior side of the thyroid itself. • The glands of the parathyroids release parathyroid hormones (PTH) and create calcium ions (Ca 2+) whenever there is a decrease in calcium level of the human body. • However, when there is too much calcium within the body, the parafollicular cells in the thyroid produces calcitonin, which reduces the calcium in the blood and stores them into the bones. • These two body structures collaborate together in order to regulate the calcium amount contained within the bloodstream. • The ovaries and testes: • the thyroid gland produces hormones that help to regulate both the female ovaries and male testes of the Reproductive System
Thyroid Diseases • Goiters: • Developed years ago in people in the Midwest who were far from the seashore. They were located in iodine-deficient soil and had a lack of fresh seafood. (Region was known as “goiter belt”) • Endemic Goiter ( a type of simple goiter) = Enlargement of thyroid gland due to iodine deficiency. • Uncommon in U.S. since most of our salt is iodized. • The signal sent to the thyroid from the pituitary gland when thyroid hormone levels are too low as a result of low iodine levels, is thyroid stimulating hormone (TSH). It causes the abnormal increase in size.
Goiter’s Disease Patient w/ enlarged thyroid (goiter) Goiter’s manifestation
C O N T I N U E D O N N E X T P A G E A: Normalthyroid gland with colloid-filled follicles B: Endemic goiter w/ abnormal proliferation of cells w/o colloid-dilled follicles
C O N T I N U E D O N N E X T P A G E Hashimoto’s Thyroiditis Is a particular form of goiter, in which the thyroid gland is destroyed by its own immune system. In this self-destructive condition, the thyroid glands become unable to produce an efficient amount of hormones needed for the body’s visceral organs. TSH is then, released as the pituitary gland (located in the brain) senses that there is a lowered –level of thyroid hormones. The TSH then excites the thyroid, in response to the lack of decreased hormone creation. This thus, causes the thyroid follicular cells to grow larger and produce more thyroglobulin, which then leads the thyroid to grow and swell. - Goiter is usually caused by a lack of IODINE within the human body. -TSH= Thyroid Stimulating Hormone Molecular Imaging
Graphic/ Physical Imaging <_< O_o
“This is a great example of what happens when "negative feedback" is shut down.” Hypothyroidism Literally means “the under-production of thyroid hormones.” Hypothyroidism occurs when not enough thyroglobulin protein (created by the thyroid gland itself) binds to iodine to form the hormones. thyroglobulin = an iodine containing protein that is obtained from the thyroid gland. Some symptoms of Hypothyroidism, as described in the video are fatigue, weight gain, and hair loss. Note: This video not only describes the causes and symptoms of this disease, it also briefly describes the regular functions of a healthy THYROID.
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