~Thyroid Gland~

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Thyroid Gland
Katie Brown Dena Livingstone
Endocrine system 3rd Quarter Project
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anatomy

• The thyroid is a butterfly-shaped organ thats
  located in the front of the neck. It is
  controlled by the hypothalamus part of the brain.
  
• It sits inferior to the Adams apple and
  anterior to the trachea.
• Its 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.

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Thyroid Gland
Illustration
Actual healthy thyroid gland
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The Thyroid is hormonal
Chemical Description of the Thyroid

• The Thyroid gland produces 2 main hormones
  thyroid hormone calcitonin
• There are 2 active 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.

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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
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• 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.

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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.

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The Thyroid Gland and the Organs it Interacts
With
C O N T I N U E D O N N E X T P A G E

• 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

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CONTINUED
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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.

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(No Transcript)
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Goiters Disease
Patient w/ enlarged thyroid (goiter)
Goiters manifestation
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C O N T I N U E D O N N E X T P A G E
A Normal thyroid gland with colloid-filled
follicles
B Endemic goiter w/ abnormal proliferation of
cells w/o colloid-dilled follicles
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C O N T I N U E D O N N E X T P A G E
Hashimotos 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
bodys 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
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Graphic/ Physical Imaging
lt_lt
O_o
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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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Sources include

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Sources Continued

• http//www.youtube.com/watch?vjnqWrrde_Fkfeature
  related
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