2. The thyroid gland is a butterfly-
shaped organ and is composed of two
cone-like lobes or wings, lobus dexter
(right lobe) and lobus sinister (left
lobe), connected via the isthmus
Each lobe is about 5 cm long, 3 cm
wide and 2 cm thick
Its size depends on:
1. age … age size.
2. sex … female > male.
3. physiological condition …
3. It starts cranially at the oblique
line on the thyroid cartilage (just
below the laryngeal prominence, or
'Adam's Apple'), and extends
inferiorly to approximately the
fifth or sixth tracheal ring.
The thyroid gland is covered
by a thin fibrous sheath, the
capsula glandulae thyreoideae,
composed of an internal and
4. The thyroid is one of the larger
endocrine glands, weighing 2-3
grams in neonates and 18-60 grams
in adults, and is increased in
pregnancy.
It participates in these processes
by producing thyroid hormones, at
3–4 week of gestation.
The thyroid gland appears as an
epithelial proliferation in the floor
5.
6. Thyrotropin-releasing hormone (TRH)
and thyroid-stimulating hormone (TSH)
start being secreted from the fetal
hypothalamus and pituitary at 18-20
weeks of gestation.
Fetal production of thyroxine (T4)
reach a clinically significant level at
18–20 weeks.
Fetal triiodothyronine (T3) remains
low (less than 15 ng/dL) until 30
weeks of gestation, and increases to
50 ng/dL at termClinical significance
7. Thyroxine (T4) or
tetraiodothyronine
andTriiodothyronine (T3) are
Secreted by Follicular cells.
they Can be stored in thyroid gland
for couple of months (2-3 months).
Having significant effect on
metabolic rate of the body
93 % of Thyroxine (T4) or
tetraiodothyronine and 7% of
Triiodothyronine (T3) are secredted
8. Almost all T4 is converted into T3 in
tissues
T3 is the active form of T4.
T3 4 times > potent
(active/important) than T4 in
tissue, but it present in much
smaller quantities in
blood, & persists for a much shorter
time than does T4.
9. Almost all THs are carried in the
blood, mostly in an
inactive form, bound to 3
different types of proteins:
a. Thyroxine binding globulin
… 80%
b. Thyroxine binding pre-
albumin … 10%
c. Plasma albumin (serum
10. 1.GOITER:
1.it is a small harmless
disorder
it is the swelling of neck or
larynx resulting from
enlargement of thyroid gland
Goiter is caused by iodine
deficiency
Small doses of iodine in the
11. there are two types of disorders
depending on the
abnormal production of thyroid
hormones
Too much thyroid hormone
results in a condition known as
hyperthyroidism , this can result
due to several disorders such as
Toxic adenomas: Nodules develop in the
thyroid gland and begin to
secrete thyroid hormones,
12. Subacute thyroiditis: Inflammation of the
thyroid that causes the gland to
"leak" excess hormones, resulting
in temporary hyperthyroidism that
generally lasts a few weeks but
may persist for months.
Pituitary gland malfunctions or
cancerous growths in the thyroid
gland can also result in
hyperthyroidism , so the excessive
13.
14. GRAVE’S DISEASE
Graves' disease is an autoimmune
disease.
It causes thyroid to enlarge to
twice its size or more
symptoms such as increased
heartbeat, muscle weakness,
disturbed sleep, and irritability. It
can also affect the eyes, causing
bulging eyes (exophthalmos).It
15. Normally, the thyroid gets its
production orders through another
chemical called thyroid-stimulating
hormone (TSH), released by the
pituitary gland in the brain. But in
Graves' disease, a malfunction in
the body's immune system releases
abnormal antibodies that mimic
TSH. Spurred by these false signals
to produce, the thyroid's hormone
16.
17. an underproduction of thyroid
hormones causes hypothyroididsm
,which is also caused due to several
other disorders such as
Hashimoto's thyroiditis: In this autoimmune
disorder, the body attacks thyroid
tissue. The tissue eventually dies and
stops producing hormones.
Removal of the thyroid gland: The thyroid may have
been surgically removed or chemically
destroyed.
Exposure to excessive amounts of iodide: Cold and sinus
medicines, the heart medicine
amiodarone, or certain contrast dyes
18. Lithium: This drug has also been implicated
as a cause of hypothyroidism.
Untreated for long periods of time,
hypothyroidism can bring on a
myoxedema coma
Myxedema :
it is caused by an accumulation of
tissue products such as
glycosaminoglycans, in the skin.
Symptoms of myxedema include
thickening of the skin , fatigue, weight
gain, depression, dry skin, and brittle
hair, Skin thickening or swelling
associated with myxedema is often
19. A lack of thyroid hormones in the
system at an early age can
lead to the development of
cretinism (mental retardation) and
dwarfism (stunted growth).
Cancer of the thyroid gland is
quite rare and occurs in about 5%
of thyroid nodules. People who
have received radiation treatment
to the