Hypo and hyperthryoidism Flashcards
Thyroid gland hormones
Triiodothyronine (T3)
Thyroxine (T4)
Follicular Cells
secrete thyroid hormones that contain iodine
Parafollicular Cells
produce calcitonin and are next to the follicular cells
Colloid
a proteinaceous material composed
mainly of thyroglobulin and stored thyroid hormones
follicles are filled with
colloid
Thyroglobulin
chain of tyrosine molecules
TRH
Thyrotropin-Releasing Hormone, released from the hypothalamus
TSH
Thyroid Stimulating Hormone, produced by the anterior pituitary when stimulated by TRH
T3/T4
iodine-containing amino acids that regulate the body’s metabolic rate
T3
produces 10% of active hormones
T4
produces 90% of inactive hormones
MIT
Monoiodotyrosine
DIT
Diiodotyrosine
order of feedback mechanism
hypothalamus–> TRH–> Pituitary–> TSH–>Thyroid–> T3/T4
T4 is a positive or negative feedback mech
negative
hyperthyroidism
The thyroid gland secretes excess thyroid hormone in
circulation
Top 3 Causes hyperthyroidism:
- Grave’s Disease: autoimmune, most common
- Toxic Nodular Goiter
- Toxic Adenoma
- hyperthyroidism high T3/T4 in blood
hypothalamus will reduce TRH release via the
hypothalamic-hypophyseal portal system
- hypothalamic-hypophyseal portal system
Collects blood from the hypothalamus and through a plexus of veins takes the blood directly to the anterior pituitary
- anterior pituitary releases less…
less TSH so thyroid gland is no longer stimulated
hyperthyroidism result
thyroid remains overactive
Grave’s disease
TSH-R antibodies bind to TSH receptors on follicular cell membranes
mimics role of TSH telling the body to produce more T3/T4 hormones
Hypothyroidism
A deficiency of thyroid hormone in
circulation
hypo causes
Hashimoto’s Thyroiditis: autoimmune, most hypocommon
o Iodine Deficiency
o Hyperthyroidism treatment
Radioactive iodine therapy
Surgery
hypo types
Types
1. Primary: caused by disease in the thyroid
2. Secondary: caused by disease in the hypothalamus or pituitary
- hypo low T3/T4 in blood
The hypothalamus will increase TRH release via the
hypothalamic-hypophyseal portal system.
- hypo
TRH stimulates the anterior pituitary gland to
release more TSH
- hypo
The thyroid gland is underactive, so despite the higher TSH levels, the thyroid will not produce enough
T3 and T4
Hashimoto’s Thyroiditis: The immune system attacks the thyroid gland producing…
autoantibodies against thyroid peroxidase, thyroglobulin,
or TSH receptors
goiter
inflammation of the thyroid gland
after goiter
Gradual destruction of thyroid follicular cells due to antibody-dependent cell-mediated cytotoxicity
released T3/T4 from destruction and over time..
synthesis and release diminish due to damage to the thyroid
