Page 88 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)

the thyroid hormones are stored in the follicles in an amount
Storage of
thyroglobulin sufficient to supply the body with its normal requirements of
hormones for 2-3 months

T4, T3 are first cleaved from the thyroglobulin molecule  free
Release of T4, T3
hormones are released into the circulating blood

❖ Most of the T4 released  slowly deiodinated to form additional T3 (active) at
the target tissues.

Control:

Hypothalamus secretes TRH ➔ ↑ Plasma level of TSH ➔↑ T3 and T4

Size of gland & I2

↓ iodide Excess iodide

↓ iodide  ↓ synthesis of thyroid Excess iodide level  -ve feedback on
hormones  ↑plasma level of TSH  thyroid & anterior pituitary  ↓all phases
enlargement of the thyroid gland (goiter) of thyroid activity  ↓ thyroid hormone
 slight decrease in the size of the gland

Endemic Goiter: decrease of iodine in all
people living in same region

| P a g e 64