ADH/Oxytocin and Thyroid Gland - Study Notes

ADH and oxytocin are mentioned as causing vasoconstriction, which increases blood pressure.
In addition to vasoconstriction, oxytocin also causes smooth muscle contraction.

The thyroid is composed of round secretory units called follicles.
Each follicle is surrounded by a single layer of follicular cells.
The cavity of each follicle is filled with a viscous colloid (described as honey-like).
Extrafollicular (parafollicular) cells lie outside the follicles.
Follicular cells produce T3 and T4; extrafollicular cells produce calcitonin.
In histology, the image described is an H&E (hematoxylin and eosin) slide showing extrafollicular cells outside follicles and follicular cells around colloid.

T4 increases the rate of energy release from carbohydrates.
T4 increases the rate of protein synthesis.
T4 increases energy absorption from carbohydrates.
T4 accelerates growth and is necessary for normal nervous system maturation.
T3 performs similar actions but is much more potent than T4.
Overall, both T4 and T3 regulate metabolism and development, with T3 having greater potency.

The thyroid removes iodine from the blood to synthesize T3 and T4, highlighting the importance of iodine in hormone production.
The histological organization (follicles with colloid and surrounding follicular cells, plus extrafollicular cells) underpins the functional separation: hormone synthesis (T3/T4) versus calcitonin production.
The sequence from hypothalamus/pituitary (as mentioned in the transcript) to the thyroid gland fits into the broader endocrine axis controlling metabolism and growth.