Endocrine physiology is a large subject. Here's the map of what it covers, then pick a topic to go deep on.

Endocrine physiology is about chemical signaling between organs via hormones released into the blood. Hormones fall into three chemical classes: peptides/proteins (insulin, GH, ACTH) which act on cell-surface receptors and trigger fast second-messenger cascades; steroids (cortisol, aldosterone, sex hormones) which are lipid-soluble, cross the membrane, and act on nuclear receptors to change gene transcription over hours; and amines (thyroid hormones, catecholamines), which are a mixed bag - thyroid hormones act like steroids (nuclear, slow, and long-lasting), while catecholamines act like peptides (membrane receptors, fast).

Almost every axis in the body follows the same hierarchical pattern: hypothalamus releases a trophic hormone, which drives the anterior pituitary to release a stimulating hormone, which drives a peripheral gland (thyroid, adrenal cortex, gonad) to release the final active hormone. That final hormone then loops back to suppress the hypothalamus and pituitary - this is negative feedback, and it is the single most important unifying concept in the entire subject. Once you understand this loop for one axis, the same logic applies to all the others (HPT, HPA, HPG).

The other big organizing principle is metabolic control: insulin and glucagon manage blood glucose from meal to meal, cortisol and GH manage it over longer stress and fasting states, and calcium is controlled independently by PTH, vitamin D and calcitonin through bone, gut, and kidney.

Endocrine physiology is a large subject. Here's the map of what it covers, then pick a topic to go deep on.

Endocrine physiology is about chemical signaling between organs via hormones released into the blood. Hormones fall into three chemical classes: peptides/proteins (insulin, GH, ACTH) which act on cell-surface receptors and trigger fast second-messenger cascades; steroids (cortisol, aldosterone, sex hormones) which are lipid-soluble, cross the membrane, and act on nuclear receptors to change gene transcription over hours; and amines (thyroid hormones, catecholamines), which are a mixed bag - thyroid hormones act like steroids (nuclear, slow, and long-lasting), while catecholamines act like peptides (membrane receptors, fast).

Almost every axis in the body follows the same hierarchical pattern: hypothalamus releases a trophic hormone, which drives the anterior pituitary to release a stimulating hormone, which drives a peripheral gland (thyroid, adrenal cortex, gonad) to release the final active hormone. That final hormone then loops back to suppress the hypothalamus and pituitary - this is negative feedback, and it is the single most important unifying concept in the entire subject. Once you understand this loop for one axis, the same logic applies to all the others (HPT, HPA, HPG).

The other big organizing principle is metabolic control: insulin and glucagon manage blood glucose from meal to meal, cortisol and GH manage it over longer stress and fasting states, and calcium is controlled independently by PTH, vitamin D and calcitonin through bone, gut, and kidney.Your credits are exhausted. You can purchase a top-up or subscribe to a plan to continue using Orris. If you're already subscribed, your daily credits will reset tomorrow.