Physiology
Endocrine Physiology
Endocrine physiology for MBBS and NEET-PG: hypothalamic-pituitary axis, thyroid, adrenal, insulin and glucagon and calcium regulation, mapped to NMC codes PY8.
MedNext Academy | 3 min read
Endocrine Physiology
Endocrine physiology for MBBS and NEET-PG: hypothalamic-pituitary axis, thyroid, adrenal, insulin and glucagon and calcium regulation, mapped to NMC codes PY8.
Endocrine physiology covers the hormones that coordinate metabolism, growth and homeostasis. It deals with the hypothalamic-pituitary axis, the thyroid and adrenal glands, the control of blood glucose by insulin and glucagon, and the regulation of calcium by parathyroid hormone.
High-yield: Endocrine Physiology
- The hypothalamus controls the anterior pituitary through releasing and inhibiting hormones carried in the portal blood.
- The anterior pituitary secretes growth hormone, prolactin, TSH, ACTH, FSH and LH.
- The posterior pituitary releases antidiuretic hormone and oxytocin, which are made in the hypothalamus.
- Growth hormone acts largely through insulin-like growth factor 1 from the liver.
- Thyroid hormones increase the basal metabolic rate and are essential for growth and brain development.
- The thyroid needs iodine to make T3 and T4, and TSH from the pituitary drives their release.
- Insulin lowers blood glucose by promoting uptake into cells and storage as glycogen and fat.
- Glucagon raises blood glucose through glycogenolysis and gluconeogenesis.
- Cortisol from the adrenal cortex raises blood glucose and has anti-inflammatory actions.
- Aldosterone from the zona glomerulosa reabsorbs sodium and excretes potassium.
- Adrenaline from the adrenal medulla prepares the body for the fight or flight response.
- Parathyroid hormone raises blood calcium by acting on bone, kidney and the gut through vitamin D.
- Calcitonin from the thyroid C cells lowers blood calcium and opposes parathyroid hormone.
- Most hormone systems are controlled by negative feedback that keeps their levels stable.
Glucose and calcium control
- **Insulin:** Lowers blood glucose; promotes uptake and storage.
- **Glucagon:** Raises blood glucose via glycogenolysis and gluconeogenesis.
- **Parathyroid hormone:** Raises blood calcium via bone, kidney and vitamin D.
- **Calcitonin:** Lowers blood calcium; from thyroid C cells.
NMC competencies in this chapter
- **PY8.1:** Organisation of the endocrine system and hormone action
- **PY8.2:** Hypothalamic and pituitary hormones
- **PY8.3:** Thyroid gland and its hormones
- **PY8.4:** Adrenal cortex and medulla
- **PY8.5:** Endocrine pancreas and control of blood glucose
- **PY8.6:** Calcium regulation and parathyroid function
Frequently Asked Questions
How does the hypothalamus control the pituitary?
The hypothalamus sends releasing and inhibiting hormones through the portal blood to the anterior pituitary, and it makes the hormones that the posterior pituitary releases directly into the blood.
What is the difference between insulin and glucagon?
Insulin lowers blood glucose by driving it into cells and storing it, while glucagon raises blood glucose by breaking down glycogen and forming new glucose in the liver.
How is blood calcium regulated?
Parathyroid hormone raises blood calcium by acting on bone, kidney and, through vitamin D, the gut, while calcitonin from the thyroid lowers it. The two work in opposition.
What are the main hormones of the adrenal gland?
The adrenal cortex makes cortisol, aldosterone and sex steroids, while the adrenal medulla makes adrenaline and noradrenaline for the stress response.
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