Hypothalamus–Pituitary Axis (HPA)

What are the main divisions of the pituitary gland?

Anterior lobe (adenohypophysis)
Posterior lobe (neurohypophysis)
Intermediary lobe

What is the hypothalamic-hypophyseal portal system?

A system of short blood vessels carrying hypothalamic hormones directly to the anterior pituitary to regulate hormone secretion.

What hormone does CRH stimulate from the anterior pituitary?

ACTH (Adrenocorticotropic Hormone)

What is the function of ACTH?

Stimulates the synthesis and secretion of cortisol from the adrenal cortex
Promotes growth of the adrenal gland

How is cortisol regulated by feedback?

High cortisol levels inhibit CRH and ACTH release via negative feedback.

Name the hormones released from the hypothalamus and their corresponding pituitary hormones.

GHRH → GH
SS (somatostatin) → ↓ GH
CRH → ACTH
GnRH → FSH & LH
PRH → PRL
PIH → ↓ PRL
TRH → TSH

What are the major anterior pituitary hormone groups and examples?

Somatomammotropin: GH, PRL
Glycoprotein: TSH, LH, FSH
POMC-derived: ACTH, MSH