MEDI211 Lecture Notes - Lecture 1: Luteinizing Hormone, Arginine, Luteal Phase
Week 4 Lecture 1 – Endocrine 3
Hypothalamus: the integrating centre for homeostatic functions; acts as the functional link
between nervous and endocrine systems.
Pituitary: receives input from the hypothalamus.
Anterior pituitary (adenohypophysis): glandular tissue; epithelial origin.
Posterior pituitary (neurohypophysis): neural tissues; hypothalamus origin.
Anterior pituitary gland:
•Highly vascularised
•Primary capillary plexus receives blood from the superior hypophyseal artery
•Secondary capillary plexus on the anterior lobe has small branches among endocrine cells
•Portal veins join the two capillary networks —> this system is called the ‘hypophyseal portal
system’ and is a one-way system.
Posterior pituitary:
•Arterial blood via inferior hypophyseal artery
•Hormones exit via hypophyseal vein into general circulation
Hypothalamic - Pituitary Peptide hormones:
•Releasing and inhibiting factors from the hypothalamus (green) influence anterior pituitary
secretion (blue).
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Document Summary
Hypothalamus: the integrating centre for homeostatic functions; acts as the functional link between nervous and endocrine systems. Primary capillary plexus receives blood from the superior hypophyseal artery. Secondary capillary plexus on the anterior lobe has small branches among endocrine cells. Portal veins join the two capillary networks > this system is called the hypophyseal portal system" and is a one-way system. Hormones exit via hypophyseal vein into general circulation. Releasing and inhibiting factors from the hypothalamus (green) influence anterior pituitary secretion (blue). Tropic hormones are hormones that result in the release of another hormone. They target other endocrine glands > are released by the anterior pituitary gland. The posterior pituitary is directly regulated by neural input from the hypothalamus (red). Feedback regulation in the hypothalamic pituitary axis (hpa): Long-loop feedback: downstream hormone from periphery > hypothalamus/pituitary. Both of these can be negative or positive feedback. Posterior pituitary: is a neural extension of the hypothalamus.
