PSL201 – Feb 14 – Endocrine 2 Hypothalamus and Pituitary Gland.docx

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11 Apr 2012
PSL201 Feb 14 Endocrine 2: Hypothalamus and Pituitary Gland
The Endocrine System: Endocrine Glands and Hormone Actions
- two types of endocrine glands
o primary endocrine organs: secrete hormones
o secondary endocrine organs: secretion of hormone is secondary to
some other function
Primary Endocrine Organs
Hypothalamus and Pituitary Gland:
- regulate virtually every body system
- hypothalamus: secretes hormones which affect the pituitary gland
- pituitary gland: connected to hypothalamus, two parts; posterior lobe and
anterior lobe
Neural Connection Between Hypothalamus and Posterior Pituitary:
- neural endings in post. Pituitary secrete ADH and oxytocin (neurohormones)
- ADH: synthesized in the paraventicular nucleus and lesser in the supraoptic
- Oxytocin: synthesized in supraoptic nucleus and lesser in paraventicular
- After synthesis they are packed into vesicles and transported to axon
terminals in the post. Pituitary
- Released into blood by exocytosis when signal is received
Blood Connection Between Hypothalamus and Anterior Pituitary
- anterior lobe secretes trophic hormones: hormones that regulate secretion
of other hormones
o can be a stimulating hormone or a inhibiting hormone
Anatomy of Hypothalamic-Pituitary Portal System:
- hypothalamic-pituitary portal system:
o connects anterior lobe and hypothalamus
o arrangement of blood vessels
o when the hypothalamus secretes hormones they travel down to the
anterior lobe
Trophic Hormones of the Hypothalamus and Anterior Pituitary:
- Prolactin realeasing Hormone (PRH): stimulates ant. pituitary to release
prolactin, which then stimulates mammary gland development and milk
- Prolactin inhibiting hormone (PIH): inhibits prolactin
- Thyrotropin releasing hormone (TRH): release of thyroid stimulating
hormone (TSH) from ant pituitary. TSH stimulates the secretion of
thyroid hormones from the thyroid
- Corticotropin realeasing hormone (CRH): release of adrenocorticotrpic
hormone (ACTH) by the ant pituitary. ACTH stimulates the secretion of
hormones from the adrenal cortex
- Growth hormone releasing hormone (GHRH): release of growth
hormone (GH) from the ant pituitary. GH regulates growth and
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