Pituitary Gland Flashcards
Where is the pituitary gland located?
- Small oval gland that lies within sella turcica
- Hangs down inferior to hypothalamus
- Connected to hypothalamus by the infundibulum
How is the pituitary gland divided?
- Divided into two lobes based on the function & developmental anatomy
A. Anterior lobe (Adenohypophysis)
B. Posterior lobe (Neurohypophysis)
What hormones does the anterior pituitary gland secrete? What organs/glands do these hormones affect?
- TSH: thyroid
- ACTH: adrenal cortex
- FSH, LH: Testes, ovaries
- Growth hormone: entire body
- Prolactin: mammary glands
- Endorphins: pain receptors in the brain
How is the anterior pituitary gland controlled?
Anterior pituitary gland is controlled by regulatory hormones secreted by the hypothalamus
How do the hormones that control the ant. pit get there?
- Hormones reach the anterior pituitary via hypothalamo- hypophyseal portal system
A. Takes venous blood carrying regulatory hormones from hypothalamus directly to the anterior pituitary
What hormones are secreted by the posterior pit gland?
- ADH
2. Oxytocin
Where are ADH and Oxytocin made?
Specialized Neurosecretory cells in the hypothalamus
What hormones control the secretion of ant pit hormones?
- Thyrotropin Releasing Hormone (TRH)
- Corticotropin Releasing Hormone (CRH)
- GHRH & GHIH
A. Growth Hormone Releasing Hormone (GHRH) - Somatotropin
B. Growth Hormone Inhibitory Hormone (GHIH) - Somatastain - Gonadotropin Releasing Hormone (GnRH)
- PIH & PRH
A. Prolactin Inhibitory Hormone (PIH)
B. Prolactin Releasing Hormone (PRH)
How many hormones are released by the ant pit?
6 peptide hormones
What is the function of TSH?
- Thyrotropin Stimulating Hormone (TSH)
- Stimulates thyroid gland to secrete thyroxine & triiodothyronine
A. As T4 & T3 increase, TRH & TSH decrease
What is the function of ACTH?
- Adrenocorticotropic Hormone (ACTH)
- Stimulates release steroid hormones from adrenal cortex
A. Glucocorticoids & mineralcorticoids - Affects metabolism of glucose, proteins, fats
- Affects immune system & inflammation
- As cortisol levels increase, CRH & ACTH decrease
What are the main functions of the growth hormones?
- Stimulates cell growth & replication by accelerating rate of protein synthesis
- Increases mobilization of fatty acids from adipose tissue & use for energy
- Controlled by hypothalamus via releasing or inhibiting hormones
What are the direct effects of GH?
- Salt retention
- Decreased insulin sensitivity
- Lipolysis
- Protein synthesis
- Epiphysial growth
- Stimulates IGF-1: insulin like growth hormone 1
What are the indirect effects of GH (through IGF-1)?
- Insulin-like activity
- Antilipolytic activity
- Protein synthesis
- Epiphysial growth
What is the major controller of GH secretion?
- Long term state of protein nutrition
A. If protein stores low, GHRH increases, leading to increase GH