The Pancreas, Hypothalamus and Pituitary Gland Flashcards
Where is the pituitary gland located?
At the base of the brain and is attached to the hypothalamus which controls the secretion of pituitary hormones
What do pituitary hormones stimulate?
Target cells and secretion of hormones by other endocrine glands
What does the posterior lobe of the pituitary gland do?
Connected to the hypothalamus by neurons
Secretes hormones into blood
How does the hypothalamus communicate with the posterior pituitary?
Posterior pituitary hormones are made in the hypothalamus, travel down the axon and are stored in axon ends until required. Releases ADH or oxytocin into the blood
What is ADH (antidiuretic hormone)?
ADH is a hormone that encourages kidneys to bring more water into the body (reabsorb) and prevents urination
What is oxytocin?
A hormone that has a positive feedback loop, stimulates contraction of uterine muscles during childbirth
What is the anterior lobe of the pituitary gland?
Connected to the hypothalamus by blood vessels. Hypothalamic hormones stimulate or inhibit release of stored hormones from specific anterior pituitary cells
How does the hypothalamus communicate with the anterior pituitary?
Stimulus is neural input within hypothalamus
Hypothalamus signals the anterior pituitary to release hormones by hormonal stimulation, secreting stored release hormone which binds to receptor on membrane of a specific cell type
What is the feedback regulation process of the anterior pituitary gland?
Hypothalamus releasing hormone, which stimulates, anterior pituitary gland pituitary hormone, which stimulates, target organ hormone
Target organ hormone inhibits anterior pituitary gland
Anterior pituitary gland inhibits hypothalamus
Releasing hormone inhibits hypothalamus
Hormone inhibits hypothalamus
Growth hormone feedback process
Hypothalamus releases GHRH causing anterior pituitary to release GH causing liver to release IGF-1 which inhibits further release of GHRH
IGF-1 encoruages release of GHRH from hypothalamus which inhibits release of GH from anterior pituitary gland
What are the direct effects of growth hormone (GH)?
Muscle: stimulates protein synthesis and inhibits cellular uptake of glucose (so that glucose can be taken up)
Liver: stimulates glucose synthesis
Fat: increases triglyceride breakdown in adipose tissue (turn fatty acids into glucose)
What are indirect effects of GH?
Promotes growth of bones, muscle and other tissues by causing release of Somatomedin C (IGF-1) which promotes cell division (long term)
What is the pattern of GH secretion over a day?
GH concentrations change throughout the day, highest during sleep
Decline with aging
