Pituitary Gland Flashcards
The pituitary gland works closely with what?
Hypothalamus
Describe the structure of the pituitary gland.
Anterior & posterior portions. There is an intermediate portion that is merely a cluster of cells. It is connected to the brain by a stalk called the “infundibulum.” Housed by sphenoid bone, sits on sella turcica.
What is special about this gland during pregnancy?
It becomes 50% larger during pregnancy.
What is the role of the intermediate lobe?
Secretes melanin (eyes, hair, skin). MSH (melanin stimulating hormone) is produced here.
Which portion of the pituitary gland is implicated in Addison’s?
intermediate lobe
The anterior lobe is also called the ___
adenohypophysis
Describe the anterior lobe
3/4 larger than the posterior portion. It is made of embryonic tissue from the pharynx. It has no nervous tissue connecting it to the hypothalamus. No neurons. Hypophyseal portal system. Synthesizes 6 hormones.
Describe the posterior lobe
Came down from the brain. Does NOT synthesize hormones. Saves hormones and releases them when necessary.
The posterior lobe is also called the ___.
Neurohypophysis
Name the 6 hormones that are synthesized in the anterior pituitary gland.
FSH (follicle-stimulating hormone), LH (luteinizing hormone), ACTH (adrenocorticotropic hormone), TSH (thyroid stimulating hormone), PRL (prolactin), GH (growth hormone)
What does FSH do?
Females: development of egg-containing follicles in ovaries. stimulates follicular cells to secrete estrogen
Males: testes-stimulates sperm production
What is the source of control of FSH & LH?
gonadotropin-releasing hormone from the hypothalamus
What does LH do?
Female: releases egg cell; stimulates progesterone. (Ovulation & corpus luteum)
Males: stimulates the testes to release testosterone
What does ACTH do?
stimulates the release of glucocorticoids from the 2nd layer (fusicularis) of the adrenal cortex
What is the source of control of ACTH?
corticotropin-releasing hormone from the hypothalamus
What does TSH do?
stimulates the thyroid gland to secrete thyroid hormone (T3 & T4)
What is the source of control of TSH?
thyrotropin-releasing hormone from the hypothalamus
What does PRL do?
plays a role in pregnancy, has no effect until AFTER a woman give birth. stimulates mammary glands to synthesize milk.
in males: amplifies effect of LH
What is the source of control of PRL?
prolactin release-inhibiting hormone (PIH) and stimulated by prolactin-releasing factor (PRF) from the hypothalamus
What does GH do?
Makes up majority of anterior pituitary hormones. 1000x more than any others. Stimulates mitosis &stimulates tissues to differentiate ex. puberty, height, etc. Enhances movement of amino acids through membranes
Too much GH before epiphyseal plates close is referred to as?
gigantism
Too much GH after epiphyseal plates close is referred to as?
acromegaly
Too little GH is referred to as?
dwarfism
What is the source of control of GH?
inhibitied by somatostatin (SS) and stimulated by growth hormone-releasing hormone (GHRH) from the hypothalamus
Which hormones are released from the posterior pituitary gland?
ADH (anti-diuretic hormone) and OT (oxytocin)
What’s another name for ADH?
vasopressin
What is the purpose of ADH?
Decreases urine formation. Reduces the volume of water the kidneys excrete.
Hypertension does what to ADH and blood pressure?
It will inhibit ADH and lower blood pressure.
What is the purpose of OT?
Can contract uterine wall. body becomes more sensitive to OT during pregnancy–late pregnancy. responsible for milk ejection. suckling of infant during breastfeeding releases OT. no established function in males: movement of sperm & fluids in reproductive tract.
