Endocrine - Pituitary Flashcards
What is the “master gland”?
pituitary gland
What is responsible for brain-endocrine interactions?
Hypothalamic pituitary axis (HPA)
Coordinating center of the endocrine system
hypothalamus
The hypothalamus consolidates signals from what 4 sources?
- Upper cortical inputs
- Autonomic fx
- Environmental cues
- Peripheral endocrine feedback
T/F: The hypothalamus delivers vague signals to the pituitary gland which will release hormones that influence other endocrine systems.
False. the hypothalamus delivers PRECISE signals
Where is the pituitary gland located?
Sella tursica (area of the the sphenoid bone)
4 divisions of the pituitary gland
- anterior pituitary / adenohypophysis (largest)
- Pars intermedius (gone after baby develops)
- Pars tubular (highly vascular, no known hormones secreted)
- Neurohypophysis
Name three ways in which the anterior and posterior portions of the pituitary are distinct from one another
- different connections to the hypothalamus
- different cell types
- secrete different hormones
What is another name for the anterior pituitary?
adenohypophysis
How is the anterior pituitary connected to the hypothalamus?
portal venous network (the anterior pituitary is highly vascularized)
The adenohypophysis is responsible for the regulation of which 6 things?
- thyroid gland
- adrenal glands
- mammary glands
- growth hormone
- gonads
- melanocytes
Type of anterior pituitary cell that is the most abundant and secretes growth hormone
Somatotropes
Type of anterior pituitary cell that secretes adrenocorticotropic hormone (ACTH)
Corticotropes
Type of anterior pituitary cell that secretes thyroid stimulating hormone (TSH)
Thyrotropes
Type of anterior pituitary cell that secretes lutenizing and follicle stimulating hormones (FSH and LH)
Gonadotropes
Type of anterior pituitary cell that secretes prolactin (PRL)
Lactotropes
What is another name for the posterior pituitary gland?
Neurophypophysis
T/F: The posterior pituitary is largely a collection of axonal projections from the hypothalamus.
True
What 2 hormones are produced by the posterior pituitary? What do they regulate?
- Oxytocin and vasopressin
- Uterine contractions and water balance
After hormones are synthesized in the hypothalamus, how are they transported to the posterior pituitary for secretion?
intracellularly
Where is vasopressin primarily synthesized?
supraoptic nucleus
What are the actions of vasopressin, and what are the results of those actions?
- Increases permeability of collecting ducts –> increased free water reabsorption
1. increased urine osmolality
2. decreased plasma osmolality
3. increased ECF volume - Causes contraction of vast smooth muscle
1. vasoconstriction
2. more prevalent in larger doses
What do effects do the V1 and V2 receptors have?
V1 - pressor effect; prevalent w extreme increases in circulating levels, i.e. hemorrhage
V2 - ADH effect
What is the stimulus for vasopressin release?
Osmoreceptor in hypothalamus (HT) activated by plasma osmolality >290 mOsm/kg
(other receptors in HT send sensation of thirst)
_____________ activates stretch receptors in the great veins, atria, and pulm veins for ADH release
Decreased ECF volume
Name 5 things (other than osmolality >290) that stimulate ADH release
angiotensin II nicotine nausea pain stress
How is release of ADH depressed?
- decreased plasma osmolality
- increased ECF volume
- ETOH
How are baroreceptors in the carotid sinus and aortic arch activated?
large volume changes