Week 2 - Ant. Pituitary Flashcards
The pituitary gland lies in the _____ ______ just below the hypothalamus.
Sella turcica (“bony saddle”)
Pituitary is connected to the hypothalamus
by a little stalk called the _________,
which contains nerve fibers and small blood
vessels
infundibulum
The pituitary gland is composed of what 3 major parts?
Anterior
Posterior
Intermediate
What does the intermediate lobe of the pituitary gland secrete?
melanocyte stimulating hormone (MSH)
T/F: Most hypothalamic & pituitary hormones
are released in a pulsatile or burst-like
manner
True
What are the 5 hormones secreted by the Anterior Pituitary?
- Growth hormone (GH)
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Gonadotropic hormones (FSH, LH)
- Prolactin (PRL)
T/F: The posterior pituitary is really a neural
extension of the hypothalamus
True
What are the 2 hormones secreted by the Posterior Pituitary?
- Antidiuretic hormone (ADH)
2. Oxytocin
What is the other name for the anterior pituitary?
Adenohypophysis
What is the other name for the posterior pituitary?
Neurohypophysis
What is the other name for growth hormone secreted by the anterior pituitary? Which cells secrete them?
Somatropin; secreted by somatotrophs
What is the hypophysiotropic hormone related to growth hormone?
Growth hormone releasing hormone (GHRH)
What are 9 stimulators of growth hormone release?
- Hypoglycemia/fasting
- Glucagon
- Ghrelin
- Estrogen
- Androgens (during puberty)
- Strenuous exercise
- Nicotine
- Vit B3
- Deep Sleep
What is the secretion amount of growth hormone in young adolescents and healthy adults?
Young adolescents: 700mcg/day
Healthy adults: 400mcg/day
Secretion is greatest about ____ hour/s after sleep onset.
1 hour
T/F: Nearly 50% of total GH secretion occurs during slow-wave sleep. What stage of sleep is this?
True; Stage 3 and 4 of NREM sleep
T/F: Sleep deprivation increases growth hormone release.
FALSE! It suppresses growth hormone release
What are 4 inhibitors of growth hormone?
- Somatostatin (Growth-hormone inhibiting factor)
- Hyperglycemia, increased free fatty acids
- Glucocorticoids (cortisol)
- Increased Dihydrotestosterone
Growth hormone is primarily a/an _________ hormone
anabolic
Growth hormone increase height in childhood by stimulating multiplication of which cells?
Chondrocytes
Excess growth hormone secretion in childhood is which disorder?
Pituitary gigantism
Prolonged growth hormone excess after closing of epiphyseal plates, causing thick bones in jaw, fingers, and toes is which disorder?
Acromegaly
Growth hormone stimulates production of insulin-like growth factor (IGF-1,2) from the liver. What are 6 effects of this on peripheral tissue?
- ↑ muscle mass
- Promotes lipolysis
- ↑ protein synthesis
- ↓ liver uptake of glucose
- Stimulates immune system
- Improve calcium retention
Adreno-corticotropic hormone (ACTH) is also known as ________ and is secreted by which cells in the anterior pituitary?
Corticotropin; corticotrophs
What is a hypophysiotropic hormone related to ACTH? What does it do?
Corticotropin-releasing hormone (CRH); stimulates ACTH in a pulsatile manner
What is the function of ACTH?
Stimulates adrenal cortex to release corticosteroids (specifically from the zona fasciculate & zona reticularis)
Which cells secrete thyroid-stimulating hormone (TSH)?
Thyrotrophs
Which sex hormone will increase sensitivity of thyrotrophs to TRH?
Estrogens
What is the hypophysiotropic hormone for TSH?
Thyrotrophin-releasing hormone (TRH)
What are 3 inhibitors of TSH?
- Somatostatin
- Dopamine
- Cortisol
How does cortisol inhibit TSH?
It impairs sensitivity of the pituitary to TRH; may lower serum to undetectable levels
What are 3 functions of TSH?
- Thyroid hormone secretion (T4 and T3)
- Hyperplasia/hypertrophy of thyroid gland
- Vascularization of thyroid gland
_____ is the primary marker used to assess thyroid function.
TSH
T/F: Levels of TSH are proportional to the concentration of
thyroid hormone in the plasma
FALSE! Levels are inversely proportional
Which 2 hormones are secreted by cells called gonadotrophs?
FSH and LH
What is the hypophysiotropic hormone related to FSH and LH?
Gonadotropin-releasing hormone (GnRH)
What is the overall function of FSH?
Stimulates growth of germ cells
What is the function of FSH in women? Which form of estrogen levels rise?
Ovary: stimulates growth of Graafian follicles to maturation; estradiol levels rise
What is the function of FSH in men?
Testes: stimulates spermatogenesis
What role does cortisol play in relation to LH?
Inhibits gonadotroph response to GnRH