Lecture 60-Pituitary Hormones Flashcards
What is growth hormone (somatotropin) secreted by?
Somatotrophs
Stimulators of growth hormones? (6)
GHRH
Decreased glucose
Decreased FFA
Increased AA
Hypoglycemia/fasting/starvation
Puberty (estrogen/testosterone)
What are stimulators of growth hormones that play a role in nutrient regulation?
Decreased glucose
Decreased FFA
Increased AA
Hypoglycemia/fasting/starvation
What are inhibitors of growth hormones?
Somatostatin
Increased glucose, FFA
GH
Obesity
Somatomedins (IGF)
What stimulates somatostatin to be released from hypothalamus?
Somatomedins (IGF)
Where are the metabolic actions of growth hormones?
Liver, muscle, adipose, bone
What are five things that growth hormones affect?
Linear growth, protein synthesis, organ growth, carbohydrate, and lipid metabolism
Direct anabolic actions -> increased ______ absorption from _____, ____ reabsorption from _____, ______ synthesis in the _____.
Ca Absorption from gut
P reabsoprtion from kidney
Protein synthesis in liver
Where are IGF-2 (somatomedin A) made?
Made in the liver
What affect do indirect anabolic actions via somatomeids have?
Increase lean muscle mass, linear bone growth, organ size/function
What are the two direct catabolic effects of growth hormone?
- Increased gluconeogenesis in liver
- Increase lipolysis in adipose tissue
By increasing lipolysis in adipose tissue what is released into the blood? What formation is increased?
-Release of FFA into blood
*FFA is used for energy
-increased formation of ketones
*a lot of ketones lead to metabolic acidosis
What does a deficiency of growth hormone result in?
Dwarfism
What does excessive growth hormone secretion result in?
Acromegaly
What does progesterone do to insulin and growth hormone?
Progesterone antagonizes insulin and stimulates growth hormone
Insulin resistance and possible ketoacidosis
Increase growth hormone -> insulin _____ -> _______ketoacidosis
Insulin Resistance
Diabetic ketoacidosis
What are the (2) hormones released from posterior pituitary?
- Antidiuretic hormone
- Oxytocin
What is ADH synthesized by and where?
Synthesized by neurons in supraoptic nuclei of hypothalamus
What is oxytocin synthesized by and where?
Synthesized primarily by neurons in paracentricular nuclei of hypothalamus
ADH peptide precursor = __________________
Prepropressophysin
Oxytocin peptide precursor = ________________
Prepro-oxyphysin
What are stimulators of ADH secretion?
Increased plasma osmolarity
Decreased blood volume (hypovolemia)
Decreased blood pressure
Pain
Nausea
Hypoglycemia
Nicotine, opiates
What do all the stimulators of ADH have in common?
They all reabsorb water
(Stimulators: increased plasma osmolarity, decreased blood volume (increased plasma osmolarity, decreased blood pressure, pain, nausea, hypoglycemia, nicotine, opiates)
What are the inhibitors of ADH secretion?
Decreased plasma osmolarity, increased blood volume (hypervolemia), increased blood pressure, ethanol, glucocorticoids
What do all the inhibitors of ADH secretion have in common?
Don’t reabsorb water—excreted in urine
(Decreased plasma osmolarity, increased blood volume (hypervolemia), increased blood pressure, ethanol, glucocorticoids)
What part of the nephron is permeable to water?
Distal consulted tubule
Collecting duct
When can water be reabsorbed into blood?
Under the influence of ADH
What are the two major actions of ADH?
Kidney and vascular smooth muscle
ADH receptor = ______ receptor
V2
What two things does the ADH receptor use?
Adenylyl Cyclades and cAMP
What is inserted into the membrane of principal cells in the kidney?
Aquaporin 2
What type of receptor does vascular smooth muscle contraction use?
Uses V1 receptor
What is the syndrome of inappropriate ADH secretion?
-excess ADH released from posterior pituitary
-hypervolemia and hyponatremia
-urine is very concentration
What is peripheral or nephrogenic diabetes insipidus?
-posterior pituitary normal but principals cells in collecting duct unresponsive to ADH
-defective V2 receptor
-dilute urine, concentration body fluids
-circulating ADH increases (high)
What is central diabetes insipidus?
-lack of ADH secretion
-can be at hypothalamus or pituitary
-circulating levels of ADH low
-can’t concentrate urine, large volume dilute urine
-plasma osmolarity increased
