Endocrine revision (Yr2) Flashcards
what are the endogenous thyroid hormones produced from the thyroid follicle?
triiodothyronine (T3)
thyroxine (T4)
what two hormones regulate thyroid hormone secretion?
thyrotropin releasing hormone (TRH)
thyroid stimulating hormone (TSH)
(influenced by plasma iodide)
what is the metabolically active thyroid hormone?
T4
what are the main actions of thyroid hormones?
stimulate metabolism… increase fat, protein and carbohydrate metabolism, increased oxygen consumption and heat production, increased HR (arrhythmias)
effects growth/development… important for normal skeletal growth, nervous system maturation, promotion of milk production
how does the parasympathetic nervous system effect insulin release?
increased parasympathetic drive increases insulin production (increased sympathetic drive decreases production)
which cells are responsible for which hormones in the pancreas?
beta cells - insulin
alpha cells - glucagon
delta cells - somatostatin
what is the main action of insulin?
facilitate uptake/storage of glucose, amino acids and fats after a meal to reduce blood glucose concentration
what effects does insulin have on the liver?
inhibits glycogenolysis and gluconeogenesis
what effect does insulin have on muscles?
upregulates transport of glucose into cells to stimulate glycogen synthesis
what stimulates glucagon production?
low glucose and fatty acid concentration
high amino acids (high protein meal)
both parasympathetic and sympathetic nervous systems stimulate release
what are the main effects of glucagon?
increases blood glucose
causes fat and protein metabolism
increase HR/contractility (this is less of an effect than the metabolic functions)
what are the three regulating factors of calcium and phosphate homeostasis?
parathyroid hormone
vitamin D (calcitriol)
calcitonin
how does vitamin D effect calcium concentration?
increases absorption of calcium from the gut
how does calitriol and parathyroid hormone contribute to calcium homeostasis?
both enhance calcium absorption from the renal tubules to reduce urinary excretion
what regulate phosphate absorption?
calcitriol