Lec 1 Intro Flashcards
What is a hormone?
substance secreted into circulation that travels through bloodstream to distant target
What are features of steroid hormones?
- hormones derived from cholesterol
- intracellular receptors present in low conc
- lipid soluble
- long half lives
- can be given orally
What are features of peptide hormones?
- have cell surface receptors in excess
- water soluble
- short half lives
- destroyed by peptidase in the stomach so much be given systemically
Which type of hormone must be given systemically?
peptide hormones –> b/c destroyed by peptidases in the stomach
What is required to assess the integrity of a hormonal axis?
need to assess axis at least 2 levels
What are two hormones whose release is stimulates by hypoglycemia?
- cortisol
- growth hormone
What is the gold standard test for ACT_cortisol deficiency?
insulin tolerance test –> make pt hypoglycemic and measure cortisol and GH levels at intervals
in truly deficient state will be unable to get a rise in GH/cortisol
What should you do to confirm state of hormone excess?
put at conditions that would normally maximally suppress hormone secretion
What can you do to check for excess mineralocorticoid [aldosterone]?
give lots of salt (which would normally suppress aldosterone secretion)
What happens in the thyroid hormone axis? Including feedback
- hypothalamic TRH stimulates TSH secretion from AP
- TSH stimulates T3/T4 secretion from thyroid
- circulating T3/T4 inhibit TRH and TSH
What is paracrine?
acts on neighboring cells
What is autocrine?
acts on cells that produced it
What is juxtacrine?
hormone bound to cell surface receptor interacts with adjacent cell surface receptor
What is intracrine?
hormone never released from cell has effects inside it
What are 3 types of steroid hormones?
adrenal hormones –> cortisol and mineralocorticoid [aldosterone]
reproductive hormones [androgen, progesterone, estrogens]
steroid type hormones = thyroid hormones [T3 and T4]
