Endocrinology Flashcards
(44 cards)
What is a peptide hormone
Made from amino acids
Act on effector cell membrane receptors and initiate internal secondary messenger cascades
*water soluble in the blood
How are peptide hormones made
Synthesized in the RER as preprohormones which are cleaved into prohormones and move to Golgi apparatus for modification into peptide hormones
Packed in secretory vesicles for release via exocytosis
What are steroid hormones
Derived from cholesterol in the smooth ER and mitochondria
Insoluble in water so require proteins for transport in the blood
How do steroid hormones have an effect on gene expression
Bind to protein to move through blood stream then they cross the cell membrane of the effector cell and bind to a receptor in the cytosol
The cytosol is receptor and the steroid complex move into the nucleus and influence gene expression
Compare peptide to steroid hormones
Peptide are fast acting short lived, water soluble
Steroid are slow acting long lived, non water soluble
What are tyrosine derivative hormones
Lipid soluble hormones derived from the amino acid tyrosine
Hydrophobic and hydrophilic properties
How do tyrosine derivative hormones work
One type is like steroid hormones
The catecholamines epinephrine and norepinephrine are like peptide hormones
Tropic vs direct peptide hormone
Tropic has another gland as its target
Direct has an organ as its target
How do hormones go from the hypothalamus to the pituitary
To the anterior pituitary vis the blood stream - hypothalamic hypophyseal portal system
To the posterior pituitary via nerve axons
What are the 2 direct peptide hormones that neurosecretory cells of the hypothalamus synthesis
Vasopressin
Oxytocin
Which hormones does the posterior pituitary synthesize
It doesnt! It only stores hormones oxytocin and vasopressin
What does vasopressin (ADH) do
Increased water reabsorption in the kidney tubules
Makes you not pee
What inhibits ADH
Caffeine and alcohol
What does oxytocin do
Secreted during child birth for uterine contractions
Stimulates milk secretion
What is somatostatin
Tropic peptide hormone made in hypothalamus that inhibits the release of GH and TSH
Which hormones does the anterior pituitary synthesize and release
FLAT PEG FSH LH ACTH TSH PRL Endorphins GH
Describe how growth hormone works
GHRH growth hormone releasing hormone made in the hypothalamus stimulates GH release which stimulates all cells for growth
releasing = tropic
Describe how adrenocorticotropic hormone works
Stimulated by CRH from hypothalamus
It works as tropic peptide hormones to stimulate the adrenal cortex to synthesis and secrete glucocorticoids during stress
How does thyroid stimulating hormone work
Stimulated for release by TRH from hypothalamus
Acts as tropic peptide hormone and stimulates thyroid glad to increase in size, absorb iodine and synthesize thyroid hormone
How does a lack of iodine effect the thyroid feedback loop
If no iodine , insufficient T3 and T4 will be produced so there will be no inhibition of TRH and the thyroid will continue to grow resulting in goiter
How is the release of luteinizing hormone stimulated
Estrogen stimulates GnRH gonadotropin releasing hormone from the hypothalamus to release LH
Estrogen and progesterone of the corpus luteum inhibits the release of GnRH
What is the function of LH
Tropic peptide hormone
In females - stimulates ovulation and formation of corpus luteum
Males - stimulates testes to synthesize testosterone
How is FSH regulated
Stimulated by GnRH which is stimulated by estrogen
Inhibited by estrogen and progesterone of corpus luteum
What is the function of FSH
Tropic peptide
Females- maturation of the ovarian follicles
Males - maturation of the seminiferous tubules for sperm production
