BIO Ch. 5 Endocrine System Flashcards
How do peptide hormones operate?
peptide hormones bind to membrane-bound receptors to initiate a signaling cascade, using second messengers like cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3), and calcium
What is the diff b/w peptide and steroid hormones?
peptide hormones are made up of amino acids derived from polypeptides, water-soluble, short-lived, charged, and travel through the bloodstream.
steroid hormones are derived from cholesterol produced by gonads and adrenal cortex, nonpolar, and can easily cross the cell membrane
How do steroid hormones work?
they bind to intracellular receptors in the cytosol or nucleus and function by binding to DNA to alter gene expression altering the amount of mRNA and protein present in a cell
How are steroid hormones activated?
while attached to carrier proteins, steroid hormones are inactive and must disassociate to carry out function, thus the levels of carrier proteins change the level of active hormones
What are some examples of amino-acid-derived hormones?
epinephrine, norepinephrine, triiodothyronine, thyroxine
What are some examples of peptide-derived hormones?
insulin, vasopressin, thyroxine, triidyronine
What are some examples of steroid-derived hormones?
testosterone, estrogen, cortisol, glucocorticoids, cholesterol
What is the diff b/w the activation of catecholamines and thyroid hormones?
catecholamines (norepinephrine and epinephrine) bind to G-protein-couple receptors while thyroid hormones bind intracellularly
How does the hypothalamus regulate?
via negative feedback which occurs when a hormone later in the pathway inhibits its hormones earlier in the pathway
What is the diff b/w direct and tropic hormones?
direct hormones are secret directly on the target tissues such as insulin secreted by the pancreas causing the increase of uptake of glucose by muscles
tropic hormones require an intermediary to act such as gonadotropin-releasing hormone (GnRH) from the hypothalamus to stimulate the release of LH and FSH which can then act to stimulate testosterone and estrogen
Where does the hypothalamus secrete its products?
it secretes compounds into the hypophyseal portal system (blood vessel system that directly connects the hypothalamus to the anterior pituitary) that travel down the pituitary stalk to bind to receptors on the anterior pituitary
Which hormones are released by the pituitary when GnRH hormone is secreted by the hypothalamus?
FSH and LH
Which hormones are released by the pituitary when GHRH hormone is secreted by the hypothalamus?
Growth hormone
Which hormones are released by the pituitary when TRH hormone is secreted by the hypothalamus?
TSH
Which hormones are released by the pituitary when CRF hormone is secreted by the hypothalamus?
ACTH
Which 2 hormones are received by the posterior pituitary?
oxytocin and antidiuretic hormone (ADH) are synthesized by the thpothalmus and reasles in the posterior pituitary
What is the exception hormone of the hypothalamus?
prolactin-inhibiting factor (PIF), which is actually dopamine, is released by the hypothalamus and causes a decrease in prolactin secretion
What is the role of oxytocin?
stimulation contractions of uterine smooth muscles during labor through a positive feedback mechanism, and milk letdown during lactation
What is the role of ADH?
Increase of water reabsorption in the collecting ducts of the nephrons in the kidneys in response to increased plasma osmolarity or increased concentration of solutes within the blood
What Are the 4 tropic hormones released by the anterior pituitary gland?
FSH, LH, ACTH, TSH
What Are the 4 Direct hormones released by the anterior pituitary gland?
prolactin, endorphins, and GH
What is the role of growth hormone?
promotes the growth of bone and muscle, prevents glucose uptake in certain tissues (those not growing), and stimulates the breakdown of FA
What is the role of prolactin?
stimulation of milk production in the mammary glands
What is the diff b/w gigantism, dwarfism, and acromegaly?
bone growth originates in the epiphyseal plates which seals during puberty. An excess of GH release in childhood before the closure of the plates can cause gigantism and a deficit results in dwarfism. Acromegaly affects the smaller bones like the hands, feet, and head
What is the role of triiodothyronine and thyroxine?
increased amounts of T3 and T4 will lead to increased cellular respiration, leading to a greater amount of protein and FA turnover by speeding up both the synthesis and degradation of these compounds
Where are triiodothyronine and thyroxine produced?
both are produced by the iodination of the amino acid tyrosine. the numbers 3 and 4 refer to the number of iodine atoms attached to the tyrosine
What is the diff b/w hyper and hypothyroidism?
hypo - insufficient or no secretion of thyroid hormones characterized by lethargy, decreased body temp, slower respiratory and heart rate, cold intolerance, and weight gain.
hyper - excessive secretion of thyroid hormone
What is cretinism?
a deficient of thyroid hormone in children that results in mental retardation and developmental delay
What are the 2 hormones produced by the thyroid?
parafollicular cells/C-cells produce calcitonin, follicular cells produce T3 and T4
What is the role of Calcitonin?
acts to decrease plasma calcium levels by decreasing calcium excretion from the kidneys, decreasing calcium absorption from the gut, and increasing storage of calcium in the bone
What is the role of calcium?
bone structure and strength, the release of neurotransmitters from neurons, regulation of muscle contraction, clotting of blood (calcium cofactors), cell movement, and exocytosis of cellular materials
What is the role of Parathyroid hormone (PTH)?
an antagonist to calcitonin and affects the phosphorous homeostasis by reabsorbing phosphate from bone and reducing reabsorption and excretion of phosphate in the kidney as urine
How does PTH antagonist calcium?
PTH raises blood calcium levels, decreases excretion of calcium by the kidneys, increases absorption of calcium in the gut via vit.D, and increases bone resorption, freeing up calcium
What are glucocorticoids?
steroid hormones that regulate glucose levels released y the adrenal cortex
What are 2 glucocorticoid hormones?
cortisone and cortisol
What are the roles of cortisone and cortisol?
raise blood glucose levels by increasing gluconeogenesis and decreasing protein synthesis, and they also decrease inflammation and immunological response
How are glucocorticoid hormones released?
corticotropin-release factors (CRF) from the hypothalamus promote the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary, which promotes the release of glucocorticoids from the adrenal cortex
What is the diff b/w aldosterone and ADH?
Aldosterone does not change the osmolarity as with ADH
What are mineralocorticoid?
hormones that balance water and salt via effecting the kidneys
How does aldosterone work?
it increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron. water follows the sodium cations into the bloodstream, increasing blood volume and pressure. Aldosterone also decreases the reabsorption of potassium and hydrogen ions in the distal convoluted tubule and collecting ducts of the nephrons, promoting their excretion through urination
How is aldosterone secreted?
decreased blood pressure causes the juxtaglomerular cells of the kidneys to secrete renin, which cleaves an inactive plasma protein angiotensin, to its active form, angiotensin I. Angiotensin I is then converted to angiotensin II by the angiotensin-converting enzyme (ACE) in the lungs. angiotensin II stimulates the adrenals to secrete aldosterone
