The Endocrine System Flashcards
glands
secrete hormones
hormones
signaling molecules that are secreted directly into the bloodstream to travel to a distant target tissue
peptide hormones
made up of amino acids; can not pass the cell membrane so they attach to the outside receptor (therefore it is a first messenger) and stimulates release of a second signal aka the second messenger
signaling cascade
connection between hormone at surface and the effect brought about by second messengers
steroid hormones
can easily cross the cell membrane to intracellular receptors; receptor binds directly to DNA, changing transcription of particular genes; slower but longer lived effects; not water soluble so they must be carried by proteins in the body in order to travel in blood; normally end in -one, -ol, or -oid
amino-acid derivative hormones
includes epinephrine, norepenephrine, trioodothryonine and thyroxine; normally end in -in or -ine
direct hormones
are secreted and then act directly on a target tissue
tropic hormones
require an intermediary to act
hypothalamus
bridge between nervous and endocrine systems; controls pituitary gland through paracrine release of hormones into a portal system that directly connects the two organs
hypophyseal portal system
blood vessel system that directly connects the hypothalamus and the anterior pituitary
Hormones released by hypothalamus and the hormones released by anterior pituitary in response
Gonadotropin-releasing hormone (GnRH):FSH and LH
Growth hormone releasing hormone: growth hormone
Thyroid-releasing hormone: thyroid-stimulating hormone
Corticotropin-releasing factor: adrenocorticotropic hormone
axes
three organ systems
posterior pituitary hormones
oxytocin and antidiuretic hormone
tropic hormones
hormones of the anterior pituitary that work by causing the release of another hormone at the organ level
direct hormones of anterior pituitary
prolactin- stimulates milk production endorphins- decrease perception of pain growth hormone (GH)- promotes growth of bone and muscle
thyroid functions
sets basal metabolic rate and calcium homeostasis
triiodothyronine and thyroxine
produced by iodination of tyrosine; thyroid hormones
hypothyroidism
thyroid hormones are secreted in insufficient amounts; weight gain, lethargy, cold intolerance etc
cretinism
low thyroid levels in children, resulting in mental retardation and developmental delay
hyperthyroidism
excess of thyroid hormone, may result from a timor or thyroid overstimulation; heightened activity level, increased body temp, increased respiratory and heart rate, heat intolerance and weight loss
calcitonin
produced by C-cells in the thyroid; acts to decrease plasma calcium levels
parathyroid hormone
serves as an antagonistic hormone to calcitonin, raising blood calcium levels; decreases excretion of calcium by the kidneys, increases absorption of calcium in the gut and increases bone resorption
vitamin D
required for the absorption of calcium and phosphate in the gut
adrenal cortex
secretes corticosteroids
glucocorticoids
steroid hormones that regulate glucose levels; also effect protein metabolism; cortisol and cortisone
cortisol and cortisone
raise blood glucose by increasing gluconeogenesis and decreasing protein synthesis; can also decrease immunologic responses
mineralocorticoids
used in salt and water homeostasis; most profoundly effect the kidneys; aldosterone
aldosterone
increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron
response to decreased BP
juxtaglomerular cells of the kidney secrete renin which cleaves angiotensinogen to angiotensin I; angiotensin 1 is then converted to angiotensin 2 by angiotensin converting enzyme; angiotensin II then stimulates the adrenal cortex to secrete aldosterone, restoring BP
cortical sex hormones
androgens and estrogens
adrenal medulla
produces epinephrine and norepinephrine; belong to catecholamines
Islets of langerhans
alpha cells: secrete glucagon
beta cells: secrete insulin
delta cells: secrete somatostatin
diabetes symptoms
polyuria and polydipsia
Type-1 (insulin dependent) diabetes
caused by autoimmune destruction of pancreatic beta cells
Type II (non-insulin-dependent) diabetes
result of receptor-level resistance to insulin
somatostatin
inhibitor of boh insulin and glucagon secretion;
pineal gland
secretes melatonin to regulate circadian rhythms
erythropoietin
stimulates bone marrow to increase production of red blood cells
atrial natriuretic peptide
helps regulate salt and water balance; lowers blood volume and pressure
thymosin
important for proper T-cell development and differentiation
