Endocrine System Flashcards
organs of endocrine system that secrete hormones
glands
signaling molecules that are secreted into blood stream, travel to target tissues, bind to receptors, and induce a change in gene expression or cellular functioning
hormones
can be classified by chemical structure (peptides, steroids, and amino acid derivatives) or by their target tissues (direct and tropic)
hormones
hormones made of amino acids and are derived from larger precursor proteins that are cleaved during post-translational modification
peptide hormones
hormones that are polar and cannot pass through plasma membrane
peptide hormones
hormones that bind to extracellular receptors because they are charged and can’t pass through plasma membrane
peptide hormones
a peptide hormone is considered the _____; it binds to the receptor and triggers transmission of the second messenger
first messenger
connection between hormone at surface and effect brought about by second messengers within the cell; possibility of amplification at every step
signaling cascade
hormones that exert effects that usually have rapid onset but are short lived
peptide hormones
hormones that are water-soluble so they are able to travel freely in the bloodstream with no need of a special carrier
peptide hormones
hormones derived from cholesterol, produced primarily in the gonads and adrenal cortex
steroid hormones
hormones that are minimally polar and can pass through the plasma membrane
steroid hormones
hormones that bind to cytosolic or intracellular receptors and promote a conformational change in them; this complex binds to DNA alternating transcription of a gene
steroid hormones
hormones that exert effects that usually have slow onset but are long lived
steroid hormones
hormones that are lipid-soluble so they cannot dissolve in the bloodstream and must be carried by specific proteins
steroid hormones
hormones derived from one or two amino acids, usually with few additional modifications; share features with both peptide and steroid hormones
include: epinephrine, norepinephrine, triiodothyronine, thyroxine
amino acid-derivative hormones
hormones that have major effects on non-endocrine tissues
direct hormones
hormones that have major effects on other endocrine tissues
tropic hormones
the bridge between nervous and endocrine systems
hypothalamus
process in the hypothalamus:
the final hormone (or product) of a pathway inhibits hormones (or enzymes) earlier in the pathway, maintaining homeostasis
negative feedback
the hypothalamus stimulates the _____ through paracrine release of hormones into the hypophyseal portal system, which directly connects the two organs
anterior pituitary
tropic hormone secreted by the hypothalamus:
promotes release of FSH and LH
GnRH (gonadotropin-releasing hormone)
tropic hormone secreted by the hypothalamus:
promotes release of growth hormone (GH)
GHRH (growth hormone-releasing hormone)
tropic hormone secreted by the hypothalamus:
promotes release of thyroid-stimulating hormone (TSH)
TRH (thyroid-releasing hormone)
tropic hormone secreted by the hypothalamus:
promotes release of adrenocorticotropic hormone (ACTH)
CRH (corticotropin-releasing hormone) / CRF (corticotropin-releasing factor)
tropic hormone secreted by the hypothalamus:
inhibits release of prolactin
PIF/dopamine (prolactin-inhibiting factor)
the hypothalamus interacts with the _____ via axons of nerves projected by the hypothalamus; ADH and oxytocin are synthesized in the hypothalamus then travel down axons to the _____, where they are released into the bloodstream
posterior pituitary
releases hormones in response to stimulation from the hypothalamus; four are tropic (FSH, LH, ACTH, TSH) and three are direct (prolactin, endorphins, growth hormone)
anterior pituitary
hormones released by the anterior pituitary
mnemonic: FLAT PEG
FSH, LH, ACTH, TSH, prolactin, endorphins, growth hormone
tropic hormone secreted by the anterior pituitary:
promotes development of ovarian follicles in females and spermatogenesis in males
FSH (follicle-stimulating hormone)
tropic hormone secreted by the anterior pituitary:
promotes ovulation in females and testosterone production in males
LH (luteinizing hormone)
tropic hormone secreted by the anterior pituitary:
promotes synthesis and release of glucocorticoids from adrenal cortex
ACTH (adrenocorticotropic hormone)
tropic hormone secreted by the anterior pituitary:
promotes synthesis and release of triiodothyronine and thyroxine from thyroid
TSH (thyroid-stimulating hormone)
direct hormone secreted by the anterior pituitary:
promotes milk production
prolactin
direct hormone secreted by the anterior pituitary:
decreases perception of pain and can produce euphoria
endorphins
direct hormone secreted by the anterior pituitary:
promotes growth of bone and muscle and shunts glucose to these tissues, raises blood glucose concentrations
GH (growth hormone)
releases two hormones produced in hypothalamus
posterior pituitary
hormone released by the posterior pituitary:
increases reabsorption of water in collecting ducts of kidneys, secreted in response to low blood volume or increased blood osmolarity
ADH (antidiuretic hormone/vasopressin)
hormone released by the posterior pituitary:
stimulates uterine contractions during labor and milk letdown during lactation; has positive feedback loop
oxytocin
controlled from anterior pituitary; located at base of neck in front of trachea; two major functions: setting basal metabolic rate (triiodothyronine and thyroxine) and promoting calcium homeostasis (calcitonin)
thyroid
hormone produced by thyroid:
produced by follicular cells and contain iodine; increase basal metabolic rate and alter the utilization of glucose and fatty acids; required for proper neurological and physical development in children
triiodothyronine and thyroxine (T3 and T4)
hormone produced by thyroid:
produced by parafollicular (C) cells; decreases plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut, and promoting calcium storage in the bone
calcitonin
release parathyroid hormone (PTH)
parathyroid glands
hormone produced by the parathyroid glands:
increases blood calcium concentration; decreases excretion of calcium by kidneys and increases bone resorption directly to increase blood calcium concentration; activates vitamin D, which is necessary for calcium and phosphate absorption from the gut; promotes resorption of phosphate from bone and reduces reabsorption of phosphate in the kidney
PTH (parathyroid hormone)
secretes corticosteroids that can be divided into three functional classes: glucocorticoids, mineralocorticoids, cortical sex hormones
adrenal cortex
functions of three functional classes secreted by adrenal cortex
glucocorticoids - sugar
mineralocorticoids - salt
cortical sex hormones - sex
functional class of corticosteroids secreted by adrenal cortex: regulate glucose levels and affect protein metabolism, release is stimulated by ACTH
glucocorticoids
glucocorticoids secreted by adrenal cortex:
increase blood glucose concentration, reduce protein synthesis, inhibit immune system, and participate in immune response
cortisol and cortisone
functional class of corticosteroids secreted by adrenal cortex: used in salt and water homeostasis
mineralocorticoids
mineralocorticoid produced by the adrenal cortex:
promotes sodium reabsorption in distal convoluted tubule and collecting duct, increasing water reabsorption; increases potassium and hydrogen ion excretion; activity is regulated by renin-angiotensin-_____ system
aldosterone
functional class of corticosteroids secreted by adrenal cortex: include androgens (like testosterone) and estrogens in both males and females
cortical sex hormones
derived from the nervous system and secretes catecholamines into the blood stream: promotes glycogenolysis, increases basal metabolic rate, increases heart rate, dilates bronchi, and alters blood flow
adrenal medulla
class of hormones produced by the adrenal medulla: includes sympathetic hormones epinephrine and norepinephrine, which are involved in fight-or-flight responses
catecholamines
endocrine function is to produce hormones that regulate glucose homeostasis
pancreas
in the pancreas:
groups of small clusters of hormone producing cells; contain three distinct cell types: alpha (α), beta (β), and delta (δ) cells
islets of Langerhans
hormone produced by the pancreas:
produced by α-cells, raises blood glucose levels by stimulating protein and fat degradation, glycogenolysis, and gluconeogenesis
glucagon
hormone produced by the pancreas:
produced by β-cells, lowers blood glucose levels by stimulating glucose uptake by cells and promoting anabolic processes like glycogen, fat, and protein synthesis
insulin
hormone produced by the pancreas:
produced by δ-cells, inhibits insulin and glucagon secretion
somatostatin
produce hormones involved in development and maintenance of reproductive systems and secondary sex characteristics
gonads
secrete testosterone in response to stimulation by gonadotropins (FSH and LH)
testes
secrete estrogen and progesterone in response to stimulation by gonadotropins (FSH and LH)
ovaries
helps to regulate circadian rhythms by releasing hormone called melatonin
pineal gland
produce hormones like secretin, gastrin, and cholecystokinin
stomach and intestine
secrete erythropoietin hormone: stimulates bone marrow to produce erythrocytes (red blood cells) in response to low oxygen levels in the blood
kidneys
secretes hormone called atrial natriuretic peptide (ANP): promotes excretion of salt and water in kidneys in response to stretching of atria (high blood volume)
atria of the heart
secretes thymosin hormone: important for proper T-cell development and differentiation
thymus
caused by autoimmune destruction of β-cells of the pancreas, leading to inability to produce insulin, and reliance on insulin injections
Type I diabetes mellitus
branch of the peripheral nervous system the adrenal medulla is involved in
the sympathetic branch of the autonomic nervous system
