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123 Cards in this Set
- Front
- Back
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what are the ductless glands of the endocrine system?
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pituitary gland
pineal gland thyroid gland parathyroid glands adrenal glands |
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to where do the glands of the endocrine system empty their hormones?
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into blood circulation
(through vessel walls) |
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what are the three classes of hormone compounds?
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steroid hormones
peptide hormones amino acid analogues and derivatives |
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which classes of hormones are water soluble?
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peptide hormones
amino acid analogues and derivatives |
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from where are steroid hormones released?
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ovary
testes adrenal cortex |
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what are two examples of amino acid analogue and derivative hormones?
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thyroxine (from thyroid)
catecholamines (from adrenal medulla) |
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what hormones are catecholamines?
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epinephrine
norepinephrine |
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what is thyroxine?
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iodinated amino acid
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what is another name for the anterior pituitary gland?
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adenohypophysis
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what is another name for the posterior pituitary gland?
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neurohypophysis
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what are the subdivisions of the anterior pituitary gland (adenohypophysis)?
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pars distalis
pars intermedia pars tuberalis |
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what are the subdivisions of the posterior pituitary gland (neurohypophysis)?
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pars nervosa
infundibulum |
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from what type of tissue is the anterior pituitary gland derived?
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ectoderm
(from oral cavity) |
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from what structure does the anterior pituitary gland develop?
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Rathke's pouch
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from what type of tissue is the posterior pituitary gland derived?
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neuroectoderm
(from base of brain) |
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what is the largest subdivision of the pituitary gland?
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pars distalis
(of anterior pituitary gland) |
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what are the three types of cells in the pars distalis subdivision of the pituitary gland?
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acidophils - stain red/orange
basophils - stain blue chromophobes - pale-staining |
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what are chromophobes in the pars distalis assumed to be?
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degranulated chromophils
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what hormones are secreted by acidophils in the pars distalis subdivision of the anterior pituitary gland?
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growth hormone (GH)
prolactin |
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what stimulates the liver and other organs to secrete insulin-like growth factor 1 (IGF-1)?
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growth hormone (GH)
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what is the effect of IGF-1?
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promotes growth of stem cells in a variety of tissues
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what are the effects of growth hormone?
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mineralizes bones
increases muscle mass increased lipolysis in adipose cells |
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what are the effects of prolactin?
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induces milk secretion
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what are the effects of oxytocin?
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induces smooth muscle contraction in the uterus
induces myoepithelial contraction in the mammary gland |
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what is the effect of ACTH?
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induces secretion (aldosterone and cortisol) from the adrenal cortex
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what are the effects of follicle stimulating hormone?
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induces estrogen secretion
induces spermatogenesis in testes |
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what are the effects of leutinizing hormone?
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induces ovulation and progesterone secretion
induces androgen secretion in testes |
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what hormones are secreted by the acidophils in the pars distalis?
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growth hormone
prolactin |
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what hormones are secreted by the basophils in the pars distalis?
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adrenocorticotropic hormone (ACTH)
thyroid stimulating hormone (TSH) follicle stimulating hormone (FSH) leutinizing hormone (LH) |
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what are the basophilic cells in the pars distalis that secrete FSH and LH in both sexes?
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gonadotropes
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what is the ultrastructure of the gonadotropes in the pars distalis?
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small secretory granules throughout cytoplasm
euchromatic nucleus |
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what is the ultrastructure of peptide hormone secreting cells?
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small secretory granules throughout cytoplasm
euchromatic nucleus |
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where is the pars intermedia located?
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between pars distalis and pars nervosa
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what are Rathke's cysts?
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remnants of Rathke's pouch
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where are Rathke's cysts in the pituitary glands?
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included in pars intermedia
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what is the primary type of cells in the pars intermedia?
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basophilic cells
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what is secreted by the basophilic cells in the pars intermedia?
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melanocyte stimulating hormone (MSH)
endorphins |
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what is the process by which thyroid hormones are released?
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TRH (hypothalamus) ->
TSH (pituitary gland) -> thyroid hormones (thyroid) |
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what is the neurohypophysis composed of?
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unmyelinated axons
pituicytes fenestrated capillaries |
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what are pituicytes?
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glial (supporting) cell of the posterior pituitary
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from where do the unmyelinated axons in the posterior pituitary arise?
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neurons in the hypothalamus
paraventricular nucleus supraoptic nucleus |
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what are Herring bodies?
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dilations or swellings of axons in the posterior pituitary, which are filled with neurosecretory vesicles
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what is contained in Herring bodies?
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neurosecretory hormones
ADH oxytocin |
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to where are the hormones from the Herring bodies released?
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blood capillaries in the posterior pituitary
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where is the primary capillary plexus of the pituitary gland?
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in the hypothalamus, along the median eminence
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what is released into the primary capillary plexus?
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releasing factors (CRH, TRH)
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from what does the pineal gland develop?
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neuroectoderm
(connected to the brain by a short stalk) |
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what two cell types does the pineal gland consist of?
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interstitial (glial) cells
pinealocytes |
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what is secreted by pinealocytes?
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melatonin
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what is corpora arenacea?
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"brain sand"
calcified concretions in the pineal gland which accumulate with age |
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what is the function of melatonin?
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regulates the day/night cycle (i.e. circadian rhythm)
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what is the circadian rhythm?
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day/night cycle
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what inhibits the secretion of melatonin?
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light input from the eye
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by what pathway does light inhibition reach the pineal gland?
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light - > eye -> suprachiasmatic nucleus -> sympathetic central pathways -> superior cervical ganglion -> pineal gland
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what disorders have abnormally high nocturnal levels of melatonin?
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hypothalamic amenorrhea
anorexia nervosa |
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why do abnormally high levels of melatonin cause amenorrhea?
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inhibits the secretion of leutinizing hormone
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what is used to treat delayed sleep phase disorder?
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melatonin
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what is delayed sleep phase disorder?
how does melatonin help this? |
difficulty falling asleep before midnight
melatonin phase-shifts their circadian rhythm backwards to actual bed-time |
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how is corpora arenacea useful?
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useful as a midline marker in x-rays and CT scans (to determine displacement of the brain)
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from what does the thyroid gland develop?
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outpocketing of endoderm lining the floor of the embryonic pharynx (in the base of the tongue)
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where does the thyroid gland store its secretory products?
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lumen of cyst-like follicles
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what forms a thyroid follicle?
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simple endothelium enclosing a lumen filled with colloid
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what is the colloid in a thyroid follicle?
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viscous gel containing mostly iodinated thyroglobulin
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what envelops thyroid follicles?
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basal lamina
reticular fibers fenestrated capillaries |
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what do follicular cells secrete?
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thyroglobulin (a prohormone)
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what forms thyroxine (T4) and triiodothyronine (T3)?
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iodination of tyrosine residues in thyroglobulin (in the lumen of the thyroid follicular cells)
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how are T3 and T4 released?
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TSH stimulates endocytosis of thyroglobulin-T3/T4 complexes
intracellularly, they are cleaved by lysosomal enzymes T3 and T4 are released into the blood |
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which thyroid hormone is more potent?
which thyroid hormone is released in higher quantity? |
T3 is more potent
T4 is released in higher quantity |
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where is T4 converted to T3?
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in the liver
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what are parafollicular cells?
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pale-staining cells, located between the thyroid follicular cells and the basal lamina
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what is secreted by parafollicular cells?
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calcitonin (a polypeptide hormone)
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what is the function of calcitonin?
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binds to its receptor on osteoclasts, causing the ruffled border to go away, reverting it to an inactive state
lowers blood calcium levels by inhibiting bone resorption |
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what is the thyroid test most often used?
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T4 by radioimmunoassay (RIA)
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what is reflected by the amount of T4 in the blood?
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serum thyroxine (if the patient does not take any thyroid medication)
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what test is used to measure pituitary production of TSH?
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immunoradiometric assay (IRMA)
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what is indicated by an elevated TSH level?
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early hypothyroidism
thyroid gland becomes inefficient and TSH will be elevated even though T4 and T3 may still be within the "normal" range |
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what is a goiter?
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swelling of the thyroid gland
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what is the most common cause of a goiter?
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iodine deficiency
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what is Hashimoto's thyroiditis?
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autoimmune disorder causing hypothyroidism
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what is Graves disease?
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autoimmune disorder with autoantibodies to TSH receptors, leading to excess production of thyroid hormone
"goiter with hyperthyroidism" |
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what are the symptoms of Graves disease?
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exophthalmos
tachycardia goiter |
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what are the symptoms of hypothyroidism?
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myxedema (puffiness of the face)
saddle nose (depressed root of the nose) |
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in what are the parathyroid glands embedded?
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four small glands embedded in the thyroid gland
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from what tissue do the parathyroid glands develop?
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endoderm
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what are the two types of cells in the parathyroid glands?
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chief cells
oxyphil cells |
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what do Chief cells in the parathyroid glands secrete?
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parathyroid hormone (PTH)
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what is the function of parathyroid hormone?
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increases blood calcium levels
increases bone resorption increases intestinal absorption of calcium stimulates kidneys to convert vitamin D to active form decrease kidney excretion of caclium |
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what is the function of oxyphil cells in the parathyroid glands?
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function is unknown
(acidophilic cells) |
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what gives oxyphil cells in the parathyroid gland their acidophilic staining character?
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abundant mitochondria
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how do parathyroid glands recognize the need to secrete PTH?
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calcium-sensing receptor (CaSR)
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when do oxyphil cells appear?
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after puberty, increasing in number with age
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what are the two major forms of vitamin D?
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vitamin D2 (ergocalciferol)
vitamin D3 (cholecalciferol) |
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what is the active form of vitamin D in the body?
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calcitriol
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how does vitamin D adjust calcium levels?
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low calcium stimulates 1alpha-hydroxylase to produce calcitriol, which binds to cytosol and nuclear receptors in enterocytes and induces the synthesis of calbindin which transports calcium across the enterocyte
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what is calbindin?
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calcium-binding protein in the duodenum which transports calcium across enterocytes into the bloodstream
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to what superfamily of steroid/thyroid hormone receptors does the vitamin D receptor belong?
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nuclear receptor superfamily
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in what organs are vitamin D receptors expressed?
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most organs, including brain, heart, skin, gonads, prostate, and breast
also in white blood cells |
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what are the clinical correlations of Vitamin D?
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possibly has protective effects against cancer development
deficiency increases risk of infections (influenza and TB) used clinically for a number of immune-related diseases |
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vitamin D is used to treat which immune-related diseases?
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psoriasis
systemic lupus erythematosus multiple sclerosis |
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from what embryonic tissue is the cortex of the adrenal gland derived?
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mesoderm
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from what embryonic tissue is the medulla of the adrenal gland derived?
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neural crest
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what are the three divisions of the adrenal cortex?
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zona glomerulosa
zona fasiculata zona reticularis |
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which division of the adrenal cortex is beneath the connective tissue capsule of the adrenal gland?
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zona glomerulosa
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what is principally secreted by the cells of the zona glomerulosa?
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mineralocorticoids (principally aldosterone)
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what stimulates the production of aldosterone?
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angiotensin II
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what is the arrangement of cells in the zona fasiculata?
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columns
vacuolated cells with many lipid droplets |
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what is secreted by the cells of the zona fasiculata?
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glucocorticoids
hydrocortisone (cortisol) |
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what is the function of glucocorticoids?
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regulate metabolism by promoting gluconeogenesis
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what stimulates the production of glucocorticoids?
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ACTH
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what is interesting about the mitochondria of zona fasciculata cells?
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tubular cristae rather than shelf cristae
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what is the process by which glucocorticoids are released?
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CRH (hypothalamus) ->
ACTH (adenohypophysis) -> glucocorticoids (adrenal cortex) |
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what is the effect of hypophysectomy on the adrenal gland?
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hypophysectomy is the surgical removal of the pituitary gland
it results in cortical atrophy |
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what are the two major cell types in the adrenal medulla?
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chromaffin cells
ganglion cells |
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what are chromaffin cells?
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modified postganglionic sympathetic neurons in the adrenal medulla without axons or dendrites
have an affinity for chromium-containing stains |
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what is secreted by chromaffin cells?
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epinephrine
adrenaline |
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what is the blood supply to the adrenal cortex?
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fenestrated capillaries supplying zona glomerulosa
sinusoids supplying the zona fasciculata and reticularis |
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what is the blood supply to the adrenal medulla?
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venous blood reaching medulla via sinusoids through the cortex
arterial blood reaching medulla via direct branches from the capsular artery |
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what is rich in the venous blood supplying the medulla?
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hormones
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what are the effects of Addison's disease?
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destruction of adrenal cortex leading to primary cortisol deficiency
hyperpigmentation of the skin and oral mucosa |
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why is there hyperpigmentation in Addison's disease?
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compensatory increase in ACTH and especially MSH from the pituitary gland
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what is a pheochromocytoma?
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typically benign tumor derived from chromaffin cells of the adrenal medulla
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how is a pheochromocytoma diagnosed?
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increased urinary excretion of catecholamines and their metabolites, as well as imaging
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why does (paroxysmal) hypertension result from pheochromocytoma?
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hyperproduces catecholamines
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