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133 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Why is communication vital for any multicellular oranism? (4 reasons)
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Maintain homeostasis; coordinate growth and development; adapt to internal and external stresses; contribute to the processes of sexual reproduction
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Two communication systems
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nervous and endocrine
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Where is interaction between the nervous and endocrine system coordinated?
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hypothalamus
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Neuroendocrine signaling mechanism
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neuron releases a chemical mediator not into a synapse but into one or both of the vascular systems. The mediator then affects a cell at some distance.
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What type of vasculature is typical for the endocrine system?
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fenestrated and sinusoidal blood capillaries
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CT of fibrous capsule around endocrine glands
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dense irregular connective tissue (type I collagen)
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4 parenchymal arrangements of endocrine system
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unicellular, cords, follicular pattern, multipolar neurons
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what do steroid secreting glands store?
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the hormone precursor cholesterol
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pro-opiomelanocortin (POMC)
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a prohormone made in several tissues in the body including the brain and pituitary that is broken down into ACTH
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positive feedback system (loop)
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the response enhances or intensifies the original stimulus
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Are most feedback systems in the body positive or negative?
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negative
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examples of negative feedback loops
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blood pressure, body temperature and blood glucose level
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examples of positive feedback loops
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blood clotting, labor contractions during childbirth and immune response that provide defence against pathogens
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What is the source of hormones that are derivatives of tyrosine?
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adrenal medulla, thyroid gland, and pineal gland
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What is the source of small peptide hormones?
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posterior pituitary, heart atria
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What is the source of small protein hormones?
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pancreas, anterior pituitary and parathyroid glands
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What is the source of steroid hormones
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adrenal cortex, ovaries and testes
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What are examples of Eicosanoid hormones? And what is the source of them?
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prostaglandins and leukotrienes; all cells except red blood cells
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What does binding to plasma proteins do to circulating hormones?
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makes them inactive
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Endocrine organs
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pineal, brain, ituitary, thyroid, parathyroid, thymus, adrenal gland, islets of langerhans of pancreas, parts of the ovary, testis, kidney, placenta, and heart
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2 parts of the pituitary gland
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neurohypophysis and adenohypophysis
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2 parts of the neurohypophysis
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pars nervosa and infundibulum (w/ infundibular stem and median eminence)
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3 parts of the adenohypophysis
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pars distalis, pars intermedia, and pars tuberalis
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What is the embryological origin of the pituitary gland?
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neural ectoderm (neurohypophysis) and ectoderm lining the oral cavity (adenohypophysis)
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Two main parencymal cell types of the pars distalis of the pituitary gland
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chromophobes and cormophils
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Chromophobes
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degranulated chromophil that is a parenchymal cell of the pars distalis of the pituitary gland (adenohypophysis) that is found in clusters away from the capillaries
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chromophils
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granulated hormone secreting cells of the adenohypophysis that are either acidophils or basophils
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What do the acidophil type of chromophils secrete?
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growth hormone and prolactin
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What do the basophil type of chromophils secrete?
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FSH, LH, TSH and ACTH
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what is the purpose of the hypophyseal portal system
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transport hormones from the hypothalamus to the adenohypophysis
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2 types of small peptide hormones synthesized in the neuron cell bodies of the hypothalamic nuclei:
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Releasing hormones and inhibiting hormones
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GnRH
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small peptide releasing hormone of the hypothalamic nuclei that stimulates gonadotrophs to release FSH and LH
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CRH
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small peptide releasing hormone of the hypothalamic nuclei that stimulates corticotrophs to release ACTH
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TRH
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small peptide releasing hormone of the hypothalamic nuclei that stimulates thyrotrophs to release TSH
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GHRH (somatotropin)
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small peptide releasing hormone of the hypothalamic nuclei that stimulates somatotrophs to release GH
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Somatostatin
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small peptide inhibiting hormone of the hypothalamic nuclei that inhibits growth hormone release from somatotrophs; inhibits gastrin release and is produced by δ cells of the pancreatic islets
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Dopamin
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small peptide inhibiting hormone of the hypothalamic nuclei that inhibits prolactin release from mammotrophs
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Pars intermedia
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thin layer of cells and colloid cyts next to the neural lobe of the pituitary. This region atrophies in adults
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Pars nervosa
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nervous tissue down-growth of the hypothalamus that makes up the posterior lobe of the pituitary gland and connects to the infundibulum. Consists of modified multipolor neurons with unmyelinated axons
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What do the unmyelinated axons of the hypothalamohypophyseal tract contain
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large granule-filled dilations called herring bodis along their length
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What do the granules of herring bodies contain?
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either oxytocin or ADH, ATP and neurophisins
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function of neurophysins
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low-affinity carriers for the hormones as they travel down the axon to the nerve terminal
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Pituitcytes
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higly branched astrocytes whose processes surround and support the axons of the hypothalamo-hypophyseal tract
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Oxytocin
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small peptide hormone of the posterior pituitary that stimulates milk ejection by the mammary glands and stimulates uterine smooth muscle contraction during copulation and childbirth
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arginine vasopressin (AVP) or antidiuretic hormone (ADH)
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small peptide hormone of the posterior pituitary that stimulates water resorption by the renal medulalary collecting duct. Regulated by the supraoptic nucleus
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APUD cells or the diffuse neuroendocrine system cells
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unicellular glands scattered among epithelial cells derived from neural crest that are polypeptide secreting with concentrated bioactive amines in secretory granules in their bases
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DNES polypeptides mechanism of signalling
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paracrine and endocrine
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gastrin
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digestive hormone that promotes secretion of gastric juice, increases gastric motility and promotes growth of gastric mucosa
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secretin
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digestive hormone that stimulates secretion of pancreatic juice and bil
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cholecystokinin
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digestive hormone that stimulates secretion of pancreatic juice rich in digestive enzymes and causes opening of sphincter of oddi which ejects bile from the gall bladder
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Embryological origin of thyroid gland
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endoderm
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2 cell types of thyroid gland
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follicular cells and parafollicular cells
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What fills the lumen of the follicle of the thyroid gland?
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colloid (mainly consists of the glycoprotein thyroglobulin)
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What is functional activity of follicular cells stimulated by?
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TSH from the anterior pituitary and by sympathetic nerves
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when is TSH increased?
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low environmental temperatures, puberty and pregnancy
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when is TSH decreased?
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emotional stress and systemic stress
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What stimulates iodide uptake by follicular cells?
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TSH
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When endosomes combine with lysosomes in follicular cells, what is iodothyroglobulin broken down into?
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2 hormones, T3 and T4.
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Function of T3 and T4
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increase basal metabolic rate (the rate at which cells use glucose), promote cell growth, increase HR, raise body temp, and enhance all energy-requiring cell functions
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parafollicular cells
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APUD cells of the thyroid gland that are derived from neural crest and secrete the peptide hormone colcitonin in response to high blood Ca
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Calcitonin
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peptide hormone secreted by parafollicular cells of the thyroid gland that inhibits bne resoprption by inhibiting osteoclasts and threby lowering blood calcium.
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What is the embryological origin of the parathyroid glands?
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endoderm of the 3rd and 4th pharyngeal pouches
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2 cell types of the parathyroid gland
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chief cells and oxyphil cells
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What is the vasculature of the parathyroid glands
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broad, irregular fenestrated capillaries channel the parenchymal cells
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Chif Cells
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most abundant parenchymal cells of the parathyroid glands that secrete parathyroid hormone
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parathyroid hormone
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peptide hormone that increases blood calcium by acting on bone, in kidneys and in the intestines
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What causes activation of a vitamin D precursor in the kidney?
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parathyroid hormone
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Oxyphil cells
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large parencymal cells of the parathyroid gland with many mitochondria and an unknown function
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What shape are the adrenal glands?
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Right: pyramid; Left: crescent shaped
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Embryological origin of cortex of the adrenal gland
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mesoderm
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what does the cortex of the adrenal gland secrete?
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3 classes of ssteroid hormones: mineralocorticoids, glucocorticoids and androgens
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What are the 3 zones of the cortex and their primary secretion?
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zona glomerulosa (mineralocorticoid: aldosterone); fasciculata (glucocorticoids); zona reticularis (androgens and glucocorticoids)
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function of mineralocorticoids
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osmotic balance and blood pressure regulation by affecting the function of renal tubules
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Atrial natriuretic peptide
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hormone released by the atrial cells of the heart in response to high BP and inhibits aldosterone release from the zona glomerulosa.
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what is the vasculature of the zona fasciculata of the adrenal glands?
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sinusoidal capillaries run between cords
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Spongiocytes
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cells in the zona fasciculata arranged in cords with large lipid droplets in their cytoplasm
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What stimulates the secretion of glucocorticoids to raise BP?
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ACTH from the anterior pituitary stimulates the zona fasciculata and zona reticularis
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2 types of cells in the medulla of the adrenal glands
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chromaffin and ganglion cells
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Chromaffin cells
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parenchymal cells of the medulla of the adrenal glands that are modified postganglionic sympathetic neurons that release epinephrine and norepinephrine
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function of epinephrine
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increases blood glucose, alertness, cardiac output and HR
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function of norepinephrine
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increases blood pressure by vasoconstriction
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What is the physiological role of the fetal adrenal in the fetal life?
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oto synthesize estrogen precursors which are converted in the placenta to estrogens.
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What is the endocrine component of the pancreas called
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islets of Langerhans
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What is the embryological origin of the islets of langerhans?
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endoderm and part of the DNES
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β cells
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parenchymal cells of the islets of langerhans that are concentrated in the center. They produce insulin in response to high blood glucose
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α cells
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parencymal cells that are in the periphery of the islets of langerhans and produce glucagon in response to low blood glucose
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δ cells
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parenchymal cells in the islets of langerhans that produce somatostatin to inhibit α cells and β cells.
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F cells (or PP cells)
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parenchymal cells located in the periphery of the islets of langerhan that produces pancreatic polypeptide that inhibit pancreatic exocrine secretion of enzymes and bicarbonate
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What is the embryological origin of the pineal gland?
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ectoderm
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2 cell types of pineal gland
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pinealocytes and astrocytes
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What is the secretion of pinealocytes?
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serotonin during the day and melatonin at night
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What are circadian rhythms controlled by?
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periodic release of NE by postganglionic sympathetic fibers which in turn is controlled by light perceived by the retina.
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What is the primary site of action for melatonin?
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hypothalamus
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Melatonin's functions:
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immune response, tep regulation, and possibly aging and senescence
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What is the primary target for FSH?
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testes
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What does diabetes insipidus result from?
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hyposecretion of ADH
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What is responsible for regulating hormone release and function throughout the body?
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the neuroendocrine system (hypothalamus, pituitary and adrenal gland)
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Two mechanisms for inactivating hormones
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removal of receptor area, inactivate hormone by enzyme
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3 types of dysfunction that diseasaes associated with hormone defects cause:
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overproduction (from tumor formation?), underproduction, or target cell insensitivity
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None
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Which glands produce peptide hormones?
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anterior pituitary, posterior pituitary, hypothalamus and pancreas
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Where is ACTH produced and what does it do?
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anterior pituitary; stimulates synthesis and secretion of adrenal cortical hormones (cortisol, androgens, and aldosterone)
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Where is prolactin produced and what does it do?
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anterior pituitary; stimulates milk production and secretion in breast
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Where is growth hormone produced and what does it do?
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anterior pituitary; stimulates protein synthesis and overall growth
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Where is Luteinizing hormone (LH) produced and what does it do?
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anterior pituitary; stimulates testosterone synthesis, and ovulation, formation of corpus luteum, estrogen and progesterone synthesis in ovaries
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Where is Follicle stimulating hormone (FSH) produced and what does it do?
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anterior pituitary; stimulates sperm maturation of testes and follicular development and estrogen synthesis in ovaries
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Where is thyroid stimulating hormone (TSH) produced and what does it do?
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anterior pituitary; stimulates synthesis and secretion of thyroid hormones
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Where is oxytocin produced and what does it do?
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posterior pituitary; stimulates milk ejection from breasts and uterine contractions
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Where is AVP or ADH produced and what does it do?
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posterior pituitary; stimulates water reabsorption in principal cells of collecting ducts and constriction of arterioles
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Where is calcitonin produced and what does it do?
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thyroid (parafollicular cells); decreases serum Ca2+
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What does PTH do?
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parathyroid hormone increases serum Ca2+
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Where is insulin produced and what does it do?
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β cells of pancreas; decreases blood glucose
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Where is glucagon produced and what does it do?
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α cells of pancreas; increases blood glucose
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Where is renin produced and what does it do?
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kidney; catalyzes conversion of angionesinogen to angiotensin I
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What does a pre-prohormone contain at it's N-terminus and why?
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a 15-25 residue signal sequence of mostly hydrophobic aa that allows entry of the pre-prohormone into the ER
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How are peptide hormones received by cells?
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receptor mediated endocytosis and then hormone and receptor are degraded by lysosomal proteases
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What does POMC become?
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ACTH
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How are peptide hormones released?
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by the regulated secretory pathway; requires stimulus (releasing hormone that causes depolarization of PM, then an influx of Ca2+ for the release of hormone)
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What are prohormones packaged in?
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immature secretory granules (IMG)
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How is ACTH inhibitted (and where)
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feedback inhibition by cortisol (anterior pituitary, hypothalamus) and negative inhibition by dopamine (anterior pituitary)
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Cushing's syndrome
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a peptide hormone disease that is an adenoma of the adrenal cortex that releases excess cortisol
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Cushing's disease
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pituitary-acth secreting tumors, most common form of cushings syndrome
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what are the 4 types of diabetes insipidus?
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nephrogenic, gestational, dipsogenic, and neurogenic (most common)
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what is diabetes insipidus characterized by?
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polyuria and polydipsia,
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What does iodination of tyrosine residues in thyroglobulin produce?
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monoiodoyrosine (MIT) and diiodotyrosine (DIT)
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Is T3 or T4 more active?
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T3
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Where are MIT and DIT synthesized? And by what?
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the follicular cells of the thyroid gland, by the enzyme thyroidal peroxidase
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How are MIT and DIT stored?
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thyroglobulin
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Where is thyroglobulin iodinated?
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colloid space of follicular cells
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What is the major site of degradation of T4 and T3?
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liver
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Exophthalmos
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protruding eyes, caused by hyperthyroidism
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None
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What are the symptoms of hypothyroidism?
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lowered basal metabolic rate, diastolic hypertension, and goiter
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levothyroxine
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treatment for hypothyroidism
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what is the cause of hyperthyroidism
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autoimmune. There are antibodies to TSH receptors
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