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51 Cards in this Set
- Front
- Back
What class of hromones are secreted from the hypothalamus and pituitary? What is the one exception?
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Peptide
Dopamine or prolactin inhibiting factor is an amine |
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The posterior pituitary secretes what two hormones?
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Oxytocin and ADH
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What organs secrete hromones that are derivatives of tyrosine?
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Thyroid (T3 and T4) and Adrenal medulla (epi and norepi)
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What hormones are secreted by the Anterior pituitary?
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FAT PIG
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Vitamin D is a hormone of what class? what is it released from?
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Steroid
Kidney |
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What hormone released from the placenta is a peptide?
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HCG and Human Somatomammotropin
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What major tissues secrete steroids?
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Adrenal cortex
Ovaries and placenta Testes |
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Where within the cell are peptide hormones synthesized? In what form are they first created? is this biologically active?
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RER
They are first synthesized as preprohormones that are biologically inactive |
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Where are peptide hormones cleaved to form their biologically active products?
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Enzymes within the Secretory vesicles cleave prohormones
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What is the major process by which peptide hormones are secreted? What is the mechanism?
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Exocytosis: The stimulus for release is an increase in cytosolic Ca2+ concentration. At other times this may occur through cAMP and protein kinases
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Stimulates testosterone synthesis in Leydig cells
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LH; this hormones also stimulates ovulation, formation of the corpus luteum, and progesterone and estrogen synthesis in the ovaries
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Causes maturation of sertoli cells in testes and growth of follicles in the ovaries
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FSH
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Inhibits growth hormone release. Where is this secreted from?
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Somatostatin
Hypothalamus |
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Translation of proteins occurs where?
Transcription? |
RER
Nucleus |
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Thyroid hormones are stored where? How are they secreted
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Thyroglobulin; they are sectreted when the amines are split from the thyroglobulin and the free hormones are then released into the blood.
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What controls negative feedback inhibition of hormone release?
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The controlled variable is not the secretory rate of the hormone itself, but the activity of the target tissue
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What major hormone mechanism is an example of positive feedback?
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Just before ovulation, estrogen from the ovaries stimulates the release of LH from the ant pituitary. This in turn causes the release of more estrogen which in turn causes more secretion of LH, causing ovulation.
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What hormone is markedly increased during the first stages of sleep?
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Growth hormone
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How are steroid and thyroid hormones transported through the blood?
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They are bound to plasma proteins
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What hormones are water-soluble, and therefore transported freely through plasma
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Peptide and catecholamines
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Metabolic clearance rate
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Rate of disappearance of hormone/concentration of hormone
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How are water-soluble hormones degraded?
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These hormones are degraded by enzymes in the blood and tissues and rapidly excreted by the kidneys and liver
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Cell receptors for steroids are located where? Thyroid receptors?
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Steroid receptors are found in the cell cytoplasm.
Thyroid receptors are found in the nucleus, often in association with chromosomes. |
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Location of catecholamine receptors
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cell membrane
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Down regulation occurs as a result of what?
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1. inactivation of receptor molecules
2. inactivation of intracellular signaling molecules 3. Sequestration of receptors to the inside of the cell membrane 4. Lysosomal destruction of internalized receptors 5. Decreased production of receptors |
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Most hormones open or close channels via what mechanism?
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Indirectly through G-protein receptors
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How many transmembrane segments do G-proteins have
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7
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G proteins bind what? What subunit binds GDP in the inactive state? How does it become activated?
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guanosine nucleotides; The alpha subunit; When the hormone binds to the receptor, it becomes activated and binds the trimeric G-protein subunits on the cytoplasmic side. The GDP is then exchanged for GTP, and thus is activated
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What causes the alpha subunit to displace from the trimeric G-Protein? How is the signaling event terminated?
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The binding of GTP to the alpha subunit causes it to dissociate from the trimeric G-Protein and bind to intracellular signaling proteins.
The hormone is removed and the alpha subunit converts the GTP to GDP. |
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Receptors that bind the hormone extracellularly and immediately activate intracellular enzymes
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Enzyme-linked receptors
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Cytokine receptors induce what type of signaling
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JAK -STAT
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Function of JAK proteins? STAT proteins?
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JAK: phosphorylate tyrosine residues to mediate receptor signalling, especially STATs. Other rapid effect enzymes are MAPK and PI3K.
STAT: Activates transcription to initiate protein synthesis. This is SLOW. |
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What hormone utilizes cGMP second messenger?
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ANP
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Lipid soluble hormones bind with what that is located on the DNA to initiate or repress transcription?
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Hormone response elements
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Hormones that use adenylyl cyclase-cAMP second messenger system
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ACTH
Catecholamines CRH FSH Glucagon HCG LH PTH TSH full table p 913 |
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Stimulates the adenylyl cyclase-cAMP
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Gs
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G-protein adenylyl cyclase-cAMP mechanism
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Binding of the hormone causes the alpha subunit of the G protein to bind to adenylyl cyclase. Stimulation of adenylyl cyclase causes ATP to be converted to cAMP, which activates protein kinases, which phosphorylate specific proteins.
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What allows for a small amount of hormone to create a powerful response?
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cAMP activates a cascade of enzymes.
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Hormones that utilize phospholipase C second messenger
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alpha receptor catecholamines
Angiotensin II GnRH GHRH Oxtocin TRH Vasopressin |
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The hormones of the posterior pituitary utilize what second messenger
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Phospholipase C
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What two hormones utilize both cAMP and phospholipase messenger systems?
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Angiotension I:
Vascular Smooth muscle: PLC Epithelial cells: cAMP Vasopressin: V1 vascular smooth muscle: PLC V2 epithelial cells: cAMP |
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PLC mechanism
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Peptide hormones bind to the transmembrane receptor which activates G-Protein signaling. The alpha subunit then binds to Phospholipase C which catalyzes the breakdown of PIP2 to IP3 and DAG. The IP3 mobilizes Ca2+ ions from mitochondria and ER. DAG activates protein kinase C, which phosphorylates a large amount of proteins
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The lipid portion of DAG is composed of what?
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Arachidonic Acid which is the precursor for PG's
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What second messenger system operates in response to entry of calcium cells?
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Calmodulin: This messenger activates and inhibits many protein kinases
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Calmodulin activates what kinase to cause smooth muscle contraction
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Myosin kinase
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What hormones increase protein synthesis?
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Steroids
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What second messengers do TRH and TSH utilize
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TRH: PLC
TSH: cAMP |
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Glucagon exerts its effects through what second messenger
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cAMP
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Steroids bind with receptor proteins where?
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cytoplasm, it is then transported into the nucleus
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Two important features of thyroid hormone function
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1. they activate the genetic mechanisms of many types of intracellular proteins. Many of which have metabolic activity.
2. Their expression within the nucleus may last days or weeks. |
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Radioimmunoassay can measure the concentrations of hormones in the body under what condition?
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There must be too little antibody to bind completely with the the natural and radioactive hormones. The natural hormone in the assay fluid and the radioactive standard hormone must compete with binding sites on the antibody. Thus, the quantity of the two hormones will be proportional to the to its concentration.
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