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level: STEP 3 A.

Questions and Answers List

STEP 3 --- CELLULAR DYSNFUNCTION AND RESULTANT TOXICITIES

level questions: STEP 3 A.

QuestionAnswer
1 The third step in the development of toxicity: 2 The reaction of a toxicant with TARGETS SERVING EXTERNAL FUNCTIONS can influence the operation of other cells and integrated organ systems. However, IF TARGET MOLECULE is involved predominantly in the cell's INTERNAL MAINTENANCE, the resultant dysfunction can ultimately compromise __1 alteration of the regulatory or maintenance function of the cell. 2 survival of the cell.
(A. TOXICANT-INDUCED CELLULAR DYSREGULATION) 1 Cells are regulated by__ that activate specific CELLULAR RECEPTORS linked to SIGNAL TRANSDUCING NETWORKS that transmit the signals to the regulatory regions of genes and/or functional proteins. 2 Receptor activation may lead to altered gene expression and/or a chemical modification of specific proteins, typically by __ 3 Programs controlling the destiny of cells affect __, whereas those regulating the ongoing activities primarily influence the activity of __. 1 signaling molecules 2 phosphorylation. 3 gene expression, functional proteins. (one signal often evokes BOTH responses bcs of branching and interconnection of signaling networks).
A. TOXICANT-INDUCED CELLULAR DYSREGULATION May occur at elements that are DIRECTLY RESPONSIBLE FOR TRANSCRIPTION, at components of the intracellular signal transduction pathway, and at the synthesis, storage, or release of the extracellular signaling molecules.Dysregulation of Gene Expression
(A. TOXICANT-INDUCED CELLULAR DYSREGULATION) 1) Dysregulation of Transcription 1 Transcription of genetic information from DNA to mRNA is controlled largely by interplay between __ and __ 2 Hormones and vitamins, influence gene expression by binding to and activating __ 3 Xenobiotics may mimic the natural ligands, both may cause toxicity when administered at extreme doses or at critical periods during __. 1 transcription factors (TFs), regulatory or promoter region of genes. 2 transcription factors (TFs) 3 ontogenesis
(A. TOXICANT-INDUCED CELLULAR DYSREGULATION) 2) Dysregulation of Signal Transduction Chemically Altered Signal Transduction with Proliferative Effect: 1 Xenobiotics that FACILITATE PHOSPHORYLATION of signal transducers often PROMOTE __ 2 __ may also be activated by interacting proteins that had been altered by a xenobiotic. 3 Aberrant phosphorylation of proteins may result from DECREASED DEPHOSPHORYLATION by __.. 4 Inhibition of phosphatases = __. 1 mitosis and tumor formation 2 Protein kinases 3 phosphatases. 4 Mitogenic effect of various chemicals, oxidative stress, and ultraviolet (UV) irradiation.
(A. TOXICANT-INDUCED CELLULAR DYSREGULATION) 2) Dysregulation of Signal Transduction 1 Down turning of increased proliferative signaling after cell injury may compromise replacement of __ 2 Downregulation of a normal __ is a step away from survival and toward apoptosis.. 1 injured cells 2 mitogenic signal
(A. TOXICANT-INDUCED CELLULAR DYSREGULATION) 3) Dysregulation of Extracellular Signal Production 1 __ exert MITOGENIC EFFECTS ON ENDOCRINE GLANDS in the periphery by acting on cell surface receptors. 2 UNDER NEGATIVE FEEDBACK CONTROL by PERIPHERAL GLAND HORMONES. 3 __ secretion of pituitary hormone produces apoptosis followed by involution of the peripheral target gland. 1 Hormones of the anterior pituitary 2 Pituitary hormone production 3 Decreased
Dysregulation of Ongoing Cellular Activity1) Dysregulation of Electrically Excitable Cells 2) Dyregulation of the Activity of Other Cells
(Dysregulation of Ongoing Cellular Activity) 1) Dysregulation of Electrically Excitable Cells 1 Many xenobiotics influence cellular activity in excitable cells, such as __ 2 Release of neurotransmitters and muscle contraction are controlled by transmitters and modulators synthesized and released by __. 1 neurons, skeletal, cardiac, and smooth muscle cells. 2 adjacent neurons.
(Dysregulation of Ongoing Cellular Activity) 1) Dysregulation of Electrically Excitable Cells Concentrations Neurotransmitter: 1 Chemicals may alter synaptic levels of neurotransmitters by interfering with their __. 1 synthesis, storage, release, or removal from the vicinity of the receptor
(Dysregulation of Ongoing Cellular Activity) 1) Dysregulation of Electrically Excitable Cells RECEPTOR FUNCTION 1 Some chemicals interact directly with neurotransmitter receptors, These are:. 1) Agonists that associate with the ligand binding site on the receptor and MIMIC THE NATURAL LIGAND, 2) Antagonists that occupy the ligand binding site but CANNOT ACTIVATE THE RECEPTOR, (3) Activators, 4 Inhibitors that bind to a site on the receptor that is NOT DIRECTLY INVOLVED IN LIGAND BINDING.
(Dysregulation of Ongoing Cellular Activity) 1) Dysregulation of Electrically Excitable Cells RECEPTOR FUNCTION 1 In the absence of other actions, agonists and activators __, whereas antagonists and inhibitors __, the physiologic responses characteristic of endogenous ligands.. 1 MIMIC 2 BLOCK
(Dysregulation of Ongoing Cellular Activity) 1) Dysregulation of Electrically Excitable Cells INTRACELLULAR SIGNAL TRANSDUCTION 1 Many chemicals alter neuronal and/or MUSCLE ACTIVITY by acting on __ 2 __ TRANSDUCE & AMPLIFY EXCITATORY SIGNALS generated by ligand gated cation channels; are activated or inactivated by several toxins. 1 signal transduction processes. 2 Voltagegated Na+ channels
(Dysregulation of Ongoing Cellular Activity) 1) Dysregulation of Electrically Excitable Cells SIGNAL TERMINATING PROCESSES 1 The cellular signal GENERATED BY CATION INFLUX is terminated by __ through channels or by transporters. 2 __ may prolong excitation. 1 removal of the cations 2 Inhibition of cation export
(Dysregulation of Ongoing Cellular Activity) 2) Dyregulation of the Activity of Other Cells 1 many signaling mechanisms operate in NONEXCITABLE CELLS, such as EXOCRINE SECRETORY CELLS, __, disturbance of these processes is usually less consequential.1 KUPFFER CELLS, and 2 Pancreatic beta cells