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25 Cards in this Set
- Front
- Back
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cell responses to signals
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cell proliferation
cell movement cell differentiation |
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signaling deficiencies
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lack of signal
insensitivity to signal hypersensitivity to signal |
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myesthenia gravis
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autoantibodies against ach receptors. results in muscle weakness and fatigue. Treatment is ach esterase inhibitors to increase signal.
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atropine
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a muscaronic ach receptor antagonist(blocker)
treatment for sarin.etc |
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categories of chemical signals
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neurotransmitters
hormones cytokines eicosanoids growth factors |
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types of signaling
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contact
paracrine autocrine endocrine |
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contact signaling
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signaling through cell to cell contact. gap junctions
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paracrine signaling
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short distance signaling between different cells. ex cytokines. short half life.
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autocrine signaling
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short distance signaling involving the same type of cells.
Ex prostaglandins. Chemical signal: low concentration short half life and high affinity. |
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endocrine signaling
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long distance signaling between endocrine glands and target cells. long half life, very dilute, cells typically respond slowly.frequently bound to carriers.produced by endocrine glands and circulated by blood.
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compare chemical signaling with neurotransmitter
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both are considered paracrine.
in chemical signaling: low concentration of signal short half live and receptors have a high affinity. In neurotransmitters: Very high concentration, very short half life, and receptors have low affinity. |
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types of receptors
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cell surface-hydrophillic signals cant cross membrane
intracellular-hydrophobic signals carried by a carrier protein can enter the cell. |
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type I nuclear receptor signaling
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cortisol
aldosterone progesterone testosterone |
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type III nuclear receptor signalling
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estradiol
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dexamethazone
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a synthetic hormone that is 30x more effective than cortisol.
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type I and III nuclear receptor mechanism
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-receptors located in cytosol in complex with hsp's(heat shock proteins)
-after steroid binding hsp is shed and a dimer is formed from 2 receptor/hormone complexes. -dimer is translocated to nucleus -binds to DNA with help of cofactors initiates gene transcription |
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type II nuclear receptor signals
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thyroid hormone
vit D3 Retanoic acid |
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type II nuclear receptors
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-receptor located in nucleus
-in dimer form -attached to DNA but unable to transcribe -corepressor is replaced by coactivator upon signal binding to receptor -gene transcription can then proceed |
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types of cell surface receptors
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ion channels linked
G-protein linked enzyme/enzyme linked |
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ion channel linked receptors
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-binding of signal opens channel
-converts chemical signal into electric signal ex nicotinic Ach receptor |
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G-protein linkes receptor
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-stands for GDP binding
-involves 7 transmembrane domain receptors that associate with a G-protein |
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examples of Gprotein receptors
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-β1 adrenergic (epinephrine, norepinephrine) receptors.
The drugs β blockers target the β1-adrenergic receptors and are used for treating cardiac arrhythmias - muscarinic ACh receptor, glucagon receptor |
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enzyme/enzyme linked receptor
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-binding of signal activates enzyme(ex kinase activates protein by phophorylating)
-starts an intercellular signaling cascade ex.insulin receptors,growth factors, integrins |
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cell's reaction to signal
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-type of receptor. Different receptor can have different repsonses to same signal(ex nicotinic vs muscarinic ach receptor)
-intracellular machinery. Even if receptors are the same the cell's response can be different depending on protein make up in cell. |
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most common second messengers
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cAMP
cGMP Ca2+ diaglycerol inositol triphosphate |
