Overview G protein-coupled receptors (GPCR) 7 transmembrane domain receptors on the cell membrane that sense the external environments ligands activate the G protein by causing a conformational change this change propagates to a second messenger which detaches from the GPCR to carry the signal to other effector proteins 3 types of GPCR second messengers and functions Gq activates phospholipase which results in the formation of inositol phosphate (IP3) → ↑ [Ca2+] diacylglycerol → activation of protein kinase C (PKC) examples of receptor types: α1, H1, V1, M1, M3 Gs activates adenyl cyclase resulting in ↑ cAMP → ↑ activity of protein kinase A (PKA) examples of receptor types: β1, β2 , D1, H2, V2 Gi inhibits adenyl cyclase resulting in ↓ cAMP → ↓ activity of protein kinase A (PKA) examples of receptor types: α2, D2, M2 Receptor Types Adrenoceptor: Sympathetic System Receptor GPCR Class Locations and Major Functions α1 q GI and GU: contraction of sphincters Eye: contraction of iris radial muscle (mydriasis) Vasculature: vasoconstriction α2 i GI: ↓ motility Vasculature: vasoconstriction of veins and arteries in heart BUT vasodilation of arteries Presynaptic adrenergic nerve terminals: ↓ sympathetic outflow by inhibiting NE release Lipocytes: ↓ decreases lipolysisPancreas: ↓ insulin and ↑ glucagon Platelets: stimulation of platelet aggregation β1 s Heart: positive chronotrope and inotrope Kidney: ↑ renin release Lipocytes: ↑ lipolysis β2 s Vasculature: vasodilation (specifically skeletal muscle vasculature) Lung: bronchodilation GI and GU: bladder and uterus relaxation Heart: positive inotrope and chronotrope Eye: ciliary muscle relaxation Lipocytes: ↑ lipolysis Pancreas: ↑ insulin release Liver: ↑ gluconeogenesis and glycogenolysis Cholinoreceptors: Parasympathetic System Receptor GPCR Class Locations and Major Functions M1 q CNS: excitatory in the CNSGlands: ↑ salivary, sweat, and stomach secretions M2 i Heart: negative chronotrope and ↓ contractility of atria M3 q Glands: ↑ salivary, sweat, stomach glands GI and GU: ↑ motility, ↑ bladder and uterus contraction Lung: bronchoconstriction Eye: ciliary and iris circular muscle contraction Dopaminergic Receptors Receptor GPCR Class Locations and Major Functions D1 s Kidney: renal vascular smooth muscle relaxation D2 i Brain: modulates neurotransmitter release Other G Protein-Coupled Receptors (Histamine and Vasopressin) Receptor GPCR Class Locations and Major Functions H1 q Glands; ↑ nasal and bronchial mucus secretion Lung: bronchoconstriction Skin: pruritus (itching), ↑ pain and irritation H2 s GI: ↑ gastric acid secretion V1 q Vasculature: vasoconstriction V2 s Kidney: antidiuretic, ↑ water permeability and reabsorption in the collecting tubules
QUESTIONS 1 of 6 1 2 3 4 5 6 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.PH.17.4817) A 5-year-old boy is brought to the emergency department by his parents for difficulty breathing. He was playing outside in the snow and had progressive onset of wheezing and gasping. His history is notable for eczema and nut allergies. The patient has respirations of 22/min and is leaning forward with his hands on his legs as he is seated on the table. Physical examination is notable for inspiratory and expiratory wheezes on exam. A nebulized medication is started and begins to relieve his breathing difficulties. Which of the following is increased in this patient as a result of this medication? QID: 109407 Type & Select Correct Answer 1 Diacylglycerol 4% (6/138) 2 Cyclic GMP 18% (25/138) 3 Cyclic AMP 67% (93/138) 4 Protein kinase C 4% (6/138) 5 ATP 4% (5/138) M 3 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.PH.13.115) A 23-year-old woman presents to the emergency department with acute onset of shortness of breath, wheezing, and chest tightness. This is her 4th visit for these symptoms in the last 5 years. She tells you she recently ran out of her normal "controller" medication. Concerned for an asthma exacerbation, you begin therapy with a short-acting beta2-agonist. What is the expected cellular response to your therapy? QID: 100631 Type & Select Correct Answer 1 Gs protein coupled receptor activates adenylyl cyclase and increases intracellular cAMP 82% (303/370) 2 Gs protein coupled receptor activates phospholipase C and increases intracellular calcium 3% (12/370) 3 Gq protein coupled receptor activates phospholipase C and increases intracellular calcium 3% (10/370) 4 Gq protein coupled receptor activates adenylyl cyclase and increases intracellular cAMP 5% (18/370) 5 Gi protein coupled receptor inhibits adenylyl cyclase and decreases cAMP 5% (17/370) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
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