Ans: B (Opening of gap junction does not depend on trans membrane voltage) Ref:Pal GK, Functional Organization of Cell, In:Textbook of Medical Physiology, 2nd ed. Ahuja Publishing House, 2011; 3: 19Pollard TD, Earns haw EC, Intercellular Junctions. In: Cell Biology, 2nd ed. 37 : 573-79Explanation:Gap Junctions - NexusMade up of connexons - trans-membrane proteinEach connexon is made up of six identical connexins (protein)Allow upto 1 KDa molecules Eg:Ions (Electrical synapse)2nd messengersPeptidesOpening depends onTrans mb voltH+, Ca++ ionProtein kinaseEg. Skin, GIT. Heart. Skeletal muscle. Glial cellOleamide, a fatty acid amide produced by the brain, blocks gap junctional communication and induces sleepOrganic alcohols (heptanol and octanol) and general anesthetics ihalothane) can also close gap junction channels reversibly: also nonspecificSigns and Symptoms for Different Classes of Shock Class IClass IIClass IIIClass IVBlood loss (mL)Upto 750750-1,5001,500-2,000>2.000Blood loss (% blood volume)Upto 15%!5%-30%30%-40%>40%Pulse rale<100>100>120>140Blood pressure (mm Hg)NormalNormalDecreasedDecreasedPulse pressure (mm Hg)Normal or increasedDecreasedDecreasedDecreasedUrinary output (mL/hr)>3020-305-15NegligibleCNS/Mental StatusSlightly anxiousMildly anxiousAnxious and confusedConfused and lethargicMutations in Connexin Subunit (Human)Cx-26b2 - Dominant and recessive mutations with deafness; skin diseaseCx-30b6 - Recessive deafness; skin diseaseCx-31b3 - Recessive deafness; skin diseaseCx-32b1 - X-linked point mutations, defective myelin, peripheral nerve degeneration; deafnessCx-43a1 - DeafnessCx-50a8 - Cataracts in lens of the eye