All are true about Gap junction except:
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
Permits amino acids upto 1000 Da mol wt.
Opening of gap junction does not depend on trans membrane voltage
Halothane closes gap junction reversibly
Gap junction is made up of connexon is made ut> of six identical connexins
Cell Physiology and Intercellular Connections