EXAM I Comparative Animal Physiology ZOO 424 Fall 2002

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1 EXAM I Comparatve Anmal Physology ZOO 424 Fall 2002 V Eq = RT X o. ln( [ zf [ X ) RT p K[K o pna[na o pcl[cl V = m ln F pk[k pna[na pcl[cl o I = g(v m V eq. ) Q = C m V m Drvng Force = V m V eq. Ionc Speces Caton Anon Sgn of Drvng Force (V m V eq. ) Drecton of Ion Flow outward nward nward outward R = J/K.mol T = 310 K F = 96,500 C/mol Total: 100 Ponts 1. (6 ponts) Complete the followng table by enterng the approprate values. Be sure to state the approprate unts where necessary. Numbers that are wthn the normal range wll be accepted. Na concentraton K concentraton Ca 2 concentraton Cl concentraton Osmolarty (mosm/l) ph Intracellular Flud Extracellular Flud 2. (6 ponts) Compare and contrast negatve and postve feedback loops. Provde at least one example of each to llustrate your pont. 1

2 3. (6 ponts) Compare and contrast the turnover rates of varous membrane transport protens. 4. (15 ponts) Lst the mnmum essental characterstcs that a cell must have n order to establsh a restng membrane potental. Then fully explan how these factors work together to establsh a potental dfference across the plasma membrane of cells. Be sure to use dagrams. 2

3 5. (6 ponts) In a typcal vertebrate axon, the absolute refractory perod s 1.2 ms and the relatve refractory perod s 3.8 ms. If the axon s contnuously stmulated wth stmul large enough n ampltude to ensure exctaton, what s the hghest frequency of acton potentals that can be generated? 6. (6 ponts) In the vertebrate retna, there are at least four types of photopgments; rhodopsn for black and whte vson, and three addtonal related opsn molecules whch are maxmally stmulated by blue, red, and green lght. The blue, red, and green photopgments are used for color vson. Explan the need for more than one photopgment for color vson. Be sure to use dagrams. 3

4 7. (6 ponts) Usng the nformaton n the table below, determne the equlbrum potental for the ons n the table. Be sure to state the approprate unt. Then assumng that V m = 70 mv, determne the drecton of flow (nto or out of the cell) for each on. Note: The concentratons lsted here do not necessarly represent physologcal concentratons (although they may). Ion Intracellular Concentraton Extracellular Concentraton Na 16 mm 145 mm K 135 mm 2 mm Ca mm 2 mm H 60 nm 40 nm Cl 25 mm 110 mm HCO 15 mm 25 mm 3 V eq. Drecton of Ion Flow 8. (6 ponts) In a cell permeable to K, Na, and Cl, the restng membrane potental s measured to be 50 mv. The followng nformaton s avalable to you. [Na = 6 mm; [Na o = 135 mm; [K = 130 mm; [K o = 2 mm; [Cl o = 110 mm; p Na = 0.15; p K = 1; p Cl = 0.5. What s the cytoplasmc Cl concentraton ([Cl ) n ths cell? Show work. 4

5 9. (20 ponts) Explan the molecular and onc bass of acton potentals n neurons. Be sure to use dagrams n conveyng the key ponts. Lmt your dscusson to detals of the acton potental at any gven pont along the axon (.e., you do not need to dscuss acton potental propagaton). 5

6 VERY Short Answers 10. (1 pont) Capllary endothelal cells contan these openngs, whch allow for the exchange of materals between the ntravascular and ntersttal flud compartments. 11. (1 pont) Ths ntegral membrane proten s referred to as t-snare n the pre-synaptc axon termnal. 12. (1 pont) Gap juncton channels form cytoplasmc brdges between adjacent cells. What s the approxmate sze cut-off for the molecules that can permeate the channel pore? 13. (2 ponts) How long s the synaptc delay n electrcal and chemcal synapses? 14. (1 pont) Passve spread of EPSPs from the dendrte toward the axon hllock s also referred to as spread. Multple Choce 15. (1 pont) What s the approxmate volume of plasma n an average 70-kg man? (A) 1 L; (B) 3 L; (C) 6 L; (D) 9 L; (E) 12 L. 16. (1 pont) Ths neurotransmtter s released from the axon termnal of pre-ganglonc sympathetc fbers. (A) Acetylcholne; (B) Norepnephrne; (C) Epnephrne; (D) Serotonn; (E) Glutamate. 17. (1 pont) Ths neurotransmtter s released from the axon termnal of pre-ganglonc parasympathetc fbers. (A) Acetylcholne; (B) Norepnephrne; (C) Epnephrne; (D) Serotonn; (E) Dopamne. 18. (1 pont) Ths neurotransmtter s released from the axon termnal of post-ganglonc sympathetc fbers. (A) Acetylcholne; (B) Norepnephrne; (C) Epnephrne; (D) Serotonn; (E) GABA. 19. (1 pont) Whch of the followng s not a classc neurotransmtter? (A) Glutamate; (B) γ- Amnobutyrc acd; (C) Substance P; (D) Glycne; (E) Serotonn. 20. (1 pont) A complete gap juncton cell-to-cell channel s composed of: (A) 2; (B) 4; (C) 6; (D) 10 (E) 12 connexn molecules. 6

7 21. (1 pont) A typcal bologcal plasma membrane separates the hydrophlc envronments of the cytoplasmc and extracellular fluds by a hydrophobc core of approxmately: : (A) 0.3 nm; (B) 3 nm; (C) 10 nm; (D) 30 nm (E) 300 nm. 22. (1 pont) Small synaptc vescles are approxmately: (A) 1 nm; (B) 10 nm; (C) 50 nm; (D) 200 nm; (E) 500 nm n dameter. True or False 23. (1 pont) The Na /K /ATPase s drectly responsble for the establshment of the membrane potental. 24. (1 pont) The absolute refractory perod s the perod durng whch stronger than normal stmul can lead to the generaton of new acton potentals. 25. (1 pont) Tetrdotoxn s an nhbtor of the voltage-gated Na channels. 26. (1 pont) Schwann cells are responsble for the formaton of myeln sheaths n the perpheral nervous system. 27. (1 pont) Cl s the most abundant ntracellular anon n mammalan cells. 28. (1 pont) Openng of K channels at the synapse leads to an IPSP. 29. (1 pont) Dense-core vescles contan the classc neurotransmtters. 31. (1 pont) Dense-core vescles always fuse wth the pre-synaptc plasma membrane at the actve zone. 32. (1 pont) Ths s a hard exam. 7