Biology 2672a: Comparative Animal Physiology

1. Biology 2672a: Comparative Animal Physiology Final review lecture

2. The Final Exam • 9 am December 8th • Talbot Hall Gym • 2 hours • If you are sick (etc) • Take documentation to the Dean’s counsellors – they will contact me. • If in doubt, sit the exam then see the Dr.

3. The Final Exam • 73 Questions • Covers everything from Lecture 2 (Krogh Principle etc) to Lecture 24 (Diving mammals) • Including animal ethics, freezing frogs, hibernation, migration and bird song • Includes labs (c. 3-5 questions) • No overt weighting on any part of the course

4. The final exam • ~40 simple definition-type questions • ~10 harder single-part questions • 5 fun graph questions (multiple parts)

5. The Make-up • 7 pm (in the evening!) • Monday 12 January • Will include written answers, as per the course outline • Format will be sent in advance to those writing the make-up • If you can’t do the make-up, the next exam will be in December 2009

6. How your mark is calculated • Added up (by the computer) and rounded to the nearest integer • Nearest integer to (e.g.) 69.45 is 69 (sorry) • I DO give 89, 79, 69 • I DON’T give marks for arbitrary reasons (so please don’t ask)

7. Important things to remember • READ THE QUESTION! • READ THE ANSWER! • LOOK AT THE GRAPH! • Just because something sounds the most scientific doesn’t mean it is true • I’m very good at generating meaningless jargon!

8. Today • Five topics • Control of vasomotor tone • Freshwater/saltwater fish • Malpighian tubules • Concentrating urine • Freezing frogs

9. Q = ΔPπr4 8Lη Regulation of circulation Change tube diameter Change Energy input

10. Local control • Myogenic stretch response • Paracrine control • e.g. release of NO • Responses to local conditions and trauma • Events in muscle cell • viagra example

11. Central control • Endocrine (Hormonal) • e.g. Adrenaline (Epinephrine) • Response depends on receptor densities, so same hormone has different effects through body • Also vasopressin and angiotensin • Neural • Sympathetic nervous system • Usually chemically mediated.

12. From Fall 2007 Final Exam • The release of Epinephrine by the adrenal glands is an example of paracrine control of vasomotor tone • True • False

13. The situation for a marine teleost

14. Chloride cells Apical (Mucosa) Water Pavement cell Lots of mitochondria Baso-lateral (serosa) Blood Fig. 26.6

15. Export of Chloride is driven by a Na+ gradient Na+ actively pumped out of cell by Na+,K+-ATPase Potassium remains at equilibrium because of K+ channels back into blood Box 26.2

16. Active removal of Cl- leads to an electrochemical imbalance that drives Na+ out of blood via paracellular channels Box 26.2

17. Chloride cell summary • Transcellular transport of Cl- • Driven by Na+,K+-ATPase (requires energy) • Paracellular transport of Na+ • Ionoregulation accounts for ~3-5% of resting MR in marine teleosts

19. The situation for a freshwater teleost Fig. 26.7a

20. Na+ uptake Note tight junction Box 3.1 Fig.A(2)

21. Cl- uptake

22. NaCl uptake summary • Exchange for CO2 • Na+ via electrochemical gradient • Cl- via HCO3- antiport • Very dilute urine gets rid of excess water without losing too much salt

24. From Final Exam, Fall 2007 • In gills of a freshwater-acclimated fish, where is the Na+,K+-ATPase pumping Na+ ions? a) From the chloride cell into the bloodstream. b) From the chloride cell into the surrounding water. c) From the bloodstream into the chloride cell. d) From the surrounding water into the chloride cell. e) From the surrounding water into the bloodstream.

25. From final exam, Fall 2007 • As well as an increase in Na+,K+-ATPase activity, what else would you expect to happen as a fish moves from fresh to salt water? • The closure of gap junctions between pavement cells. • Increased activity of the Cl-/HCO3- antiporter in chloride cells. • Expression of chloride channels on the apical (mucosal) surface of the chloride cells. • Removal of K+ channels from the basal (serosal) surface of the chloride cells. • Increase in gill surface area.

26. Malpighian tubules Cells Haemolymph Lumen Fig 27.21

27. Haemolymph Principal cell Stellate cell Mitochondria packed into evaginations Lumen

28. Proton pump generates electrochemical gradient Requires ATP K+ follows via electrogenic transporter Haemolymph K+ Channel V-ATPase (H+ pump) Lumen

29. Cl- follows K+ gradient Water follows osmotic gradient into tubule lumen Haemolymph Cl- Channel Aquaporin V-ATPase (H+ pump) Lumen

30. Malpighian tubules summary • Active transport sets up ion gradients • Proton pump; K+, Cl- • Water follows • Passive transport of nitrogenous wastes, amino acids etc. down electrochemical gradients • Active transport of large molecules • Alkaloids, proteins etc.

31. Water and solute reabsorption • Urine from tubules is dilute and contains lots of things the insect doesn’t want to lose • Reabsorption of water and solutes in hindgut/rectum • Determines final concentration of the urine

32. Final exam, Fall 2007 • Chloride ions pass from the haemolymph to the lumen of the Malpighian tubule largely via the Principal cells. • True. • False.

33. New Question • Chloride concentrations are high in the lumen of the Malpighian tubule because... • Active transport of chloride ions from the haemocoel by the stellate cells. • The chloride ions follow an electrochemical gradient set up by sodium pumping in the principal cells. • The chloride ions follow an electrochemical gradient set up by proton pumping in the Principal cells. • All of the above. • None of the above.

34. Concentrating Urine

35. Bowman’s capsule Ultrafiltration, Production of primary urine Thick ascending loop of Henle Salt Re-absorption Thick segment of descending loop of Henle Collecting Duct Urine out, concentration of definitive Urine Re-absorption of sugars, amino acids, water Loop of Henle Thin segment of descending loop of Henle Thin ascending loop of Henle Fig. 27.6

36. Concentration gradient in kidney Fig. 27.13

37. Concentration of urine • Occurs in collecting ducts • Driven by osmotic gradient across kidney • Both urea and salts • Can be manipulated by altering permeability of collecting duct to water Fig. 27.14a

38. Changing concentration of definitive urine Fig. 27.14

39. Medullary thickness is positively correlated to maximum urine concentration Fig. 27.8

40. Concentrating Urine • Bigger concentration gradient = higher maximum concentration of urine • Longer loop of Henle (i.e.: relatively thicker medulla) = longer concentration gradient = higher maximum concentration of urine

41. Modulating urine concentration • Modulate permeability of collecting duct to water • Permeable • Concentrated urine • Antidiuresis • Impermeable • Dilute urine • Diuresis

42. Final exam Fall 2007 • A longer loop of henle allows for a shorter concentration gradient, increasing kidney tubule efficiency. • True. • False.

43. Final Exam, Winter 2007 • Which change is primarily responsible for the shift in production from concentrated to dilute urine? • Increased absorption of amino acids by the descending loop of Henle. • Decreased absorption of amino acids in the descending loop of Henle. • Increased permeability of the collecting duct. • Decreased permeability of the collecting duct.

44. To freeze a frog… Freezing initiated Massive conversion of glycogen to glucose (liver) and circulation around body (Glycogen phosphorylase) • Protein Synthesis slows to 1% • Pumps & channels closed • Energy Production slows to 5% • Energy Utilization slows to 2% • Few ‘SAP’ kinases activated • Gene ‘inactivation’ (mRNA) • Few Genes activated • NRF-2 (= more antioxidants, especially GST) Dehydration of major organs (water relocated to the coelom and lymph system)

45. New Question • Freezing in frogs results in decreased production of NRF-2 and subsequent gene activation. • True. • False.