Biology 2672a: Comparative Animal Physiology Final review lecture

The Final Exam  9 am December 8 th  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.

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

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

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

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

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!

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

Regulation of circulation Change Energy input Q = ΔPπr 4 8Lη8Lη Change tube diameter

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

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.

From Fall 2007 Final Exam  The release of Epinephrine by the adrenal glands is an example of paracrine control of vasomotor tone a) True b) False

The situation for a marine teleost

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

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

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

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

Salt WaterFresh Water DrinkingLots UrineLittle, concentrated Ion fluxPassive into fish; active out of fish Na +,K + -ATPaseNa+ into bloodstream Tight junctionsNo Cl - Transcellular transport driven by Na+ gradient Na + Paracellular driven by electochemical gradient

The situation for a freshwater teleost Fig. 26.7a

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

Cl - uptake

NaCl uptake summary  Exchange for CO2 Na + via electrochemical gradient Cl - via HCO 3 - antiport  Very dilute urine gets rid of excess water without losing too much salt

Salt WaterFresh Water DrinkingLotsLittle UrineLittle, concentratedCopious, dilute Ion fluxPassive into fish; active out of fish Passive out of fish, active into fish Na +,K + -ATPaseNa+ into bloodstream Tight junctionsNoYes Cl - Transcellular transport driven by Na + gradient Transcellular via HCO3 - antiporter (driven by H + pump) Na + Paracellular driven by electochemical gradient Transcellular driven by electrochemical gradient (set up by H + pump and Na +,K + -ATPase)

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.

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? a) The closure of gap junctions between pavement cells. b) Increased activity of the Cl-/HCO3- antiporter in chloride cells. c) Expression of chloride channels on the apical (mucosal) surface of the chloride cells. d) Removal of K+ channels from the basal (serosal) surface of the chloride cells. e) Increase in gill surface area.

Fig Haemolymph Lumen Cells Malpighian tubules

Haemolymph Lumen Stellate cellPrincipal cell Mitochondria packed into evaginations

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

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

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.

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

Final exam, Fall 2007  Chloride ions pass from the haemolymph to the lumen of the Malpighian tubule largely via the Principal cells. a) True. b) False.

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

Concentrating Urine

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

Concentration gradient in kidney Fig

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 a

Changing concentration of definitive urine Fig

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

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

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

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

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

To freeze a frog… Freezing initiated Massive conversion of glycogen to glucose (liver) and circulation around body (Glycogen phosphorylase) Dehydration of major organs (water relocated to the coelom and lymph system) 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)

New Question  Freezing in frogs results in decreased production of NRF-2 and subsequent gene activation. a) True. b) False.