Lecture 11 Outline of Last Lecture a. Embryonic Development & Germ Layers b. Segmentation II. Te t r a p o d s Take t h e l a n d III. Physiological Concepts a. Homeostasis Outline of Current Lecture b. Homeostasis continued i. Countercurrent c. Energy Requirements !Current Lecture Quiz question 9 clarification: Based only on these enzymes’ Km which animal is best adapted to the broadest temperature range? (see graph in lecture notes) Answer = A But E explains why E. But what’s most important for the cell is that the enzyme continues working the same way and in rat the km is very stable over a large range even if it’s a higher Km than the icefish. It stays between 16 and 14 between 10 and 37 degrees (endotherm, and won’t survive down at lower temperatures) - but going just by the Km it is very stable - the rat doesn’t need to work at a lower Km (but that’s good for the icefish) ***a stable Km is better because that means that the rat is better able to more easily survive in a range of more temperatures (the icefish’s Km triples over the range of temperatures while the rats stays around the same) ! Bio 152 1!!!These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best !used as a supplement to your own notes, not as a substitute. !!Countercurrent •crossover of some property between two liquids or gases flowing next to each other in opposite directions •a gradient is minted throughout the length of transfer •whale tongue — blood vessels wrapped in veinous tissue coming back from the tongue •whale is not wasting heat in the tongue, same thing is true on flippers •in the kidneys to concentrate the urine (fish gills also do it) •Allows for greater transfer of heat •note that the blue line on the right gets too a higher point •in countercurrent the blue starts at same point as left (concurrent) but it ends higher, show that its more efficient !**Clicker Question** !Which is a countercurrent oxygen exchange system? !!!A (they go in opposite directions) — the blood is going up, and the water is going down • B is concurrent (they’re going together) •purpose of this is to get more complete exchange of whatever you’re exchanging !!!!!**Clicker Question** The arteries that lead to duck and geese feet are surrounded by veins coming back from the feet. This means that the: A. arterial blood is cooled by the venous blood as it heads towards the feet B. venous blood is as cold near the abdomen as it is near the feet C. blood in the feet is as warm as the blood in the abdomen D. temperature at the abdomen is less than the temperature at the feet •Answer = Arterial blood is cooled by the venous blood as it heads towards the feet •the feet are cold, don’t want to be losing heat from the organism into the ice (why its not C) •really it’s more that the venous blood is warmed by the aerial blood (for A) !**Clicker Question** Fennec foxes live in parts of the Sahara desert. Their ears serve an important adaptive function for homeostasis. How do they work? •C = large surface to volume ratio of their ears, means the capillaries running through their ears can cool rapidly which helps to keep their bodies ear their set point •countercurrent heat doesn’t apply here— it is meant for keeping heat within the body, and what’s happening with the foxes is the opposite (trying to get rid of excess body heat, not retain the heat) •Widely used adaptation in elephants — african elephant is more adapted to hotter temperatures than the asian elephant which is why it’s ears are larger !Energy Requirements !**Clicker Question** This snake is incubating her eggs — contractions are a part of the incubation process, not birthing. why does oxygen consumption have a positive correlation with contractions? A. She uses more oxygen as the hatching date approaches B. The wee snakelettes used ore oxygen as their temperature goes up!C. in order to make contractions she must metabolize more glucose D. When she contracts her body she breaths in E. She uses the contractions to move the eggs around so that they get more oxygen •Answer = C !**Clicker Question** The oxygen consumption and the contractions in this case are both dependent variables. What do you think the independent variable could be? A. Amount of oxygen in the chamber B. Te m p e r a t u r e C. Humidity D. Snakes per chamber E. Snake species •Answer = B •but humidity could also play a role !**Clicker Question** What do these data suggest? •B = metabolic rate and mass are positively correlated (as the mass of the organism increases, the metabolic rate goes up) •E is the exact opposite to B — enodtherms have larger mass •slope is a virtually universal constant in organisms (all the way down to unicellular organisms) •mass scales at 3/4 (goes up, also known as the slope) !!!**Clicker Question** Mass-specific metabolic rate question about elephant vs. shrew: Why do small animals have such high-mass specific metabolic rates? •They have a high surface area to volume ratio •smaller surface area to volume ratio, you lose heat to the environment so you have to eat more •nutrients have to go much farther in large animals and it slows things down •small animals are still endotherms, and there are fairly large cold blooded animals like sharks so size and endothermic don’t correlate •they run around so much because they need to get food (it’s a side effect, not a causal effect)