Exam 1: Homeworks

Question 1

after pythons eat a meal, their organs

Answer 1

almost double in size within a day without damage (esp heart damage)

fast for months

Question 2

python blood after a meal

Answer 2

full of triglycerides (a form of cholesterol)

appears milky

Question 3

usually, the influx of cholesterol would be deposited… but…

Answer 3

in the heart muscle

snakes escape without damage

Question 4

how do the snakes escape heart damage?

Answer 4

burn fats as fuel very efficiently

Question 5

athlete hearts vs. heart disease hearts

Answer 5

athlete: grow large and chambers that pump blood grow too
disease: heart swells but chambers do not grow (less blood pumped with each beat)

Question 6

python –> human goal

Answer 6

drug therapy that nudges diseased hearts toward healthy growth

Question 7

python/rat experiment

Answer 7

fasted for 28 days then ate a mouse or rat weighing 25% of body weight (test blood of fed vs fasting pythons)

Question 8

put the blood plasma of fed pythons onto rat heart cells to see if they’d grow

Answer 8

they did

found batch of fatty acids that triggered a flood of heart-protecting enzymes

injected mice with this mix and their hearts grew without damage

Question 9

downregulation and upregulation

Answer 9

pythons downregulate organs like stomach (secreting acid) and GI tract when not feeding

upregulate when feeding to digest prey

Question 10

how many days after feeding does it take to downregulate again?

Answer 10

6-7

Question 11

regulation of GI function and morphology is not a novel phenomenon in pythons alone…

Answer 11

vertebrates also (to some extent)

Question 12

any organism that feeds infrequently benefits from a reduced rate of …

Answer 12

basal energy expenditure

selection favors depression of GI activity during fasting

Question 13

firefly flashing mechanism

Answer 13

light emitting chemical reactions

luciferin phosphorylated by ATP –> luciferyl-AMP –> add O2 –> release photons of light

Question 14

firefly in the dark state

Answer 14

mitochondria intercept O2 and light reactions cannot complete

Question 15

light cell in flashing state

Answer 15

nitric oxide is produced under nervous control and bathes mitochondria to prevent interception of O2

Question 16

salmon survive in fresh and ocean water

Answer 16

in ocean water it drinks a TON and makes little urine which is very concentrated

in fresh it doesn’t drink at all and makes a lot of urine that is dilute

Na Cl ATPase enzymes pump both against their concentration gradients

Question 17

homework diffusion equation

Answer 17

t = x^2 / 2D

t = time

x = mean distance travelled by solute in one direction on one axis

2 = diffusion coefficient

Question 18

diffusion homework conclusions

Answer 18

diffusion times over short distances are adequate but are unrealistic over larger distances

this is why we have a cardiovascular system

no cell is more than 10 micrometers from a capillary