Animal Physiology Exam 4 Part 2

answer for slow oxidative muscle fibers:

1. primary mechanism of ATP production

2. number of mitochondria

3. myoglobin

4. phosphagen activity

5. amount of lactate dehydrogenase

6. diameter

7. number of surrounding capillaries

8. maximal force production

aerobic / many / yes / low / low / small / many / low

answer for fast glycolytic muscle fibers:

1. primary mechanism of ATP production

2. number of mitochondria

3. myoglobin

4. phosphagen activity

5. amount of lactate dehydrogenase

6. diameter

7. number of surrounding capillaries

8. maximal force production

anaerobic / few / no / high / high / large / few / high

answer for fast oxidative glycolytic fibers:

1. primary mechanism of ATP production

2. number of mitochondria

3. amount of lactate dehydrogenase

4. diameter

5. number of surrounding capillaries

6. maximal force production

7. resistance to fatigue and duration of muscle twitches

mixed / many / intermediate / intermediate / many / intermediate / intermediate

why are fast glycolytic fibers called type 2x

they have type 2x isoform of myosin heavy-chain

rank speeds of myosin heavy-chain isoforms from fastest to slowest

types 2x, type 2a, type 1

how do different protein isoforms differ

how quickly they can hydrolyze ATP and release ADP (how quickly they can do cross bridge cycle)

which type of muscle fiber has the lowest shortening velocity

type 1

what type of muscle fibers found in soleus and why? what happened when inactive?

lot of type 1 and little type 2x / active all the time but not for explosive activity / had more type 2x and 2a

what type of muscle fibers found in tibialis anterior and why? what happened when stimulated consistently?

more type 2x and type 2a but little type 1 / more type 1 than before

What allows muscles to relax faster and ready it for the next contraction

faster calcium ATPase pumps

which type of muscle fiber do you think would benefit most from being able to perform multiple contractions in quick succession?

fast glycolytic (type 2x)

what types of sport does this person likely play

something with short, explosive movements, sprinter

what types of sport does this person likely play

something that requires long term endurance

the quads of extreme endurance athlete would have what types of muscle fibers?

lot of type 1 and some 2a

compare the muscles of average couch potato and average active person. explain the reason for the difference in 2x

active person has more type 1 and 2a but less 2x / 2x is easier to maintain when inactive

the muscles of a person with a spinal injury would have what fibers?

lot of 2a and 2x and barely any type 1

how did the muscle fibers change after endurance training

increase in type 2a, decrease in 2x, increase in capillary density, no change in type 1

explain how type 2x fibers became 2a fibers after endurance training

changed gene expression (no evidence of cell death and replacement)

how did capillaries increase after endurance training

vascular endothelial growth factor (VEGF) promotes new branches of blood vessels to form and increases in just a few days (process called angiogenesis)

the volume of what two things changed during endurance training within muscle cells. what effect does this have on muscle strength?

increase in mitochondria and lipid droplet volume (produce more energy and greater source of energy) / decreases strength (less room for contractile elements)

what changes do you expect to see in muscle fiber composition with strength training

increase in 2x because that gives explosive movement (doesn’t happen tho)

what are the muscle fiber changes after strength training

no change in type 1, increase in 2a, decrease in 2x

what are the muscle fiber changes after strength training but then 90 days post-detraining

no change in type 1, decrease in 2a, large increase in 2x called overshoot phenomenon (double)

why does strength training and endurance training have the same affect on fibers

to sustain physical activity

if you are a world class sprinter for the Olympics and have a competition in a few months. should you training with even more intensity than before or decrease intensity of training

decrease so that your body overshoots type 2x explosive fibers

in general, what happens to muscle fibers during strength training

they grow by hypertrophy

explain in more detail the process of muscle fibers growing by hypertrophy during strength training

resistance training creates small tears in myofibrils that stimulate production of more myofibrils in each muscle fiber. insulin-like growth factor is secreted and stimulates protein synthesis (myostatin is downregulated). fibers get larger in diamtere which increases force potential. VEGF and mitochondria are not upregulated

during hypertrophy, what specifically allows for new growth in muscle fibers

satellite cells usually dormant but then get added into muscle fibers and forms new nuclei to allow for more gene expression and make more protein

as fiber cross sectional area increases, (__) increases in frequency. why?

nuclei / diffusion distance is larger so need greater concentration of genetic material to increase that rate they will diffuse

does the addition of satellite cells or hypertrophy come first

addition of satellite cells

when muscles are not used or strength training stops, they (__). what happens to muscle nuclei

atrophy and diameter gets smaller / remain constant

when a person lifts weights for a long period of time and then stops, their muscles will atrophy from their hypertrophic state. if that person then begins a weight training program a few months later, how do you think the speed of their strength/muscle mass gains will compare with the first time they began a program? why?

will be faster because already have nuclei to code for the proteins instead of having to wait for satellite cells

what is the difference in atrophy after being immobilized in animals that estivate or hibernate vs. animals that don’t

estivating/hibernating animals had no atrophy

atrophy response is related to (__). how?

mass specific metabolic rate / linearly, a greater mass specific MR (smaller animals) has higher atrophy

explain why higher mass specific MR has greater atrophy

aerobic metabolism produces reactive oxygen species that damage cells and a tachymetabolic animal is more active and immobolization would lead to a greater disuse stimulus and thus atrophy

other than MR, what also affects atrophy? explain

muscle fiber type / slow oxidative fibers make a lot of ATP by oxidative phosphorylation and thus produce a lot of ROS. they are also regularly used and would have a greater disuse stimulus compared to the fast fibers that are only occasionally used

some estivating frogs prevent atrophy especially in jumping muscles. what is a potential mechanistic explanation why they dont atrophy compared to the other muscles

has more fast glycolytic fibers that have less of a disuse stimulus and less ROS produced

after estivation, would slow oxidative or fast glycolytic fibers be smaller

slow oxidative

what happens to levels of superoxide dismutase during estivation and why? what about other antioxidants like catalase and glutathione peroxidase?

goes down because metabolic rate is lower / go up to neutralize free radicals to prevent atrophy

loss of muscle mass with age

sarcopenia

peak running speed age for a sprint? peak running speed age for a marathon?

early 20s / late 20s-early 30s