lec 11 lab 10 - muscle

Question 1

muscles and their 2 types

Answer 1

muscles - tissues made of contractile cells

striated (skeletal and cardiac)

smooth (intestine, uterus, blood vessels)

Question 2

summation vs tetanus

Answer 2

S - it’s when multiple nerve impulses (like messages from your brain) come in quick succession, causing the muscle fibers to contract more strongly than they would with just one impulse.

T - It happens when nerve impulses come so quickly and so often that the muscle fibers don’t have time to relax in between. So, instead of contracting and relaxing like they normally do, the muscle fibers stay contracted for a longer period of time, creating a sustained contraction.

Question 3

motor unit

Answer 3

So, a motor unit is made up of a motor neuron and all the muscle fibers it controls. When the motor neuron sends a signal, all the muscle fibers in that motor unit get activated at once, working together to perform a task, like lifting something or moving a body part. It’s like the supervisor telling the workers what to do, and they all pitch in to get the job done!

Question 4

what did the red and white muscle fibers in the lab represent

Answer 4

red and white muscle fibers (aerobic and anaerobic)

• red = muscle endurance, white = muscle strength

Question 5

strength / resistance exercise (powered by what, high or low forces, example)

Answer 5

strength / resistance exercise is powered by anaerobic metabolism (glycolysis) → high forces

• This type of exercise is usually powered by fast-twitch fibers, which are usually larger in diameter than slow-twitch fibers, have fewer mitochondria and are less vascularized to facilitate the use of glycogen and glucose energy stores in the muscle.
• example - weightlifting, fish - running from predator

Question 6

endurance exercise (powered by what, high or low forces, example)

Answer 6

endurance exercise is powered by aerobic metabolism (regeneration of ATP through oxidative phosphorylation) → low forces

• This type of exercise is usually powered by slow-twitch fibers, which are usually smaller in diameter, have lots of mitochondria and more vascularized to facilitate oxygen unloading during prolonged or sustained exercise.
• example - cycling, fish - long migrations