Question

1) You are about to pick up a heavy box. Starting from when you first put your hands on the box before you lift then to actually lifting the box, decribe the types of contractions occurring and what order they occur in.

2) compare the force needed for a box of book vs. a box of cotton fluff. What type of summation is being used for the box of the books? What is happening within the muscle?

Answer 1

1. When you lift weight, your muscles works together and concentric and eccentric muscles contractions happen at the same time.As you lift the weight up towards your shoulder during an arm curl,your bicep muscles shorten (concentric muscles contraction) and your triceps lengthen (eccentric muscle contraction).

2. If we consider same weight of books and cotton fluff.Books occupy very less area compare to cotton fluff.thus,You apply much greater force to lift box of cotton compared to box of books due to the larger force you can lift the box of cotton easily which makes you think that is lighter.

In the muscle a series of repeated events occurs.first calcium triggers a change in the shape of troponin and reveals the myosin-binding sites of actin beneath tropomyosin.Then the myosin head bind to actin and cause the actin filaments to slides.