Skeletal muscle

Question 1

What is the structure of a muscle

Answer 1

The outer layer is connective tissue called epimysium. It surrounds the whole muscle.
Deep to this are small bundles of fibers called a fasciculus. There is a sheath of connective tissue surrounding each fasciculus called the perimysium.

Deep to the perimysium and within each fasciculus are the muscle fibers, which are individual muscle cells.

A layer of endomysium surrounds each muscle fiber.

The muscle fiber is surrounded by a plasma membrane called the plasmalemma.

The plasmalemma is part of the sarcolemma, which consists of the plasmalemma and the basement membrane.

A single muscle fiber contains multiple myofibrils

Each myofiber is made up of connected units of sarcomeres.

Question 2

What is the function of the plasmalemma?

Answer 2

It has folds that allow the muscle fibers to contract and then stretch.

The plasmalemma transports metabolites from the capillary blood into the muscle fiber to helps to maintain the acid-base balance.

Question 4

What is the sarcoplasm and what does it do?

Answer 4

It is a gelatin-like layer between the myofibrils.

This is the cells cytoplasm that contains glycogen and oxygen-binding myoglobin.

Question 5

What are T-tubules?

Answer 5

Transverse tubules are extensions of the plasmalemma that pass through muscle fibers and connect the myofibrils allowing nerve impulses received by the plasmalemma to be rapidly transmitted to to the individual myofibrils.

The tubules also allow things to enter and exit the muscle fibre.

Question 6

What is the function of the sarcoplasmic reticulum?

Answer 6

It is a storage for calcium and surrounds the myofibrils within a muscle fiber.

Question 7

Draw a sarcomere with proteins

Answer 7

p30

Question 8

How does the action potential cause muscle contraction?

Answer 8

p32, 33, 34

Question 9

What are the different types of muscle cells, their different function and different proportion within a muscle?

Answer 9

Type 1 (slow twitch)
Type IIa ( fast oxidative)
Type IIb/IIx (fast glycolytic)
Type IIc

p37/38/39

Type 1 fibers have a high level of aerobic endurance. They are efficient at producing ATP from the oxidation of carbohydrate and fat. As long as oxidation occurs, type I fibers continue producing ATP allowing the fibers to remain activ. Therefore, they are recruited most during low intensity endurance events, such as marathon running and during walking.

Question 10

What are the differences between the different fiber types?

Answer 10

Table 1.1 page 38