Lecture 1 Skeletal Muscle 1

Question 1

Describe and explain the functions of the regulatory proteins such as troponin-tropomyosin

Answer 1

.Troponin is a regulatory protein which allows CA2+ to bind to it. This activates the Troponin causing a change in Tropomyosin which allows Tropomyosin to uncover the myosin head binding site.

Question 2

Define term myofilament

Answer 2

.Myofilament is the proteins within a Myofibril, it consists of actin, myosin, titin, Z discs and other enzymes and mitochondria.

Question 3

What does the epimysium surround?

Answer 3

It surrounds the entire muscle

Question 4

What are the three macro layers of importance in muscles?

Answer 4

Epimysium -> Perimysium -> Endomysium

Question 5

What zone is the only zone with Myosin in it?

Answer 5

H-Zone

Question 6

Describe general shape of the protein actin and structure of thin filament.

Answer 6

.Actin is a single molecule structure called G-Actin, Once formed into a blue-like rope in most illustrations, looks like two strains twisting around each other. Each strand that is wrapped around is called an F-actin.

Question 7

Define a sarcomere and describe its structure

Answer 7

.a sarcomere is the smallest structure within the skeletal muscles, it contracts in on itself to form movement and force using actin and myosin proteins that pull each other.

Question 8

Explain the importance of the Z disc and M line

Answer 8

.Z discs/Z-lines (Zwischen meaning between) are the scaffolding protein. The length between two Z lines determines the length of a sarcomere. The M line in similar in that it too is a scaffolding protein which keeps the sarcomere straight and tight. Without it the sarcomere would become wavy and prone to bumping into other sarcomeres.

Question 9

What does endomysium surround?

Answer 9

it surrounds individual muscle fibres.

Question 10

What are the two major proteins a myofibril contain?

Answer 10

Actin and Myosin

Question 11

Name and describe the causes of the different coloured bands when a myofibril is viewed in cross section under a microscope.

Answer 11

.the dark section on either side of the M line is called the A band, the A band consists of both Actin and Myosin. The White on the fair ends of the sarcomere is the I band and is mainly just actin or thin filaments.

Question 12

What is inside the I band of the Sarcomere?

Answer 12

The I band consists of Actin, Titin and Z discs, zero Myosin

Question 13

How many myofibrils are in a typical muscle cell?

Answer 13

Around 3000

Question 14

How does Actin bind with Myosin?

Answer 14

Each G-actin or molecule has a binding site for the myosin head.

Question 15

Where is the Troponin and Tropomyosin located?

Answer 15

Within the thin filament of the sarcomere called Actin

Question 16

Describe shape and components of myosin molecule.

Answer 16

.Myosin is a thick filament, yellow in illustrations, they have mushroom like projections on the ends called Myosin heads. These heads attach and detach to the actin. It has a long tail section also known as an anchor, two globular heads and a light chain located next to the head.

Question 17

What does the perimysium surround?

Answer 17

it surrounds the bundles of muscle fibres called fascicles

Question 18

Describe structure of skeletal muscle from a hierarchical perspective.

Answer 18

.Tendon > fascia > fascial > muscle fibre (muscle cell) > myofibrils > sarcomere

Question 19

What is the scientific name of Connective tissues

Answer 19

Fascia

Question 20

Define term Myofibril

Answer 20

.Myofibrils are groups of sarcomeres that bind together. Myofibrils are what make up a muscle cell or muscle fibre.

Question 21

Define term muscle fibre

Answer 21

.Muscle fibre is the muscle cell which houses the myofibrils. Muscle fibres form together to make fascicles.

Question 22

What fascia wraps around the tendon to help protect it?

Answer 22

Epimysium. Epi = Outside

Question 23

Describe the function of titin

Answer 23

.Titin affixes thick filaments such as the Myosin to the Z-discs to keep them straight.