Skeletal muscle

Question 1

The four main characteristics of muscle tissue

Answer 1

Extensibility (the ability to stretch & lengthen).

Contractility (the ability to contract & shorten).

Elasticity (the ability of muscle to recoil to its original shape/resting length).

Excitability (the capacity of muscle to respond to stimulus from the Nervous System).

Question 2

Skeletal Muscle and its Structure

Answer 2

voluntary muscle, we can actively control its function.

It is attached to the bone and forms a distinct organ of muscle tissue, blood vessels, tendons, and nerves that covers our bones and allows movement.

Often exist in pairs, whereby one muscle is the primary mover and the other acts as an antagonist.

Consists of elongated multinucleated cells called the myocytes (or myofibers).

The muscle cells can be anything from 1 mm to 30 cm in length with most of the cells usually 2 to 3 cm.

The longest muscle cell in our bodies can be found in the sartorius muscle which is the thin, long, superficial muscle in the anterior compartment of the thigh & can exceed 50 cm in length.

Skeletal muscle has various layers that aid in the structure & function of the muscles overall performance.

Question 3

Cellular Structure of Skeletal Muscle

Answer 3

Epimysium

Fasciculi

Perimysium

Endomysium

Question 4

Epimysium

Answer 4

● The outermost membrane, covering the whole Muscle.

● Made up from a series of collagen-based membranes that surround & protect the Muscle (epi – meaning ‘upon’)

Question 5

Fasciculi

Answer 5

● Groups of Muscle Fibres, formed into Bundles, located within the Epimysium.

Question 6

Perimysium

Answer 6

● Each Fascicle has its own Outer Sheath that surrounds them (Peri – meaning ‘around’)

Question 7

Endomysium

Answer 7

● Within each Fascicle are bundles of Muscle Fibres.

● Separated from another membrane, being, Endomysium (endo – meaning ‘inside’)

Question 8

Myofibril Structure

Answer 8

Made up of two protein filaments – Actin and Myosin aka Thin and Thick.

These filaments form partially overlapping layers, laid out in compartments called Sarcomeres.

Inside the sarcomere compartments contains cell fluid called Sarcoplasm aka Cytoplasm.

Calcium stores called Sarcoplasmic Reticulum surround the myofibrils with network tubes and release calcium into the Sarcoplasm containing Actin and Myosin during an action potential.

The Sarcolemma is the cell membrane which action potential travels, then producing a nervous system stimulation of the S.R causing the release of calcium which initiates the desired action.