Question

What are the different types of fibres that make up muscle tissue and how they work together to produce movement relating to their properties. 

Compare and construct fibre types of skeletel muscle.

Answer 1

In the muscular system, muscle tissue is categorized into three distinct types: skeletal, cardiac, and smooth. Each type of muscle tissue in the human body has a unique structure and a specific role. Skeletal muscle moves bones and other structures. Cardiac muscle contracts the heart to pump blood. The smooth muscle tissue that forms organs like the stomach and bladder changes shape to facilitate bodily functions.

Skeletal Muscle: Skeletal muscles attach to and move bones by contracting and relaxing in response to voluntary messages from the nervous system. Skeletal muscle tissue is composed of long cells called muscle fibers that have a striated appearance. Muscle fibers are organized into bundles supplied by blood vessels and innervated by motor neurons.

Smooth Muscle:

Smooth muscle is found in the walls of hollow organs throughout the body. Smooth muscle contractions are involuntary movements triggered by impulses that travel through the autonomic nervous system to the smooth muscle tissue. The arrangement of cells within smooth muscle tissue allows for contraction and relaxation with great elasticity. The smooth muscle in the walls of organs like the urinary bladder and the uterus allow those organs to expand and relax as needed. The smooth muscle of the alimentary canal (the digestive tract) facilitates the peristaltic waves that move swallowed food and nutrients. In the eye smooth muscle changes the shape of the lens to bring objects into focus. Artery walls include smooth muscle that relaxes and contracts to move blood through the body

Cardiac Muscle:

The heart wall is composed of three layers. The middle layer, the myocardium, is responsible for the heart’s pumping action. Cardiac muscle, found only in the myocardium, contracts in response to signals from the cardiac conduction system to make the heart beat. Cardiac muscle is made from cells called cardiocytes. Like skeletal muscle cells cardiocytes have a striated appearance, but their overall structure is shorter and thicker. Cardiocytes are branched, allowing them to connect with several other cardiocytes, forming a network that facilitates coordinated contraction.

Skeletal muscle fibers:

1. Contracting muscle fibre Type 1:

High capacity for ATP production via oxidative phosphorylation. High levels of intracellular myoglobin Low myosin ATPase activity (compared with Type II fibres) and very dense capillary network.

b.   Contracting muscle fiber Type 2

High capacity for ATP production via oxidative phosphorylation High levels of intracellular myoglobin . Higher myosin ATPase activity than Type I fibres Dense capillary network.

    c.    Contracting muscle fibre Type 3:

   Lower capacity for ATP production via oxidative phosphorylation than ‘red’ fibers. No intracellular myoglobin. Higher myosin ATPase activity than Type I fibers and sparser capillary network