What is a muscle fiber? Why it appears striated?

Question

What is a muscle fiber? Why it appears striated?

Answer 1

no clue

Answer 2

Muscles are made up of muscle fibers. When you look under a microscope, you can see the muscles are made of fibers. Each one of these fibers are made up of myofibrils which are made up of actin or myosin filaments. Each myofibril can be broken down into functional units called sacromeres. when the muscle contracts the actin filaments are pull inwand toward the center of each sacromere, causes the sacromeres to shorten during contraction; this is called the sliding filament theory.  So you see striations because it is the actin and myosin filaments lined up.  Keep in mind not all muscles are striated. For example, smooth muscles make up involuntary organs and are spindle-shaped.

Answer 3

There are three common types of muscle fiber:

(1) Skeletal muscle or "voluntary muscle" is anchored by tendons to bone and is used to affect skeletal movement such as locomotion and in maintaining posture. An average adult male is made up of 40–50% of skeletal muscle and an average adult female is made up of 30–40% (as a percentage of body mass).

(2) Smooth muscle or "involuntary muscle" is found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder, blood vessels, and even the skin (in which it controls erection of body hair). Unlike skeletal muscle, smooth muscle is not under conscious control.

(3) Cardiac muscle is a type of smooth muscle unique to the heart.

STRIATIONS

Striations are found in skeletal (and to some extent cardiac) muscle.  Long skeletal fibers are characterized by alternating light and dark bands under the microscope, which are known as transverse or oblique striations.

A muscle's striational appearance corresponds to its sarcomeres, an array of overlapping thick (myosin) and thin (actin) filaments within each muscle cell.