Lesson Six: Muscular System (Part Two)

Muscular System

(Part Two)

Think Quest

Structure
We all know that living organisms can move on their own or can perform other types of movement.
Muscle tissue has a ability to relax and contrast and so bring about movement and mechanical work in various parts of the body.
There are other movements in the body too which are necessary for the survival of the organism such as the heart beat and the movements of the alimentary canal.

 ~ Muscles can be divided into three main groups according to their structure ~

Smooth (Visceral) Muscle Tissue:

Visceral muscle, is found in various parts of the body such as the arteries, the bladder, the digestive tract, as well as in many other organs.

Visceral muscle is also called smooth muscle because it doesn't have cross striations. Visceral muscle contracts slower than skeletal muscle, but the contraction can be sustained over a longer period of time.

Skeletal Muscle Tissue:

Skeletal muscle, which is attached to bones by tendons, is associated with the body's voluntary movements. Skeletal muscle is striated muscle. Unlike cardiac muscle, the cells are not branched.

 

Cardiac Muscle Tissue:

Cardiac muscle is so named because it is found in the heart. Cells are joined to one another by intercalated discs which allow the synchronization of the heart beat. Cardiac muscle is branched, striated muscle.

Interestingly, adults have a certain number of muscle cells. Through exercise, such as weight lifting, the cells enlarge but the overall number of cells does not increase.
Skeletal muscles are voluntary muscles because we have control over their contraction. Visceral muscles are involuntary since, for the most part, they are not consciously controlled.

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Homework Time:

1-Draw and label one of the Muscle Tissues