Striated Muscle
The muscles attached to the skeleton are called skeletal, voluntary, or striated muscles. Examine the slide of striated muscle cells. The striations are best viewed under reduced light. Each cell has many nuclei and appears to have dark bands or stripes. These bands are made up of fibrils that slide together when stimulated by a nerve. Contraction occurs. View the site: http://kentsimmons.uwinnipeg.ca/cm1504/15lab42006/lb4pg7.htm
and complete the following activity.
Questions
1.
In what directions do the striations run?
2.
Can you locate individual cells?
3.
Are nuclei present?
4.
Are the striated muscles classified in terms of voluntary or involuntary control?
5.
What other names can be given to this type of muscle?
6.
Where can you find these muscle cells in the body?
Non-Striated Muscle Cells
The muscles of the internal organs are called involuntary, visceral, or smooth muscle tissue. Examine the smooth muscle cells and observe the differences from striated muscles. The is only one nucleus and no stripes.
Also, smooth muscles are arranged in sheaths and bundles rather than fibers. They work more slowly and more continuously than do the skeletal muscles.
1.
Can individual cells be seen?
2.
Describe the shape of the cells?
3.
Are nuclei present?
4.
Do you see striations?
5.
Are smooth muscles classified as voluntary or involuntary?
6.
What other names can be given to this muscle?
7.
Where can you find these muscle cells in the body?
8.
Sketch several non-striated muscle fibers. Label the nuclei.
Cardiac Muscle
Cardiac muscle is found in the heart and large arteries. Like skeletal muscle, it is striated. With the striations, it is able to work faster and harder than smooth muscle. Unlike skeletal muscle, the parts of the cardiac muscle are not insulated from each other. A nerve impulse to one causes them all to contract. This is an important feature in control of the heartbeat.
1.
Are the fibers striated?
2.
Are the fibers branched?
3.
Where do you find these muscle cells?
4.
Sketch several cardiac muscle fibers. Label the nuclei and striations.

Study the types of muscles shown in the table. Identify each of the drawings and complete other data.
Type of Muscle
Where found in the body?
Voluntary or
Involuntary?
Operation of Skeletal Muscles
Study the diagram. Label the numbered parts.
To study these muscles in actual operation, draw up you lower arm firmly and feel the bodies of muscles in your upper arm. Feel the inside right elbow with fingers of your left hand. The hard cords that you feel are the tendons.
1.
Which muscle has contracted?
2.
Is it a flexor or an extensor muscle?
3.
Which tendon (upper or lower) is fixed to the movable bone? Name the bone(s).
4.
Locate the attachment to the immovable bone.
Name the bone.
Now straighten your arm and draw the muscles tight.
5.
Which muscle is contracted?
6.
Feel the biceps muscle. Is it contracted or relaxed?
7.
Which muscle is larger when contracted, biceps or triceps?
8.
In terms of work done, explain why this is true.