Muscular System

Question 1

Muscle Fibers

Answer 1

Muscles are organs composed mainly of muscle cells, which are also called muscle fibers (mainly in skeletal and cardiac muscle) or myocytes (mainly in smooth muscle).

Question 2

Myocytes

Answer 2

Muscles are organs composed mainly of muscle cells, which are also called muscle fibers (mainly in skeletal and cardiac muscle) or myocytes (mainly in smooth muscle).

Question 3

Peristalsis

Answer 3

In the organs of the digestive system, smooth muscles squeeze food through the gastrointestinal tract by contracting in sequence to form a wave of muscle contractions called peristalsis.

Question 4

Hypertrophy

Answer 4

Muscles can grow larger, or hypertrophy.

Question 5

Atrophy

Answer 5

Muscles can also grow smaller, or atrophy, which can occur through lack of physical activity or from starvation.

Question 6

Sarcopenia

Answer 6

As people grow older, there is a gradual decrease in the ability to maintain skeletal muscle mass, known as sarcopenia.

Question 7

Neuromuscular Junction

Answer 7

The point where a motor neuron attaches to a muscle is called a neuromuscular junction.

Question 8

Tendons

Answer 8

The two systems together are often referred to as the musculoskeletal system. Skeletal muscles are attached to the skeleton by tough connective tissues called tendons.

Question 9

Skeletal Muscle

Answer 9

Skeletal muscle is muscle tissue that is attached to bones by tendons, which are bundles of collagen fibers.

Question 10

Slow-twitch Muscle Fibers

Answer 10

Slow-twitch muscle fibers are dense with capillaries and rich in mitochondria and myoglobin, which is a protein that stores oxygen until needed for muscle activity. Relative to fast-twitch fibers, slow-twitch fibers can carry more oxygen and sustain aerobic (oxygen-using) activity.

Question 11

Fast-twitch Muscle Fibers

Answer 11

Fast-twitch muscle fibers contain fewer capillaries and mitochondria and less myoglobin. This type of muscle fiber can contract rapidly and powerfully, but it fatigues very quickly.

Question 12

Smooth Muscle

Answer 12

Smooth muscle is muscle tissue in the walls of internal organs and other internal structures such as blood vessels.

Question 13

Cardiac Muscle

Answer 13

Cardiac muscle is found only in the wall of the heart. It is also called myocardium.