muscular system

What are the three main types of muscle tissues in the human body?

1- skeletal muscle: attached to bones, voluntary control

2- smooth muscle: found in walls of internal organs, involuntary control

3- cardiac muscle: found in the walls of the heart, involuntary control

How do cardiac and skeletal muscle differ from smooth muscle in appearance ?

Cardiac and skeletal muscles are striated because the cells are arranged in bundles.

Smooth muscle is not striated because their cells are arranged in sheets

What is a sarcomere?

It is the basic functional unit of skeletal and cardiac muscles. It is the region between two Z lines (or Z discs) and contains thin filaments of actin and thick filaments of myosin.

Explain the Sliding Filament Theory

explains how muscles contract. Myosin filaments use energy from ATP to “walk” along actin filaments. This pulls the actin filaments and Z lines closer together, shortening the sarcomere

Compare slow-twitch (Type I) and fast-twitch (Type II) muscle fibers?

Slow-twitch: Rich in mitochondria and myoglobin; used for endurance activities like distance running.

Fast-twitch: Contract rapidly and powerfully but fatigue quickly; used for short bursts like sprinting or weight lifting.