Muscular System Luna Lannoy, Paulina Joo, Valentina Kochian, Isa Lopez

Science Instituto Tepeyac

6th Grade

Introduction

Over 600 skeletal muscles function for body movement. These muscles are attached to bones, and are typically under conscious control for locomotion, facial expressions, posture, and other body movements. Muscles are resistant and elastic. They are involved in movement. Muscles provide strength, balance, posture, movement and heat for the body to keep warm.

Types of MusclesThere are three types of muscles in your body; skeletal, smooth, and cardiac.

•Cardiac muscle is only in the heart and makes up the atria and ventricles (heart walls). This type of muscle never stops. Cardiac muscles pumps blood with its movement. Cardiac muscle contains striated fibers. Cardiac muscle is called involuntary muscle because conscious thought does not control its contractions. Specialized cardiac muscle cells maintain a consistent heart rate.

•Smooth Muscles form parts inside the human body. They make involuntary movements. Smooth muscle is nonstriated (not banded). It is extensively within the walls of digestive tract organs, causes peristalsis (wave-like contractions).

•Skeletal Muscles work together with bones, they are responsible for voluntary movements, like chewing gum. Skeletal muscle is a system of pairs that relax and contract to move a joint. Skeletal muscles have muscle tone (remain partly contracted), which helps maintain body posture. Ongoing signals from the nervous system to the muscle cells help maintain tone and readiness for physical activity.

Facts •Muscles account for approximately 40 percent of body weight. •There are nearly 650 skeletal muscles in the human body!•Skeletal muscles are attached to the skeleton•They work in pairs: one muscle moves the bone in one direction and the other moves it back again•Skeletal muscles are voluntary muscles - in other words we think about what movements we want to make (at least, usually!) and send messages via our nervous system to tell the appropriate muscle(s) to contract. •Muscle contractions can be short, single contractions or longer ones.