The Muscular System

Functions Produces movement by contracting Posture (result of muscles contracting) Joint stability Generates heat (85% of the heat produced in the body is from muscles!) This is why people who have more muscle in their bodies burn fat faster- even at rest.

Involuntary Muscles Involuntary muscles are muscles that you generally do not control Whether or not you think about them, they contract and do their job For example, breathing and heart beat are involuntary processes, so the muscles of the lungs and heart are said to be involuntary muscles

Voluntary Muscles Voluntary muscles are muscles that you control You make these muscles move by thinking about moving them For example, kicking a ball, waving your hand, skating, jumping, and walking are voluntary actions, so the muscles that allow movement are voluntary muscles.

Skeletal Muscles 1. These muscles are attached to the skeleton. 2. The contraction of these muscles are under your voluntary control. 3. These muscles are striated, which means they have a striped appearance.

Skeletal Muscle

Cardiac Muscle This muscle makes up the walls of the heart It is under the brain’s control, so it is an involuntary muscle It is striated, with intercalated discs which pass on electrical impulses Throughout life it contracts about 70 times per minute pumping about 5 liters of blood per minute

Cardiac muscle is an involuntary muscle because it beats without you having to think about it

Cardiac Muscle

Smooth Muscle Found in the walls of all the hollow internal organs in the body (except the heart), such as the bladder, stomach, intestines, uterus, and in the walls of the blood vessels Its contraction reduces the size of these structures making them effective at pushing out/ squeezing things It is under involuntary control It has a smooth appearance

Most hollow internal organs are composed of smooth muscle. Examples include: walls of blood vessels, uterus, bladder, and intestines

Smooth Muscle