8 - 1 Muscle Types By the end of today, you should be able to: By the end of today, you should be able to: List several functions of muscles. List several functions of muscles. List and describe the three different types of muscle. List and describe the three different types of muscle. Identify the “rules” of muscle activity. Identify the “rules” of muscle activity.

More than 50% of body weight is muscle ! You have over 30 facial muscles which create looks like surprise, happiness, sadness, and frowning. Eye muscles are the busiest muscles in the body. Scientists estimate they may move more than 100,000 times a day! The largest muscle in the body is the gluteus maximus muscle in the buttocks.

8 - 3 Functions of Muscles Movement Posture Stabilize joints Generate heat Protects organs

8 - 4 Types of muscle 1. Skeletal 2. Smooth 3. Cardiac

Skeletal muscle Large muscles Large muscles muscles Voluntary muscles Multi-nucleated cells (more than 1 nucleus) Multi-nucleated cells (more than 1 nucleus) Approximately 650 in human body Approximately 650 in human body Maintain posture Maintain posture Facilitate locomotion Facilitate locomotion Move jointed bones Move jointed bones Striated (striped) appearance Striated (striped) appearance

Skeletal muscle Found in antagonistic pairs Found in antagonistic pairs Antagonistic pairs are needed in the body because muscles can only exert a pulling force, and can't push themselves back into their original positions. An example of this kind of muscle pairing is the biceps and triceps. Antagonistic pairs are needed in the body because muscles can only exert a pulling force, and can't push themselves back into their original positions. An example of this kind of muscle pairing is the biceps and triceps.biceps tricepsbiceps triceps When the biceps is contracting, the triceps is relaxed, and is able to be stretched back to its original position. This is the opposite when the triceps is contracting. When the biceps is contracting, the triceps is relaxed, and is able to be stretched back to its original position. This is the opposite when the triceps is contracting. Joined to bones by tendons Joined to bones by tendons

8 - 7 Origin vs. Insertion Immovable end of a skeletal muscle is called its ORIGIN Immovable end of a skeletal muscle is called its ORIGIN Movable end is called its INSERTION Movable end is called its INSERTION Some muscles have more than one origin or insertion Some muscles have more than one origin or insertion When a muscle contracts, its insertion is pulled towards it origin When a muscle contracts, its insertion is pulled towards it origin

8 - 8 Seven Golden Rules of Muscle Activity 1. Muscles get shorter as they contract. 2. Muscles cross at least one joint (with few exceptions). 3. The bulk of the muscle lies proximal to the joint crossed. (closer to the joint that it is moving) 4. All muscles have an origin and insertion. 5. During contraction, the insertion moves toward the origin. 6. Muscles only pull; they never push. 7. Muscles work in pairs (antagonistic pairs).

Types of Skeletal Muscle 1. Slow-twitch fibers Fatigue-resistant Fatigue-resistant More mitochondria More mitochondria More efficient at using oxygen More efficient at using oxygen These help athletes run marathons & bicycle for hours These help athletes run marathons & bicycle for hours 8 - 9

Types of Skeletal Muscle 2. Fast-twitch fibers 2. Fast-twitch fibers Easily fatigue Easily fatigue More forceful contractions/short bursts of strength or speed More forceful contractions/short bursts of strength or speed Having more of these is an asset to a sprinter Having more of these is an asset to a sprinter

Slow-twitch vs. Fast-twitch

Types of Skeletal Muscle On average, we have 50% slow twitch & 50% fast twitch fibers in our bodies On average, we have 50% slow twitch & 50% fast twitch fibers in our bodies The more FAST twitch fibers you have, the greater the ultimate muscle size could be The more FAST twitch fibers you have, the greater the ultimate muscle size could be To train SLOW twitch, train these fibers with higher reps, shorter rest, and higher volume To train SLOW twitch, train these fibers with higher reps, shorter rest, and higher volume To train FAST twitch fibers, you'll need to train with low to moderate reps (e.g. 4 to 8 reps), rest periods of around 1 to 2 minutes and a moderate training volume To train FAST twitch fibers, you'll need to train with low to moderate reps (e.g. 4 to 8 reps), rest periods of around 1 to 2 minutes and a moderate training volume Click image

Cardiac muscle Main muscle of heart Pumping mass of heart Heart muscle cells behave as one unit Heart always contracts to its full extent Involuntary muscle Striated appearance

Structure of cardiac muscle Cardiac muscle cells (fibers) are short, branched and interconnected (by intercalated disks) Cells are striated & have a single nucleus

Smooth muscle Lines walls of viscera Found in longitudinal or circular arrangement One cell may stimulate another Alternate contraction of circular & longitudinal muscle in the intestine leads to peristalsis Involuntary muscle Striations (stripes) not observed

Classification of Muscle