Unit 5 MUSCULAR SYSTEM

2. the 3 Types of MUSCLE TISSUE

• SMOOTH- in walls of organs, 1 nucleus, involuntary, slowest

• CARDIAC- heart, rythmical, involuntary, 1 nucleus, least fatigue, striated

• SKELETAL- attach to skeleton, voluntary, many nucleus, striated

The 5 functions of MUSCLES

• Stabilize joints

• Allow us to hold positions

• Movement

• Produce heat

• Keep blood moving

1.Structure of Muscle

• Tendons attach muscle to bone

• Muscles are covered with FASCIA

• A bundle of muscle fibers are wrapped in a Fascicle

• One muscle FIBER is made up of many actin and myosin

• Actin and Myosin are the contractile unit .

• They slide from Z line to Zline( a SARCOMERE)

How does a Muscle Contract?

• A nerve stimulates the muscle

• Calcium and ATP are released

• This stimulates actin filaments to slide past myosin filaments

• All or none Law- when a muscle is stimulated it contracts completely or not at all

3. Muscle Tone

• Strength of contraction depends on the # of muscle fibers stimulated

• Origin- stationary bone

• Insertion- moving bone

• Muscle Tone- some fibers are always contracted

4. Isotonic & Isometric Contractions

• Muscle short & thick • Muscle length not change, just tension

• Muscle Tone

Locate the following Muscles

• Deltoid- shoulder• Pectoralis- chest• Biceps- anterior upper

arm• Quadreceps- front

and side of thigh

Muscles continued

• Triceps- posterior upper arm

• Gluteus- buttock and back of thigh, largest muscle of body

• Hamstring- behind knee

5 Muscles of Facial Expression

• Frontalis- forehead• Obicularis oris- lip,

pucker• Obicularis oculi- eye• Buccinator- cheek• Zygomatic- cheek to

corner of lip, smile

4 Muscles of MASTICATION (chewing)

The End