Chapter 9 Key Terms 1 ActinMyosin OriginInsertion TroponinTropomyosin Electrical Potential Fascia AntagonistsAction Potential SarcomereSkeletal Muscle Smooth MuscleCardiac Muscle AcetylcholineAgonists

ANATOMY & PHYSIOLOGY CHAPTER 9: MUSCULAR SYSTEM 2

Muscular System  Main function of the muscular system is movement  3 types  Skeletal muscles: move the body in the environment  Smooth muscles: moves substances through body  Cardiac muscles: pumps blood through the body (only found in the heart) 3

Types of Muscles  Skeletal  Voluntary, multinucleated, and striated  Long fibers  Smooth  Involuntary, uninucleated, and non-striated  Cardiac  Involuntary, uninucleated, and striated 4

Skeletal Muscle  Longest muscle fibers 1. Blood vessel 2. Perimysium 3. Epimysium 4. Muscle Fiber 5. Fascicle 6. Endomysium 7. Tendon 5

Skeletal Muscle 6

Muscles 7  Motor unit: all the muscle cells innervated by one motor neuron  Muscle cell properties  Excitability: they can be excited by a stimulus  Conductivity: response travels throughout the cell  Contractility: ability to contract  Elasticity: ability to return to its original shape  The interaction of 3 factors control muscle contraction  Neuroelectrical factors, chemical interactions, and energy sources

Neuroelectrical factors 8  Resting Potential  Inside of cell is negatively charged, outside is positively charged  Neurotransmitter (acetylcholine) is released from the neuron and causes Na + to rush into the cell  This is known as the electrical potential  This causes the action potential (contraction of the muscle)

Chemical Interactions  Troponin and Tropomyosin  Inhibit interaction of actin and myosin  Presence of Ca+ ions moves the tropomyosin to all the myosin to bond with the actin  This interaction causes the contraction 9

Energy Sources  ATP is the energy source for contraction to occur  ATP breaks down, releasing energy, allowing the myosin head to “pull” on the actin filament 10

Muscle Characteristics  Origin  Fixed attachment of a muscle; the basis for the action  The proximal point of attachment  Insertion  The movable attachment where the effects of the contraction can be seen  The distal point of attachment  General names for muscles are based on the type of movement they produce (flexor, extensor, abductor…) 11

Facial Muscles 12

Muscles of the body 13

Muscles of the body 14