Study guide… What are the three types of muscle tissue, their structure and location? What are the functions of the muscular system? How are skeletal muscles and muscle fibers structured from largest to smallest? What are the steps of skeletal muscle contraction? How do skeletal muscle cells acquire ATP for contraction? Distinguish between slow and fast twitch fibers. What are some common muscular disorders?

Review: 3 types of muscle tissue

What are the functions of skeletal muscles? Support Movement Homeostasis-How do skeletal muscles help us maintain body temperature? Protection internal organs and stabilize joints

How are skeletal muscles arranged? Attachments: Tendon Origin Insertion Action: Antagonistic Synergistic

An example of muscle arrangement

Examples of how skeletal muscles are named Size –gluteus maximus, vastus lateralis Shape – deltoid, trapezius Location –frontalis, tibialis anterior Direction of muscle fiber – rectus abdominus, external oblique Attachment – brachioradialis Number of attachments –biceps brachii Action –extensor digitorum

Skeletal Muscle Structure Terminology for cell structure plasma membrane =______________________ Cytoplasm=___________________ ER=_______________ ___________________ Muscle fascicle (bundle of fibers) Muscle fiber Myofibrils Sarcomeres consisting of myofilaments

Visualizing muscle structure

The sarcomere Made of protein myofilaments Thick: myosin Thin: actin, troponin, tropomyosin These filaments slide over one another during muscle contraction

The beginning of muscle contraction: The sliding filament model 1. What type of neuron carries information toward the muscle? 2. What is released from the pre-synaptic cell? 3. What does it bind to? (This binding will cause calcium to be released from the SR.)

The beginning of muscle contraction

Muscle contraction continued… 4. Released calcium combines with troponin 5. Myosin binding sites exposed 6. Cross-bridges form 7. ATP binds and power stroke occurs

Visualizing the role of calcium and myosin in muscle contraction

What are the sources of ATP for muscle contraction? Limited amounts of ATP are stored in muscle fibers Creatine phosphate pathway (CP) – fastest way to acquire ATP but only sustains a cell for seconds; builds up when a muscle is resting Fermentation – fast-acting but results in lactate build up Cellular respiration (aerobic) – not an immediate source of ATP but the best long term source

Muscle fibers come in two forms Fast-twitch fibers: rely on CP and fermentation (anaerobic) Designed for strength Light in color Few mitochondria Fewer blood vessels Slow-twitch fibers: Rely on aerobic respiration Designed for endurance Dark in color Many mitochondria Many blood vessels Where in the body would you have examples of each of these?

Types of muscle fibers

Muscular diseases Fibromyalgia – chronic achy muscles that is not well understood Muscular dystrophy – group of genetic disorders in which muscles progressively degenerate and weaken Myasthenia gravis – immune system attacks ACh receptor and weakens muscles of the face, neck and extremities-What kind of disorder is this?

Amyotrophic lateral sclerosis (ALS) commonly known as Lou Gehrig’s disease motor neurons degenerate and die leading to loss of voluntary muscle movement