Muscular

Muscular System

Muscular System Functions:1. produce movement2. Maintain posture3. Stabilize joints4. Generate heat5. Move substances (fluid, food etc)

Properties of Muscles: Excitability: capacity of muscle to respond to a stimulus

Contractility: ability of a muscle to shorten and generate pulling force

Elasticity: ability of muscle to recoil to original resting length after stretchedMuscles are responsible for all types of body movement they contract or shorten and are the machine of the bodyThree basic muscle types are found in the bodySkeletal muscleCardiac muscleSmooth muscleMuscular System

Skeletal Muscles: structureMuscle Coverings:

Epimysium tissue that covers the entire skeletal muscle. Separates the muscle from all other organsFascicleA group of muscle fibersPerimysium- surrounding a group a fascicle. Contains blood vessels and nerves.

Endomysium- surrounds individual muscle fiber. Also has blood vessels and nerves.

Muscle Coverings:

Head and Neck Muscles

Muscles of the cephalic area:

Trunk Muscles

Muscles of the Anterior Trunk area:

latissimus dorsiMuscles of the Posterior Trunk area:

Posterior of legAnterior of legMuscles of the Posterior and Anterior Leg:Types of Ordinary Body Movements

Flexion decreases angle of joint and brings two bones closer togetherExtension- Increase the angle or extending somethingRotation- movement of a bone in longitudinal axis (back and forth), shaking head no

Abduction: Moving away from the body or anatomical positionAdduction: Moving towards the body or anatomical position. Circumduction: moving in a circular motion

Types of Ordinary Body Movements

Types of Ordinary Body Movements

Flexion decreases angle of joint and brings two bones closer togetherExtension- Increase the angle or extending somethingRotation- movement of a bone in longitudinal axis (back and forth), shaking head no

Abduction: Moving away from the body or anatomical positionAdduction: Moving towards the body or anatomical position. Circumduction: moving in a circular motion

Types of Ordinary Body Movements

Anatomy of Skeletal Muscles:Cells are multinucleate

Myofibril- The smallest unitBundles of myofilamentsMyofibrils are aligned to give distinct bandsI band = light bandA band = dark band

Anatomy of Skeletal Muscles:Anatomy of Skeletal Muscles:Sarcomere- one segment on a myofibril (from Z disc to Z disc)(these are what allow the muscle to contract and move)

Components of a Sarcomere: Thick filaments = myosin filamentsHas ATP(for energy to be broken down and used in order to move)

Anatomy of Skeletal Muscles:

Anatomy of Skeletal Muscles:Components of a Sarcomere:

Thin filaments = actin filaments

How skeletal muscles move or slideThin Actin slide past the thick Myosin so that the actin and myosin filaments overlapIn the relaxed state, thin and thick filaments overlap only slightlyIn order for this process to start sodium must ender the cell (active transport) and the nervous tissue sends a signal to begin contraction

How skeletal muscles move or slideStep 1: Activation by nerve causes Calcium to be released. Step 2: This allows the myosin heads to attach to the actin. Step 3: ATP is used and broken down in order to pull the myosin over the actin (contracting the muscle)Step 3: Myosin heads then bind to the next site of the actin filament and get ready for a second contraction. This shortens the Z line and they over lap. Step 4; They continue until the muscle contracts and the two over lap more and more until the H zone disappears. Step 5: To release the contraction the Calcium is taken back into the muscle fibers which covers the location so myosin cant bind. Now the muscle is relaxedIF calcium doesnt go back in the contraction is prolonged and called a charlie horse or Cramp!

How skeletal muscles move or slide

Within a skeletal muscle, not all fibers may be stimulated during the same intervalMuscle force depends upon the number of fibers stimulatedMore fibers contracting results in greater muscle tensionMuscles can continue to contract unless they run out of energy

How skeletal muscles move or slideEnergy for Muscle contraction and fatigueMuscles use stored ATP for energyOnly 4-6 seconds worth of ATP is stored by muscles

1. After this initial time, other pathways must be utilized to produce ATPMuscle cells contain creatine phosphate (CP)CP regenerates new ATPCP supplies only last 20 secondsEnergy for Muscle contraction and fatigue

Energy for Muscle contraction and fatigue2.GlycolysisReaction that breaks down glucose with or without oxygen to make ATPWithout Oxygen glucose breaks into lactic acid which is what builds up and produces muscle fatigue.

Muscle Fatigue and Oxygen DebtWhen a muscle is fatigued, it is unable to contractThe common reason for muscle fatigue is oxygen debt or lactic acid build up. Oxygen is required to get rid of accumulated lactic acidDisorders relating to the Muscular SystemMuscular Dystrophy: inherited, muscle enlarge due to increased fat and connective tissue, but fibers degenerate and atrophyMyasthemia Gravis: progressive weakness due to a shortage of acetylcholine receptors