Presentation on theme: "How do Muscles Work? Muscles serve FOUR functions for us:"— Presentation transcript:
1How do Muscles Work? Muscles serve FOUR functions for us: -- motion; they move us-- stability and posture-- controlling organ function-- generate body heat
2Characteristics of Muscle Tissue Excitability – ability of the muscles to be stimulated by nervesContractility – muscles can contractExtensibility – muscles lengthenElasticity – after shortening or lengthening, muscle can return to its original shapeMuscles PULL, they never push!
3Roman Ship Analogy…Muscles work much like an old roman ship that used a galley of slaves roaring the oars in unison.Each slave had only so much strength, but together gave the ship’s oars incredible power.
5Muscles need help…Muscles need to be connected to the rest of the body-- they need motor nerves-- they need energy and O2-- H20, CO2 waste & glucose transportRequires nerves, blood vessels, andthe lymphatic system to carry themThese are held in connective tissues calledFASCIA
6Fascia Galore! Fascia is connective tissue that surrounds muscles Provides protection and stability
7Superficial Fascia Closest to the skin and holds muscle to the skin Also contains adipose tissueStores fat and water, provides insulation from heat loss, protects, and is a place for vessels and nerves to carry things in and out of muscles
8Deep Fascia Separates muscle groups Allows muscles to contract without interference from other musclesEach muscle has its own outer fascia called epimysium which is then surrounded by deep fascia
9Myofibers Individual muscle fibers are called myofibers (muscle cells) Arranged in groups of myofibers and these groups are called fasciclesPerimysium surrounds fasciclesEndomysium surrounds individual myofibers
14Skeletal Muscle Fiber Contraction “Sliding Filament Theory”When muscle fibers are stimulated to contract, myofilaments (actin an myosin) slide past one another.This causes sarcomeres (muscle units) to shorten and the whole muscle fiber shortens.
18Whole Muscle Contraction The whole length of one muscle fiber must contract; however, the whole muscle does not have to contact.The number of muscle fibers contracting determines the strength of the contraction.
20The Effect of Exercise A regular exercise program will bring about 1. Increased endurance2. Increased strength of muscles.Muscle enlarge, not due to increase in number of muscle fibers, but increased amounts of actin and myosin myofibrils inside each muscle fiber making them bigger and stronger.“Use it or lose it !”
22Exercise increases muscle size, strength, and endurance Aerobic (endurance) exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigueMakes body metabolism more efficientImproves digestion, coordinationResistance exercise like weight lifting increases muscle size and strength