Muscular System Sports Training and Physiology Kociuba http

Muscular System Sports Training and Physiology Kociuba http: //kidshealth. org/Page. Manager. jsp? lic=1&article_set=59302&cat_id=20607

Muscular System - Objectives l List the major functions of muscles l Describe 4 major properties of muscles l Compare and contrast the 3 different types of muscles l Explain the sliding filament theory l Define a muscle twitch and it’s 3 phases l Define the different types of muscle contractions

Muscular System – Objectives 2 l Name and compare the types of skeletal muscle fibers l Discuss the causes of fatigue during exercise l Explain how fibers obtain energy l Discuss causes of hypertrophy and atrophy l Discuss age related changes in skeletal muscle

Functions of the Muscular System l Body Movement l Maintenance of posture l Respiration l Production of body heat l Communication l Constriction of organs and vessels l Heartbeat

Functional Properties of Muscles l Contractility l l l The ability to shorten forcefully Extensibility l Excitability l Ability to respond to a stimulus l Ability of a muscle to be stretched beyond it’s normal resting length Elasticity l Ability of a muscle to recoil to it’s original shape after it has been stretched

Muscle Tissue 3 kinds or types Skeletal Muscle • Attached to bones Smooth Muscle • Walls of hollow organs • Blood vessels • Eyes, glands, and skin Cardiac Muscle • Found only in The heart

Connective tissue coverings of a Muscle

Anatomy of the Skeletal Muscle l Filaments found in the myofibrils Actin l Myosin l Together they make sarcomeres that make up… l Myofibrils: threadlike structure that extends from one end of the muscle to the other l

How do muscles contract? Sliding Filament Model

Muscle Twitch: contraction and relaxation to a stimuli that causes action potential in one or more muscle fibers l Lag/Latent phase: time it takes to stimulate the motor neuron to cause the muscle to contract l Contraction phase: time during which a contraction occurs l Relaxation phase: time in which relaxation occurs

Types of Muscle Contractions l Isometric: l l Length doesn’t change, but tension increases during the contraction phase l Isotonic: l Amount of tension is constant but length changes l Concentric: shortening a muscle l Eccentric: lengthening a muscle Muscle Tone: l Constant tension produced over long periods of time

How do the muscles get energy to contract? l ATP is the immediate source of energy used by the muscles l ATP must be used continuously in order to keep a muscle contracted l 3 ways body makes ATP production for the muscles l Creatine phosphate l Anaerobic glycolysis l Aerobic respiration

ATP Production happens in the mitochondria l Creatine Phosphate: Energy Source is creatine phosphate l Creates 1 ATP l Oxygen is NOT required l Duration of energy is 10 seconds l l Anaerobic Glycolysis: Energy Source is glucose l Creates 2 ATP l Oxygen is NOT required l Duration of energy is up to 3 minutes l

ATP Production happens in the mitochondria l Aerobic Respiration Energy Source is glucose, lactic acid, fatty acids, amino acids l Oxygen is required l Creates up to 36 ATP l Duration of energy is hours!!! l

Exercise and Fatigue l Fatigue: decreased capacity to do work and the reduced efficiency of performance to do work l Psychologic fatigue: most common type. Individual perceives that they can not use the muscle anymore l Muscular fatigue: the reduced or absent ability of muscle fibers to respond to stimuli

Hypertrophy and Atrophy l Hypertrophy Muscle size increases l Slow and fast twitch muscle fibers increase depending upon what exercises you do l l Atrophy Decrease in muscle size l Disuse Atrophy l l Denervation Atrophy

Age related changes in skeletal muscle Loss of muscle fibers as early as the age of 25 l By 80 50% of muscle mass is gone l Fast-twitch muscle fibers deteriorate faster than slowtwitch l

Gross Anatomy Generalized Groupings of the Muscles of the Body *We will go over in depth starting next week with anatomy Mondays and Injury/Rehab Fridays

The Muscular System