Muscular System Sports Training and Physiology Kociuba

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

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

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

Functional Properties of Muscles Contractility Contractility The ability to shorten forcefully The ability to shorten forcefully Excitability Excitability Ability to respond to a stimulus Ability to respond to a stimulus Extensibility Extensibility Ability of a muscle to be stretched beyond it’s normal resting length Elasticity Elasticity 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 Filaments found in the myofibrils Filaments found in the myofibrils Actin Myosin Together they make sarcomeres that make up… Together they make sarcomeres that make up… Myofibrils: threadlike structure that extends from one end of the muscle to the other Myofibrils: threadlike structure that extends from one end of the muscle to the other

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 Lag/Latent phase: time it takes to stimulate the motor neuron to cause the muscle to contract Lag/Latent phase: time it takes to stimulate the motor neuron to cause the muscle to contract Contraction phase: time during which a contraction occurs Contraction phase: time during which a contraction occurs Relaxation phase: time in which relaxation occurs Relaxation phase: time in which relaxation occurs

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

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

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

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

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

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

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

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 Injury/Rehab Fridays

The Muscular System