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Muscles. Function of Muscle. Muscle tissue is responsible for all body movements. This includes body motion as in walking (Skeletal Muscle) but also organ movement (smooth muscle) such as dilation of blood vessels or heart contraction (Cardiac Muscle).
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Function of Muscle • Muscle tissue is responsible for all body movements. This includes body motion as in walking (Skeletal Muscle) but also organ movement (smooth muscle) such as dilation of blood vessels or heart contraction (Cardiac Muscle). • Muscles support the functions of most our systems that keep us alive: ie – respiration, digestion, blood circulation … • Heating of body, muscle contractions give off heat and help maintain body temperature. Shivering warms the body when muscles in the skin contract reflexively due to cold.
Cardiac Muscle • Found only in the heart. Able to contract independently of the brain but requires signals from the brain to beat in correct sinus rhythm.
Anatomy of a Skeletal MuscleSkeletal muscle attaches to bone and moves our skeletonSkeletal muscle is called voluntary muscle as it requires a conscious command from the brain in order to move
Smooth Muscle tissue is found in the organs and vessels of the body. Smooth muscle is called an involuntary muscle because it requires no conscious signal from the brain to do its function and movements.
How Many?? • There are over 600 different muscles in our body. Some are very large for gross motor movement (kicking a ball) and some very tiny fine motor control (blinking).
Tendon vs LigamentTendon – attaches muscle to boneLigament – attaches bone to bone
Properties of Muscle FibreConductivity – can transmit an electrical or neural impulseContractibility – ability to shorten in lengthExtensibility – able to extend and become longer over time (flexibility training/stretching)Elasticity – able to be stretched and return to normal lengthIrritability – ability to respond to a stimulus (nerve impulse)
Muscle Fibers • Muscle Fibers are about the diameter of a human hair, they can contract about ½ their length and can lift about 1000 times their weight. • Muscle Fibers are malleable. When stimulated by an electrical impulse they contract but need to be pulled back by another force to return to their original length.
Motor Unit A motor unit consists of the nerve (neuron) and all the fibers connected to it. When a neuron is stimulated all of its fibers will contract completely. This is called the All or None Principal. The number of motor units stimulated the stronger the muscle contraction and vice versa.
Gross Motor MovementsBig muscles with small # of motor units but each motor unit controls larger numbers of muscle fibers
Fine Motor • Small muscles with lots of motor units to control them but each motor unit controls fewer numbers of muscle fibers.
Muscle Strength • Muscles can adapt to use. Muscle fibres get thicker and stronger if they are exercised regularly over time.
Micro Tears, Overload, Rest and RecoveryStrength Training • During weight resistance training we try to overload a muscle. This means work it beyond its normal strength • Overloading results in micro tears in the muscle fibers. Tiny lesions in the fibers open up. • During rest and recovery over the next 24 hours the tears heal and make the fiber a bit larger in diameter and as a result stronger • Over time repeated training will result in larger fibers and bigger, stronger muscles.
Muscle Concepts • Transient Hypertrophy – Muscle temporarily get larger during exercise due to increased blood flow. This lasts only for 30 minutes or so after exercise. Does not increase strength. • Chronic Hypertrophy – Muscle fibers diameters get bigger as they adapt to repeated exercise training. As fibers get larger the muscle gets bigger and stronger over time. • Muscle Atrophy - Muscle fiber diameters get smaller over time as a result of lack of use or training. Results in loss of strength. • Hyperplasia – An unproven theory that increases in strength due to exercise actually result in muscle fibers splitting and increasing in number to account for increased strength. • Voluntary Muscle – muscles that we consciously control like leg muscles for walking • Involuntary Muscle – muscles that function without conscious control like our organs – blood vessels, stomach, heart…
Transient Hypertrophy the muscle increases size from increased blood flow, temporary (30 min) and no strength gain
Chronic Hypertrophy – muscle gets larger and stronger from training
Voluntary and involuntarymuscle • Voluntary like writing • Involuntary like pupil dilation
Naming Muscles • Location: Tibialis Anterior muscle • Shape: Trapezius • Action: Extensor Digitorum • Direction of Fibres: TranversusAbdominus • Attachment Points: Sternocleidomastoid • Number of Heads: Biceps, Triceps
Muscle PairsAgonist and Antagonist • Example – Muscles work in pairs to counteract each other’s movement. Example: the bicep is called the agonist (primary mover) and the tricep is the antagonist (returns the arm to its original position.
Tendons, Origin and Insertion • Tendons connect the muscle to bone. • Origin is the connection we call an anchor, it does not move during the contraction • Insertion is the connection that moves a bone during the contraction. • www.getbodysmart.com/ap/muscularsystem/menu/menu.html
Treatment of muscle injury Rest – it takes time for the muscle to repair Ice – helps reduce the swelling and pain Compression – helps hold muscle in line and reduce the pain and swelling Return to action when function is no longer impaired. Returning too soon may result in re injury
