The Muscular System

The Muscular System Muscles are responsible for all movement of the body There are three basic types of muscle Skeletal Cardiac Smooth

3 Types of Muscles

Three types of muscle Skeletal Cardiac Smooth

Classification of Muscle Skeletal- found in limbs Cardiac- found in heart Smooth- Found in viscera Striated, multi- nucleated Striated, 1 nucleus Not striated, 1 nucleus voluntary involuntary

Characteristics of Muscle Skeletal and smooth muscle are elongated Muscle cell = muscle fiber Contraction of a muscle is due to movement of microfilaments (protein fibers) All muscles share some terminology Prefixes myo and mys refer to muscle Prefix sarco refers to flesh

Skeletal Muscle Most are attached by tendons to bones Cells have more than one nucleus (multinucleated) Striated- have stripes, banding Voluntary- subject to conscious control Tendons are mostly made of collagen fibers Found in the limbs Produce movement, maintain posture, generate heat, stabilize joints

Structure of skeletal muscle Each cell (fibre) is long and cylindrical Muscle fibres are multi-nucleated Typically 50-60mm in diameter, and up to 10cm long The contractile elements of skeletal muscle cells are myofibrils

Skeletal muscle - Summary Voluntary movement of skeletal parts Spans joints and attached to skeleton Multi-nucleated, striated, cylindrical fibres

Smooth Muscle No striations Spindle shaped Single nucleus Involuntary- no conscious control Found mainly in the walls of hollow organs

Smooth muscle Lines walls of viscera Found in longitudinal or circular arrangement

Structure of smooth muscle Spindle shaped uni-nucleated cells Striations not observed

Smooth muscle - Summary Found in walls of hollow internal organs Involuntary movement of internal organs Elongated, spindle shaped fibre with single nucleus

Cardiac Muscle Striations Branching cells Involuntary Found only in the heart Usually has a single nucleus, but can have more than one

Cardiac muscle Main muscle of heart Pumping mass of heart Critical in humans Heart muscle cells behave as one unit

Structure of cardiac muscle Cardiac muscle cells (fibres) are short, branched and interconnected Cells are striated & usually have 1 nucleus Adjacent cardiac cells are joined via electrical synapses (gap junctions) These gap junctions appear as dark lines and are called intercalated discs

Cardiac muscle - Summary Found in the heart Involuntary rhythmic contraction Branched, striated fibre with single nucleus and intercalated discs

Day 2: Sliding Filament Theory

Muscle Control Type of muscle Nervous control Type of control Example Skeletal Controlled by CNS Voluntary Lifting a glass Skeletal Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis CNS = central nervous system ANS = autonomic nervous system

Muscular System Functions Provides voluntary movement of body Enables breathing, blinking, and smiling Allows you to hop, skip, jump, or do push-ups Maintains posture Produces heat http://images.google.com/imgres?imgurl=http://www.justinsokolowski.net/graphics/animatedBlinkingEyeSlowgreen.gif&imgrefurl=http://www.justinsokolowski.net/&h=95&w=95&sz=31&hl=en&start=4&um=1&tbnid=8QMsDOH5nTCixM:&tbnh=80&tbnw=80&prev=/images%3Fq%3Danimated%2Bblinking%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN http://images.google.com/imgres?imgurl=http://www.eyethinkinc.com/rulers/images/blinkingeyes.gif&imgrefurl=http://www.eyethinkinc.com/rulers/blinkingeyes.html&h=148&w=416&sz=34&hl=en&start=58&um=1&tbnid=AmuUAWlJKeLVwM:&tbnh=44&tbnw=125&prev=/images%3Fq%3Danimated%2Bblinking%26start%3D40%26ndsp%3D20%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN http://i81.photobucket.com/albums/j215/Oblivion_fan/Animatedflames.gif

Functions Continued Causes heart beat Directs circulation of blood Regulates blood pressure Sends blood to different areas of the body http://images.google.com/imgres?imgurl=http://acousticheart.com/library/HeartBeatingAnimation.gif&imgrefurl=http://acousticheart.com/learning_heart_and_lung_sounds.html&h=155&w=150&sz=59&hl=en&start=41&um=1&tbnid=XTtO99cxr5BobM:&tbnh=97&tbnw=94&prev=/images%3Fq%3Dbeating%2Bheart%2Banimation%26start%3D40%26ndsp%3D20%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN http://www.websystem2.com/images/Migraine_Brain_animated.gif http://www.economy-class.co.uk/images/anim_flow_slow_veinstockings_ec.gif

Functions Continued Provides movement of internal organs Moves food through digestive tract (peristalsis) Enables bladder control Causes involuntary actions Reflex actions Adjusts opening of pupils Causes hair to stand on end http://bimari-jankari.mla.iitk.ac.in/image/dsanim.gif http://www.visionsource-arenaeyeworks.com/images/Wild%20Eyes%20-%20animated.gif http://www.search.com/reference/Goose_bumps http://www.ebcl.lib.id.us/ebcl/images/goosebump.gif

M u s c l e Muscles are made up of bundles of muscle fibers, called fascicles Fascicle is a bundle of muscle fibers A muscle fiber is a muscle cell….made up of many small myofibrils Myofibrils contain filaments Two types of protein filaments T I s s u e A n a t o m y Muscle Fascicle http://images.google.com/imgres?imgurl=http://www.docfleetwood.net/anatomy/muscular41/connective%2520tissue.jpg&imgrefurl=http://www.docfleetwood.net/anatomy/muscular41/muscular41.html&h=460&w=480&sz=33&hl=en&start=23&um=1&tbnid=XT_T9iRrCLmhGM:&tbnh=124&tbnw=129&prev=/images%3Fq%3Dmuscles%2Bof%2Bblood%2Bvessels%26start%3D20%26ndsp%3D20%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN Muscle Fibers Myofibrils Filaments

Myofibril Contain two types of protein filaments Actin- thin protein filaments Myosin - thick protein filaments Z disc - point of anchor of actin Sarcomere - functional unit of a myofibril, region between Z discs, http://people.eku.edu/ritchisong/RITCHISO//myofilaments2.gif

Structure of skeletal muscle Muscular System Structure of skeletal muscle

Mechanics of a Muscle Contraction When each sarcomere becomes shorter it causes each myofibril to become shorter. When each myofibril becomes shorter it causes the muscle fibers to become shorter When each muscle fiber shortens the overall muscle contracts. Sarcomere

Sarcomere

Sliding Filament Theory

Three roles for ATP in the contraction of muscle. Provide the energy for the power stroke (myosin head bends) B. Disconnecting the myosin head from actin Actively transporting Ca++ (calcium) out to the sarcoplasmic reticulum

RIGOR MORTIS Condition in which muscles become rigid after death Why…Lack of ATP leads to the inability of the cells to actively pump calcium back into the sarcoplasmic reticulum and the myosin heads are unable to detach from the actin.