The Muscular System 6 minute video clip on image

- more than 50% of body weight is muscle ! Did you know that ? - more than 50% of body weight is muscle ! Video link on image (10:30 min).

Three types of muscle Skeletal Cardiac Smooth Where would we find smooth muscles in the body? Skeletal Cardiac Smooth

Classification of muscle Voluntary Involuntary Skeletal Cardiac Smooth Limbs Heart Viscera What are striations? Tissue that is marked by transverse dark and light bands (appearance) Viscera? Hollow organs (ex: Intestines) Striated Non-striated

Skeletal muscle Large muscles Maintain posture Facilitate locomotion Move jointed bones Found in antagonistic pairs Joined to bones by tendons Antagonistic means? As one muscle contracts, the other relaxes- work as a pair EX; biceps and triceps: To contract the triceps relaxes while the biceps contracts the arm.

Structure of skeletal muscle Each cell fibre is long and cylindrical Muscle fibres are multi-nucleated The contractile elements of skeletal muscle cells are called myofibrils How do muscles contract? Form and have multiple nuclease Myofibril is a basic rod-like unit of a muscles cell. Muscles are composed of tubular cells called myocytes, these contain many chains of myofibrils. VIDEO CLIP

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

Cardiac muscle Main muscle of heart Pumping mass of heart Heart muscle cells behave as one unit Heart always contracts to it’s full extent

Structure of cardiac muscle Cardiac muscle cells are short, branched and interconnected Cells are striated & multi-nucleated Adjacent cardiac cells joined via electrical synapses (gap junctions) These gap junctions appear as dark lines when viewed under a microscope and are called intercalated discs What other body system did we see this same principal take place?

Cardiac muscle - Summary Found in the heart Involuntary rhythmic contraction Branched, striated fibres with intercalated discs Intercalated discs are microscopic identifying features of cardiac muscles. Cardiac muscles consist of individual heart mucles cells (cardiomyocytes) connected by intercalated discs to work as a single functional organ.

Smooth muscle Lines walls of viscera Found in longitudinal or circular arrangement Alternate contraction of circular & longitudinal muscle in the intestine leads to peristalsis Also found in blood vessels to help with vasoconstriction

Structure of smooth muscle Spindle shaped uni-nucleated cells Striations not observed Actin and myosin filaments are present Myosin filaments are attached to dense bodies at the end of each cell Muscles are composed of Proteins (thick) myosin and (thin) actin. Muscle contractions occur when these filaments slide over one another in a series of repetitive events.

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

Muscle Control Stop Day One Notes  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 Peristalsis? CNS= brain and spinal cord ANS= Autonomic Nervous System also controls exocrine glands (sweat, salivary, sebaceous glands) outside Smooth Controlled by ANS Involuntary Peristalsis Stop Day One Notes 

Muscular System Vocabulary Flexion – Movement that decreases angle between 2 bones.

Muscular System Extension – movement that increases angle between 2 bones

Muscular System Abduction – movement away from the midline of the body

Muscular System Adduction – movement towards the midline of the body

Muscular System Rotation – movement around a longitudinal axis

Muscular System Supination – Hand turned upward

Muscular System Pronation – occurs when palms rotate downward or posteriorly

Muscular System Dorsiflexion – elevation of the top of the foot Plantar flexion – bottom of foot is directed downward