MUSCULAR SYSTEM OVERVEIW “the power system” Nearly half our weight comes from muscle tissue. There are 650 different muscles in the human body. Muscles give us form and shape. Muscles produce most of our body heat.

MUSCLE TYPES SKELETAL SMOOTH TYPES OF MUSCLES CARDIAC

Skeletal Muscle Attached to bone Striated (striped) appearance VOLUNTARY Multinucleated muscle cell bundles (muscle cells = muscle fibers) SARCOLEMMA = cell membrane Contract quickly, fatigue easily, can’t maintain contraction for long period of time

Smooth Muscle Visceral (organ) muscle Found in walls of digestive system, uterus and blood vessels Cells small and spindle-shaped INVOLUNTARY Controlled by autonomic nervous system Act slowly, do not tire easily, can remain contracted for long time

Cardiac Muscle Found only in the heart Striated and branched Involuntary Cells are fused – when one contracts, they all contract

Four important roles in body: MAIN FUNCTIONS Four important roles in body: 1. Responsible for all body movement. 2. Responsible for body form and shape (posture) 3. Stabilize joints 4. Responsible for body heat and maintaining body temperature.

SKELETAL MUSCLE ACTIVITY Stimulation and Contraction of Skeletal Muscle Cells EXCITEABILITY (IRRITABILITY) – the ability to respond to certain stimuli by producing impulses. CONTRACTIBILITY – the ability of a muscle to reduce the distance between the parts of its contents or the space it surrounds.

SKELETAL MUSCLE ACTIVITY MOTOR UNIT – a motor neuron plus all the muscle fibers it stimulates. NEUROMUSCULAR JUNCTION – the junction between the motor neuron’s fiber which transmits the impulse – and the muscle cell membrane. ACETYLCHOLINE – chemical neurotransmitter, diffuses across the synaptic cleft (carries impulse across synaptic cleft) MUSCLE FATIGUE – caused by the accumulation of lactic acid in the muscles. OXYGEN DEBT – after exercise, the amount of oxygen needed by the muscle to change lactic acid back to glucose. MUSCLE TONE - When muscles are slightly contracted and ready to pull. DIAPHRAGM – Dome-shaped muscle that separates the abdominal and thoracic cavities, aids in breathing

MUSCLE CONTRACTIONS Muscle Tone In order to function, muscles should always be slightly contracted and ready to pull. Muscle contractions may be isotonic or isometric. ISOTONIC CONTRACTION When muscles contract and shorten. (Walk, talk, etc.) ISOMETRIC CONTRACTION When the tension in a muscle increases but the muscle does not shorten. (exercises such as tensing the abdominal muscles.)

MUSCULAR SYSTEM MUSCLE MOVEMENT Muscles move bones by pulling on them. “the power system” MUSCLE MOVEMENT Muscles move bones by pulling on them. As a muscle contracts, it pulls the insertion bone closer to the origin bone. Movement occurs at the joint between the origin and the insertion. 2. Groups of muscles usually contract to produce a single movement. 3. When the antagonist muscles contract, they produce a movement opposite to that of the prime movers.

Anterior Surface of Body Gross Anatomy of Skeletal Muscles Anterior Surface of Body Frontalis Orbicularis oris Sternocleidomastoids Deltoid Pectoralis major Biceps brachii Intercostals muscles Rectus abdominus External oblique Sartorius Quadriceps group p.120,121

Gross Anatomy of Skeletal Muscles Posterior Surface of Body Occipitallis Trapezius Deltoid triceps brachii Latissimus dorsi Gluteus medius Gluteus maximus Hamstrings Gastrocnemius Soleus Achilles tendon

p. 122 and 123 look at the muscles of the head/neck and arms Label the worksheets

Disorders and Related Terminology ATROPHY – wasting away of muscle due to lack of use. HYPERTROPHY – an increase in the size of the muscle cell. STRAIN – tear in the muscle resulting from excessive use. Bleeding inside the muscle can result in pain and swelling. Ice packs will help stop bleeding and reduce swelling. MUSCLE SPASM (cramp) – sustained contraction of the muscle, usually because of overuse. MYALGIA – muscle pain TENDONITIS – inflammation of a tendon

Activity Break into groups of 2 Complete the Lab activity 7-3 Muscle Fatique on p. 134 and 135 Complete Applying theory to practice #3 with your partner instead of a mirror Individually complete Review questions # 2, 4, 9 on p. 132