Muscular System “The power system” This is what happens without muscles 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.

#One Main Muscle Function Responsible for all body movement.

#Two Main Muscle Functions Responsible for body form and shape (Posture)

Responsible for body heat and maintaining body temperature. #Three Main Muscle Functions

Test Your Gray Matter…. Muscles are responsible for producing most of our : White blood cells, Hormones, Protein synthesis, or Body Heat.

Types of Muscles Skeletal Muscle Smooth Muscle Cardiac Muscle Attached to bone Visceral muscle Found only in the heart VoluntaryInvoluntary

Skeletal Muscles Attached to bone Striated (striped) appearance Voluntary Sarcolemma = cell membrane Contract quickly, fatigue easily, can’t maintain contraction for a long period of time

Test your skeletal muscles… Open and close your dominant hand until the teacher tells you to stop.

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

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

Test your gray matter.. Which of the following muscles are considered “voluntary” Which kind of muscle forms the walls of the heart? Striated, cardiac, skeletal, visceral Cardiac, Skeletal, Smooth, Visceral

Sphincter Special circular muscles in openings of esophagus and stomach, and small intestine, anus, urethra and mouth

How Do muscles get their names? Location Size Direction Number of origins Location of origin and insertion Action flexor

Muscle Fiber Each muscle fiber is encased in a cell membrane called the sarcolemma which contains functional units called myofibrils. In order for muscle contraction to take place, each fiber must possess many functional contractile units called sarcomeres. Each sarcomere has 2 types of threadlike structures called thick and thin myofilaments Composed of: Myosin--protein that makes up thick myofilaments Actin--protein that makes up thin myofilaments

Characteristics of Muscles Contractibility Excitability Extensibility Elasticity The ability of a muscle to reduce the distance between the parts of its content or the space it surrounds. The ability to respond to certain stimuli by producing impulses. The ability to be stretched. Ability of muscle to return to its original length when relaxing.

Muscle Movement How do we move?

Muscle Movement Muscle move bones by pulling on them. As a muscle contracts, it pulls the Insertion one closer to the Origin bone. Movement occurs at the joint between the origin and the insertion. Rule: A muscle’s insertion bone moves toward its origin bone.

Groups of muscles usually contract to produce a single movement A. Prime mover muscle whose contraction is mainly responsible for producing a given movement

B. Antagonist muscle whose actions oppose the action of prime mover in any given movement. When the antagonist muscles contract, they produce a movement opposite to that of the prime movers

C. Synergist helps steady a movement and stabilize joint 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 Fatigue Oxygen Debt Muscle chemical neurotransmitter, diffuses across the synaptic cleft (carries impulse across synaptic cleft) caused by the accumulation of lactic acid in the muscles 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