MUSCULAR SYSTEM Nearly half our weight comes from muscle tissue. There are 650 different muscles in the human body.

THREE MAIN FUNCTIONS Responsible for all body movement. Responsible for body form and shape (posture) Responsible for body heat and maintaining body temperature.

MUSCLE TYPES SKELETAL TYPES OF MUSCLES SMOOTH CARDIAC

Skeletal Muscle Attached to bone VOLUNTARY Contract quickly, fatigue easily, can’t maintain contraction for long period of time

Cardiac Muscle Found only in the heart Involuntary Creates it’s own stimulus Cells are fused – when one contracts, they all contract

Cardiac Muscle Review of Cardiac Muscle What is the pacemaker of the heart called? SA node What are they vessels that provide O2 to the heart called? Coronary arteries When the heart is deprived of O2, what happens? MI

Cardiac Muscle What is the chest pain felt when the heart is deprived of O2? Angina What do we call beats that are originated outside of the SA node? Ectopic beats/arrhythmias What is the deadliest arrhythmia? Ventricular fibrillation

Smooth Muscle Visceral (organ) muscle Found in walls of digestive system, uterus and blood vessels INVOLUNTARY= Autonomic Nervous System Act slowly, do not tire easily, can remain contracted for long time

SPHINCTER special circular muscles in openings between the esophagus, stomach and small intestines What are they called???? Cardiac sphincter pyloric sphincter Also found at anus, urethra and mouth.

CHARACTERISTICS OF MUSCLES CONTRACTIBILITY – the ability of a muscle to reduce the distance between the parts of its contents or the space it surrounds. Unique to muscle tissue EXCITEABILITY (IRRITABILITY) – the ability to respond to certain stimuli by producing impulses. Only muscle and nervous tissue have this ability

CHARACTERISTICS OF MUSCLES EXTENSIBILITY – the ability to be stretched. ELASTICITY – ability of muscle to return to its original length when relaxing.

Contraction of Muscle Tissue Muscle contraction occurs as a result of 2 events: 1. “myoneural stimulation” stimulation of the muscle nerve 2. contraction of the muscle MOTOR UNIT – a motor neuron plus all the muscle fibers it stimulates.