Exercise Science Review: Muscles and Joints
CHAPTER 3: THE MUSCULAR SYSTEM
Three Types of Muscle * Muscle tissue is a collection of cells that shorten during contraction which create tension that results in movement * Tendons are touch bands of connective tissue that join muscle with bones
Skeletal muscles * Muscles that are attached to bone (by tendons and other tissue) * Comprise 30 to 40% of human body weight * Humans have conscious control (conscious muscle) over these muscles (the brain can tell them what to do) * Referred to “striated” or “striped” muscle due to their appearance under a microscope
Cardiac muscles * Found in the heart * Responsible for pumping blood from the heart the rest of the body * Involuntary muscles; not controlled consciously, are directed to act by the autonomic nervous system * Striated, like skeletal muscle
Smooth muscles * Surrounds internal organs * Contracts more slowly than skeletal muscles, but can be contracted for longer amounts of time * Involuntary muscle; fibres are arranged in dense sheets Properties of muscle fibre Irritability | Ability of a muscle to respond to a stimulus | Contractibility | Muscle’s ability to shorten in length | Elasticity | Muscle’s ability to stretch and return to its normal position | Extensibility | Muscle’s ability to extend in length | Conductivity | Muscle’s ability to transmit nerve impulses |
The Neuromuscular System * General term referring to the complex linkages between the muscular system and the nervous system * Constant use and regular practice will improve the quality and efficiency of the two systems, and their ability to work together
The Motor Unit * Nerves transmit impulses in “waves” that ensure smooth movements * A single nervous impulse, and the resulting contraction, is called a muscle twitch * The motor neuron, the axon and the muscle fibres it stimulates are together referred to as the motor unit * Nerves
Three Types of Muscle * Muscle tissue is a collection of cells that shorten during contraction which create tension that results in movement * Tendons are touch bands of connective tissue that join muscle with bones
Skeletal muscles * Muscles that are attached to bone (by tendons and other tissue) * Comprise 30 to 40% of human body weight * Humans have conscious control (conscious muscle) over these muscles (the brain can tell them what to do) * Referred to “striated” or “striped” muscle due to their appearance under a microscope
Cardiac muscles * Found in the heart * Responsible for pumping blood from the heart the rest of the body * Involuntary muscles; not controlled consciously, are directed to act by the autonomic nervous system * Striated, like skeletal muscle
Smooth muscles * Surrounds internal organs * Contracts more slowly than skeletal muscles, but can be contracted for longer amounts of time * Involuntary muscle; fibres are arranged in dense sheets Properties of muscle fibre Irritability | Ability of a muscle to respond to a stimulus | Contractibility | Muscle’s ability to shorten in length | Elasticity | Muscle’s ability to stretch and return to its normal position | Extensibility | Muscle’s ability to extend in length | Conductivity | Muscle’s ability to transmit nerve impulses |
The Neuromuscular System * General term referring to the complex linkages between the muscular system and the nervous system * Constant use and regular practice will improve the quality and efficiency of the two systems, and their ability to work together
The Motor Unit * Nerves transmit impulses in “waves” that ensure smooth movements * A single nervous impulse, and the resulting contraction, is called a muscle twitch * The motor neuron, the axon and the muscle fibres it stimulates are together referred to as the motor unit * Nerves