The MUSCULAR SYSTEM Muscle – “a tissue that contracts to produce movement or tension” Video 2
The Human Muscular System a human has 600 muscles making up over 40% of your total body weight!! the overall responsibility of the muscles is to provide movement, but also -breathing -eating -beating of the heart Types of Muscles SKELETAL: CARDIAC: SMOOTH: -attached to tendons; most prevalent -voluntary and striated -found only in the heart -involuntary and striated -surround internal organs and hair follicles -involuntary -dense sheets
CARDIAC SKELETAL SMOOTH
Properties of muscle fibre Irritability Contractibility Elasticity Extensibility Conductivity Ability of a muscle to respond to stimuli Ability of a muscle to shorten in length Ability to stretch and return to original position Ability to extend in length Ability to transmit nerve impulses Use page 34 to fill out the table below
Before we look at a muscle fibre, we first have to look at how we break down a muscle MUSCLE BUNDLE (FASCICLE) -composed of many muscle fibres MUSCLE FIBRE -each fibre is a single cell with many nuclei -striated with a light and dark banding MYOFIBRIL -tiny cylindrical structures -made up of protein filaments FILAMENTS* Video
The MUSCLE FIBRE -the basic unit of movement -where contraction occurs Sarcolemma Sarcoplasmic Reticulum Transverse Tubule System Terminal cisternae Transverse tubule Terminal cisternae Myofibril Sarcomere Myosin Actin
StructureFunction Sarcolemma Sarcoplasmic Reticulum Transverse Tubule system Terminal cisternae Transverse tubule Myofibril Sarcomere Actin Myosin Using your textbook, find the function for each of the following terms you just labelled Plasma membrane that encloses the myofibrils Network running through fibres; release and absorption of calcium Interconnecting rings; link between outside of fibre and filaments inside Release and removal of calcium into sarcoplasm Stores calcium Thread-like structures; run length of fibre; contain actin and myosin Structural units of striated muscle containing actin and myosin Thin protein filament Thick protein filament
Looking ahead... Next class we will be looking at the principle function of a muscle, which is to CONTRACT. Where, how and why do muscle contractions occur? But first, we are going to introduce the 3 types of contraction: Concentric: Eccentric: Isometric: (shortening); occurs when muscle fibres shorten – eg biceps curl (lengthening); occurs when muscle fibres lengthen – eg returning the weight down after a biceps curl (static); occurs muscle fibres do not change in length – eg lifting something immoveable. Remember that contraction does not always refer to muscle shortening