Download The Muscular System

The MUSCULAR SYSTEM
Video 2
Muscle – “a tissue that contracts to produce movement or tension”
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: -attached to tendons; most prevalent
-voluntary and striated
CARDIAC: -found only in the heart
-involuntary and striated
SMOOTH: -surround internal organs and hair follicles
-involuntary
-dense sheets
SKELETAL
CARDIAC
SMOOTH
Use page 34 to fill out the table below
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
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
Terminal cisternae
Transverse tubule
Terminal cisternae
Transverse
Tubule
System
Sarcolemma
Sarcoplasmic Reticulum
Myofibril
Myosin
Actin
Sarcomere
Using your textbook, find the function for each of the following terms you just labelled
Structure
Function
Sarcolemma
Plasma membrane that encloses the
myofibrils
Sarcoplasmic Reticulum
Network running through fibres;
release and absorption of calcium
Transverse Tubule system
Interconnecting rings; link between
outside of fibre and filaments inside
Terminal cisternae
Release and removal of calcium into
sarcoplasm
Transverse tubule
Stores calcium
Myofibril
Thread-like structures; run length
of fibre; contain actin and myosin
Sarcomere
Structural units of striated muscle
containing actin and myosin
Actin
Thin protein filament
Myosin
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:
(shortening); occurs when muscle fibres shorten –eg biceps curl
Eccentric:
(lengthening); occurs when muscle fibres lengthen –eg returning the
weight down after a biceps curl
Isometric:
(static); occurs muscle fibres do not change in length –eg lifting
something immoveable.
Remember that contraction does not always refer to muscle shortening