Download Muscular System

Muscular System
Chapter 6
The 3 Muscle Types
• The job of all muscles is to contract
• They are all fibrous because cells are
elongated
• The 3 Muscle Types Are:
–Skeletal Muscle
–Cardiac Muscle
–Smooth Muscle
Skeletal Muscle
•
•
•
•
•
Cigar Shaped
Multinucleated
Striated
Voluntary
Can Be Involuntary When Reflexes Are
Involved
• Very Strong and Fast But Need Rest
• Most Attached to Bone
Skeletal Muscle Overview
Of
Skeletal Muscle
Skeletal Muscle Cell
Cardiac Muscle
Smooth Muscle
Long thin nuclei
and no striations
How are Muscles Structured?
• Muscle Cells have a plasma
membrane called a Sarcolemma.
• The muscle fiber is enclosed in
Endomysieum. (Endo= , Mys= )
• Many Muscle fibers bound together
make a Fascicle.
• The Fascicle is wrapped in a
membrane called the Perimysieum
(Peri= ).
Muscle Structure Continued
• Many fascicles are wrapped together
by an Epimysium. (Epi= )
• Epimysia attach to tendons or
Aponeuroses. (Pg. 86)
• Tendons: Strong, Thin, and made up
of collagen (dense connective tissue).
Aponeuroses are sheet-like tendons.
Skeletal Muscle (pg. 174)
Quiz
Yourself
What is the major Organelle of the
Muscle Cell?
• Myofibril(s)=Working unit of the
muscle cell. Made of Subunits called
sarcomeres.
–Give muscles the striped or striated
appearance
–The light band is the I-band
Match the
Terms
–The dark band is the A-band
–Between the I-bands is the Z-line
–Between the A-bands is the H-zone
Mechanism of muscle contraction
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• The above micrographs show that the
sarcomere gets shorter when the muscle
contracts
• The light (I) bands become shorter
• The dark bands (A) bands stay the same length
Take a long deep breath, its not
that bad.
• And remember a bicycle cannot stand
alone, because it is two tired.
• Now lets go on.
• But lets first watch this short video clip.
Overview of the
Job of the Bands
So how do these bands work?
• The myofibrils are surrounded by the
sarcoplasmic reticulum, a specialized
form of smooth endoplasmic reticulum that
releases calcium.
• They are made of bands of
– Actin (the thin filaments) that make up the Ibands
– Myosin (the thick filaments) that make up the
A-bands
So what is the Molecular Basis of
Muscle Contraction? (pg. 176)
• 1) Nerve sends out Acetylcholine or Ach
• 2) Motor Unit= All muscles triggered by
nerve. (1 nerveTriggers 100’s of cells)
• 3) The Sarcolema becomes permeable to
Na+
• 4) Na+ causes an action potential
because it disturbs the electrical
conditions of the sarcolema (pg.178)
How does ACh stimulate the
muscle?
• ACh causes the sarcolema to release
Calcium (Ca+)
• Ca+ binds to the actin causing it to
change shape.
• Myosine finds actin’s new shape
attractive and grabs hold.
What happens after the Myosin
grabs hold? (pg. 179)
• Myosin’s head snap towards the H-band of
the sarcomere.
• ATP releases and re-cocks the myosin
• Only some myosin heads move at one
time.
• Over all: Pg. 181
Description of
Muscle movement
How does the muscle relax?
• When the action potential ends:
–Sarcomere absorb Ca+
–ATP releases myosin heads
–Actin takes on its former and less
attractive shape.
Best Movie on
–Muscle Cells can relax Muscle
Contraction
Revisited
Write one paragraph explaining
how a muscle works.
Do this from memory.
This will help you learn.
So, What is this Action Potential?
• Action Potential
– Electrical Current or Charge
– In order to return the cell to its original
condition, K+ is pumped into the cell by the
sodium potassium pump. Fig 3.10
Sodium/
Potassium
Pump
How
together?
Howdo
domuscles
Muscles work
work Together?
• Prime Mover: Major muscle doing the bulk
of the work contracting.
• Synergist: Group of muscles working
together to contract.
• Antagonist: Muscle that works against the
prime mover and or synergists.
• http://www.bbc.co.uk/science/humanbody/
body/interactives/3djigsaw_02/index.shtml
?muscles
• http://www.healthchecksystems.com/exerc
ise1.htm#hyper
Types of Muscle Movements
To exercise the:
Quadriceps
To exercise the:
Gastronemius
To exercise the:
Hamstring
Group
Includes the bicepts
femoris
Exercise the:
Trapezius
Exercise for:
Latissimus Dorsi
Exercise for:
Deltoid
Exercise For:
Gluteus Maximus
Exercises for:
Oblique
Exercises for:
Rectus Abdominus
Exercise for:
Pectoralis
Major
Push up: Works Pecs on
The Up-Motion
Exercises for:
Bicep
Exercises for:
Triceps
Now Quiz Yourself!
See if you know your muscles…
Another good
Quiz site
Interesting Aspects:
• Some of us may have a spare muscle: the
Plantaris muscle 1 in 10 don’t. Plantaris
In
• Want to see it? Click the link.
Action
• Groin pull? Here is the problem:
Groin Pull