Download Of Muscle

Muscular System
Chapter 8
Learn your
muscles
Poke a Muscle
The 3 Muscle Types
• The job of all muscles is to contract
• They are all fibrous because cells are
elongated
Overview
Of
• The 3 Muscle Types Are:
Muscle
–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
• Do not undergo mitosis. Once dead, dead.
Skeletal Muscle Cell
Cardiac Muscle
Do not undergo mitosis. Once dead, dead.
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= ).
Pg. 174 Tortora
Muscle Structure Continued
• Many fascicles are wrapped together
by an Epimysium. (Epi= )
• Epimysia attach to tendons or
Aponeuroses. (pg. 192: Tortora)
• 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? Pg. 176
• 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 snaps 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
Best Movie review
of the muscle
Revisited
Write one paragraph explaining
how a muscle works.
Do this from memory.
This will help you learn.
Paul Anderson
Review
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.
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.
Summation and Tetanus
• Twitch: a single action potential causing
the muscle to contract for a millisecond
and then relax.
Latent...Contraction...Relaxation period
• Summation effect: a second action
potential arrives before the first is over.
The contraction is larger. Wave summation
• Tetanus: multiple summation effects
causing a smooth sustained contraction.
• Fatigue will set in and forces relaxation.
What is Recruitment?
• Motor unit recruitment: various motor
neurons in a whole muscle do not fire at
the same time. Some are relaxed some
are contracted.
• Why?
– Creates smooth muscle units not jerky
movements.
– Put your hand out and hold it still…..
Types of Skeletal Muscle Fibers
• Slow…Slow Oxidative Fibers (SO)
– Red, Make ATP Aerobiclatly, Fatigue
resistant. Marathon runners getting out of a
chair when old.
• Fast
– Fast oxidative –glycolytic Fibers (FOG).
• Red, ATP by anaerobic Medium fast
– Fast glycolytic Fibers (FG)
• White. Anaerobic. Short, Fast, circuit trainers
Why can you crack your joints?
Click here to find out!
Muscle Movements
• http://www.healthchecksystems.com/exerc
ise1.htm#hyper
Types of Muscle Movements
Flexion: decrease
in the angle
between
articulating bones.
Extension:
increase in the
angle between
articulating bones.
Abduction:
movement of
bone away from
the midline
Adduction:
movement of
bone towards
from the midline
To exercise the:
Quadriceps:
straighten the knee
To exercise the: Gastrocnemius.
Stand on your toe.
To exercise the:
Hamstring
Group
Bend the knee. Flexes
thigh. Includes the
bicepts femoris
Exercise the:
Trapezius : rotates
shoulder., shoulder
shrugs. Extends head.
Exercise for:
Latissimus Dorsi:
moves arm down and
backwards.
Exercise for:
Deltoid: abducts, flexes,
extends & rotates arm at
shoulder joint.
Exercise For: Gluteus
Maximus extends and rotates thigh
laterally at hip joint.
Exercises for: Oblique: Flexes vertebral
column, contracts sides, rotates.
Exercises for:
Rectus Abdominis: flexes
vertebral column / compresses
abdomen (think crunches)
Exercise for : Pectoralis Major
Adducts and rotates arm medially.
Extends arm at shoulder
Push up: Works Pecs on
The Up-Motion
Exercises for: Bicep
contracts arm into L shape
Exercises for: Triceps
…extends arm at
shoulder and elbow
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
Or strain.