Download The Muscular System

The Muscular System
• FQ: What is the hierarchal structure of a
muscle cell from the tiniest fiber to the largest
muscle mass?
• ET: Grab a copy of the article from the front of
the room? Read and highlight important
information from the article
The Muscular System
• Focus Questions
1. FQ: What are the following:
endomysium, perimysium,
epimysium, tendon, and
aponeurosis?
• Coloring Sheet
• POGIL
The Function of Muscles
• Four important roles for the body:
1.
2.
3.
4.
Produce movement
Maintain posture
Stabilize joints
Generate Heat
Review of Muscle Tissue Types
• All muscle cells are elongated,
thus we call them fibers
• All muscle cells can contract
• Myo/Mys (muscle)
• Sarco (flesh)
• Connects muscle to
bone
• Appears striped
(striated)
• Voluntary
• May contract rapidly,
and forcefully but
tires easily
• Structure
1. Endomysium
2. Perimysium
3. epimysium
Smooth Muscle
• No striations
• Involuntary, slow and
constant contractions
• Lines hollow visceral
organs – stomach,
bladder, intestines
• Propels substances along
a definite track within
the body – food
• Double layered Sheet of
thin cells running
circularly and
longitudinally
• Heart only
• Striated
• Slow, constant
contractions
• Figure-8 shaped
bundles that
pump blood
Microscopic Anatomy of
Skeletal Muscle
• Sarcolemma – the
plasma membrane
• Myofibrils – bundles
of myosin (thick) and
actin (thin) proteins
• Sarcoplasmic
reticulum – Store and
release calcium for
muscle contraction
Muscular System
Lesson 2
Skeletal Muscle Activity
Stimulation and Contraction
of Muscles
• ET: Review anatomy of a
skeletal muscle cell
using your coloring
sheet.
Nerve Stimulus and Action Potential
• The neurotransmitter
•
Acetylcholine (Ach) is released
by Axon terminal.
• This makes the membrane of
the muscle fiber (sarcolemma)
permeable to sodium ions.
This rush of positively charged
ions creates a concentrations
gradient/electrical current
called an Action Potential.
Mechanism of Muscle Contraction
1. Ca+ ions cause troponin and tropomyosin (regulatory proteins)
on the actin filament to change shape and move out of the way so
that myosin can bind to it forming a cross bridge
2. using ATP, the myosin head bends toward the center of the
sarcomere pulling actin filament (power stroke)
3. Detachment – ATP binds to the myosin head and weakens the
cross bridge bond
4. The energy released by ATP reactivates the myosin for another
contraction to occur
Muscular System
Lesson 3
Providing Energy for Contraction
How does muscle keep up with all
the ATP that they need?
• 3 Pathways
1. Direct phosphorylation of
ADP by creatine phosphate
2. Aerobic respiration
3. Lactic acid fermentation
Direct phosphorylation of ADP
by Creatine Phosphate
• Creatine phosphate gives
its phosphate to ADP to
make ATP
• CP stores only last about
20 seconds
Aerobic Respiration
• Requires Oxygen
• 36 ATP / Glucose
• Slow compared to CP
Lactic Acid Fermentation
• Does not require oxygen
• Quicker than CR (2.5 x
faster)
• Uses huge amounts of
glucose for not a lot of ATP
• Good for 30 to 40 seconds
of strenuous exercise
• Build up of lactic acid
causes muscle fatigue and
soreness
2 Types of Muscle Contraction
• Isotonic – Normal muscle
contraction where the fibers
are successful in their sliding
motion
• Isometric – when the fibers
attach but cannot slide, like
when you try and lift
something too heavy. The
muscle cannot contract, even
though you are engaging it to
lift something
• Continuous partial
contraction that cannot
be consciously
controlled
• The nervous system
stimulates these fibers
in a systematic way all
the time so that you can
move when you decide
to move
What is Muscle
“TONE”??
How Does Exercise Effect Muscles?
• Aerobic exercise causes muscles
to become flexible with a greater
resistance to fatigue
– Blood supply to the cell
increases
– Mitochondria increase in
number
– Increases overall body cell
metabolism
– Strengthens bone
– Strengthens and enlarges the
heart
– Improves gas exchange in the
lungs
How Does Exercise Effect Muscles?
• Resistance training (isometric)
causes individual muscle cells
to develop more fibers and
connective tissue
– Increases strength and
ability to lift
– If you exercise your core
you’re a providing stability
to your entire body