Download Muscular Systemcp - Appoquinimink High School

Muscular System
Muscular System Functions:
 1. produce
movement
 2. Maintain posture
 3. Stabilize joints
 4. Generate heat
 5. Move substances
(fluid, food etc)
Properties of Muscles:

Excitability: capacity of muscle to respond
to a stimulus

Contractility: ability of a muscle to
shorten and generate pulling force

Elasticity: ability of muscle to recoil to
original resting length after stretched
 Muscles are responsible for all types of
body movement – they contract or
shorten and are the machine of the
body
 Three basic muscle types are found in
the body
 Skeletal muscle
 Cardiac muscle
 Smooth muscle
Muscle Coverings:

Epimysium –tissue that covers the
entire skeletal muscle. Separates the
muscle from all other organs

Fascicle–A group of muscle fibers
 Perimysium- surrounding a group a
fascicle.
Contains blood vessels and nerves.
 Endomysium- surrounds individual
muscle fiber. Also has blood vessels and
nerves.
Muscle Coverings:
Head and Neck Muscles
Muscles of the cephalic area:
Trunk Muscles
Muscles of the Anterior Trunk area:
Muscles of the Posterior
Trunk area:
latissimus dorsi
Posterior of leg
Muscles of the Posterior
and Anterior Leg:
Anterior of leg
Types of Ordinary Body Movements

Flexion – decreases angle of joint and
brings two bones closer together

Extension- Increase the angle or extending
something

Rotation- movement of a bone in
longitudinal axis (back and forth), shaking
head “no”
Types of Ordinary Body Movements

Abduction: Moving away from the body or
anatomical position

Adduction: Moving towards the body or
anatomical position.

Circumduction: moving in a circular motion
Types of Ordinary Body Movements

Flexion – decreases angle of joint and
brings two bones closer together

Extension- Increase the angle or extending
something

Rotation- movement of a bone in
longitudinal axis (back and forth), shaking
head “no”
Types of Ordinary Body Movements

Abduction: Moving away from the body or
anatomical position

Adduction: Moving towards the body or
anatomical position.

Circumduction: moving in a circular motion
Anatomy of Skeletal Muscles:
 Cells are multinucleate
Anatomy of Skeletal Muscles:
 Myofibril- The smallest unit
 Bundles of myofilaments
 Myofibrils are aligned to give distinct bands
 I band =
light band
 A band =
dark band
Anatomy of Skeletal Muscles:
 Sarcomere- one segment on a
myofibril (from Z disc to Z disc)
 (these are what allow the muscle
to contract and move)
Anatomy of Skeletal Muscles:
 Components of a Sarcomere:
 Thick filaments = myosin filaments
 Has ATP
(for energy to be broken down and
used in order to move)
Anatomy of Skeletal Muscles:
 Components
of a Sarcomere:
 Thin filaments = actin filaments
How skeletal muscles move or “slide”
Thin Actin slide past the thick Myosin so
that the actin and myosin filaments overlap
 In the relaxed state, thin and thick filaments
overlap only slightly
 In order for this process to start sodium
must ender the cell (active transport) and
the nervous tissue sends a signal to begin
contraction

How skeletal muscles move or “slide”

Step 1: Activation by nerve causes Calcium to be
released.

Step 2: This allows the myosin heads to attach to the
actin.

Step 3: ATP is used and broken down in order to “pull” the
myosin over the actin (contracting the muscle)

Step 3: Myosin heads then bind to the next site of the actin
filament and get ready for a second contraction. This
shortens the Z line and they over lap.

Step 4; They continue until the muscle contracts and the
two over lap more and more until the H zone disappears.

Step 5: To release the contraction the Calcium is taken
back into the muscle fibers which covers the location so
myosin can’t bind. Now the muscle is relaxed

IF calcium doesn’t go back in the contraction is prolonged
and called a charlie horse or Cramp!
How skeletal muscles move or “slide”
How skeletal muscles move or “slide”


Within a skeletal muscle, not all fibers
may be stimulated during the same
interval
Muscle force depends upon the
number of fibers stimulated

More fibers contracting results in
greater muscle tension

Muscles can continue to contract
unless they run out of energy
Energy for Muscle contraction and fatigue
 Muscles use stored
ATP for energy
 Only 4-6 seconds
worth of ATP is stored
by muscles
Energy for Muscle contraction and fatigue

1. After this initial time,
other pathways must be
utilized to produce ATP
 Muscle cells contain
creatine phosphate (CP)
 CP regenerates new ATP
 CP supplies only last 20
seconds
Energy for Muscle contraction and fatigue
 2.Glycolysis
 Reaction that breaks down
glucose with or without
oxygen to make ATP
 Without Oxygen glucose
breaks into lactic acid
which is what builds up
and produces muscle
fatigue.
Muscle Fatigue and Oxygen Debt
 When a muscle is fatigued, it is unable to
contract
 The common reason for muscle fatigue is
oxygen debt or lactic acid build up.
 Oxygen is required to get rid of accumulated
lactic acid
Disorders relating to the Muscular
System
Muscular Dystrophy: inherited, muscle enlarge
due to increased fat and connective tissue, but
fibers degenerate and atrophy
 Myasthemia Gravis: progressive weakness due
to a shortage of acetylcholine receptors

For the test..
Muscular and Skeletal
For Skeletal – skeletal diagram
 Bone formation
 Joints – types, range of motion

For Muscular- the study guide except the
following:
 6, 7, 12, 13, 14, 17, 18, 25
