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
1. Draw a picture of a sarcomere

2. Label actin, myosin, Z-line, H-zone, I

3. What is the difference between actin and
myosin?

band, A band
4. List the hierarchy of muscle structures
starting with the whole muscle down to
myofilaments.
 Explain
how muscles
contract
 Describe the sliding
filament model
 Compare and contrast
origins, insertions,
agonists, and antagonists
 You
will need to know 8 steps to
muscle contraction
 p.348-349 in your textbook is
your best friend
 Motor
neuron receives an impulse
Motor Unit or Neuromuscular
Junction
1. Neuron
3. Vesicle
2. Sarcolemma (or motor end plate)
4. Synapse
5. Mitochondria
 Motor
neuron releases the
neurotransmitter acetylcholine
into the gap between the neuron
and the muscle
 The
acetylcholine attaches to
receptors on the muscle fiber
membrane
 The
muscle responds by releasing
calcium ions into the myofibrils
 The
calcium ions attach to the
Actin and unlock the binding site
 The
cross-bridges from the
myosin attach to the binding sites
 The
cross-bridges fire and pull
the actin which shortens the
sarcomere
 All
of the shortening sarcomeres
lead to shortening (contracting) of
the muscle
What is rigor mortis?
A few hours after a person or animal dies,
the joints of the body stiffen and become
locked in place. This stiffening is called
rigor mortis. Depending on temperature
and other conditions, rigor mortis lasts
approximately 24-72 hours. The
phenomenon is caused by the skeletal
muscles partially contracting. The muscles
are unable to relax, so the joints become
fixed in place.
Tetanus causes cholinosterase to not break down the
acetylcholine in the synapse. This results in a person's
muscles contracting and not relaxing.
A tetanus shot
must be
administered
shortly after
exposure to
the bacteria.
Once you
develop
tetanus, there
is no cure.


Create a model of muscle contraction
The model must show all stages of actinmyosin binding
◦ Think beyond a poster – possible ideas could
include a series of photographs, short video, 3D
models

You may work by yourself or with a partner
 Muscles
and Bones work together
to create MOVEMENT!



Origin = the
immovable end of
the muscle
Insertion= the
movable end of the
muscle
Typically, the origin
lies proximal to the
insertion

When a muscle contracts, it shortens & thus
pulls the insertion closer to the origin
 Extension
of joint
 Flexion
= increases the angle
= decreases angle of joint
 Think
about one of the quad
muscles (rectus femoris)
◦ EXTENSION at the knee joint
◦ FLEXION at the hip joint


List three examples of flexion
List three examples of extension
 Agonist
= main muscle
 Synergists
agonist
= assist & stabilize the
 Antagonists
= capable of doing
opposite movement

Agonist =
◦ Biceps!

Synergists =
◦ Pectorals, deltoids, laterals, trapezius

Antagonists=
◦ triceps