Download Muscular System

Muscular System
The primary function of the muscular system is to produce __________________. The contraction of muscle tissue requires
______, so muscles are constantly carrying out _____________________and have a large number of ________________.
Individual muscle cells are called muscle _____________. All humans have the _____________ number of fibers. Muscle
bulk occurs because of __________________ of muscle fibers, not an increase in the number of muscle cells. The number
of fibers that can contract at one time determine an individual’s __________________. The length of the contraction time is
known as _____________________.
Muscle Types
1. Skeletal Muscle - _________________, _____________ muscle cells that fuse together to form a
_______________________ muscle fiber. Muscle fibers are arranged _______________________ to produce strong
_______________________. If the oxygen supply to muscle cells is depleted, they can switch to
_______________________________ for energy production.
2. Cardiac Muscle - ____________________, _______________ muscle cells found only in the _____________, with each
cell having its own ________________. Cardiac muscle cells are arranged in _______________ that lattice together.
When the muscle contracts, the entire lattice of cells contracts together producing a powerful contraction.
3. Smooth Muscle - ____________________, _______________ muscle cells. Smooth muscle contractions are slow and
prolonged. Found in the ___________________________________________________________________________.
Skeletal Muscle Function
1. Skeletal muscles are attached to bones by tough, ____________________ tissue called _________________. Every
muscle has at least 2 tendons, each attached to a different bone:
a. origin – muscle attachment site(s) that _____________________________________
b. insertion – bone that is _________________________________________.
For example, the ______________________ has _____________ attaching it to the scapula and the radius. The origin
is the _______________ and the insertion is the ________________.
2. Skeletal muscles attached to the bones of the _______________________ skeleton work in opposing pairs.
a. flexor – muscle that causes limb to _______________ at ________________.
b. extensor – muscle that causes limb to _________________ at _______________.
For example, contraction of the biceps brachii ______________ the arm and contraction of the triceps brachii
____________________ the arm.
Muscle Contraction
- Muscle fibers in skeletal muscles are composed of smaller structures called __________________. Each myofibril is
made up of even smaller structures called __________________.
- The striations in skeletal muscle cells are formed by an alternation pattern of ___________________________ filaments.
- The thick filaments contain a protein called __________________.
- The thin filaments are made up mainly of a protein called ________________.
- The filaments are arranged along the muscle fiber in units called ____________________ separated by regions called
______________________.
Sliding Filament Model of Muscle Contraction:
- When a muscle contracts, the thin filament (actin) in the muscle fiber slides over the thick filament (myosin),
____________________ the sarcomere.
- Thick myosin filament forms a ______________________ with the thin actin filament.
- Powered by _________, cross-bridge changes shape and pulls the actin filament toward the center of the
sarcomere.
-This happens in every sarcomere within a muscle fiber _____________________ so the entire fiber is shortened and the
muscle __________________.
Control of Muscle Contraction
- The impulses from ____________________________ control the contraction of skeletal muscle fibers.
- The __________________________________ is the point of contact between a motor neuron and a skeletal muscle cell.
- The impulse in the muscle fiber begins with the release of the neurotransmitter __________________________ from the
motor neuron. This sets off a series of events that allow actin and myosin filaments to interact.
- A muscle cell remains contracted until an _________________ produced at the axon terminal __________________ any
remaining acetylcholine.
Muscle contraction at the sarcomere level:
Cross-bridge: