Located in the walls of hollow visceral organs and blood vesels
located in skeletal muscles
Appears striated or banded. Skeletal muscle tissue and cardiac muscle are both striated in appearance and smooth muscle is not.
What happens to the length of a muscle when it contracts?
it creates a pulling force on its attachments that attempts to pull them towards each other.
aka Concentric contractions, it shortens towards the center and is determined by the strength of the pulling force. It can go both ways, by generating force that increases action, or can be relaxed and shortened by another mover.
aka eccentric contraction, if the force of the muscle is less than the resistance the muscle will lengthen instead of shorten. It can contract and lengthen, or relax and lenghen.
stays the same length
aka Isometric contractions
if an attachment doesn't move it's fixed.
If an attachment moves it is mobile.
why/when does it occur?
the attachment that is usually fixed is now mobile and the attachment that is usually mobile is now fixed.
Name the location of the attachments
ex: proximal and distal, superior and inferior
Origin: The point where a muscle attaches to the non-movable bone
Insertion: The other attachment site of the muscle that contracts into the origin.
It is rare for muscle fivers to run the entire length of the muscle, usually they lay end to end or parallel and overlap. Thses fibers are organized in bundles known as fascicles.
are oriented within the cytoplasm running the entire length of the muscle fiver.
myofibrils are composed of units called sarcomeres that are laid end to end from one end to another.
actin and myosin filaments
Actin filments are thin and myosin filaments are thick. Action are Z lines at both ends of the sacromeres and myosin are located in the center of the sacromere.
Sliding Filament Mechanism
Is how the sacromeres shorten, the actin and the myosin slide along each other. A message is sent from the nervous system to tell it to contract, the message causes the sarcoplasmic reticulum to release stored calcium into the sacroplasm. These calcium ions attach onto the actin.
The myscle that is concentrically contracting is called a mover.
is a muscle that can do the opposite action f the action in question
is a muscle that con stop unwanted action at the mobile attachement of the muscle that is working and work at insertion.
A second muscle that contracts to fix a body part would be a fixator or stabilizer.
is defined as the coordering od muscles in the body in their various roles to create smooth and efficent movement.
where the muscle contracts and shortens with joint action
when a muscle contracts and lengthens
is where in the muscle contracts and stay the same length
1. the type of motion that has occured. 2. name of the body par that has moves 3. name of the joint where the movement has occured.
fibrous fascia that surrounds a group of muscle fibers, dividing the muscle into bundles known as fascicles