Skeletal Muscle Structure And Function - Lecture 8 Flashcards
What are the 3 main types of muscles in the human body
- smooth - these muscles mainly line hallow organs and are not under voluntary control
- cardiac - these muscles are located only in the heart. It generates force to pump blood around the body and is not under voluntary control
- skeletal - these muscles applies force to the bones to control posture and body movements. And is mostly under voluntary control
What does not under voluntary control mean
Happening automatically
Whatbis the primary job for skeletal muscle fibres
Develop force!
And is important for both movement and posture, eg: if you were to take away the skeletal muscle you would fall because the skeleton would not be able to hold itself
How do the skeletal muscles develop force
By contracting ( shortening )
What are the secondary jobs that a skeletal muscle has
- support and protection for soft internal organs
- provides voluntary control over major openings ( allow passage of substances in and out of the body )
- converts energy into heat, which is used to maintain core temperature, eg: shivering
What are individual muscle cells called
Fibres and they gather into bundles called fascicles
What do the fascicles do
They are further bundled into muscles, we want this structure because our goal is to develop force by shortening. The muscle is set up so that it’s almost identically in the same direction, so we can get the most contraction possible
What do fibres, fascicles and muscles contain
Many blood vessels ( has to burn a lot of ATP and produce a lot of energy so the muscles can work, so to do this we need a constant supply of oxygen, glucose, sugars) and nerves ( we need some way for the brain and the muscles to know when to contract ) , and they are wrapped around in connective tissue.
Why are they fibres sheathed in connective tissue
By wrapping the fibres in connective tissue they are able to protect one another, so they can rub against each other but not loose their shape
What do all of the connective tissues do
They gather together to form tendons, which connect muscle to bone
What is a muscle fibre comprised of
Bundles of myofibrils, which are made of repeating units called SARCOMERES
What are sarocomeres made of
Contractile proteins or myofilaments
- actin ( thin filaments )
- myosin ( thick filaments )
SARCOMERES get shorter as it contracts
And therefore it has a striped / strained appearance
How do we know when do contract
We need to signal the skeletal muscles to make it contract
What are sarcolemma
This is where the muscle fibres are lined up and it plays a critical role I’m muscle contraction
What are transverse tubules and its job
Tube like extensions of the sarcolemma, its job is to conduct electrical signals ( action potentials ) deep into the core of the fibre
