Aliding filament theory
- Myosin heads attach to actin mollecules (at binding (active) site)
- Myosin “pulls” on actin, causing thin myofilaments to slide across thick filaments, towards the center of the sarcomere.
- Sarcomere shortens, I bands get smaller, H zone gets smaller, & zone of overlap increases.
- as sarcomeres shorten, myofibril shortens. As myofibrils shorten, so does muscle fiber.
- once a muscle fiber begins to contract, it will contract maximally.
- this is known as the “all or none” principle.
Describe muscle organization
Muscles are bundles of fascicles. Fasiscles are made up of bundles of fibers. A fiber is a cylindrical, multinucleate cell composed of numerous myofibrils that contracta when stimulated.
Thin filaments -> Myofibrils -> Buncle of fibers -> Fasicles -> Muscles
Nueromucular function
- an action potential (AP), an electrical impulse, travels down the axon of the motor neuron to the end bulbs (synaptic terminals)
- the AP causes the synaptic vesicles to fuse with the end bulb membrane, resulting in the release of Acetylcholine (ACh) into the synaptic cleft
- ACh diffuses across the synaptic cleft and binds to ACh receptors on the motor end plate
- the binding of ACh to its receptors causes a new AP to be generated along the muscle cell membrane
- immediately afternit binds to its receptors, ACh will be broken down by Acetylcholinesterase (AChE) - an enzyme present in the symaptic cleft
Flexion
The action of bending or the condition of being bent, especially the bending of a limb or joint.
Extension
The movement by which the two ends of any jointed part are drawn away from each other.
Abduction
The movement of a limb away from the midline of the body.
Origin
Muscle attachment that remains fixed
Insertion
Muscle attachment that moves
Action
What joint movement a muscle produces
For muscles to create a movement, they can only do what?
They can only pull, not push
Agonist or prime mover
A muscle that contracted to create the desired action
Synergist
A muscle that helps the agonist
Rotation
The process of turning around an axis
Internal
Medial
External
Lateral
Pronation
The act of assuming the prone position, or the state of being prone
Supination
The act of assuming the supine position; placing or lying on the back
Dorsiflexion
Backward flexion or bending, as of the hand or foot. (It’s what you do when you get a cramp, you pull your foot back)
Plantarflexion
Extension of the ankle, pointing of the foot or toes
Inversion
A turning inward, inside out, or other reversal of the normal relation of a part
Eversion
A turning inside out; a turning outward. (What some people to do their eye lid to make it look weird)
Study major muscles on body
Okay
Skeletal muscle
An organ made of several different types of tissue including muscle tissue, vascular tissue, and nervous tissue
Tendon
Attaches the skeletal muscle to bone and pulls on bone when the muscle contracts
Origin
The attachment of a muscle on a stationary bone
Insertion
The attachment of a muscle on the moveable bone
Belly
The fleshy portion of muscle between the origin and insertion
How many muscles in the body?
Over 700 skeletal muscles in the body
Rictus
Parallel to the midline
Transverse
Perpendicular to the midline
Oblique
Diagonal to the middle
Maximus
Largest
Minimum
Smallest
Longus or longissimus
Longest
Latissimus
Wildest
Magnus
Large
Major
Larger
Minor
Smaller
Vastus
Great
Shape
General shape of the muscle
Deltoid
Triangle
Trapezius
Trapezoid
Serratus
Saw toothed
Thomboid
Diamond shaped
Orbicularis
Circular
Piriformis
Pear shaped
Platys
Flat
Quadratic
Square
Gracilis
Slender
Levator
Elevates body part
Depressor
Lowers body part
Sphincter
Decreases the size of an opening
Tensor
Makes a body part rigid
Skeletal muscle tissue
- associated to and attached with the skeleton
- voluntary control
- striated
- cells are long, cylindrical, and multinucleate
Cardiac muscle tissue
- makes up myocardium of heart
- involuntary controlled
- striated
- cells are short, branching and have single nucleus
- cells connect to each other at interacted discs
Smooth muscle
- makes up walls of organs and blood vessels
- non striated and involuntary
- cells are short, spindle shaped and have a single nucleus
- tissue is extremely extensible, while still remaining ability to contract
Myofibril is made of what?
Thin and thick filaments
Thin filaments are made of what?
Actin
Thick filament is made of what?
Myosin
Sarcomeres
Contractile units made of muscle fibers, made of thin and thick filaments
Motor neurons
Cells that cause muscle fibers to contract
Skeletal muscles require what?
Stimulation from the nerve system in order to connect
