Intro to Muscular System Flashcards
Muscle is Latin for
“little mouse”
(myo- ; mys- ; sarco-)
Approximately how many muscles are in the body?
700
Muscle accounts for what percentage of total body weight?
40-50%
Muscle Characteristics
- Excitability
- responds to external stimuli (hormones/nervous stimulus)
- Contractibility
- actively shortens along longitudinal axis
- Extensibility
- can stretch beyond original length without tearing
- Elasticity
- recoils to its original length
Muscle Organ =
muscle fibers (cells) + connective tissue + nervous tissue + epithelial tissue
Skeletal Muscle Function
Change chemical energy into mechanical energy
Chemical Energy (Muscle)
The chemical energy for the cell is ATP
ATP → ADP + Pi + energy
Mechanical Energy (Muscle)
- Skeletal / Skin Movement
- Controls Posture / Body Positions / Joints
- Supports soft tissue
- Regulation of incoming and outgoing material
- Mantains Body Temperature
Skeletal (Somatic) Muscle Characteristics
- Striations (sarcomeres)
- Cylindrical-fibers
- Multiple, peripheral nuclei
- Voluntary control
- Cannot divide
- Will fatigue over time
- Attached to skeleton and skin
Every muscle organ has…
- at least one artery, one vein, and one nerve
- travel within CT to get to cells
- activate for contraction
- provide blood fro cells
- Muscle fibers (cells)
- Fascicles
- bundles of muscle cells
- Connective tissue
- wraps the muscle organ into multiple “tubes within a tube within a tube”
Innervation of Muscle cells
neuron connections to musccle cells
Action Potential travels down motor neuron to the…
neuromuscular junction
Neuromuscular Junction
The connection betwen the motor neuron’s syaptic knob and the sketetal muscle cell membrane’s motor end plate
Motor end plate
portion of the muscle cell’s sarcolemma in contact with the axon terminals
Neuron’s synatic knobs release…
Acetycholine (ACh)
Motor unit
one motor neuron and all attached muscle fibers
Formation of a tendon
Epimysium fibers blend with Perimysium fibers and Endomysium fibers
Tendon
connect muscle to bone
myosatellite cells
- myoblasts that sit in connective tissue between two connected muscle cells
- may be activated with exercise, disease, or damage
- may help with repair/regeneration of muscle cells
Myofibril
complex organelle composed of bundles of myofilaments
What you should know for the Sliding Filament Theory
- myofilaments (contractile proteins) are located in bundles called myofibrils
- Myofilaments = Actin + Myosin
- ATP is the “fuel” that runs the contraction
- ATP → ADP + inorganic phosphate + energy
- A sarcomere is the distance from one z-line to the next z-line
- The sarcoplasmic reticulus (SR) of the cell stores and releases Ca2+
- The sarcolemma has invaginations that extend towards the cell center called Transverse Tubules (T-tubules). The lay next to the SR
