Muscular System - TEAS prep

muscular system

• composed of muscle cells & tissues that brings about movement of an organs or body part

types of muscle tissue

• cardiac muscle

• smooth muscle

• skeletal muscle

cardiac muscle

• specialized, organized type of tissue that only exists in the heart

• involuntary control

  • controlled by autonomic nervous system

  • no conscious control

• consists of

  • striated appearance

  • one nucleus per fiber

  • intercalated discs

smooth muscle

• narrow, spindle shaped cells with a single centrally located nucleus

• involuntary control

  • controlled by autonomic nervous system

  • no conscious control

• found in the digestive system, arteries & veins, bladder & eyes

• consists of:

  • one nucleus per fiber

  • spindle shaped

  • is non-striated

skeletal muscle

• highly organized tissues that attach to bones or skin to produce movements

• voluntary control

  • controlled by the somatic nervous system

  • conscious control of movement

• tongue, diaphragm, upper esophagus

• consists of:

  • striations

  • multiple nuclei per fiber

muscle tissue key components

• extensibility

• elasticity

• excitability

• contractability

extensibility

• ability of the muscle to be stretched or extended

elasticity

• ability of the muscle to its original length when relaxed

excitability

• ability of the muscle to respond to a stimulus from a motor neuron or hormone

contractibility

• ability of the muscle to shrink or contract

actin

• thin filaments

• protein that forms the contractile filaments of muscle cells

myosin

• thick filaments

• fibrous globulin of muscles that can split ATP and react to actin in muscle contraction

cross-bridge formation

• myosin head binds to ATP, becomes hydrolyzed & turns into ADP and a phosphate group

• this process enables the myosin heads to bind to the actin

power-stroke

• myosin head releases the ADP & phosphate group and undergoes a bending motion as it drags that thin filament towards the center sarcomere

bridge detachment

• a new ATP binds to the myosin head again, which allows that head to detach from the actin

cross-bridge formation, power stroke & bridge detachment

• microscopic level

• this process continuously forming and breaking with some of the heads always attached to the actin prevents the thin filaments from slipping back into their original positions, ensuring that we have an effective muscle

rigor mortis

• this necessity for ATP is also why muscles become rigid after death

• because of no ATP, the myosin heads don’t know whether they can detach from the actin

ligament

• connective tissue that attaches bone to bone

tendon

• connective tissue that attaches muscle to bone

cartilage

• connective/supporting tissue

fascia

• muscle to muscle

• muscle to surrounding tissue