Muscle Tissues
What are the three types of muscle tissue?
Skeletal, Cardiac, Smooth
What are the three connective tissue coverings of skeletal muscle from outermost to innermost?
Epimysium, perimysium, and endomysium.
What neurotransmitter is released at the neuromuscular junction?
Acetylcholine (ACh).
What is a motor unit?
One motor neuron and all the muscle fibers it controls.
What is another name for a joint?
An articulation.
Which muscle type is voluntary and striated?
Skeletal muscle.
What is the functional unit of a muscle fiber called?
A sarcomere.
What ion is released from the sarcoplasmic reticulum to trigger contraction?
Calcium ions (Ca²⁺).
What molecule provides the energy for muscle contraction?
ATP (adenosine triphosphate).
What type of joint allows the greatest range of motion?
Ball-and-socket joint (e.g., shoulder or hip).
What property allows muscle cells to respond to stimuli?
Excitability (responsiveness).
What protein forms the thick filaments?
Myosin.
What theory explains how filaments slide past each other during contraction?
The sliding filament model.
Which muscle fiber type is most fatigue-resistant?
Slow oxidative fibers (Type I).
What are the three structural types of joints?
Fibrous, cartilaginous, and synovial.
Name two ways muscles help maintain homeostasis.
By generating heat and maintaining posture.
What do troponin and tropomyosin do in muscle contraction?
They regulate binding between actin and myosin by blocking or exposing binding sites.
List the four steps of the cross-bridge cycle.
Cross-bridge formation → Power stroke → Cross-bridge detachment → Cocking of myosin head.
How does motor unit recruitment affect muscle force?
More motor units activated = stronger contraction.
Which factor contributes most to joint stability?
Muscle tone.
What’s the difference between extensibility and elasticity?
Extensibility means the muscle can stretch; elasticity means it can recoil to its
What happens to the sarcomere during contraction?
The sarcomere shortens as actin slides over myosin, pulling Z-discs closer together.
Why does rigor mortis occur?
ATP runs out, preventing myosin heads from detaching from actin, causing stiffness.
What’s the difference between aerobic and anaerobic ATP production?
Aerobic uses oxygen and makes more ATP; anaerobic doesn’t use oxygen and produces lactic acid.
What’s the difference between abduction and adduction?
Abduction moves a limb away from the midline; adduction moves it toward the midline.