Skeletal Muscle Physiology

Motor neurons

Motor neurons

Nerves that innervate muscle cells

Neuromuscular junction

Point of contact between a motor neuron and a muscle cell

Acetylcholine

Neurotransmitter released by motor neurons that binds to receptors on muscle cell membrane

T-tubules

Extensions of the muscle cell membrane that allow electrical impulses to travel inside the cell

Sarcoplasmic reticulum

Specialized endoplasmic reticulum in muscle cells that stores and releases calcium

Sliding filament mechanism

Process by which muscle contraction occurs through the interaction between actin and myosin molecules

Cross bridges

Connections formed between myosin heads and actin molecules during muscle contraction

Sarcomere

Basic unit of muscle contraction, consisting of actin and myosin filaments

Rigor mortis

Stiffening of muscles after death due to the prolonged presence of calcium and cross bridges

ATP

Adenosine triphosphate, the energy currency of cells used for muscle contraction

Creatine phosphate

Molecule similar to ATP that can be used as a quick source of energy for muscle contraction

Anaerobic metabolism

Metabolic process that breaks down glycogen without the use of oxygen to produce ATP

Glycogen

Storage form of glucose in the body

Cellular respiration

Metabolic process that uses oxygen to produce ATP for muscle contraction

Cardiac muscle

Muscle tissue found in the heart that contracts and relaxes to pump blood

Pacemaker cells

Specialized cells in the heart that generate electrical impulses to regulate the heartbeat

Gap junctions

Channels between cardiac muscle cells that allow electrical signals to pass through

Smooth muscle

Muscle tissue found in the walls of organs and blood vessels that contracts slowly and involuntarily

Intercalated discs

Structures that connect cardiac muscle cells and allow for coordinated contraction

Resting state

State of smooth muscle where it is partially contracted