Muscle Cell Structure and Function

Flashcards covering key concepts related to muscle cell structure, function, and physiology.

What is the cytoplasm of a skeletal muscle cell called?

Sarcoplasm.

What are the two main types of filaments found in myofibrils?

Thick filament (myosin) and thin filament (actin).

What is the functional unit of a myofibril called?

Sarcomere.

What does the term 'striated' mean in the context of skeletal muscles?

Refers to the light and dark bands formed by the arrangement of actin and myosin proteins.

What is the role of the Z disc in a sarcomere?

It marks the boundaries of each sarcomere and anchors the thin filaments.

What does the A band consist of?

Both thick (myosin) and thin (actin) filaments.

What is the role of the H band in a sarcomere?

It is the area where only thick filaments (myosin) are present.

What triggers muscle contraction at the cellular level?

The release of calcium ions from the sarcoplasmic reticulum.

What is the purpose of the sodium-potassium ATP pump in muscle cells?

To maintain the resting membrane potential by moving sodium out and potassium into the cell.

What happens during depolarization of a muscle cell?

Sodium ions enter the cell, making it more positively charged.

What neurotransmitter is released at the neuromuscular junction to stimulate muscle contraction?

Acetylcholine.

Why is calcium important for muscle contraction?

Calcium binds to troponin, allowing myosin to attach to actin.

What happens to ATP during muscle contraction?

ATP is hydrolyzed to ADP and inorganic phosphate, providing energy for the myosin heads to pull actin.

What occurs when acetylcholine is removed from the synaptic cleft?

Muscle contraction ceases and the muscle begins to relax.

What is rigor mortis?

The stiffening of muscles after death due to lack of ATP production.

What is glycolysis?

The process of breaking down glucose, which generates ATP without the need for oxygen.

What happens to pyruvate if oxygen is present after glycolysis?

It enters the mitochondria for further breakdown to produce additional ATP.

How is glucose stored in muscles?

As glycogen.

What is a triad in muscle cells?

A combination of a T tubule and two terminal cisternae of the sarcoplasmic reticulum.

What role do microtubules play in the transport of vesicles in neurons?

They act as tracks along which vesicles travel from the cell body to the axon terminal.

What do acetylcholinesterase enzymes do at the neuromuscular junction?

They break down acetylcholine to prevent prolonged muscle contraction.