muscle tissues 3/26

What does the term 'sarcoplasmic reticulum' refer to in a muscle fiber?

The specialized endoplasmic reticulum in muscle fibers that stores calcium.

What are the two main types of myofilaments in a myofibril?

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

What is the smallest functional unit of a myofibril called?

A sarcomere.

What is the function of the motor neuron at the neuromuscular junction?

To transmit nerve impulses that stimulate muscle contraction.

What neurotransmitter is used by motor neurons to communicate with muscle fibers?

Acetylcholine (ACH).

What is the space between the neuron's plasma membrane and the muscle fiber's plasma membrane called?

The synaptic cleft.

What is the membrane potential?

The electrical charge difference across the plasma membrane of neurons and muscle fibers.

What are cations and give examples important for muscle and nerve function?

Cations are positively charged ions; important examples include sodium (Na+) and potassium (K+).

What is the role of the Z line in muscle fibers?

It is where thin myofilaments attach and defines the boundaries of a sarcomere.

What changes occur in the sarcomere during muscle contraction?

The sarcomere shortens as the thick and thin myofilaments increase their overlap.

What is the primary function of myoglobin in muscle cells?

To store oxygen for muscle contraction.

What are the three types of muscle tissue in the human body?

Skeletal, cardiac, and smooth muscle.

What is the role of troponin in muscle contraction?

Troponin binds calcium ions and causes tropomyosin to move, exposing binding sites on actin.

How does ATP relate to muscle contraction?

ATP provides the energy required for muscle fibers to contract.

What is the link between the nervous system and muscle contraction?

The nervous system controls muscle contraction through motor neurons that stimulate muscle fibers.

What is the purpose of the transverse tubules in muscle fibers?

To transmit the action potential deep into the muscle fiber.

What happens to calcium ions during muscle relaxation?

They are pumped back into the sarcoplasmic reticulum.

What is an isometric contraction?

A type of muscle contraction where the muscle length does not change despite tension being applied.

How does the sliding filament theory explain muscle contraction?

It states that muscle contraction occurs when thin myofilaments slide over thick myofilaments, causing sarcomeres to shorten.

What role does creatine phosphate play in muscle metabolism?

It serves as a quick energy source to regenerate ATP during short bursts of high-intensity activity.