section3_quizlet_flashcards

A single muscle response to a single action potential is known as a muscle __________.

The brief delay between the stimulus application and the beginning of muscle contraction is the __________ period.

During the latent period, action potentials travel down T-tubules and __________ is released from the sarcoplasmic reticulum.

Smooth, sustained muscle contraction produced by high-frequency stimulation without relaxation is called __________.

Twitch __________ occurs when a second stimulus arrives before the muscle has completely relaxed from the first.

In an __________ contraction, muscle tension remains constant while the muscle length changes.

In an __________ contraction, the muscle develops tension but does not change in length.

An isotonic contraction where the muscle shortens while generating force is called a __________ contraction.

An isotonic contraction where the muscle lengthens under tension is called an __________ contraction.

A __________ unit is defined as a single lower motor neuron and all the muscle fibers it innervates.

For fine motor control (like ocular muscles), motor units have a __________ neuron-to-muscle fiber ratio.

Increasing the number of active motor units to produce greater muscle force is called motor unit __________.

Neurons that originate in the cerebral cortex and travel down the spinal cord are __________ motor neurons.

Neurons that originate in the spinal cord and directly innervate skeletal muscle fibers are __________ motor neurons.

Central fatigue originates in the __________ system and involves psychological or neural mechanisms.

Peripheral fatigue occurs within the __________ tissue due to glycogen depletion, lactic acid, or phosphate buildup.

The non-contractile structures like tendons and connective tissue that must be stretched during contraction are called __________ elastic components.

Maximum active muscle tension is developed at the __________ resting length of the sarcomere.

The fundamental functional and contractile unit of a myofibril bounded by two Z lines is a __________.

The __________ line forms the structural boundary and anchor point for thin filaments at each end of a sarcomere.

The dark band containing the full length of thick (myosin) filaments is called the __________ band.

The light band that contains only thin (actin) filaments is called the __________ band.

The lighter central region within the A band that contains only thick filaments is the __________ zone.

The structural center line located in the middle of the H zone is called the __________ line.

According to the sliding filament theory, during contraction the A band remains constant while the I band and H zone __________.

Thick filaments are primarily composed of the protein __________.

Thin filaments are primarily composed of the protein __________ along with tropomyosin and troponin.

In a resting muscle, the protein __________ physically blocks the myosin-binding sites on actin filaments.

Calcium binds directly to the regulatory protein __________, causing a conformational shift that moves tropomyosin.

Action potentials arriving at the axon terminal of a motor neuron trigger the opening of voltage-gated __________ channels.

The neurotransmitter released at the neuromuscular junction into the synaptic cleft is __________.

Acetylcholine binds to __________ ACh receptors on the motor end plate of the muscle fiber.

Binding of ACh to motor end plate receptors triggers an influx of Na+, producing a local depolarization called an __________ plate potential.

Inward extensions of the sarcolemma that conduct action potentials deep into the muscle fiber are called __________-tubules.

Action potentials in T-tubules stimulate voltage-sensitive DHP receptors to open ryanodine receptors on the __________ reticulum.

The sarcoplasmic reticulum functions primarily to store and release __________ ions.

During the power stroke, the myosin head pivots and pulls the thin filament toward the center of the __________.

Binding of a fresh molecule of __________ to the myosin head is required to detach it from actin.

Hydrolysis of ATP into ADP and inorganic phosphate by myosin __________ re-cocks the myosin head.

The stiffening of muscles after death caused by the lack of ATP preventing myosin detachment is known as __________.

Muscle relaxation requires active transport of Ca2+ back into the sarcoplasmic reticulum by the __________ pump.

Black widow spider venom causes an explosive, uncontrolled release of __________ at the neuromuscular junction.

Botulinum toxin (Botox) prevents muscle contraction by blocking the __________ release of ACh from axon terminals.

The plant alkaloid __________ acts as a competitive antagonist by blocking nicotinic ACh receptors on the motor end plate.

Chemical agents like nerve gas and organophosphate pesticides inhibit the enzyme __________, causing continuous ACh buildup.