Personal Trainer Practice Questions Flashcards

What are the three types of muscle tissue?

Answer: Cardiac, smooth, skeletal

The human body contains three distinct types of muscle tissue, each with specialized functions. These are cardiac muscle, found only in the heart; smooth muscle, which lines internal organs and blood vessels; and skeletal muscle, which is attached to bones and responsible for voluntary movement. These three types differ in their structure, location, and control mechanisms.

Which of the following facts is not true about skeletal muscles?

Answer: They can be stretched to up to 250% of their resting length.

Skeletal muscles are highly extensible but cannot be stretched to 250% of their resting length without severe damage. While they are the most plentiful tissue, account for a significant portion of body weight, and often work in functional groups, their extensibility is typically limited to about 120-150% of their resting length. Stretching beyond this range would likely cause muscle tears and injury.

Which of the three types of muscle action has a constant speed of shortening and lengthening?

Answer: Isometric

Isometric muscle action occurs when a muscle contracts and generates force, but its length does not change, meaning there is no movement at the joint. In this type of contraction, the speed of shortening and lengthening is considered constant (zero) because the muscle is holding a static position against a resistance. Concentric and eccentric contractions involve changes in muscle length and movement.

What is the correct order of structures of a muscle from smallest to largest?

Answer: Muscle fiber, endomysium, fascicles, perimysium, epimysium

Skeletal muscle tissue is organized in a hierarchical structure. The smallest unit is the individual muscle fiber, which is surrounded by the endomysium. Multiple muscle fibers are bundled together into fascicles, which are then encased by the perimysium. Finally, many fascicles are grouped to form the entire muscle, which is enveloped by the outermost layer, the epimysium.

Which muscular structure surrounds the actual muscle fiber and is responsible for depolarization of the surface of the fiber and protection and insulation of the fiber from others around it?

Answer: Sarcolemma

The sarcolemma is the specialized plasma membrane that surrounds each individual muscle fiber. Its primary functions include receiving and propagating the electrical impulse (action potential) across the muscle fiber's surface, initiating muscle contraction. It also plays a role in protecting and insulating the muscle fiber from its surroundings.

What part within the muscle fiber stores glycogen and myoglobin and is made up of lipids, enzymes and various types of cellular organelles?

Answer: Sarcoplasm

The sarcoplasm is the cytoplasm of a muscle cell, or muscle fiber. It contains various cellular organelles, including mitochondria, and is rich in glycogen (stored glucose for energy) and myoglobin (an oxygen-binding protein). These components are crucial for providing energy and oxygen to support muscle contraction.

Within the myofibril, which of the following is the lighter band that contains only actin?

Answer: I band

Within a myofibril, the sarcomere is the basic contractile unit, characterized by distinct bands. The I band is the lighter region that contains only thin (actin) filaments and extends from the Z-disc to the beginning of the thick (myosin) filaments. The A band contains both actin and myosin, while the H zone and M line are found within the A band.

Which of the following correctly describes what happens within the muscle fiber during contraction?

Answer: Myosin cross-bridges bind, actin slides over myosin, Z lines are pulled together

According to the sliding filament theory, muscle contraction begins when myosin cross-bridges bind to active sites on the actin filaments. This binding causes the actin filaments to slide inward over the myosin filaments, effectively shortening the sarcomere. As the sarcomeres shorten, the Z lines (which anchor the actin filaments) are pulled closer together, resulting in overall muscle contraction.

What is the function of calcium in the muscle stimulation process?

Answer: Binds with troponin to open up binding sites

In muscle stimulation, calcium ions (Ca2+) play a crucial role in initiating contraction. When released from the sarcoplasmic reticulum, calcium binds to troponin, a protein associated with actin filaments. This binding causes a conformational change in troponin, which then moves tropomyosin away from the active binding sites on the actin filaments, allowing myosin heads to attach and begin the contraction cycle.

Which of the following does not correctly describe fast-twitch muscles fibers?

Answer: They are used during aerobic exercises.

Fast-twitch muscle fibers are primarily designed for rapid, powerful, short-duration contractions and are predominantly used during anaerobic activities, not aerobic exercises. They have a quick rate of calcium ion release, rely on blood glucose and muscle glycogen for energy, and generate fast, powerful muscle actions. Slow-twitch fibers, in contrast, are better suited for sustained aerobic activity.

Why are slow-twitch muscles more resistant to fatigue during exercise, thus making them better for longer duration exercises?

Answer: They have less developed sarcoplasmic reticula, which release calcium more slowly.

Slow-twitch muscle fibers are more resistant to fatigue because they have a less developed sarcoplasmic reticulum, leading to a slower release of calcium ions. This slower calcium release results in a slower contraction speed but allows for more sustained, efficient contractions. Additionally, slow-twitch fibers are rich in mitochondria and myoglobin, making them highly efficient at aerobic metabolism, which contributes to their endurance.

What is the correct name for the type of nerves that excite organ systems, such as the digestive system or the circulatory system?

Answer: Autonomic

The autonomic nervous system is a division of the peripheral nervous system that controls involuntary bodily functions, such as heart rate, digestion, respiration, and glandular secretions. It excites or inhibits the activity of internal organs and smooth muscles, operating largely unconsciously to maintain homeostasis. The somatic nervous system, in contrast, controls voluntary muscle movements.

What part of a nerve cell allows for saltatory conduction?

Answer: Nodes of Ranvier

Saltatory conduction is the rapid propagation of action potentials along myelinated axons, where the impulse 'jumps' from one Node of Ranvier to the next. These nodes are unmyelinated gaps in the myelin sheath, allowing for the regeneration of the action potential and significantly increasing the speed of nerve impulse transmission.

What controls the process of changing membrane potential in the nerve cell membrane by allowing sodium ions to rush into the cell?

Answer: Sodium-potassium pump

The sodium-potassium pump is crucial for maintaining and restoring the resting membrane potential in nerve cells. After depolarization, it actively transports three sodium ions out of the cell and two potassium ions into the cell, re-establishing the ion gradients necessary for subsequent action potentials and thus controlling the overall process of membrane potential changes.

What principle is at play when the electrical threshold of the nerve cell membrane is reached, causing the propagation of the action potential?

Answer: The all-or-none principle

The all-or-none principle states that once the electrical threshold of a nerve cell membrane is reached, an action potential will fire with its full, consistent strength, or it will not fire at all. The intensity of the stimulus beyond the threshold does not affect the amplitude of the action potential, only its frequency.

What is the anatomical name for the location on a muscle fiber where a nerve impulse is received?

Answer: Motor endplate

The motor endplate is the specialized region of the muscle fiber membrane (sarcolemma) that forms a neuromuscular junction with the axon terminal of a motor neuron. It contains receptors for acetylcholine, the neurotransmitter that initiates muscle contraction upon receiving a nerve impulse.

What relays information to the central nervous system about changes in the body and limbs’ positions due to muscular motions?

Answer: Proprioceptors

Proprioceptors are specialized sensory receptors located in muscles, tendons, and joints that detect changes in body position, movement, and muscle tension. They constantly relay this vital information to the central nervous system, enabling coordination, balance, and awareness of limb positions without visual input.

Which part of the muscle fiber protects the muscle from injury due to excessive or rapid stretching?

Answer: Muscle spindles

Muscle spindles are stretch receptors located within the belly of skeletal muscles. They detect changes in muscle length and the rate of change, initiating a stretch reflex that causes the muscle to contract and resist excessive or rapid stretching, thereby protecting it from injury.

What specialized sensor is located near the musculotendinous junction and provides input regarding bodily movements or pressure?

Answer: Pacinian corpuscles

Pacinian corpuscles are specialized mechanoreceptors found deep in the skin, tendons, ligaments, and near musculotendinous junctions. They are highly sensitive to deep pressure and vibrations, providing crucial sensory input about external forces and bodily movements.

Which part of the muscle fiber senses changes in the tension of the muscle?

Answer: Golgi tendon organs

Golgi tendon organs (GTOs) are proprioceptors located at the junction between a muscle and its tendon. They are sensitive to changes in muscle tension, particularly during muscle contraction or extreme stretch, and can trigger a reflex to inhibit muscle contraction, protecting the muscle and tendon from excessive force.