Chpt. 10 & 11 Multiple Choice II Created By Day

Muscle fibers are arranged in bundles called fascicles. Fascicles are a collection of muscle fibers that are surrounded by a connective tissue sheath called the perimysium. This arrangement allows for efficient force production and transmission within the muscle.

Aerobic respiration produces approximately 36 more ATPs per glucose molecule than glycolysis does. This is because aerobic respiration involves the complete breakdown of glucose in the presence of oxygen, which leads to the production of a large amount of ATP through the electron transport chain and oxidative phosphorylation. Glycolysis, on the other hand, only produces a small amount of ATP through substrate-level phosphorylation. Therefore, the difference in ATP production between aerobic respiration and glycolysis is approximately 36.

When athletes train at high altitudes, the decrease in oxygen availability stimulates the production of more red blood cells. This increase in red blood cells allows for a greater oxygen supply during exercise. With more oxygen available, the body can engage in longer aerobic respiration, which is the process that produces energy in the presence of oxygen. This allows the athletes to sustain their exercise for longer periods of time before fatigue sets in.

In skeletal muscle, alternating light and dark bands are termed striations. These striations are caused by the arrangement of contractile proteins called actin and myosin within the muscle fibers. The overlapping pattern of these proteins creates the bands of different densities, resulting in the striated appearance of skeletal muscle under a microscope. This pattern is important for the contraction and relaxation of the muscle fibers during muscle movement.

The triceps brachii is a muscle located on the back of the upper arm, responsible for extending the elbow joint. The antagonist muscle works in opposition to the triceps brachii, and in this case, it is the biceps brachii. The biceps brachii is located on the front of the upper arm and is responsible for flexing the elbow joint. When the triceps brachii contracts to extend the elbow, the biceps brachii relaxes and vice versa, creating a balanced movement.

The minimum stimulus needed to cause muscle contraction is called the threshold. This refers to the minimum level of stimulation required to initiate a response in the muscle fibers. Once the threshold is reached, an action potential is generated, leading to the contraction of the muscle. The other options mentioned in the question are not accurate explanations for the minimum stimulus needed for muscle contraction.

Recruitment refers to the process of bringing more motor units into use during a muscle contraction. Motor units consist of a motor neuron and the muscle fibers it innervates. When a muscle needs to generate more force, additional motor units are recruited to contract. This allows for a smooth increase in muscle force. Wave summation refers to the increased force of contraction due to rapid stimulation of a muscle. Treppe refers to the phenomenon where the force of muscle contractions increases with each subsequent contraction. Incomplete tetanus occurs when muscle contractions are rapid but still have some relaxation between them. Complete tetanus occurs when muscle contractions are so rapid that there is no relaxation between them.

Myology is the study of the muscular system. It focuses on the structure, function, and diseases of muscles. This field of study involves examining the different types of muscles, their actions, and how they work together to create movement in the body. Kinesiology is the study of human movement, pathophysiology is the study of abnormal physiological processes, biology is the study of living organisms, and neurology is the study of the nervous system.

Isotonic contraction is the correct answer because it refers to the shortening of a muscle while maintaining constant tension. In isotonic contractions, the muscle changes length as it contracts and the tension remains constant. This is different from isometric contraction, where the muscle contracts but does not change length, and isokinetic contraction, where the muscle contracts at a constant speed. Treppe refers to the phenomenon where the force of muscle contractions increases with repeated stimulation, while tetanus refers to a sustained muscle contraction.

Collagen is a protein found in connective tissues that provides strength and support to various parts of the body. It is known for its ability to stretch and recoil, making it elastic. This elasticity allows collagen to withstand stretching forces and then return to its original shape, making it an important component in maintaining the integrity and flexibility of tissues such as skin, tendons, and blood vessels.

Plasticity is not a characteristic of a muscle cell. Muscle cells have the ability to contract, which is known as contractility. They can conduct electrical signals, allowing for communication between cells, which is known as conductivity. Muscle cells can also be stretched or extended, which is known as extensibility. Lastly, muscle cells are able to respond to stimuli, which is known as excitability. However, plasticity refers to the ability to change or adapt, and this is not a characteristic of muscle cells.

Loss of muscle mass from lack of activity is termed atrophy. Atrophy refers to the wasting or shrinking of muscle fibers due to disuse or inactivity. This can occur when muscles are not used or exercised regularly, leading to a decrease in muscle size, strength, and function. Myopathy refers to any disease or disorder affecting muscles, dystrophy refers to a group of inherited disorders characterized by muscle weakness and degeneration, apathy refers to a lack of interest or motivation, and treppe refers to a staircase-like increase in muscle contraction strength with repeated stimulation.

Contraction of smooth muscle would cause goose bumps. When smooth muscle contracts, it causes the hair follicles to stand upright, resulting in the appearance of goose bumps on the skin. This response is often triggered by emotions such as fear or cold temperatures.

Cardiac muscle has very little capacity for regeneration because it lacks satellite cells. Satellite cells are responsible for muscle growth and repair, as they can differentiate into new muscle cells. Without satellite cells, the cardiac muscle is unable to regenerate effectively, leading to limited repair and regeneration capabilities.

The diaphragm is innervated by the phrenic nerve. The diaphragm is the primary muscle of respiration and plays a crucial role in the process of breathing. When the phrenic nerve is stimulated, it causes the diaphragm to contract and move downward, allowing the lungs to expand and fill with air. This contraction and relaxation of the diaphragm facilitate inhalation and exhalation, making it an essential muscle for respiration.

Muscles are responsible for various functions in the body, including stability, heat production, control of openings, and respiration. However, muscles do not have the ability to secrete substances. Secretion is typically carried out by glands, such as sweat glands or salivary glands. Therefore, the correct answer is secretion.

Skeletal muscle depends solely on the sarcoplasmic reticulum as its calcium source. The sarcoplasmic reticulum is an organelle within muscle cells that stores and releases calcium ions, which are necessary for muscle contraction. In skeletal muscle, the release of calcium from the sarcoplasmic reticulum triggers the contraction of the muscle fibers. Smooth muscle and cardiac muscle also rely on the sarcoplasmic reticulum for calcium, but they also have other sources of calcium such as extracellular calcium influx. Therefore, the correct answer is skeletal muscle.

Myokinase is very important for muscle to continue contraction during anaerobic respiration. Myokinase is an enzyme that plays a crucial role in the conversion of ADP (adenosine diphosphate) to ATP (adenosine triphosphate) during anaerobic respiration. ATP is the main source of energy for muscle contraction, and myokinase helps replenish ATP levels by converting ADP, which is produced during muscle contraction, back into ATP. Therefore, myokinase ensures that an adequate supply of ATP is available for continuous muscle contraction during anaerobic respiration.

During muscle contraction, a single myosin head consumes ATP at a rate of about 5 ATP per second. This is because ATP is required for the myosin head to detach from actin and reset its position for another contraction. The energy from ATP is used to power the movement of the myosin head, allowing it to bind to actin, pivot, and release. This process occurs repeatedly during muscle contraction, requiring a continuous supply of ATP to sustain the movement.

Type IIB fast glycolytic fibers are primarily responsible for producing lactic acid. Lactic acid is produced during anaerobic glycolysis, which occurs when there is a high demand for energy and oxygen supply is limited. Type IIB fibers are known for their fast contraction speed and high glycolytic capacity, making them efficient at producing energy through anaerobic glycolysis. This process produces lactic acid as a byproduct, which can contribute to muscle fatigue and soreness.

The release of acetylcholine at a neuromuscular junction increases the permeability of the sarcolemma to Na+. This allows sodium ions to enter the muscle fiber, leading to depolarization and the initiation of an action potential. This is a crucial step in muscle contraction as it triggers the release of calcium ions from the sarcoplasmic reticulum, leading to muscle contraction.

If a nerve stimulus arrives at a muscle fiber before it has fully relaxed from the previous twitch, the muscle fiber will experience partial relaxation and contraction. This repeated stimulation without allowing the muscle fiber to fully relax results in incomplete tetanus. Incomplete tetanus is characterized by a sustained contraction with partial relaxation between twitches. This is different from complete tetanus, where the muscle fiber is stimulated so rapidly that it does not have any relaxation phase between twitches. Fatigue refers to a decrease in muscle performance due to prolonged activity, treppe is a phenomenon where the force of muscle contraction increases with repeated stimulation, and flaccid paralysis is a condition where the muscles are limp and unable to contract.

The temporalis muscle is responsible for mandibular elevation. It is one of the main muscles of mastication and is located on the side of the head above the ear. When the temporalis muscle contracts, it pulls the mandible (lower jaw) upwards, allowing for the closing of the mouth and the chewing of food.

The pronator quadratus and supinator are considered antagonists because they have opposing actions. The pronator quadratus pronates the forearm, rotating it medially, while the supinator supinates the forearm, rotating it laterally. As these muscles perform opposite movements, they work against each other, making them antagonistic in nature.

Cardiac muscle has the largest mitochondria because it requires a constant supply of energy to sustain its continuous contractions. Mitochondria are responsible for producing ATP, the energy currency of cells, and cardiac muscle needs a high amount of ATP to maintain its pumping action. Additionally, the large mitochondria in cardiac muscle ensure that it has a high oxidative capacity, allowing it to efficiently utilize oxygen for energy production.

A fleshy attachment describes the appearance of red muscular tissue emerging directly from bone without the presence of an obvious tendon separating them. This means that the muscle appears to be directly connected to the bone, giving it a fleshy appearance.

Isotonic eccentric contraction refers to a type of muscle contraction where the muscle lengthens while maintaining a constant tension. This means that the muscle is actively resisting an external force that is greater than the force being generated by the muscle itself. As a result, the muscle is stretched and lengthened, but the tension within the muscle remains constant. This type of contraction is commonly seen during activities such as lowering a weight or descending stairs.

Smooth muscle contracts more slowly but relaxes more slowly compared to skeletal muscle.

An elastic filament is a myofilament that flanks a thick filament and anchors it to a Z disc. It provides stability and helps maintain the alignment of the thick filament within the muscle fiber. This allows for proper contraction and relaxation of the muscle during movement.

The modiolus is a point of convergence for several muscles of the lower face. It is located at the corner of the mouth and serves as an attachment site for muscles that control facial expressions, such as the orbicularis oris muscle. The other options, retinaculum, aponeurotica, nuchal line, and galea, do not specifically refer to a point of convergence for muscles of the lower face.

The accessory nerve, also known as cranial nerve XI, innervates the sternocleidomastoid and trapezius muscles. It is responsible for controlling the movement of these muscles, which are important for head and neck movements. The other cranial nerves listed in the options have different functions and do not innervate these specific muscles.

Exposure to Clostridium tetani does not have any effect on smooth muscle. This is because the release of acetylcholine, which is responsible for muscle contraction, is not affected by the bacteria. Therefore, there is no paralysis or any other effect on smooth muscle.

Creatine kinase is an enzyme that catalyzes the transfer of a phosphate group from creatine phosphate (CP) to adenosine diphosphate (ADP), forming adenosine triphosphate (ATP). This process is crucial for the regeneration of ATP, the main energy source for muscle contraction. Therefore, the correct answer is that creatine kinase catalyzes the transfer of phosphate from CP to ADP.

Dystrophin, the protein that is defective in muscular dystrophy, is normally found between the outermost myofilaments and the sarcolemma of a muscle fiber. This means that it is located in the space between the contractile filaments of the muscle fiber and the cell membrane. This positioning allows dystrophin to provide structural support and stability to the muscle fiber during contraction and relaxation. When dystrophin is defective or absent, as in muscular dystrophy, the muscle fibers become weak and damaged, leading to the characteristic symptoms of the disease.

The bladder's ability to greatly distend and return to normal tension suggests that the smooth muscles in the bladder have the property of plasticity. Plasticity refers to the ability of a material or tissue to change shape or size without breaking or losing its original form. In the case of the bladder, the smooth muscles can stretch to accommodate a large volume of urine and then contract back to their original size once the urine is expelled. This flexibility and adaptability of the smooth muscles allow the bladder to function effectively.

Lactic acid is produced by skeletal muscle during intense exercise when there is not enough oxygen available. This lactic acid is then converted to pyruvic acid through a process called the Cori cycle. The Cori cycle occurs primarily in the liver, where the lactic acid is transported from the muscles via the bloodstream. In the liver, the lactic acid is converted back to pyruvic acid, which can then be used in various metabolic pathways. Therefore, the correct answer is "in the liver."

The deltoid is a muscle located in the shoulder region and is responsible for the movement of the arm. It is considered an extrinsic muscle because it originates from a different location (the scapula and clavicle) and inserts onto the humerus bone. In contrast, intrinsic muscles are those that originate and insert within the same region. The terms fusiform, involuntary, and parallel do not accurately describe the deltoid muscle.

The goal of medications used to treat myasthenia gravis is to inhibit the function of cholinesterase. Myasthenia gravis is an autoimmune disorder that affects the neuromuscular junction, causing muscle weakness and fatigue. Cholinesterase inhibitors work by blocking the enzyme cholinesterase, which breaks down acetylcholine, a neurotransmitter involved in muscle contraction. By inhibiting cholinesterase, more acetylcholine is available in the neuromuscular junction, improving muscle strength and reducing symptoms of myasthenia gravis.

Fascia is a connective tissue that separates groups of muscles. It forms a dense, fibrous sheath around muscles, providing support and protection. It helps to compartmentalize and organize the muscles, allowing them to move independently and efficiently. The other options, such as epimysium, perimysium, and endomysium, are also connective tissues but they are not specifically responsible for separating groups of muscles like fascia does.

All three types of muscles, skeletal, smooth, and cardiac muscles, are capable of contracting without the need for nervous stimulation. Skeletal muscles can be voluntarily contracted, while smooth and cardiac muscles contract involuntarily. This is because these muscles have their own inherent electrical activity and specialized cells called pacemaker cells that generate electrical impulses, allowing them to contract without direct nervous stimulation.