The Muscular System (Part 1) - Review For Quiz #4

The thin myofilament protein is called actin. Actin is a globular protein that forms filaments, which are an essential component of muscle fibers. These filaments interact with thick myofilament proteins, such as myosin, to generate muscle contractions. Actin is responsible for the sliding mechanism that allows muscles to contract and relax. It is found in abundance in muscle cells and plays a crucial role in muscle contraction and movement.

Voluntary because it is under conscious control.

A muscle cell is commonly referred to as a muscle fiber. This is because muscle fibers are the individual cells that make up muscle tissue. These fibers are long and cylindrical in shape, and they work together to contract and relax, allowing for movement in the body. Therefore, muscle fiber is another term used to describe a muscle cell.

The muscle attachment to the stationary bone is called its origin. This is where the muscle begins and remains fixed during contraction. The origin is typically located closer to the body's midline and is responsible for providing stability and anchoring the muscle in place.

The muscle's attachment to the more moveable bone is called the insertion. This is because the insertion point is where the muscle is attached to the bone that moves when the muscle contracts. The insertion point is usually located towards the distal end of the muscle and is responsible for the movement produced by the muscle's contraction.

Muscle contraction requires energy in the form of ATP. ATP, or adenosine triphosphate, is a molecule that stores and releases energy for cellular processes. During muscle contraction, ATP is broken down into ADP (adenosine diphosphate) and inorganic phosphate, releasing energy that is used to power the contraction. This energy is needed to fuel the sliding of actin and myosin filaments, which causes the muscle fibers to shorten and generate force. Therefore, ATP is essential for muscle contraction to occur.

Lactic acid is a waste product that is produced during metabolism, specifically during anaerobic respiration. When the body's oxygen supply is limited, such as during intense exercise, lactic acid is produced as a byproduct. Accumulation of lactic acid in the muscles can lead to muscle fatigue and soreness. Therefore, lactic acid is the correct answer as it is a waste product of metabolism that causes muscle fatigue.

A tendon is a fibrous connective tissue that attaches muscle to bone. It is responsible for transmitting the force generated by the muscle to the bone, allowing movement to occur. Tendons are strong and flexible, enabling them to withstand tension and provide stability to the joints. They play a crucial role in the body's movement and overall functioning.

Skeletal muscles and bones work together to produce movement at the joints. Joints are the points where two or more bones meet, allowing for movement and flexibility. Muscles attach to bones via tendons and when they contract, they pull on the bones, causing movement at the joints. Therefore, joints are essential for coordinating and enabling the various movements of the body.

Myosin is the correct answer because it is the thick myofilament protein responsible for muscle contraction. It interacts with the thin myofilament protein called actin to generate force and movement. Myosin has a unique structure consisting of a head and a tail region, with the head region containing ATPase activity that allows it to bind and hydrolyze ATP, providing the energy necessary for muscle contraction.

Skeletal muscle is attached to bones or bone. Skeletal muscles are responsible for movement and are connected to bones through tendons, which are strong cords of connective tissue. These tendons attach the muscle to the periosteum, a thin layer of connective tissue that covers the bone. This attachment allows the contraction of skeletal muscles to move the bones, enabling various movements and actions in the body.

The tough connective tissue sheath that encases an entire muscle is known as fascia. Fascia is a layer of fibrous tissue that surrounds muscles, providing support and protection. It helps to separate and compartmentalize different muscles, allowing them to function independently. Fascia also plays a role in transmitting forces generated by muscle contractions, aiding in movement and stability.

During a muscle contraction, myosin and actin first attach to one another forming bridges. This is a fundamental process in muscle contraction where myosin, a thick filament, binds to actin, a thin filament, to generate the sliding movement of the filaments. The binding of myosin to actin allows for the cross-bridge formation, which is essential for the contraction of muscle fibers. Therefore, the correct answer is myosin, actin.

During increased muscle activity, the demand for energy is high. In anaerobic metabolism, glucose is broken down without the presence of oxygen to produce energy. This process is less efficient than aerobic metabolism, but it allows for a rapid production of energy when oxygen supply is limited. Therefore, during intense exercise or when oxygen demand exceeds supply, the body relies on anaerobic metabolism to meet the energy requirements of the muscles.

Calcium is needed for muscle contraction. Calcium ions play a crucial role in the process of muscle contraction. When a muscle receives a signal from a motor neuron, calcium ions are released from the sarcoplasmic reticulum into the muscle cell. These calcium ions then bind to proteins called troponin, which causes a conformational change in the muscle fibers, allowing them to slide past each other and contract. Without an adequate supply of calcium, muscle contraction cannot occur effectively.

Glucose that is stored in the muscle cell is known as glycogen. Glycogen is a polysaccharide that serves as a form of energy storage in animals, including humans. It is synthesized and stored in the liver and muscles, where it can be broken down into glucose when the body needs energy. Glycogen acts as a readily accessible source of fuel for muscles during physical activity and is an essential component of the body's energy metabolism.

A motor neuron is the nerve fiber that sends nerve impulses to muscle fibers. It is responsible for controlling muscle movement by transmitting signals from the brain or spinal cord to the muscles. These impulses travel along the motor neuron and stimulate the muscle fibers to contract, leading to movement.

The correct answer is smooth, cardiac, skeletal. This is because the three types of muscle tissue in the human body are smooth muscle, cardiac muscle, and skeletal muscle. Smooth muscle is found in the walls of organs and blood vessels, cardiac muscle is found in the heart, and skeletal muscle is attached to bones and allows for voluntary movement.

Most skeletal muscles attach to two bones that have a movable joint between them. The muscles work by contracting and pulling on the bones, causing movement at the joint. The joint acts as a pivot point, allowing the bones to move in different directions. This arrangement allows for a wide range of movement in the body.

Motor neurons release chemicals called neurotransmitters, specifically acetylcholine, at the neuromuscular junction. When acetylcholine binds to receptors on the muscle cell membrane, it triggers a series of events that result in the contraction of the muscle cell. This contraction leads to the shortening of the muscle fiber, allowing it to generate force and produce movement. Therefore, the correct answer is contraction and shortening.

When a muscle cell is stimulated by a nerve to contract, calcium is released into the cytoplasm. Calcium plays a crucial role in muscle contraction as it binds to specific proteins within the muscle cell, allowing the actin and myosin filaments to interact and generate force. This release of calcium into the cytoplasm triggers a series of events that ultimately leads to muscle contraction. Therefore, both "calcium" and "cytoplasm" are correct in this context, and "calcium cytoplasm" is a combination of these two essential components involved in muscle contraction.

Myoglobin is a protein found in muscle cells that is responsible for storing and transporting oxygen. It has a higher affinity for oxygen than hemoglobin, which allows it to efficiently store oxygen in muscle tissue. This stored oxygen can be used during periods of increased demand, such as during exercise or when oxygen supply is limited. Therefore, myoglobin is the correct term for the oxygen stored in muscle cells.

When the body performs intense exercise, it requires energy to meet the increased demand. However, during such exercise, the body may not be able to supply enough oxygen to the muscles, resulting in the muscles relying on anaerobic respiration. This anaerobic respiration produces lactic acid as a byproduct. The accumulation of lactic acid leads to an oxygen debt, as the body needs to repay the oxygen it couldn't provide during exercise to break down the lactic acid and restore normal functioning.

The human body consists of numerous muscles that are responsible for various movements and functions. With over 600 skeletal muscles alone, when combined with smooth and cardiac muscles, the total number exceeds 700. These muscles work together to enable actions such as walking, talking, and even breathing. Therefore, the statement that there are over 700 muscles in the body is accurate.

Skeletal muscle tissue is the correct answer because it is the most abundant type of muscle tissue in the body. Skeletal muscles are attached to bones and are responsible for voluntary movements such as walking and lifting. They are striated in appearance and can be consciously controlled. Smooth muscle tissue is found in the walls of organs and blood vessels, while cardiac muscle tissue is found only in the heart. However, neither of these types of muscle tissue are as abundant in the body as skeletal muscle tissue.

Muscle fibers are organized into bundles known as fascicles, which are held together by connective tissue. This arrangement allows for the efficient transmission of force generated by the muscle fibers and provides structural support to the muscle.

Each muscle fiber contains many threadlike structures made up of two kinds of proteins called thick and thin myofilaments. These myofilaments are responsible for the contraction of the muscle fiber. The thick myofilaments are made up of a protein called myosin, while the thin myofilaments are made up of a protein called actin. When the muscle fiber receives a signal to contract, the myosin and actin filaments slide past each other, causing the muscle to shorten and generate force. Therefore, myofilaments play a crucial role in muscle contraction.

Calcium is stored in the endoplasmic reticulum (ER) when the muscle is relaxed. The ER is a network of membranes within the cell that plays a role in protein synthesis, lipid metabolism, and the storage and release of calcium ions. In muscle cells, the ER is particularly important for regulating calcium levels, as it can release calcium into the cytoplasm when the muscle needs to contract, and store calcium when the muscle is at rest. So, the correct answer is endoplasmic reticulum (ER).

The neuromuscular junction is the point where a nerve ending and a muscle fiber come into contact. This junction is responsible for transmitting signals from the nerve to the muscle, allowing for muscle contraction to occur.

The middle portion of the muscle that is between the origin and the insertion is referred to as the body. This term is commonly used to describe the main bulk or central region of a muscle. It is the part of the muscle that contracts and generates force during movement. The body of a muscle is responsible for producing the desired movement by shortening and pulling on the insertion point, which is the attachment point of the muscle to the bone.

When viewed under a microscope, skeletal muscle appears threadlike and cylindrical. This means that the muscle fibers are long and thin, resembling threads. The cylindrical shape indicates that the muscle fibers are arranged in parallel, giving the muscle its characteristic shape. This microscopic appearance is due to the organization of the muscle fibers and the presence of protein filaments within them. The threadlike nature allows the muscle to contract and relax efficiently, enabling movement and providing support to the body.

Muscle cells require oxygen and glucose to produce ATP. Oxygen is necessary for aerobic respiration, which is the process that generates ATP in the mitochondria. Glucose is the main source of fuel for cellular respiration, as it is broken down through glycolysis and the citric acid cycle to produce ATP. Therefore, both oxygen and glucose are essential for the production of ATP in muscle cells.

"MOVEMENT" of the skeleton
Maintain "POSTURE"
Generation of "HEAT"