A&p Chapter 9 Review: Muscle Tissue

The fluid in a muscle cell is called sarcoplasm, which is a specialized cytoplasm found in muscle cells. Cytoplasm is found in all cells, nucleoplasm is the fluid inside the nucleus of a cell, and endoplasm is not a scientifically recognized term related to cell biology.

Glycogen is primarily stored in the glycosomes of the sarcolemma in muscle cells due to its proximity to where energy is needed for muscle contractions.

Oxygen is stored in the muscle primarily in the myoglobin of the sarcolemma, which serves as an oxygen reservoir for the muscle cells during periods of high demand.

Calcium is primarily stored in the sarcoplasmic reticulum, specifically in the paired terminal cisterna within the t-tubule's, not in the mitochondria, nucleus, or Golgi apparatus of muscle cells.

The correct answer explains that the striated look of a muscle comes from the repeating series of dark and light bands, known as A and I bands, as well as the Z and M lines, and the overlapping actin and myosin. The three incorrect answers have no direct relevance to the structural aspects of muscle tissue that create its striated appearance.

In striated muscle, the A bands are the dark bands that contain the thick filaments of myosin. The I bands are the light bands between A bands containing thin filaments of actin. H bands are located in the center of A bands and contain only myosin filaments. M bands are located in the center of H bands and help stabilize the position of the thick filaments.

In muscle anatomy, I bands are the light bands containing mainly actin filaments, while A bands are the dark bands containing both actin and myosin filaments. M bands are in the center of the A band, and H bands are regions within the A band where only myosin filaments are present.

During muscle contraction, the H zone disappears as the actin filaments slide over the myosin filaments, causing overlapping and hiding the H zone. This leads to the shortening of the sarcomere and the muscle overall.

The sarcomere is the basic unit of muscle structure where the Z disc serves as the boundary for each sarcomere. The other options, such as sarcoplasmic reticulum, myofibril, and endomysium, are also important components of muscle tissue but do not specifically represent the space between Z discs.

The sarcomere is specifically related to muscle function and contraction, not skin color, blood flow, or digestion.

Actin is a thin myofilament that extends the longest across a muscle fiber. Myosin is a thick myofilament that does not extend as far. Titin and nebulin are structural proteins in muscles but do not extend as far as actin across a muscle fiber.

Titin is a large protein that plays a significant role in maintaining muscle structure and function by acting as a molecular spring, assisting in muscle contraction and relaxation. The other options listed are involved in muscle contraction but do not specifically contribute to rebounding muscle shape after stretch and resisting excessive stretch.

In muscle contraction, the cross-bridges formed by myosin heads act as motors to generate tension by interacting with actin filaments through a series of molecular events involving ATP and sliding filaments. The incorrect answers do not accurately describe the role of the cross-bridges in muscle contraction.

Muscle tissue is specialized for contraction. The three types of muscle tissue are Skeletal (striated and voluntary), Smooth (non-striated and involuntary), and Cardiac (striated and involuntary).

Muscle fibers are the building blocks of muscle tissue and play a critical role in muscle contraction. They are distinct from other types of cells in the body, such as nerve cells or skin cells.

Myofilaments are the filaments that make up myofibrils in muscle cells, not a type of cell, hormone, or protein.

The Sarcolemma is specifically related to muscle fibers and is not associated with proteins in milk, bones in the upper arm, or brain functions.

Excitability in muscles specifically refers to their ability to receive and respond to a stimulus accordingly. This is essential for muscle contraction and movement.

Muscles primarily respond to neurotransmitters and pH changes as the two main chemical stimuli that trigger reactions in the muscle. Temperature changes, light exposure, and hormonal fluctuations do not directly stimulate muscle responses.

Contractility refers to the ability of muscle fibers to shorten when a stimulus is present, leading to movement.

Extensibility refers to the ability of a material or technology to be stretched or extended without breaking or losing functionality.

Elasticity refers to the property of a material or structure to return to its original shape or size after being deformed by an external force. It is not about the ability to stretch indefinitely without breaking, harden under pressure, or conduct electricity efficiently.

Skeletal muscles are the only type of muscle that can be consciously controlled by the individual. Cardiac muscle is found in the heart and contracts involuntarily. Smooth muscles are found in various internal organs and are also involuntary. Involuntary muscles are muscles that are not under conscious control, unlike skeletal muscles.

Smooth and Cardiac muscles are controlled involuntarily by the autonomic nervous system, whereas Skeletal muscles are under voluntary control by the somatic nervous system. Therefore, Skeletal and Smooth, Cardiac and Skeletal, and Voluntary and Cardiac are incorrect choices.

Contracting muscle tissue requires a lot of oxygen and energy while also producing waste products. Extensive capillary branching helps in bringing in oxygen and nutrients, as well as removing waste like carbon dioxide and lactic acid to support continuous muscle contractions.

Muscles are responsible for various functions in the body, but digestion of food, transport of oxygen in the blood, and regulation of body temperature are not among the primary functions of muscles.

Insertion in anatomy refers to the attachment of a muscle to a bone, particularly the more movable bone. It is an essential concept in understanding how muscles function and move the body.

Origin, in the context of muscle anatomy, specifically refers to a type of muscle attachment to bone where the muscle is attached to a less movable bone. This definition is specific to muscle origins and does not refer to other general meanings of the term.

When a muscle acts as a syncytium, all muscle cells are fused together and contract at essentially the same time.