Mcat Biology Ch. 11 The Musculoskeletal System

Skeletal muscle is attached to bones and is responsible for voluntary movements. Smooth muscle is found in internal organs and is involuntary. Cardiac muscle is found in the heart and is responsible for pumping blood.

Skeletal muscle is mainly involved in support, movement, and various other functions related to movement and thermoregulation. It is characterized by being multinucleated, striated, and under voluntary control. The two main types of fibers are red (slow-twitch) fibers and white (fast-twitch) fibers, each with distinct metabolic pathways.

Smooth muscle is not limited to the skeletal system, is nonstriated (not striped), and is under involuntary control. Additionally, it is uninucleated and exhibits myogenic activity, distinguishing it from other types of muscle tissue.

Cardiac muscle is specialized muscle tissue found in the heart with unique characteristics such as striations, involuntary control, and myogenic activity, which differentiate it from smooth muscle, skeletal muscle, and nervous tissue.

Red fibers, also known as slow-twitch fibers, have specific characteristics that distinguish them from other types of muscle fibers. Understanding these characteristics is essential in the study of muscle physiology and exercise science.

White fibers, also known as fast-twitch fibers, are characterized by their ability to contract quickly and generate high force. They contain much less myoglobin than red fibers, giving them a white color. In terms of energy production, white fibers primarily derive energy through anaerobic pathways.

Intercalated discs and gap junctions specifically facilitate the flow of ions between cardiac muscle cells, allowing for rapid and coordinated muscle depolarization for efficient contraction.

A sarcomere is the fundamental unit of a muscle's structure and function, responsible for muscle contraction. It is not related to cells in the liver, skin layers, or bone joints.

Troponin and Tropomyosin are proteins found on the thin filament in muscle cells and play a crucial role in regulating muscle contractions by controlling the interactions between actin and myosin. The incorrect answers provide false information about their locations and functions, highlighting the importance of understanding their specific roles in muscle physiology.

The components of the sarcomere play crucial roles in muscle contraction and relaxation. The M-Line, I-Band, H-Zone, and A-Band all have specific functions within the sarcomere, contributing to the overall contraction process. The incorrect answers provided do not accurately represent the structures found within the sarcomere.

Myofibrils are composed of sarcomeres that attach end to end to form the structure. Sarcomeres are the basic contractile units of muscle fibers.

Myocytes are specialized muscle cells that play a crucial role in muscle contraction. They are distinct from nerve cells, bone cells, and skin cells in terms of structure and function.

The sarcoplasmic reticulum is a structure that surrounds myofibrils in muscle cells and is responsible for storing and releasing calcium ions during muscle contractions. It is not involved in digestion, red blood cell production, or blood sugar regulation.

The sarcolemma specifically refers to the cell membrane of a myocyte, which is a muscle cell. It plays a crucial role in muscle contraction and function.

T-Tubules play a crucial role in transmitting signals throughout muscle cells, allowing for coordinated muscle contractions. The incorrect answers provided do not accurately describe the function of T-Tubules.

The correct answer explains the process of muscle contraction at the Neuromuscular Junction, highlighting the role of acetylcholine released by motor neurons. The incorrect answers are unrelated functions to the Neuromuscular Junction, which do not involve the process of muscle contraction.

The Sliding Filament Model involves the interaction of myosin heads with actin filaments to produce muscle contraction by sliding the filaments past each other. Option A is incorrect as it describes the opposite effect of muscle contraction. Option B is incorrect as it suggests no interaction between myosin and actin, which is essential for muscle contraction. Option C is incorrect as it describes an incorrect mechanism where actin pushes and stretches myosin, which is not how the contraction process occurs.

In muscle contraction, the sequence of events involves an all or nothing response of muscle cells, a latent period where action potential spreads allowing calcium release, followed by the contraction period and relaxation period as described in the correct answer.

Frequency summation in muscle physiology refers to the phenomenon where multiple stimuli are provided to a muscle before it fully relaxes, leading to a graded muscle response. This process is crucial for generating sustained muscle contractions.

Tetanus is characterized by the continuous contraction of muscles leading to spasms and stiffness. It is caused by the bacterium Clostridium tetani and is commonly known as lockjaw.

Oxygen Debt is specifically related to the difference between the amount of oxygen needed and the amount present in the body after intense exercise. It is not about the immediate oxygen levels in the blood, carbon dioxide exhalation, resting oxygen consumption rate, or hemoglobin saturation.

The correct muscle energy reserves are Creatine Phosphate and Myoglobin, while Glycogen is used for storing energy but not considered as an immediate energy reserve, Lactic Acid is a byproduct of metabolism, and Cholesterol is not directly involved in energy production.

Endoskeletons are internal skeletons that provide support and protection for an organism's body. They are typically found in vertebrates, like humans, as opposed to exoskeletons which are external skeletons found in arthropods and some other invertebrates.

Bones are primarily classified into two main types - compact and spongy. Compact bone provides strength due to its dense nature, forming the outer layer of bones. Spongy bone, also known as cancellous bone, has a lattice-like structure with bony spicules called trabeculae and is filled with bone marrow. The incorrect answers do not accurately describe the main types of bone.

Long bones are composed of three main parts: the diaphyses, which is the thin shaft in the middle; the metaphyses, which are where the diaphyses flares out; and the epiphyses, which are where the metaphyses end.

The Epiphyseal Growth Plate is located in the epiphyses of bones and its main function is to promote longitudinal growth of bones during childhood and adolescence.

The periosteum is a connective tissue layer that surrounds bones, providing important functions such as nourishing bones and assisting in bone repair and growth.

Tendons are fibrous connective tissues that connect muscles to bones, allowing for movement and providing stability to the skeletal system.