Exercise Physiology - Qp4

Sarcomeres have a highly organized structure and are composed of two protein-based myofilaments. These myofilaments are called actin and myosin. Actin filaments are thin and extend from the Z-discs towards the center of the sarcomere, while myosin filaments are thick and are located in the center of the sarcomere, overlapping with actin filaments. The interaction between actin and myosin filaments is responsible for muscle contraction. Therefore, sarcomeres consist of these two types of myofilaments, making the correct answer "two".

The brain and spinal cord are referred to as the central nervous system because they are the main components responsible for coordinating and controlling the body's activities. The central nervous system receives and processes information from the senses, sends signals to the muscles and organs, and regulates bodily functions. The parasympathetic and sympathetic nervous systems are components of the autonomic nervous system, which works in conjunction with the central nervous system to regulate involuntary bodily functions.

Motor neurones, also known as nerves, consist of three main components: the cell body and the axon. The cell body is the central part of the neurone, containing the nucleus and other organelles necessary for its functioning. The axon, on the other hand, is a long, slender projection that transmits electrical impulses from the cell body to other neurons or muscle cells. The nuclei, which are not mentioned in the given options, are clusters of cell bodies found within the central nervous system. Therefore, the correct answer is the cell body and the axon.

The relaxation of muscle is not an active process. When a muscle relaxes, it is actually returning to its resting state passively, without requiring any active effort or energy expenditure. This is in contrast to muscle contraction, which is an active process that requires the expenditure of energy. Therefore, the statement that the relaxation of muscle is an active process is false.

The statement is false because proprioceptors are not located between skeletal muscle fibers. Proprioceptors are sensory receptors that are located in muscles, tendons, and joints, and they provide information about body position and movement. They play a crucial role in maintaining balance and coordinating movements.

The explanation for the given correct answer is that the muscle belly, which refers to the main body of the muscle, is indeed surrounded by a dense and protective connective tissue called epimysium. This epimysium serves as a sheath that encloses the muscle and provides structural support, allowing the muscle to contract and generate force effectively. It also helps to maintain the shape and integrity of the muscle. Therefore, the statement "The muscle belly is completely surrounded by a thick connective tissue called epimysium" is true.

The statement given in the question is incorrect. The action of the sliding filaments during contraction does not cause lengthening of all sarcomeres and muscle fibers. Instead, it causes the sarcomeres to shorten, resulting in the contraction of the muscle fibers. Therefore, the correct answer is False.

The myelin sheath is not continuous. It is made up of individual segments called internodes, which are separated by small gaps called nodes of Ranvier. This non-continuous structure allows for saltatory conduction, where the electrical signal jumps from one node to the next, increasing the speed of nerve impulse transmission.

The All or None Law is a principle in physiology that states that when a motor unit, which consists of a motor neuron and the muscle fibers it innervates, receives a stimulus that is strong enough to elicit a response, all the muscle fibers within that unit will contract simultaneously and to their maximum extent. This means that either all the muscle fibers contract or none of them do, there is no in-between. Therefore, the statement "all the muscle fibers within the unit will contract at the same time, and to the maximum possible extent" accurately describes the All or None Law, making the answer true.

The Golgi tendon organs are not thick capsules of connective tissue. They are actually sensory receptors located within the tendons near the muscle-tendon junction. These receptors are responsible for detecting changes in muscle tension and transmitting this information to the central nervous system. Therefore, the statement that Golgi tendon organs are thick capsules of connective tissue is incorrect.