Chapter 9 Muscles And Muscle Tissue

Cardiac and skeletal muscle are both striated because they have a striped appearance due to the arrangement of the filaments within the muscle cells.

Cardiac and smooth muscles are classified as involuntary muscles because they are not under conscious control, unlike voluntary muscles which can be consciously controlled by the individual. The terms 'flexible' and 'rigid' do not accurately describe the nature of these muscles.

Smooth muscle is responsible for involuntary movements and is commonly found in the listed locations, with airways being one of the key areas where smooth muscle is present.

Skeletal muscle cells, also known as muscle fibers, are responsible for movement in the body.

Epimysium is the outermost layer of connective tissue that surrounds an entire skeletal muscle. Endomysium surrounds individual muscle fibers, perimysium surrounds bundles of muscle fibers, and myosin is a type of protein found in muscle tissue.

Perimysium is the connective tissue that surrounds each bundle of muscle fibers, while endomysium encases individual muscle fibers, epimysium surrounds the entire muscle, and superficial fascia is a layer of connective tissue beneath the skin.

Fascicles are bundles of muscle fibers surrounded by endomysium in a muscle. While endomysium and muscle fibers are also components of muscle structure, fascicles specifically refer to bundles of muscle fibers.

The sarcoplasm is the correct answer because it is the cytoplasm of a muscle cell and plays a crucial role in muscle contraction. The mitochondria, nucleus, and cytoskeleton are important components of muscle cells but do not directly constitute the functional unit of muscle contraction like the sarcolemma, sarcoplasmic reticulum, and sarcoplasm.

Thin myofilaments are primarily made up of actin and troponin, with tropomyosin regulating the interaction between actin and myosin. Myokinase is not a component of thin myofilaments.

The sarcoplasmic reticulum of muscle fibers is responsible for storing calcium ions and releasing them when stimulated by action potential to initiate muscle contraction.

T-tubules are invaginations of the sarcolemma in striated muscle cells that play a key role in excitation-contraction coupling.

An action potential is a rapid change in voltage from negative to positive values across a membrane, indicating a significant shift in electrical charge. The word 'value' accurately describes this shift in voltage.

Resting membrane potential is maintained by the sodium potassium ATP pump, which helps in maintaining the concentration gradients of sodium and potassium ions across the cell membrane.

Acetyl choline is a neurotransmitter that is released from vesicles in the synaptic knob of neurons, not muscle cells, glands, or synapses.

Excitation-Contraction Coupling is the process by which an electrical signal triggers the release of calcium and leads to muscle contraction. The correct sequence involves nerve signal, release of calcium, acetylcholine diffusion, conformational changes, potassium gate opening, depolarization, calcium binding to troponin, exposure of active sites, and ATP causing release of G-Actin.

Motor units are composed of a motor neuron and the muscle fibers it innervates, allowing for voluntary muscle control.

The correct answer is 'stimulation' because the level of muscle tension and force of contraction are influenced by the activity or signal that triggers the muscle to contract, which is typically stimulation from the nervous system.

Concentric muscle contraction refers to when the muscle shortens and causes movement (e.g. lifting a weight up). In contrast, eccentric muscle contraction involves the muscle lengthening while under tension as it resists a force (e.g. lowering a weight down).