A&p Muscle And Nervous System

The correct answer is "thick." This is because myosin is a protein that is found in the thick filaments of muscle fibers. The thick filaments are responsible for generating force during muscle contraction. On the other hand, the thin filaments contain actin, another protein involved in muscle contraction. Therefore, the statement that the structure contains myosin indicates that it is referring to the thick filaments.

The correct answer is neuromuscular junctions. These junctions are the sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal muscle cell membranes. At the neuromuscular junction, the nerve ending releases a chemical called acetylcholine, which binds to receptors on the muscle cell membrane, causing the muscle to contract. This communication between the nerve and muscle is essential for muscle movement and coordination. Sacromeres, myofilaments, and Z discs are all components of the muscle cell structure, but they are not directly involved in the transmission of nerve impulses.

A contraction elicited by a single brief stimulus is called a "twitch." This means that when a muscle receives a single stimulus, it contracts and then relaxes. It is a quick and isolated contraction that occurs in response to a single signal from the nervous system. This is in contrast to other options such as wave summation, multiple motor unit summation, and fused tetanus, which involve sustained or repeated contractions that are not elicited by a single brief stimulus.

Ependymal cells are a type of glial cell that line the cavities of the brain. They are responsible for producing cerebrospinal fluid (CSF) and helping to circulate it throughout the brain and spinal cord. Ependymal cells have cilia on their surface, which aid in the movement of CSF. These cells also play a role in regulating the chemical composition of the CSF and providing structural support to the brain. Overall, ependymal cells contribute to the maintenance of a stable brain environment and the proper functioning of the central nervous system.

The correct answer is obicularis oculi because this muscle is responsible for squinting the eye. The corrugator supercilii muscle is involved in frowning and wrinkling the forehead, while the zygomaticus muscle is responsible for smiling. Therefore, the obicularis oculi is the most appropriate name for the muscle that squints the eye.

Thick filaments in muscle cells contain ATPases. ATPases are enzymes that hydrolyze ATP, releasing energy that is necessary for muscle contraction. These ATPases are found in the myosin heads of the thick filaments. When ATP is hydrolyzed, the energy released is used to power the sliding of the thick and thin filaments, leading to muscle contraction. Therefore, the correct answer is "Thick".

Microglia are a type of phagocytic cells found in the central nervous system (CNS). They are the resident immune cells in the brain and spinal cord, responsible for immune surveillance and defense against pathogens. Microglia are derived from macrophages and play a crucial role in maintaining brain homeostasis. They are involved in the clearance of dead cells, debris, and pathogens through phagocytosis. Additionally, microglia also participate in neuroinflammation and contribute to the immune response in the CNS. Therefore, microglia is the correct answer in this context.

The zygomaticus muscle is responsible for smiling. When this muscle contracts, it pulls the corners of the mouth upward, creating a smile. The other two muscles mentioned, obicularis oris and corrugator supercilii, are not specifically associated with smiling. The obicularis oris muscle is responsible for puckering the lips, while the corrugator supercilii muscle is involved in frowning or furrowing the eyebrows. Therefore, zygomaticus is the correct answer as it is directly related to the action of smiling.

A fascicle is a bundle of muscle fibers enclosed by a connective tissue sheath. This sheath, known as the perimysium, provides support and protection to the muscle fibers within the fascicle. The fascicle is a structural unit of a muscle and is responsible for transmitting force generated by the muscle fibers to produce movement.

Schwann cells are responsible for myelinating nerve fibers in the peripheral nervous system (PNS). Myelination is the process of forming a protective covering around nerve fibers, which allows for faster and more efficient conduction of electrical impulses. Schwann cells wrap around individual nerve fibers, forming multiple layers of myelin sheaths. In contrast, oligodendrocytes are responsible for myelinating nerve fibers in the central nervous system (CNS), and microglia are immune cells that protect the CNS by removing damaged cells and foreign substances. Therefore, the correct answer is Schwann cell.

Aerobic respiration of glucose provides the highest yield of ATP per glucose molecule. During aerobic respiration, glucose is broken down completely in the presence of oxygen, leading to the production of a large amount of ATP through the processes of glycolysis, the Krebs cycle, and oxidative phosphorylation. This process is highly efficient and can generate up to 36-38 ATP molecules per glucose molecule. In contrast, anaerobic glycolysis produces only 2 ATP molecules per glucose molecule, and the coupled reaction of creatine phosphate with ADP produces a small amount of ATP as well. Therefore, aerobic respiration of glucose yields the most ATP.

The occipital belly of the epicranius muscle is responsible for pulling the scalp posteriorly. This muscle is located at the back of the head and connects to the frontalis muscle via the epicranial aponeurosis. When the occipital belly contracts, it causes the scalp to move backward, helping to create facial expressions like raising the eyebrows or wrinkling the forehead.

Heavily myelinated, large-diameter fibers have the greatest velocity of nerve impulse conduction because myelin acts as an insulating layer that allows for faster transmission of electrical signals. Additionally, the larger diameter of these fibers allows for less resistance to the flow of ions, further increasing the speed of conduction. On the other hand, myelinated, small-diameter fibers have a slower conduction velocity due to their smaller size and unmyelinated fibers have the slowest conduction velocity as they lack the insulation provided by myelin.

The diaphragm is the primary muscle responsible for inspiration. It contracts and moves downward, causing the thoracic cavity to expand and the lungs to fill with air. This creates a pressure gradient that allows air to flow into the lungs. The internal and external intercostal muscles also play a role in inspiration by helping to elevate the ribcage and expand the chest cavity. The abdominal wall muscles are primarily involved in expiration by compressing the abdominal contents and pushing air out of the lungs.

The statement "attaches to the Z disc" refers to the attachment of a structure to the Z disc. In the context of muscle anatomy, the Z disc is a protein structure that anchors the thin filaments. The thin filaments, composed of actin, are responsible for muscle contraction. Therefore, the correct answer is "thin" since the thin filaments attach to the Z disc.

Astrocytes are a type of glial cell found in the central nervous system (CNS). One of their main functions is to regulate the ionic composition of the extracellular fluid in the CNS. They help maintain the balance of ions such as potassium, sodium, and calcium, which is crucial for proper neuronal function. Astrocytes also play a role in neurotransmitter clearance and recycling, as well as providing structural support to neurons. Therefore, astrocytes are the correct answer as they are directly involved in regulating the ionic composition of the CNS extracellular fluid.

The correct answer is "Thin" because thin filaments in muscle cells contain a protein called troponin. Troponin plays a crucial role in muscle contraction by regulating the interaction between actin and myosin filaments. It helps in the binding of calcium ions, which triggers the movement of the thin filaments and leads to muscle contraction. On the other hand, thick filaments are composed of myosin protein and are responsible for generating the force during muscle contraction.

Aerobic respiration of glucose is the most important in endurance sports because it provides a sustained and efficient energy supply. Endurance activities require prolonged periods of energy production, and aerobic respiration can generate ATP (adenosine triphosphate) continuously by breaking down glucose in the presence of oxygen. This process produces a large amount of ATP, allowing athletes to maintain their performance for extended periods. In contrast, the other options, such as the coupled reaction of creatine phosphate with ADP and anaerobic glycolysis, provide energy for shorter bursts but are not as efficient or sustainable for endurance activities.

Myoglobin is a protein found in muscle tissue that has a high affinity for oxygen. It binds to oxygen molecules and stores them within the muscle cells, providing a reserve supply of oxygen for when it is needed during periods of increased activity or low oxygen availability. This allows the muscle to continue functioning properly even when oxygen levels are low, such as during strenuous exercise. Therefore, the statement "holds a reserve supply of oxygen in the muscle" accurately describes the special function of myoglobin in muscle tissue.

The statement "Contains actin" indicates that the filament being described is thin. Actin is a protein that makes up the thin filaments in muscle cells. Thick filaments, on the other hand, are composed of the protein myosin. Since actin is mentioned, it implies that the filament being referred to is thin.

The given statement states that (6) does not lie in the I band. Since the options are "Thick" and "Thin," we can infer that the I band represents a region associated with thin filaments. Therefore, if (6) does not lie in the I band, it must be associated with thick filaments.

Somatic motor neurons are responsible for transmitting signals from the central nervous system to skeletal muscles, causing them to contract. The neurotransmitter released by these neurons is acetylcholine. Acetylcholine binds to receptors on the muscle fibers, leading to the generation of an action potential and subsequent muscle contraction. Acetylcholine is then broken down by the enzyme acetylcholinesterase to prevent continuous muscle contraction. Norepinephrine is not released by somatic motor neurons, but rather by the sympathetic nervous system to regulate functions such as heart rate and blood pressure.

The correct answer is orbicularis oris because this muscle is responsible for puckering the lips. It is a circular muscle that surrounds the mouth and allows for movements such as closing and protruding the lips. The other two muscles mentioned, depressor anguli oris and orbicularis oculi, are not directly involved in puckering the lips.

The correct answer is the frontal belly of epicranius. The frontal belly of epicranius is a muscle located in the forehead region. When this muscle contracts, it raises the eyebrows, causing a visible movement in that area. The occipital belly of epicranius is located at the back of the head and is responsible for pulling the scalp backward. The depressor anguli oris is a muscle in the lower face that pulls the corners of the mouth downward. Therefore, the most appropriate answer in this context is the frontal belly of epicranius, as it specifically relates to raising the eyebrows.

A nerve is not part of the central nervous system. The central nervous system consists of the brain and spinal cord, which are responsible for processing and coordinating information. Nerves, on the other hand, are part of the peripheral nervous system, which connects the central nervous system to the rest of the body. Nerves transmit signals to and from the central nervous system, allowing for communication between the brain and other parts of the body. Therefore, a nerve is not considered part of the central nervous system.

The quadriceps are a group of muscles located in the front of the thigh. They include the vastus lateralis, vastus intermedius, and vastus medialis, all of which are responsible for extending the knee joint. The biceps femoris, on the other hand, is a muscle located in the back of the thigh and is part of the hamstring muscle group, not the quadriceps. The rectus femoris is also a quadriceps muscle responsible for extending the knee and flexing the hip joint. Therefore, the biceps femoris is the correct answer as it is not included in the quadriceps muscle group.

Aerobic respiration of glucose produces carbon dioxide and water as byproducts. During this process, glucose is broken down in the presence of oxygen to produce energy, carbon dioxide, and water. This occurs in the mitochondria of cells and is the most efficient way to generate ATP (adenosine triphosphate) for cellular energy. The carbon dioxide produced is transported to the lungs and eliminated through exhalation, while water is either used by the body or excreted through various processes.

Single unit smooth muscle is the correct answer because it is found in the walls of digestive and urinary system organs, and it exhibits gap junctions and pacemaker cells. Single unit smooth muscle cells are connected by gap junctions, allowing for coordinated contractions. They also contain pacemaker cells, which are specialized cells that generate electrical impulses to initiate contractions. This type of smooth muscle is responsible for the rhythmic contractions seen in organs like the stomach and bladder. Multiunit smooth muscle, on the other hand, consists of individual muscle fibers that contract independently and is found in structures like blood vessels and the iris of the eye.

When an EPSP (Excitatory Postsynaptic Potential) is generated on the dendritic membrane, a single type of channel will open, allowing the simultaneous flow of Na+ (sodium) and K+ (potassium) ions. This is known as a non-selective cation channel. The opening of these channels allows both Na+ and K+ ions to move across the membrane, which can depolarize the neuron and contribute to the generation of an action potential.

Acetylcholine is not a biogenic amine neurotransmitter. Biogenic amine neurotransmitters are a specific group of neurotransmitters that are derived from amino acids and play important roles in the central nervous system. Norepinephrine, dopamine, and serotonin are all examples of biogenic amine neurotransmitters. Acetylcholine, on the other hand, is a neurotransmitter that is derived from choline and is not classified as a biogenic amine.

During the steep phase of repolarization, the axolemma experiences a change in electrical potential, causing the cell to return to its resting state. This is primarily achieved through the movement of potassium ions out of the cell. As potassium channels open, potassium ions flow out of the cell, leading to an efflux of positive charge and repolarization. Therefore, the correct answer is chiefly a potassium current.

The T tubules in muscle contraction are responsible for transmitting the action potential deep into the muscle cells. This allows for synchronized contraction of the entire muscle fiber. The action potential travels along the T tubules, triggering the release of calcium ions from the sarcoplasmic reticulum, which then initiates the sliding of the actin and myosin filaments, leading to muscle contraction. Therefore, the T tubules play a crucial role in the excitation-contraction coupling process in muscles.

During action potential generation in skeletal muscles, sodium ions enter the cell. This influx of sodium ions occurs through voltage-gated sodium channels, which open in response to depolarization of the cell membrane. This influx of sodium ions helps to further depolarize the cell, leading to the propagation of the action potential along the muscle fiber. The other ions mentioned, calcium, chloride, and potassium, also play important roles in muscle function, but they are not primarily responsible for the initial depolarization and generation of the action potential.

Chemical synapses are characterized by the release of neurotransmitter by the presynaptic membranes, postsynaptic membranes bearing receptors that bind neurotransmitter, and a fluid-filled gap separating the neurons. However, ions flowing through protein channels from the presynaptic to the postsynaptic neuron is not a characteristic of chemical synapses. Instead, this is a characteristic of electrical synapses, where ions directly flow from one neuron to another through gap junctions.

In converging neural pathways, many neurons send signals to a smaller number of neurons. This allows for the integration of information from multiple sources and the processing of complex stimuli. The converging pathway is important for sensory perception, decision-making, and memory formation. It ensures that different inputs are combined and processed in a coordinated manner, leading to a more accurate and efficient neural response.

Parallel after-discharge refers to a neural circuit where a single stimulus can activate multiple pathways simultaneously, leading to prolonged and synchronized firing of neurons. This type of circuit is often associated with complex mental activities such as problem-solving, decision-making, and memory retrieval. Therefore, the statement suggests that (4) may be involved in exacting types of mental activity, as it describes a neural circuit that allows for the simultaneous activation and synchronization of multiple pathways.

The biceps brachii is the correct answer because it is the muscle that both flexes the elbow and supinates the forearm. The brachialis muscle also flexes the elbow, but it does not have the ability to supinate the forearm. The brachioradialis muscle is responsible for flexing the elbow, but it does not supinate the forearm. The triceps brachii muscle is responsible for extending the elbow, but it does not flex or supinate the forearm.

Isometric contractions are characterized by the absence of shortening. Unlike isotonic contractions where the muscle changes length, isometric contractions occur when the muscle contracts but does not change in length. This means that there is no shortening of the muscle during an isometric contraction. The other characteristics mentioned in the options, such as increased muscle tension throughout the contraction phase and the use of isometric contractions in resistance training, are true for isometric contractions.

The coupled reaction of creatine phosphate with ADP provides ATP the fastest. Creatine phosphate is a high-energy molecule that can quickly donate its phosphate group to ADP, forming ATP. This reaction occurs in the cytoplasm of muscle cells and does not require oxygen, making it readily available for immediate energy needs during muscle contraction. In contrast, aerobic respiration of glucose requires oxygen and takes place in the mitochondria, which takes longer to produce ATP. Anaerobic glycolysis also occurs in the cytoplasm but is less efficient than creatine phosphate reaction, resulting in slower ATP production. Therefore, the coupled reaction of creatine phosphate with ADP is the fastest source of ATP during muscle contraction.

Anaerobic glycolysis is the process that results in the formation of lactic acid. During anaerobic glycolysis, glucose is broken down into pyruvate in the absence of oxygen. However, since there is no oxygen available to further metabolize the pyruvate, it is converted into lactic acid. This process occurs in various tissues and cells, such as muscle cells, when there is a high demand for energy and insufficient oxygen supply. The accumulation of lactic acid can lead to muscle fatigue and discomfort.

Inhibition of acetylcholinesterase prevents the breakdown of acetylcholine (ACh), leading to its accumulation in the synaptic cleft. This excess ACh continuously stimulates the postsynaptic cell, causing prolonged depolarization. This prolonged depolarization can lead to muscle spasms and paralysis, as neurotransmission is disrupted and the normal balance of excitation and inhibition is disturbed.

Diverging is the correct answer because it refers to the process in which one or a few inputs influence large numbers of neurons. In a diverging pathway, a single input signal branches out and activates multiple neurons, leading to the spread of information across different neural circuits. This allows for the amplification and distribution of signals, enabling widespread communication and processing in the nervous system.

A synergist is a muscle that assists an agonist by causing a similar movement or by stabilizing a joint over which the agonist acts. This means that the synergist works together with the agonist to produce a coordinated movement. It helps to enhance the action of the agonist and ensure smooth and efficient movement.

The correct answer is endomysium. The endomysium is the connective tissue covering that surrounds and protects the sarcolemma, which is the cell membrane of a muscle fiber. It is the innermost layer of connective tissue and provides support and insulation for the individual muscle fiber. The epimysium, perimysium, and periosteum are also connective tissues, but they do not specifically enclose the sarcolemma of a muscle fiber.

The correct answer is "reverberating." In a reverberating neuronal circuit, impulses continue to travel in a loop, causing a continuous feedback loop and the firing of neurons in a repetitive pattern. This type of circuit is commonly found in processes such as breathing, where the repetitive firing of neurons is necessary for the continuous movement of muscles involved in respiration.

The gluteus maximus is the correct answer because it is the largest and strongest muscle in the gluteal region. It is responsible for extending the hip joint against resistance, such as when standing up from a seated position or climbing stairs. The gluteus medius, biceps femoris, and semi-membranosus are also muscles involved in hip movement, but they do not primarily function as the prime mover for hip extension against resistance.

Aerobic exercise primarily focuses on improving cardiovascular health and endurance rather than increasing muscle size and strength. During aerobic exercise, the body utilizes oxygen to produce energy, leading to increased efficiency of the cardiovascular system. Additionally, aerobic exercise promotes the development of more mitochondria in muscle cells, which enhances their ability to produce energy. Moreover, aerobic exercise improves neuromuscular system coordination, allowing for better control and coordination of muscle movements. However, it does not directly cause significant increases in the size and strength of existing muscle cells, which is typically associated with resistance training.

The iliopsoas muscle is a prime mover of hip flexion. It is composed of two muscles, the iliacus and the psoas major, which work together to flex the hip joint. The rectus femoris is also involved in hip flexion, but it is not the primary muscle responsible for this movement. The vasti muscles are a group of muscles in the quadriceps that primarily extend the knee, not flex the hip. The gluteus maximus is a hip extensor, meaning it works to straighten the hip joint rather than flex it. Therefore, the correct answer is iliopsoas.

An IPSP is inhibitory because it hyperpolarizes the postsynaptic membrane. Hyperpolarization refers to an increase in the membrane potential, making it more negative than the resting potential. This makes it harder for an action potential to be generated, reducing the likelihood of the neuron firing. Therefore, when an IPSP hyperpolarizes the postsynaptic membrane, it inhibits the transmission of signals between neurons, preventing the generation of an action potential and ultimately inhibiting neuronal activity.

Pennate muscle fibers are arranged at an angle to a central longitudinal tendon. This arrangement allows for a greater number of muscle fibers to be packed into a smaller space, resulting in increased strength and force generation. The angle of the fibers can vary, with some pennate muscles having a more oblique angle and others having a more perpendicular angle to the tendon. This arrangement is commonly found in muscles that require a lot of strength, such as the quadriceps in the thigh.