1.
Which of the following structures is not part of the central nervous system?
Correct Answer
B. A nerve
Explanation
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.
2.
Identify which type(s) of supporting cell is being described. Myelinates nerve fibers in the CNS
Correct Answer
F. Schwann cell
Explanation
The correct answer is schwann cell. Schwann cells are a type of supporting cell that myelinates nerve fibers in the peripheral nervous system (PNS). They wrap around and insulate nerve fibers, allowing for faster transmission of electrical signals. In contrast, oligodendrocytes are the type of supporting cells that myelinate nerve fibers in the central nervous system (CNS). Astrocytes, ependymal cells, microglia, satellite cells are other types of supporting cells in the nervous system with different functions.
3.
Lines brain cavities
Correct Answer
B. Ependymal cell
Explanation
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.
4.
Myelinates nerve fibers in the PNS
Correct Answer
A. Schwann cell
Explanation
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.
5.
CNS Phagocytes
Correct Answer
B. Microgilia
Explanation
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.
6.
Helps regulate the ionic composition of CNS extracellular fluid
Correct Answer
A. Astrocytes
Explanation
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.
7.
What type of current flows through the axolemma during the steep phase of repolarization?
Correct Answer
B. Chiefly a potassium current
Explanation
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.
8.
Assume that an EPSP is being generated on the dendritic membrane. Which will occur?
Correct Answer
C. A single type of channel will open, permitting simultaneous flow of Na+ and K+
Explanation
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.
9.
The velocity of nerve impulse conduction is greatest in
Correct Answer
A. Heavily myelinated, large-diameter fibers
Explanation
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.
10.
Chemical synapses are characterized by all of the following except
Correct Answer
C. Ions flowing through protein channels from the presynaptic to the postsynaptic neuron
Explanation
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.
11.
Biogenic amine neurotransmitters include all but
Correct Answer
B. Acetylcholine
Explanation
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.
12.
The neuropeptides that act as natural opiates are:
Correct Answer
D. EnkepHalins
Explanation
Enkephalins are neuropeptides that act as natural opiates. These small molecules are produced by the body and play a role in pain relief and mood regulation. They bind to specific receptors in the brain and spinal cord, inhibiting the transmission of pain signals and producing analgesic effects. Enkephalins are part of the endogenous opioid system, which also includes other natural opiates like endorphins. By binding to opioid receptors, enkephalins can produce feelings of euphoria and well-being.
13.
Inhibition of acetylcholinesterase by poisoning blocks neurotransmission at the neuromuscular junction because
Correct Answer
C. ACh is not degraded, hence prolonged depolarization is enforced on the posysynaptic cell
Explanation
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.
14.
The anatomical region of a multipolart neuron that has the lowest threshold for generating an AP is the
Correct Answer
C. Axon hillock
Explanation
The axon hillock is the correct answer because it is the region of a multipolar neuron that has the lowest threshold for generating an action potential (AP). The axon hillock is located at the junction between the soma (cell body) and the axon. It contains a high concentration of voltage-gated ion channels, particularly sodium channels, which are responsible for initiating and propagating the action potential. Due to its high density of ion channels, the axon hillock is more excitable than other regions of the neuron, such as the dendrites or the distal axon.
15.
An IPSP is inhibitory because
Correct Answer
A. It hyperpolarizes the posysynaptic membrane
Explanation
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.
16.
Identify the neuronal circuits described the choosing the correct response. (1) Impulses continue around and around the circuit until one neuron stops firing.
Correct Answer
D. Reverberating
Explanation
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.
17.
(2) One or a few inputs ultimately influence large numbers of neurons
Correct Answer
B. Diverging
Explanation
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.
18.
(3) Many neurons influence a few neurons
Correct Answer
A. Converging
Explanation
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.
19.
(4) may be involved in exacting types of mental activity
Correct Answer
C. Parallel after-discharge
Explanation
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.
20.
A muscle that assists an agonist by causing a like movement or by stabilizing a joint over which an agonist acts is
Correct Answer
C. Synergist
Explanation
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.
21.
The arrangement of muscle fibers in which the fibers are arranged at an angle to a central longitudinal tendon is
Correct Answer
C. Pennate
Explanation
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.
22.
Match the facial muscle description to the appropriate name. (1) Squints the eye
Correct Answer
C. Obicularis oculi
Explanation
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.
23.
(2) raises the eyebrows
Correct Answer
A. Frontal belly of epicranius
Explanation
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.
24.
(3) Smiling muscle
Correct Answer
B. Zygomaticus
Explanation
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.
25.
(4) Puckers the lips
Correct Answer
C. Orbicularis oris
Explanation
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.
26.
(5) Pulls the scalp posteriorly
Correct Answer
B. Occipital belly of epicranius
Explanation
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.
27.
The primer mover of inspiration is the
Correct Answer
A. DiapHragm
Explanation
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.
28.
The arm muscle that both flexes the elbow and supinates the forarm is the
Correct Answer
C. Biceps brachii
Explanation
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.
29.
The chewing muscles that protrude the mandible and produce side-to-side grinding movements are
Correct Answer
D. Pterygoids
Explanation
The chewing muscles that protrude the mandible and produce side-to-side grinding movements are the pterygoids. These muscles are located in the jaw and are responsible for moving the mandible from side to side during chewing. The pterygoids work in conjunction with other muscles such as the masseters and temporalis to facilitate proper chewing and grinding of food.
30.
Muscles that depress the hyoid bone and larnyx include all but the
Correct Answer
C. Geniohyoid
Explanation
The geniohyoid muscle is not involved in depressing the hyoid bone and larynx. The sternohyoid, omohyoid, and sterno-thyroid muscles are responsible for depressing the hyoid bone and larynx.
31.
Intrinsic muscles of the back that promote extension of the spine (or head) include all but
Correct Answer
C. Scalene muscles
Explanation
The scalene muscles are not intrinsic muscles of the back that promote extension of the spine. The scalene muscles are located in the neck and are responsible for various movements of the neck, such as lateral flexion and rotation. They do not directly contribute to the extension of the spine or head. On the other hand, the splenius muscles, semispinalis muscles, and erector spinae are all intrinsic muscles of the back that play a role in promoting extension of the spine or head.
32.
Several muscles act to move and/or stabilize the scapula. Which of the following are small rectangular muscles that square the shoulders as they act together to retract the scapula?
Correct Answer
B. Rhomboids
Explanation
The rhomboids are small rectangular muscles that act together to retract the scapula. When these muscles contract, they pull the scapula towards the midline of the body, helping to square the shoulders. The levator scapulae muscle helps elevate the scapula, the serratus anterior muscle protracts the scapula, and the trapezius muscle has multiple functions including elevating, retracting, and rotating the scapula. Therefore, the correct answer is rhomboids.
33.
The quadriceps include all but
Correct Answer
D. Biceps femoris
Explanation
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.
34.
A prime mover of hip flexion is the
Correct Answer
B. Iliopsoas
Explanation
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.
35.
The prime mover of hip extension against resistance is the
Correct Answer
A. Gluteus maximus
Explanation
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.
36.
Muscles that cause plantar flexion include all but the
Correct Answer
C. Tibialis anterior
Explanation
The muscles that cause plantar flexion are the gastrocnemius, soleus, tibialis posterior, and fibularis muscles. The tibialis anterior is the only muscle listed that does not cause plantar flexion. Instead, it is responsible for dorsiflexion, which is the movement that lifts the foot upwards.
37.
In walking, which two lower limb muscles keep the forward-swinging foot from dragging on the ground?
Correct Answer
D. Gluteus medius and tibialis anterior
Explanation
The gluteus medius and tibialis anterior muscles play a role in keeping the forward-swinging foot from dragging on the ground during walking. The gluteus medius, located in the hip, helps to stabilize the pelvis and prevent excessive hip drop, allowing for a smooth and efficient gait. The tibialis anterior, located in the front of the lower leg, is responsible for dorsiflexion of the foot, which lifts the toes and prevents them from dragging on the ground during the swing phase of walking.
38.
Which criterion (or criteria) are used in naming the gluteus medius?
Correct Answer(s)
A. Relative size
B. Muscle location
Explanation
The criteria used in naming the gluteus medius are relative size and muscle location. The term "gluteus" refers to the muscle group it belongs to, which is the gluteal muscles. The term "medius" indicates its relative size compared to other muscles in the same group, suggesting that it is located in the middle or intermediate position.
39.
Which of the following is a large, deep muscle that protracts the scapula during punching?
Correct Answer
A. Serratus anterior
Explanation
The serratus anterior is a large, deep muscle that is responsible for protracting the scapula during punching. It is located on the lateral aspect of the rib cage and attaches to the scapula, allowing it to move forward and away from the spine. This muscle is important for stabilizing the scapula and providing the necessary movement for effective punching.
40.
The connective tissue covering that encloses the sarcolemma of an individual muscle fiber is called the
Correct Answer
C. Endomysium
Explanation
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.
41.
A fascicle is a
Correct Answer
B. Bundle of muscle fibers enclosed by a connective tissue sheath
Explanation
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.
42.
Thick and thin myofilaments have different compositions. For each descriptive phrase, indicate whether the filament is thick or thin. (1) Contains actin
Correct Answer
B. Thin
Explanation
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.
43.
(2) Contains ATPases
Correct Answer
A. Thick
Explanation
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".
44.
(3) attaches to the Z disc
Correct Answer
B. Thin
Explanation
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.
45.
(4) Contains myosin
Correct Answer
A. Thick
Explanation
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.
46.
(5) Contains troponin
Correct Answer
B. Thin
Explanation
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.
47.
(6) does not lie in the I band
Correct Answer
A. Thick
Explanation
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.
48.
The function of the T tubules in muscle contraction is to
Correct Answer
C. Transmit the action potential deep into the muscle cells
Explanation
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.
49.
The sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal muscle cell membranes are the
Correct Answer
A. Neuromuscular junctions
Explanation
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.
50.
Contraction elicited by a single brief stimulus is called a
Correct Answer
A. Twitch
Explanation
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.