Bioscience II : Test 1

The right carotid artery arises from the subclavian artery while the left carotid artery arises from the aortic arch.

The role of the Center in the conduction pathway is to receive incoming sensory impulses and generate an outgoing impulse. This suggests that the Center acts as a processing center, receiving information from sensory receptors and generating an appropriate response. It is responsible for interpreting the sensory input and initiating the appropriate motor output in response to changes in the internal or external environment.

The correct answer is 150 ml. Cerebrospinal fluid (CSF) is a clear, colorless fluid that surrounds the brain and spinal cord. It acts as a protective cushion, providing nutrients and removing waste products. The average adult has about 150 ml of CSF circulating in their body at any given moment. This fluid is constantly being produced and absorbed, maintaining a balance and ensuring the proper functioning of the central nervous system.

After leaving the cisterna magna, CSF flows into the subarachnoid space to circulate around the brain and spinal cord. The subarachnoid space is located between the arachnoid mater and the pia mater, and it is filled with CSF. This space allows for the distribution of CSF throughout the central nervous system, providing nutrients and removing waste products.

The efferent system is responsible for carrying signals from the central nervous system to the muscles and glands. It is subdivided into two parts: the somatic nervous system and the autonomic nervous system. The somatic nervous system controls voluntary movements and transmits signals to skeletal muscles. The autonomic nervous system controls involuntary functions and regulates activities of internal organs, glands, and smooth muscles.

Noncommunicating hydrocephalus is the most common form of hydrocephalus. This condition occurs when there is a blockage in the flow of cerebrospinal fluid (CSF) within the ventricles of the brain. The blockage prevents the fluid from flowing properly, leading to an accumulation of CSF and an increase in pressure within the brain. This can cause symptoms such as headaches, nausea, and cognitive problems. Treatment for noncommunicating hydrocephalus often involves the surgical placement of a shunt to redirect the flow of CSF and relieve the pressure on the brain.

During the pre-embryonic period, the mesoderm is the primary germ layer that will give rise to muscle and bone. The mesoderm is located between the ectoderm (which forms the skin and nervous system) and the endoderm (which forms the digestive and respiratory systems). It is responsible for the development of various tissues and structures including muscle, bone, connective tissue, blood vessels, and the circulatory system. Therefore, the correct answer is Mesoderm.

The neural tube differentiates into three layers: the ependymal layer, the marginal layer, and the mantle layer. The ventral layer is not one of the three layers.

The sagittal suture is located between the two parietal bones. It is a fibrous joint that runs from the front to the back of the skull, separating the two parietal bones and connecting them together. This suture is important for the growth and development of the skull, as well as providing stability to the cranial bones. The other sutures listed, such as the lambdoidal, coronal, and squamosal sutures, are located in different areas of the skull and do not connect the parietal bones.

The fontanel that closes around 18 months and is located between the frontal and parietal bones is the anterior fontanel.

Injury to the sciatic nerve can lead to foot drop. The sciatic nerve is the largest nerve in the body and controls the muscles that lift the foot. When the nerve is injured, it can result in weakness or paralysis of these muscles, causing difficulty in lifting the foot and making it difficult to walk normally. This condition is known as foot drop. Tingling of the lateral thigh, loss of sensation over the inner thigh, and inability to flex the leg are not typically associated with injury to the sciatic nerve.

The correct answer is Cauda Equina. The cauda equina is a collection of nerve roots that descend from the lower portion of the spinal cord. It is located below the level of the conus medullaris, which is the tapered end of the spinal cord. The filum terminale is a thin strand of fibrous tissue that extends from the conus medullaris to the coccyx. The lumbosacral plexus is a network of nerves that arises from the lower lumbar and sacral spinal nerves. Therefore, the correct answer is Cauda Equina.

The cerebrum is the largest part of the brain and occupies most of the cranium. It is responsible for higher cognitive functions such as thinking, memory, and voluntary movements. The diencephalon, which includes structures like the thalamus and hypothalamus, is located at the base of the cerebrum and acts as a relay center for sensory information and helps regulate various bodily functions. Therefore, the diencephalon is the correct answer as it is part of the cerebrum and occupies a significant portion of the cranium.

The thalamus is responsible for interpreting pain, temperature, light touch, and pressure sensations. It acts as a relay station for sensory information, receiving signals from various parts of the body and transmitting them to the appropriate areas of the cerebral cortex for further processing and interpretation. The thalamus plays a crucial role in the perception of sensory stimuli and is involved in the integration of sensory information to create our conscious experience of pain, temperature, touch, and pressure sensations.

The motor neuron's role in the conduction pathway is to transmit the impulse to the organ of the body that will respond. This means that the motor neuron carries the nerve impulse from the central nervous system (CNS) to the specific organ or muscle that needs to take action in response to the stimulus. By transmitting the impulse, the motor neuron enables the body to initiate a physical response to changes in the internal or external environment.

The largest nerve coming from the lumbar plexus is the Femoral nerve. The lumbar plexus is a network of nerves in the lower back that supplies the lower limb. The Femoral nerve is the largest branch of the lumbar plexus and it innervates the muscles of the anterior thigh and the skin over the front and medial aspects of the thigh and leg. It also plays a crucial role in knee extension and hip flexion.

Marginal cells develop into white matter. White matter refers to the areas of the central nervous system that are primarily composed of myelinated axons. These axons form connections between different regions of the brain, spinal cord, and other parts of the nervous system. The development of white matter is crucial for proper communication and transmission of signals within the nervous system.

The anterior fontanel is the soft spot on a baby's head where the skull bones have not yet fully fused. It typically closes between the ages of 18 to 24 months. During this time, the bones of the skull gradually come together and solidify, providing protection to the brain. The closure of the anterior fontanel is an important developmental milestone that indicates the maturation of the baby's skull and brain.

The thalamus is responsible for interpreting sensory information such as pain, temperature, touch, and pressure. It acts as a relay station, receiving these sensory signals from the body and sending them to the appropriate areas of the brain for further processing and interpretation. This allows us to perceive and respond to various stimuli in our environment. The other options listed, controlling activities of the ANS and controlling body temperature, are not primary functions of the thalamus.

The marginal layer eventually develops into the white matter of the nervous system. The white matter is composed of myelinated axons, which are responsible for transmitting signals between different regions of the nervous system. The marginal layer is located on the outermost part of the neural tube and contains these myelinated axons. Therefore, it is the correct answer for the given question.

After leaving the lateral ventricles, CSF flows through the interventricular foramina into the 3rd ventricle. The interventricular foramina are small openings that connect the lateral ventricles to the 3rd ventricle in the brain. This allows the CSF to continue its circulation within the ventricular system. From the 3rd ventricle, the CSF can then flow through other pathways to reach the cerebral aqueduct, 4th ventricle, and eventually into the subarachnoid space to circulate around the brain and spinal cord.

During the embryonic period, the primary vesicles are formed, which eventually develop into different parts of the brain. The hindbrain, also known as the rhombencephalon, is one of these primary vesicles. It is responsible for controlling vital functions such as breathing, heart rate, and coordination of movement. Therefore, the correct answer is Rhombencephalon.

The posterior fontanel is the soft spot on the back of a baby's head. It is formed by the junction of several skull bones and gradually closes as the baby grows. The correct answer is 2 months because by this age, the posterior fontanel is typically fully closed.

The subdural space is the cavity between the dura mater and the arachnoid mater, which are two of the membranes surrounding the brain. This space contains only a few drops of cerebrospinal fluid (CSF). The CSF is a clear fluid that surrounds and cushions the brain and spinal cord. The subdural space is important for the protection and support of the brain, as well as for the circulation and absorption of CSF.

Spinal nerves are mixed because they contain both sensory and motor fibers. They carry information from the body to the spinal cord (sensory) and transmit signals from the spinal cord to the muscles and organs (motor). This allows for the integration of sensory information and the coordination of motor responses, enabling us to sense and respond to our environment.

The absorption of CSF is inversely proportional to cerebral venous pressure. This means that as cerebral venous pressure increases, the absorption of CSF decreases, and vice versa. This relationship suggests that changes in cerebral venous pressure can affect the rate at which CSF is absorbed, potentially leading to alterations in CSF dynamics and pressure within the brain.

Efferent neurons are responsible for carrying signals from the central nervous system to the muscles and glands, enabling movement and other bodily functions. These neurons are found within the ventral and lateral horns of gray matter in the spinal cord. The ventral horns are located on the front side of the spinal cord and contain motor neurons that control voluntary muscle movement. The lateral horns are present in the thoracic and upper lumbar regions of the spinal cord and are responsible for controlling the autonomic nervous system, which regulates involuntary bodily functions.

CPP stands for Cerebral Perfusion Pressure, which is the pressure gradient that drives blood flow to the brain. It is calculated by subtracting the intracranial pressure (ICP) from the mean arterial pressure (MAP). In this case, the MAP can be estimated by taking the average of the systolic and diastolic blood pressure (BP). Therefore, the MAP is (156+82)/2 = 119. The CPP is then calculated as 119 - 10 = 109. Therefore, the correct answer is 109.

H+ ions do not easily cross the blood brain barrier (BBB) because the BBB is highly selective and only allows certain substances to pass through. H+ ions are charged particles and therefore cannot freely pass through the BBB, which is primarily composed of tightly packed endothelial cells. The BBB acts as a protective barrier for the brain, preventing the entry of potentially harmful substances while allowing essential nutrients and gases like O2 and CO2 to pass through.

The correct answer is Prosencephalon. During the embryonic period, the brain develops from three primary vesicles: prosencephalon, mesencephalon, and rhombencephalon. The prosencephalon is the most anterior of the three and will eventually develop into the forebrain. The mesencephalon will become the midbrain, while the rhombencephalon will develop into the hindbrain. Therefore, the prosencephalon is the correct answer as it is the primary vesicle that will become the forebrain.

The terminal end of the spinal cord is called the Conus Medullaris. This is the tapered, cone-shaped portion of the spinal cord located at the L1-L2 level of the vertebral column. It is the final part of the spinal cord before it branches out into the cauda equina, which consists of nerve roots that continue down the vertebral canal. The Conus Medullaris is an important landmark in spinal cord anatomy and is often used as a reference point in spinal surgeries and procedures.

Injury to the radial nerve can result in wrist drop, which is the inability to extend or lift the wrist. This occurs because the radial nerve controls the muscles responsible for wrist extension. Numbness and tingling in the palm may be present if the injury affects the sensory branches of the radial nerve. Inability to spread the fingers may also occur if the injury affects the muscles responsible for finger abduction. Therefore, all of the above symptoms can be seen in cases of radial nerve injury.

The correct answer is "all of the above are actions generated by efferent motor neurons." Efferent motor neurons are responsible for transmitting signals from the central nervous system to the muscles and glands in the body. They can generate various actions, including motor actions (such as movement), inhibitory actions (such as stopping or preventing certain actions), and secretory actions (such as releasing hormones or other substances). Therefore, all of the options listed are actions that can be generated by efferent motor neurons.

The correct answer is Diencephalon. During the embryonic period, the three primary vesicles that form are the prosencephalon (forebrain), the mesencephalon (midbrain), and the rhombencephalon (hindbrain). The diencephalon is a secondary vesicle that develops from the prosencephalon, so it is not one of the three primary vesicles.

The pons is not contained within the diencephalon. The diencephalon is a region of the brain located between the cerebral hemispheres and the midbrain. It consists of several structures, including the thalamus, hypothalamus, and pineal gland. The pons, on the other hand, is part of the brainstem, which is located below the diencephalon. It plays a role in relaying signals between the cerebrum and the cerebellum, as well as in controlling certain functions such as breathing and sleep.

As intracranial pressure (ICP) increases, the absorption of cerebrospinal fluid (CSF) will increase. This is because the body tries to maintain a balance between the production and absorption of CSF to regulate the pressure within the brain and spinal cord. When ICP increases, the body responds by increasing the absorption of CSF to reduce the pressure. Therefore, as ICP increases, the absorption of CSF will also increase.

Isoflorane is the correct answer because it has been shown to increase the absorption of cerebrospinal fluid (CSF). This is important because increased absorption of CSF can help reduce intracranial pressure and prevent complications such as cerebral edema. The other volatile anesthetic agents listed, Desflorane, Halothane, and Nitrous Oxide, do not have the same effect on CSF absorption.

An association neuron does not link the incoming motor neuron to the outgoing sensory neuron. Instead, an association neuron is responsible for connecting different neurons within the central nervous system. It helps in the processing and integration of information. The correct order of conduction of an impulse is receptor --> sensory neuron --> center --> motor neuron --> effector.

The carotid arteries pass through the temporal bone on their way to supply the brain. The temporal bone is located on the sides and base of the skull, and it houses important structures such as the middle and inner ear, as well as the carotid canal through which the carotid arteries pass. These arteries are responsible for delivering oxygenated blood to the brain, making the temporal bone a crucial pathway for their supply.

The hypothalamus is responsible for controlling rage issues, sleep cycle, and integrating and controlling the autonomic nervous system (ANS). It plays a crucial role in regulating emotions, including anger and rage, through its connections with other brain regions. Additionally, it regulates the sleep-wake cycle by controlling the release of melatonin from the pineal gland. The hypothalamus also controls various functions of the ANS, such as heart rate, blood pressure, and digestion, through its influence on the sympathetic and parasympathetic nervous systems.

Injury to the median nerve can result in numbness and tingling in the palm. The median nerve provides sensation to the palm, thumb, index finger, middle finger, and half of the ring finger. When this nerve is damaged, it can cause altered sensation in these areas, leading to numbness and tingling. Other symptoms that may occur with median nerve injury include weakness in the hand and fingers, difficulty gripping objects, and muscle wasting in the thumb. However, wrist drop and inability to spread fingers are not associated with median nerve injury, but rather with other nerve injuries.

Motor cranial nerves originate from cells within the brain stem, while sensory cranial nerves originate from cells outside the brain stem. This means that the motor cranial nerves have their cell bodies located within the brain stem, while the sensory cranial nerves have their cell bodies located outside of the brain stem.

The medulla is responsible for regulating the diameter of blood vessels through its vasomotor center. This region of the medulla controls the constriction or dilation of blood vessels, which in turn affects blood pressure and blood flow throughout the body. The medulla receives input from various sensory receptors and sends signals to smooth muscles in the blood vessels, adjusting their diameter to maintain proper blood pressure and circulation.

The sphenoid bone is the correct answer because it articulates with all other cranial bones, forming connections with the frontal, parietal, temporal, occipital, and ethmoid bones. Additionally, the sphenoid bone contains the sella turcica, which is a bony depression that houses the pituitary gland.

The ventricles in the brain are responsible for producing cerebrospinal fluid (CSF), which helps protect and nourish the brain and spinal cord. Unlike other areas of the brain, the ventricles do not have a blood-brain barrier. The blood-brain barrier is a protective mechanism that prevents certain substances from entering the brain tissue. Since CSF is produced in the ventricles, it needs to be able to freely exchange substances with the bloodstream, which is why the ventricles lack a blood-brain barrier. Therefore, the statement that the ventricles where CSF is formed do not have a blood-brain barrier is true.

The basilar artery is a major blood vessel in the brain that supplies blood to various regions, including the occipital lobe and brain stem. The posterior cerebral artery is a branch of the basilar artery and is responsible for supplying blood to the occipital lobe and brain stem. Therefore, the correct answer is the Posterior Cerebral Artery. The Circle of Willis, Posterior Communicating Artery, and Middle Cerebral Artery are other important blood vessels in the brain, but they do not directly supply the occipital lobe and brain stem as mentioned in the question.

A patient diagnosed with meningitis is most likely to display communicating hydrocephalus. Meningitis is an infection that causes inflammation of the meninges, which are the protective membranes surrounding the brain and spinal cord. This inflammation can block the flow of cerebrospinal fluid (CSF) within the ventricles of the brain, leading to a buildup of fluid and increased pressure. Communicating hydrocephalus occurs when there is impaired CSF absorption or circulation throughout the entire ventricular system, which can be caused by inflammation or scarring from meningitis.

The coronal suture is located between the frontal and two parietal bones. This suture runs in a horizontal direction and separates the frontal bone from the parietal bones. It is one of the major sutures of the skull and plays a crucial role in the development and growth of the skull bones.

The glossopharyngeal nerve is responsible for regulating blood pressure and supplying special receptors in the carotid body, which help control heart rate and respirations. This nerve plays a crucial role in maintaining homeostasis and ensuring proper functioning of the cardiovascular and respiratory systems.

After leaving the 4th ventricle, CSF flows through the median and lateral apertures into the cisterna magna. The cisterna magna is a large subarachnoid space located at the base of the brain. From there, the CSF can circulate around the brain and spinal cord, providing nutrients, cushioning, and removing waste products. The median and lateral apertures allow the CSF to exit the ventricular system and enter the subarachnoid space, ensuring the proper flow and distribution of CSF throughout the central nervous system.

Injury to the ulnar nerve can result in a condition known as ulnar nerve palsy, which can cause weakness or paralysis of the muscles responsible for spreading the fingers apart. This can lead to an inability to spread the fingers properly. Therefore, the correct answer is "Inability to spread fingers."

Cerebrospinal fluid (CSF) is produced in the ventricles of the brain. It serves as a cushion for the brain and spinal cord, as well as a medium for nutrient delivery and waste removal. The correct answer of 0.35 ml/min indicates the production rate of CSF per minute. This answer suggests that a relatively small amount of CSF is produced daily, emphasizing the importance of its continuous circulation and reabsorption to maintain normal brain function.

The hypothalamus is a small region in the brain that plays a crucial role in regulating various bodily functions. It is responsible for regulating emotions such as rage and aggression, communicating with the pituitary gland to control hormone release, and controlling functions related to temperature, eating, drinking, and sleep. However, the hypothalamus is not directly involved in processing pain and touch sensations. These sensory functions are primarily controlled by other parts of the brain, such as the thalamus and somatosensory cortex.

The temporal bones form the inferior sides of the cranium and also contribute to the cranial floor. They are located on each side of the skull, above the ears. The temporal bones house important structures such as the middle and inner ear, as well as the temporomandibular joint. They also contain the mastoid process, which serves as an attachment point for muscles and provides protection for the middle ear.

Hypoventilation refers to inadequate ventilation of the lungs, leading to an increase in carbon dioxide levels and a decrease in oxygen levels in the blood. This causes vasodilation, which is the widening of blood vessels, leading to an increase in intracranial pressure (ICP). This occurs because the body tries to compensate for the low oxygen levels by dilating the blood vessels to increase blood flow and oxygen delivery to the brain. As a result, the correct answer is vasodilation, increase in ICP.

D5W is a hypotonic solution, meaning it has a lower concentration of solutes compared to the brain. When this solution is infused, it will cause water to move from an area of lower concentration (D5W) to an area of higher concentration (brain). Therefore, the infusion of D5W will cause water to move into the brain.

Injury to the femoral nerve can lead to a condition called femoral nerve palsy, which can cause weakness or paralysis of the muscles that extend the leg. This means that the person may have difficulty straightening or extending their leg at the knee joint.

The cranial nerves that have solely sensory function are the Optic and Acoustic nerves. The Optic nerve is responsible for transmitting visual information from the eyes to the brain, while the Acoustic nerve is responsible for transmitting auditory information from the ears to the brain.

The role of the receptor in the conduction pathway is to respond to changes in the internal or external environment by initiating a nerve impulse. This means that when there is a change in the environment, the receptor detects it and sends a signal in the form of a nerve impulse to the central nervous system (CNS). This allows the body to recognize and respond to stimuli, such as temperature changes, pressure, or pain. The receptor serves as the first step in the conduction pathway, converting the stimulus into a nerve impulse that can be transmitted and processed by the CNS.

The circle of Willis is a ring-like structure of arteries located at the base of the brain. It is responsible for supplying blood to the brain and its surrounding areas. The internal carotid arteries and the basilar artery are the major arteries that feed into the circle of Willis. The internal carotid arteries supply blood to the anterior part of the circle, while the basilar artery supplies blood to the posterior part. Together, these arteries ensure a constant blood supply to the brain, allowing for proper functioning.

The cranial vault is a rigid structure with 80% brain, 12% blood and 8% CSF. Page 618 M&M states in increase in one compartment (blood from SAH) will result in a decrease in another. The brain itself can't change so CSF decreases.

The role of the sensory neuron in the conduction pathway is to pass the impulse to the terminating axon in the central nervous system (CNS). This means that the sensory neuron receives the incoming sensory impulse and transfers it to the axon, which then carries the impulse to the CNS where further processing and interpretation of the sensory information occurs.

The correct answer is T8. The question is asking about the level of sympathetic blockade if the patient cannot feel touch at the level of the umbilicus. The umbilicus is innervated by the T10 dermatome, so if there is a sympathetic blockade at the level of T8, it would affect the nerves responsible for transmitting touch sensation to the umbilicus.

The subarachnoid space is the area between the arachnoid mater and the pia mater, two of the protective layers covering the brain. It contains cerebrospinal fluid (CSF) and is located beneath the arachnoid membrane. In the given scenario, the person falls off the horse and hits their head, resulting in a small bleed. Given that the bleed is within the brain, it is most likely to occur within the subarachnoid space, where blood vessels are present. The other spaces mentioned (subdural, sulcal, and epidural) are not typically associated with bleeding within the brain.

**vagus is mixed, so has sensory and MOTOR.

Cranial nerves V, VI, VII, and VIII originate in the Pons. The Pons is a region in the brainstem that acts as a bridge between the medulla and the midbrain. It plays a crucial role in relaying signals between different parts of the brain and the body. The cranial nerves originating in the Pons are responsible for various functions such as facial movement, eye movement, and sensation in the face and head.