PATHO: Chapter 10: Altered Neuronal Transmission
A client diagnosed with Parkinson disease is displaying the following manifestations: tremor, rigidity, and slowness of movement. The nurse would interpret these as: Signs of clinical deterioration Manifestations of another disease process Signs of clinical improvement Normal manifestations of Parkinson disease
Normal manifestations of Parkinson disease Explanation: The client is manifesting normal responses of the disease. The cardinal manifestations of Parkinson disease are tremor, rigidity, and bradykinesia (slowness of movement).
Which chemical does blood-brain and CSF-brain barrier control with easy entrance? Oxygen Glutamate Protein Potassium
Oxygen Explanation: Two barriers, the blood-brain barrier and the cerebrospinal fluid (CSF)-brain barrier, provide the means for maintaining the stable chemical environment of the brain. Only water, carbon dioxide, and oxygen enter the brain with relative ease. Large molecules such as proteins are largely excluded from crossing the blood-brain barrier. In the brain, ammonia is converted to glutamine by astrocytes. Potassium has controlled entrance into the brain; the result of slight fluctuations of potassium concentration in the brain would be uncontrolled neural activity because ions such as potassium influence the threshold for neural firing.
At which level of the cervical spine would a complete cord injury result in the client retaining the ability to flex and extend the fingers? C5 C8 C6 C4
C8 Explanation: Functional abilities are lost in complete spinal injuries based on the level of the injury. The higher on the spine, the greater functional loss. Therefore, injury to C1 will present with the greatest functional loss including voluntary movements of the upper extremities and loss of diaphragm control. At the C5 level, function of the deltoids and biceps is retained, allowing normal shoulder strength and full elbow flexion and hands. At the C6 level, dorsiflexion of the wrist is possible, but finger movement is still impaired. A functional C7 to C8 injury allows full elbow flexion and extension, wrist plantar flexion, and some to full finger flexion and extension.
Sweating is mediated by which neurotransmitter? Enkephalin Catecholamines Glutamic acid Acetylcholine
Acetylcholine Explanation: Sweating occurs through the sweat glands and is controlled by the sympathetic nervous system. Sweating is mediated by acetylcholine. Proenkephalin peptides are present in areas of the spinal cord and PAG that are related to perception of pain. Glutamic acid is an important amino acid for the synthesis of proteins. The catecholamines serve as neuromediators. Catecholamines cause general physiologic changes that prepare the body for physical activity (fight-or-flight response).
Myasthenia gravis is characterized by muscle weakness caused by antibody-mediated loss of which physiologic function? Periorbital muscles Thymus gland cells Skeletal muscle fibers Acetylcholine receptors
Acetylcholine receptors Explanation: Now recognized as an autoimmune disease, myasthenia gravis is caused by an antibody-mediated loss of acetylcholine receptors in the neuromuscular junction, which disrupts motor neuron impulses to/from the skeletal muscle fibers. The result is muscle weakness, mainly the eye and periorbital muscles, and fatigability with sustained effort. Most persons with myasthenia gravis also have thymic abnormalities, such as a thymoma (i.e., thymus tumor) or thymic hyperplasia.
A nurse is teaching a client newly diagnosed with a seizure disorder. Which statement is most important for the nurse to provide regarding antiepileptic medications? Antiepileptic medications should never be discontinued abruptly. All antiepileptic medications should be taken with food. Children can build up a tolerance to the medication quickly. Pregnant women should reduce the dose of medication or discontinue until after delivery.
Antiepileptic medications should never be discontinued abruptly. Explanation: Consistency in taking seizure medications is essential to obtaining and maintaining therapeutic blood levels of the medication. Abrupt withdrawal can cause seizure recurrence. Monitoring and assessment of drug levels are important. Each prescribed drug will provide information regarding administration to provide client safety. For women with epilepsy who become pregnant, antiseizure drugs increase the risk for congenital abnormalities. However, these medications need to be continued throughout the pregnancy.
A teenager has been in a car accident and experienced an acceleration-deceleration head injury. Initially, the client was stable but then started to develop neurological signs/symptoms. The nurse caring for this client should be assessing for which type of possible complication? Momentary unconsciousness TIAs and cerebrovascular infarction Status epilepticus Brain contusions and hematomas
Brain contusions and hematomas Explanation: Contusions (focal brain injury) cause permanent damage to brain tissue. The bruised, necrotic tissue is phagocytized by macrophages, and scar tissue formed by astrocyte proliferation persists as a crater. The direct contusion of the brain at the site of external force is referred to as an acceleration injury, whereas the opposite side of the brain receives the deceleration injury from rebound against the inner skull surfaces. As the brain strikes the rough surface of the cranial vault, brain tissue, blood vessels, nerve tracts, and other structures are bruised and torn, resulting in contusions and hematomas. TIAs and cerebral vascular infarction (stroke) are often caused by atherosclerotic brain vessel occlusions that cause ischemic injuries. In mild concussion head injury, there may be momentary loss of consciousness without demonstrable neurologic symptoms or residual damage, except for possible residual amnesia. Status epilepticus is not related to this situation.
Which intracranial volume is most capable of compensating for increasing intracranial pressure? Brain cell tissue Surface sulci fluid Intravascular blood Cerebrospinal fluid
Cerebrospinal fluid Explanation: Initial increases in intracranial pressure (ICP) are largely buffered by a translocation of cerebrospinal fluid (CSF) to the spinal subarachnoid space and increased reabsorption of CSF. Of the intracranial volumes, the tissue volume is least capable of undergoing change. Surface sulcus fluid is negligible and not a factor in increased ICP. The compensatory ability of the intravascular blood compartment is also limited by the small amount of blood that is in the cerebral circulation. As the volume-buffering capacity of this compartment becomes exhausted, venous pressure increases and cerebral blood volume and ICP rise.
A client with a diagnosis of epilepsy has required surgical removal of part of her prefrontal cortex. Which effect should her family and care team anticipate? Deficits in regulation of the endocrine system Sensory losses Lapses in balance and coordination Changes in behavior and judgment
Changes in behavior and judgment Explanation: The prefrontal cortex is thought to be involved in anticipation and prediction of consequences of behavior. It does not contribute directly to balance, sensation, or endocrine function.
The health care provider is concerned that a client may be at risk for problems with cerebral blood flow. The most important data to assess would be: Decreased hydrogen ions Decreased level of carbon dioxide Decreased level of oxygen Decreased level of PCO2
Decreased level of oxygen Explanation: Regulation of blood flow to the brain is controlled largely by autoregulatory or local mechanisms that respond to the metabolic needs of the brain. Metabolic factors affecting cerebral blood flow include an increase in carbon dioxide and hydrogen ion concentrations; cerebral blood flow is affected by decreased O2 levels and increased hydrogen ions, carbon dioxide, and PCO2 levels.
A client with Parkinson disease presents with bradykinesia and an altered gait. These symptoms arise in response to the progressive deterioration of which structure in the brain? Cerebellum Limbic system Dopamine nigrostriatal system Serotonergic system
Dopamine nigrostriatal system Explanation: The destruction of the dopamine nigrostriatal system upsets the balance of the basal ganglia, resulting in uncontrolled and uncoordinated movement. The cortex is involved in higher processing, serotonin is involved in the limbic system, and the cerebellum is unrelated to Parkinson disease; cerebellar disorders, however, will cause Parkinsonism.
Which of the meninges provides the major protection for the brain and spinal cord? Pia mater Tentorium cerebelli Arachnoid membrane Dura mater
Dura mater Explanation: All surfaces of the spinal cord, brain, and segmental nerves are covered with a delicate connective tissue layer called the pia mater. A second, very delicate, nonvascular, and waterproof layer, called the arachnoid, encloses the entire central nervous system. Immediately outside the arachnoid is a continuous sheath of strong connective tissue, the dura mater, which provides the major protection for the brain and spinal cord. The tentorium cerebelli is the inner layer of the dura that anchors the brain to the skull.
The underlying causative problem in Parkinsonism is: Failure of dopamine release Autoimmune disorder Viral infection Genetic defect
Failure of dopamine release Explanation: Lack of dopamine release is the primary cause of Parkinson disease and associated symptoms.
Following a car accident that has resulted in partial amputation of the lower limbs, the client's body has implemented a compensatory mechanism releasing antidiuretic hormone (ADH) into the bloodstream, causing retention of water and vasoconstriction of blood vessels. What physiologic principle is responsible for this action? Fast axonal transport of ADH from the hypothalamus into the posterior pituitary Dendrites conducting information and ADH toward the cell body Afferent, or sensory, neurons of the PNS transmitting information to the CNS Extension of Nissl bodies and free ribosomes carrying ADH into the dendrites
Fast axonal transport of ADH from the hypothalamus into the posterior pituitary Explanation: Antidiuretic hormone (ADH) and oxytocin, which are synthesized by neurons in the hypothalamus, are carried by rapid axonal transport to the posterior pituitary, where the hormones are released into the bloodstream. ADH increases peripheral vascular resistance (vasoconstriction) and thus increases arterial blood pressure. This becomes an important compensatory mechanism for restoring blood pressure in hypovolemic shock, such as that which occurs during hemorrhage. The proteins and other materials used by the axon are synthesized in the cell body and then flow down the axon through its cytoplasm. The Nissl bodies and free ribosomes extend into the dendrites, but not into the axon. The dendrites (i.e., "treelike") are multiple, branched extensions of the nerve cell body; they conduct information toward the cell body and are the main source of information for the neuron. The dendrites and cell body are studded with synaptic terminals that communicate with axons and dendrites of other neurons.
The nurse measures a blood glucose level of 40 mg/dL (2.22 mmol/L) for a client with type 1 diabetes. Why would it be important for the nurse to institute an intervention to elevate the glucose level in this client? Glucose is not stored in the brain and is a major fuel source for brain function. Small amounts of glucose may be stored in the brain for a short period of time but are rapidly metabolized. It is not necessary for glucose to be replaced immediately because the client will have enough stored to function for a while. The nurse should administer a food source of protein in order to increase the glucose level for improved cardiac function.
Glucose is not stored in the brain and is a major fuel source for brain function. Explanation: Glucose is the major fuel source for the nervous system but neurons have no provision for storing glucose. Ketones can provide for limited temporary energy requirements. However, these sources are rapidly depleted.
A client has sustained damage to cranial nerve VIII. The nurse recognizes that the client may experience difficulty with: Smell Hearing Taste Motor
Hearing Explanation: Cranial nerve VIII (vestibulocochlear nerve) is associated with hearing. The other options involve different nerves.
Among the treatments for multiple sclerosis (MS), which medication will reduce the exacerbation of relapsing-remitting MS? Baclofen, a muscle relaxer Mitoxantrone, an antineoplastic agent Interferon-β, a cytokine injection Long-term corticosteroid administration
Interferon-β, a cytokine injection Explanation: Disease-modifying agents include interferon-β and glatiramer acetate. These agents have shown some benefit in reducing exacerbations in persons with relapsing-remitting MS. Interferon-β is a cytokine that acts as an immune enhancer. Corticosteroids are the mainstay of treatment for acute attacks of MS. These agents are thought to reduce the inflammation, improve nerve conduction, and have important immunologic effects. Long-term administration does not, however, appear to alter the course of the disease and can have harmful side effects. Mitoxantrone, an anticancer drug, is recommended for persons with worsening forms of the disease. Baclofen is a muscle relaxer for helping with symptom relief.
Reflexes are basically "hard-wired" into the CNS. Anatomically, the basis of a reflex is an afferent neuron that synapses directly with an effector neuron to cause muscle movement. Sometimes the afferent neuron synapses with what intermediary between the afferent and effector neurons? Intersegmental effectors Neurotransmitter Interneuron Suprasegmental effectors
Interneuron Explanation: The anatomic basis of a reflex consists of an afferent neuron, which synapses either directly with an effector neuron that innervates a muscle or with an interneuron that synapses with an effector neuron.
The health care provider is performing a spinal tap on a client with suspected infection. The provider would perform the procedure at: L3 or L4 T3 or T4 S3 or S4 C3 or C4
L3 or L4 Explanation: A pocket of CSF, the dural cisterna spinalis, extends from approximately L2 to S2. Because this area contains an abundant supply of CSF and the spinal cord does not extend this far, the area often is used for sampling the CSF. A procedure called a spinal tap, or puncture, can be done by inserting a special needle into the dural sac at L3 or L4. The spinal roots, which are covered with pia mater, are in little danger of trauma from the needle used for this purpose.
Feelings of dread, high anxiety, or exquisite pleasure can be elicited by stimulation of areas in which structure? Limbic system Temporal lobe Cerebellum Occipital lobe
Limbic system Explanation: Stimulation of specific areas of the limbic system can lead to feelings of dread, high anxiety, or exquisite pleasure. The temporal lobe is involved with auditory functions, the cerebellum with proprioception, and the occipital lobe with visual function.
The region of the brain involved in emotional experience and control of emotional behavior is the: Limbic system Occipital lobe Cerebral hemisphere Parietal lobe
Limbic system Explanation: The limbic region of the brain is involved in emotional experience and in the control of emotion-related behavior. Stimulation of specific areas in this system can lead to feelings of dread, high anxiety, or exquisite pleasure. It also can result in violent behaviors, including attack, defense, or explosive and emotional speech. The occipital lobe plays an important role in the meaningfulness of visual experience, including experiences of color, motion, depth perception, pattern, form, and location in space. The parietal lobe is necessary for perceiving the meaningfulness of integrated sensory information from various sensory systems, especially the perception of "where" the stimulus is in space and in relation to body parts. Axons of the olfactory nerve, or cranial nerve I, terminate in the most primitive portion of the cerebrum—the olfactory bulb, where initial processing of olfactory information occurs.
The region of the brain involved in emotional experience and control of emotional behavior is the: Parietal lobe Occipital lobe Cerebral hemisphere Limbic system
Limbic system Explanation: The limbic region of the brain is involved in emotional experience and in the control of emotion-related behavior. Stimulation of specific areas in this system can lead to feelings of dread, high anxiety, or exquisite pleasure. It also can result in violent behaviors, including attack, defense, or explosive and emotional speech. The occipital lobe plays an important role in the meaningfulness of visual experience, including experiences of color, motion, depth perception, pattern, form, and location in space. The parietal lobe is necessary for perceiving the meaningfulness of integrated sensory information from various sensory systems, especially the perception of "where" the stimulus is in space and in relation to body parts. Axons of the olfactory nerve, or cranial nerve I, terminate in the most primitive portion of the cerebrum—the olfactory bulb, where initial processing of olfactory information occurs.
The emergency room doctor suspects a client may have bacterial meningitis. The most important diagnostic test to perform would be: Blood cultures CT of the head Sputum culture Lumbar puncture
Lumbar puncture Explanation: The diagnosis of bacterial meningitis is confirmed with abnormal CSF findings. Lumbar puncture findings, which are necessary for accurate diagnosis, include a cloudy and purulent CSF under increased pressure. The other options do not confirm the diagnosis.
A 60-year-old woman has been recently diagnosed with multiple sclerosis, a disease in which the oligodendrocytes of the client's central nervous system (CNS) are progressively destroyed. Which physiologic process within the neurologic system is most likely to be affected by this disease process? Production of cerebrospinal fluid Oxygen metabolism Nerve conduction Neurotransmitter synthesis
Nerve conduction Explanation: The oligodendrocytes form the myelin in the central nervous system (CNS). As with peripheral myelinated fibers, the covering of axons in the CNS increases the velocity of nerve conduction. Oxygen metabolism and synthesis of CSF and neurotransmitters are not directly affected.
Which peripheral nerve injury will likely result in cellular death with little chance of regeneration? Cutting injury where slow-regeneration axonal branches are located Incomplete amputation where tubular implants are used to fill in the gaps of nerves Nerve fibers destroyed close to the neuronal cell body Crushing injury where the nerve is traumatized but not severed
Nerve fibers destroyed close to the neuronal cell body Explanation: The successful regeneration of a nerve fiber in the PNS depends on many factors. If a nerve fiber is destroyed relatively close to the neuronal cell body, the chances are that the nerve cell will die; if it does, it will not be replaced. If a crushing type of injury has occurred, partial or often full recovery of function occurs. Cutting-type trauma to a nerve is an entirely different matter. A number of scar-inhibiting agents have been used in an effort to reduce this hazard, but have met with only moderate success. Various types of tubular implants have been used to fill longer gaps in the endoneurial tube but again only with moderate success.
Multiple sclerosis is characterized by what type of neuron damage? Polyneuropathy Mononeuropathy Aneuropathy Transneuropathy
Polyneuropathy Explanation: MS is classified as a polyneuropathy due to many nerves being affected by the disease, involving demyelination of peripheral nerves.
Neurotransmitters exert their actions through specific proteins that are known as: Transformers Autoantigens Receptors Antibodies
Receptors Explanation: Neurotransmitters exert their actions through specific proteins that are known as receptors, embedded in the postsynaptic membrane.
The nurse is planning care for a client with advanced Parkinson disease. Which intervention(s) will the nurse include? Select all that apply. Request a swallowing assessment to prevent aspiration. Establish a toileting routine to reduce incontinence. Maintain bed rest to prevent falls. Offer fresh changes of clothing during the day. Assess for postural blood pressure changes.
Request a swallowing assessment to prevent aspiration. Establish a toileting routine to reduce incontinence. Assess for postural blood pressure changes. Offer fresh changes of clothing during the day. Clients with Parkinson disease have various manifestations, including feeding difficulties, that can increase the risk for aspiration, making a swallowing assessment indicated. Increased sebaceous, sweat, and saliva secretions are common. For this reason, the nurse should offer to help the client change clothes and freshen up during the day. Autonomic dysfunctions, including altered blood pressure and thermal regulation, may occur—and some medications to treat Parkinson disease can also affect blood pressure. Therefore, the nurse should assess the client if their blood pressure drops when making postural changes (orthostatic hypotension), because this is a safety concern due to increased risk for falls. Other complications include constipation and incontinence, which can be reduced by creating a toileting routine. The nurse will not restrict the client to bed rest, which would increase the risk for immobility-related complications; this is not an accepted approach to preventing falls.
A client with a diagnosis of myasthenia gravis underwent a mastectomy. The surgery was a success, but the client has gone into a myasthenic crisis on postoperative day 1. Which priority measure should the care team initiate immediately? Monitoring the client for painful dyskinesias Seizure precautions with padded side rails and bed at lowest height Positioning the client to minimize hypertonia and muscle rigidity Respiratory support and protection of the client's airway
Respiratory support and protection of the client's airway Explanation: Myasthenic crisis occurs when muscle weakness becomes severe enough to compromise ventilation to the extent that ventilatory support and airway protection are needed. Seizures, dyskinesias, hypertonia, and muscle rigidity are not associated with myasthenia gravis in general or myasthenic crisis in particular.
A client is devastated to receive a diagnosis of amyotrophic lateral sclerosis (ALS). The symptomatology of this disease is a result of its effects on upper and lower motor neurons. The health care provider caring for this client will focus on which priority intervention for this client? Respiratory ventilation assessment and prevention of aspiration pneumonia Ability to turn from side to side, thereby preventing skin breakdown Assessment of lower extremities to prevent deep vein thrombosis Ability to empty bladder completely, thereby preventing autonomic dysreflexia
Respiratory ventilation assessment and prevention of aspiration pneumonia Explanation: Amyotrophic lateral sclerosis is a mixed upper motor neuron (UMN) and lower motor neuron (LMN) disorder. In the more advanced stages of ALS, muscles of the palate, pharynx, tongue, neck, and shoulders become involved, causing impairment of chewing, swallowing (dysphagia), and speech. Dysphagia with recurrent aspiration and weakness of the respiratory muscles produces the most significant acute complications of the disease. Airway/breathing is always the priority over bladder emptying, skin breakdown, and assessing for DVT.
Through what specific component do neurotransmitters exert their action? Water Specific proteins Carbon dioxide Oxygen
Specific proteins Explanation: Neurotransmitters exert their actions through specific proteins, called receptors, embedded in the postsynaptic membrane. Water, carbon dioxide, and oxygen enter the brain with relative ease.
The nurse is explaining to a client's family how vasogenic brain edema occurs. The most appropriate information for the nurse to provide would be: Normal physiologic circumstances result in decreased adsorption of CSF. The blood-brain barrier is disrupted, allowing fluid to escape into the extracellular fluid. There is an increase in the production of cerebrospinal fluid volume. There is a decrease in the amount of fluid volume in the brain.
The blood-brain barrier is disrupted, allowing fluid to escape into the extracellular fluid. Explanation: Vasogenic brain edema occurs with conditions that impair the function of the blood-brain barrier and allow the transfer of water and protein from the vascular space into the interstitial space. Increased production of CSF and decreased absorption result in hydrocephalus. It occurs in conditions such as hemorrhage, brain injury, and infectious processes.
A client asks the nurse if the brain is always receiving oxygen. The best response would be: The brain only needs oxygen during activity and does not consume extra oxygen. The brain receives 15% of the body's resting cardiac output and consumes 20% of its oxygen. The brain receives 15% of the body's resting cardiac output and consumes 20% of its carbon dioxide. The brain receives 20% of the body's resting cardiac output and consumes 10% of its oxygen.
The brain receives 15% of the body's resting cardiac output and consumes 20% of its oxygen. Explanation: The brain receives 15% to 20% of the body's resting cardiac output and consumes 20% of its oxygen.
Which message is most likely to be carried by general somatic afferent (GSA) neurons? Information about the position of a joint The sensation of cold when touching ice The message to move a finger and thumb The message to move the larynx during speech
The sensation of cold when touching ice Explanation: General somatic afferent (GSA) neurons innervate the skin and other somatic structures, responding to stimuli such as those that produce pressure or pain. Initiation of motion is the control of efferent neurons, whereas information about the position of a joint is undercarried by the special somatic afferent (SSA) fibers.
A client who is being seen in the outpatient clinic reports a single episode of unilateral arm and leg weakness and blurred vision that lasted approximately 45 minutes. The client is most likely experiencing: Thrombotic stroke Cardiogenic embolic stroke Lacunar infarct Transient ischemic attack (TIA)
Transient ischemic attack (TIA) Explanation: Transient ischemic attacks are brief episodes of neurologic function resulting in focal cerebral ischemia not associated with infarction that usually resolve in 24 hours. The causes of transient ischemic attack are the same as they are for stroke. Embolic stroke usually has a sudden onset with immediate maximum deficit. Lacunar infarcts produce classic recognizable "lacunar syndromes" such as pure motor hemiplegia, pure sensory hemiplegia, and dysarthria with clumsy hand syndrome.
A client is devastated to receive a diagnosis of amyotrophic lateral sclerosis (ALS). The symptomatology of this disease is a result of its effects on which region of the brain? Basal ganglia Upper and lower motor neurons Neuromuscular junctions The vestibulocerebellar system
Upper and lower motor neurons Explanation: Amyotrophic lateral sclerosis is a mixed upper motor neuron (UMN) and lower motor neuron (LMN) disorder; the pathophysiology of the disease is not rooted in the vestibulocerebellar system, the basal ganglia (like Parkinsonism), or at neuromuscular junctions.
A soccer player has been diagnosed with a brain contusion after being injured in a game. The best explanation of the injury by the nurse would be that: tearing of brain tissue occurred. hypoxia to the brain occurred. bruising on the surface of the brain occurred. transient neurogenic dysfunction caused by mechanical force to the brain occurred.
bruising on the surface of the brain occurred. Explanation: Contusions represent bruising on the surface of the brain, and lacerations are a tearing of brain tissue. A cerebral concussion is a transient neurogenic dysfunction caused by mechanical force to the brain. Hypoxia usually is seen in conditions such as exposure to reduced atmospheric pressure, carbon monoxide poisoning, severe anemia, and failure of the lungs to oxygenate the blood.
Severe head trauma from a coup-contrecoup injury may result in which type of brain injury? development of ataxia cerebral hematoma cerebrovascular infarction arteriovenous malformation
cerebral hematoma Explanation: The direct contusion of the brain at the site of external force is referred to as a coup injury; whereas, the opposite side of the brain receives the contrecoup injury from rebound against the inner skull surfaces. As the brain strikes the rough surface of the cranial vault, brain tissue, blood vessels, nerve tracts, and other structures are bruised and torn, resulting in contusions and hematomas. Cerebral vascular infarction (stroke) is often caused by atherosclerotic brain vessel occlusions that cause ischemic injuries. Arteriovenous malformations are an underlying condition not associated with trauma head injury. Ataxia describes the lack of muscle coordination when a voluntary movement is attempted. It may affect any motion that requires muscles to work together to perform a function, from walking to picking up an object to swallowing. Ataxia may be inherited and caused by a genetic defect or it may be acquired due to structural damage to the cerebellum or spinal cord.
Drugs like diazepam, a benzodiazepine, exert their action on ion channels. These drugs do not open the GABA-operated ion channel, but they: change the effect that GABA has when it binds to the channel at the same time as the drug. modulate the peripheral sympathetic nerves and can have both a transmitter and modulator function. modulate the release from axon terminals. play a necessary role in the long-term survival of presynaptic neurons.
change the effect that GABA has when it binds to the channel at the same time as the drug. Explanation: Amino acids, such as glutamine, glycine, and GABA, serve as neurotransmitters at most CNS synapses. GABA mediates most synaptic inhibition in the CNS. Drugs such as the benzodiazepines (e.g., the tranquilizer diazepam) and the barbiturates exert their action by binding to their own distinct receptor on a GABA-operated ion channel. The drugs by themselves do not open the channel, but they change the effect that GABA has when it binds to the channel at the same time as the drug. Another class of messenger molecules, known as neuromodulators, also may be released from axon terminals. In contrast to neurotransmitters, neuromodulators do not directly activate ion channel receptors but bring about long-term changes that subtly enhance or depress the action of the receptors. Neuromodulators, such as dopamine, serotonin, acetylcholine, histamine, and others, may act at either presynaptic or postsynaptic sites.
The nurse is assessing a client with multiple sclerosis (MS) to determine if the client is experiencing an MS exacerbation. Which data will the nurse report to the health care provider as evidence to support an exacerbation? Select all that apply. temperature between 97.8°F-99.3°F (36.6°C-37.4°C) for past 24 hours nausea and vomiting several times in past 48 hours episodes of urinary incontinence over past 48 hours decreased vision in right eye for past 6 hours increased fatigue for the past 48 hours
increased fatigue for the past 48 hours temperature between 97.8°F-99.3°F (36.6°C-37.4°C) for past 24 hours episodes of urinary incontinence over past 48 hours An exacerbation of multiple sclerosis (MS) is defined as a demyelinating event of at least 24-hour duration without fever or infection. Therefore, having increased MS-associated symptoms such as fatigue and urinary incontinence over the past 48 hours support the client is experiencing an exacerbation. A normal temperature is also supportive data. However, nausea and vomiting could be evidence of a viral infection and are not symptoms associated with MS; this does not align with the criteria for an exacerbation. Because the decreased vision has only been present for 6 hours, this would not be considered a supporting finding until it persisted greater than 24 hours.
The nurse is caring for a client who is displaying signs of an acute ischemic stroke. The nurse associates the neurologic symptoms with which primary pathophysiologic process? lack of access to oxygen and glucose, resulting in cellular dysfunction release of excitatory neurotransmitters, causing disorganized neural responses vasodilation and cerebral edema, causing increased intracranial pressure anaerobic cellular activity, causing the accumulation of lactic acid
lack of access to oxygen and glucose, resulting in cellular dysfunction Explanation: In acute ischemic stroke, the interruption in cerebral blood flow causes cellular function to cease because of the inability to use anaerobic metabolic processes or absorb glucose and glycogen. Because the brain is not able to efficiently switch to anaerobic activity, there is no accumulation of lactic acid. Although increased intracranial pressure and excitatory neurotransmitters may also contribute to ischemia, these processes are secondary to the lack of oxygen and glucose supply in creating cellular dysfunction.
The nurse is aware that the primary function of the sympathetic nervous system is: maintenance of vital functions and responding when there is a critical threat to the integrity of the individual. maintenance of organ function during periods of minimal activity. suppression of responses during threatened periods. conservation of energy and resource replenishment.
maintenance of vital functions and responding when there is a critical threat to the integrity of the individual. Explanation: The sympathetic division maintains vital functions and responds when there is a critical threat to the integrity of the individual—the "fight-or-flight" response. The parasympathetic nervous system is concerned with conservation of energy, resource replenishment, and maintenance of organ function during periods of minimal activity.
A client has been brought to the emergency department following an overdose of insulin that resulted in unconsciousness. When explaining the rationale for this to the family, the nurse will emphasize that neurons: must rely on glucose from the blood to meet their energy needs. can cause the liver to convert triglycerides into energy if needed quickly. store glycogen within the brain cavity. require many amino acids in order to produce enough energy to function properly.
must rely on glucose from the blood to meet their energy needs. Explanation: Nervous tissue has a high rate of metabolism. Glucose is the major fuel source for the nervous system. Unlike muscle cells, neurons have no glycogen stores and must rely on glucose from the blood or the glycogen stores of supporting glial cells to meet their energy needs. Persons receiving insulin for diabetes may experience signs of neural dysfunction and unconsciousness when blood glucose drops because of insulin excess. Neither amino acid production nor liver conversion of triglycerides will produce the quick energy that the brain requires to function properly.
A client with laryngeal dystonia has gotten to the point that people on the telephone cannot understand her. She has heard about getting Botox injections into her vocal cords. The nurse will teach about the actions of Botox. What is the most accurate description? This drug: produces paralysis of the larynx muscles by blocking acetylcholine release. will slow the decline in muscle strength and function. inhibits the peripheral metabolism of dopamine. prevents the depolarizing effect of the neurotransmitters.
produces paralysis of the larynx muscles by blocking acetylcholine release. Explanation: Pharmacologic preparations of the botulinum toxin (botulinum type A toxin [Botox] and botulinum type B toxin [Myobloc]) produce paralysis by blocking acetylcholine release. Glucocorticoids are the only medication currently available to slow the decline in muscle strength and function in DMD. Curare acts on the postjunctional membrane of the motor endplate to prevent the depolarizing effect of the neurotransmitter. Neuromuscular transmission is blocked by curare-type drugs during many types of surgical procedures to facilitate relaxation of involved musculature. Levodopa, a dopamine agonist used in Parkinson disease, is administered with carbidopa, which inhibits its peripheral metabolism, allowing therapeutic concentrations of the drug to enter the brain without disabling adverse effects.
A client with laryngeal dystonia has gotten to the point that people on the telephone cannot understand her. She has heard about getting Botox injections into her vocal cords. The nurse will teach about the actions of Botox. What is the most accurate description? This drug: will slow the decline in muscle strength and function. produces paralysis of the larynx muscles by blocking acetylcholine release. prevents the depolarizing effect of the neurotransmitters. inhibits the peripheral metabolism of dopamine.
produces paralysis of the larynx muscles by blocking acetylcholine release. Explanation: Pharmacologic preparations of the botulinum toxin (botulinum type A toxin [Botox] and botulinum type B toxin [Myobloc]) produce paralysis by blocking acetylcholine release. Glucocorticoids are the only medication currently available to slow the decline in muscle strength and function in DMD. Curare acts on the postjunctional membrane of the motor endplate to prevent the depolarizing effect of the neurotransmitter. Neuromuscular transmission is blocked by curare-type drugs during many types of surgical procedures to facilitate relaxation of involved musculature. Levodopa, a dopamine agonist used in Parkinson disease, is administered with carbidopa, which inhibits its peripheral metabolism, allowing therapeutic concentrations of the drug to enter the brain without disabling adverse effects.
The nurse is assessing a client and notes the client is now displaying decerebrate posturing. The position would be documented as: prone position with arms placed above the head and legs elevated; deep tendon reflexes showing hyperreflexia. flexion of the arms, wrists, and fingers, with abduction of the upper extremities, internal rotation, and plantar flexion of the lower extremities. active range of motion with increased strength in the upper extremities when painful stimulation applied. rigidity of the arms with palms of the hands turned away from the body and with stiffly extended legs and plantar flexion of the feet
rigidity of the arms with palms of the hands turned away from the body and with stiffly extended legs and plantar flexion of the feet. Explanation: Decerebrate (extensor) posturing results from increased muscle excitability. It is characterized by rigidity of the arms with palms of the hands turned away from the body and with stiffly extended legs and plantar flexion of the feet. Flexion of the arms, wrists, and fingers, with abduction of the upper extremities, internal rotation, and plantar flexion of the lower extremities, would be a response of decorticate posturing. The other options are not specific to a diagnosis.
While walking down the street, a cat jumps out of an alley into the pathway of an adult. They note that the man's heart is "racing." This physiologic response is primarily due to: parasympathetic effects on the vagus nerve. secretions of sympathetic neurotransmitters produced in the adrenal medulla. postganglionic neurons sending axons to glandular cells, which modulate their function. the cell body of the first motor neuron that lies in the brain stem.
secretions of sympathetic neurotransmitters produced in the adrenal medulla. Explanation: The organization of many life-support reflexes occurs in the reticular formation of the medulla and pons. These areas of reflex circuitry, often called centers, produce complex combinations of autonomic and somatic efferent functions required for the cough, sneeze, swallow, and vomit reflexes, as well as for the more purely autonomic control of the cardiovascular system. The adrenal medulla, which is part of the sympathetic nervous system, contains postganglionic sympathetic neurons that secrete sympathetic neurotransmitters directly into the bloodstream. The vagus nerve provides parasympathetic innervation for the heart, trachea, lungs, esophagus, etc. Postganglionic neurons send axons to glandular cells, which modulate their function by increasing secretions. The cell body of the first motor neuron, called the preganglionic neuron, lies in the brain stem or the spinal cord.
