How are Type IV hypersensitivity reactions different from all other types (I, II, or III) of hypersentivity reactions?
The usual types of reactions are mediated by antibodies.
B-lymphocytes produce the offending substances.
They typically occur with the first exposure to an antigen.
Delayed reactions are characterized by cytokine release.
The Correct Answer is A
A) The usual types of reactions are mediated by antibodies:
Correct. Types I, II, and III hypersensitivity reactions are mediated by antibodies (IgE, IgG, or IgM) that bind to antigens and trigger immune responses. In contrast, Type IV hypersensitivity reactions are T-cell mediated and do not involve antibodies.
B) B-lymphocytes produce the offending substances:
This statement is incorrect. B-lymphocytes are involved in antibody-mediated immune responses (types I, II, and III hypersensitivity reactions), not Type IV hypersensitivity reactions, which are primarily mediated by T-lymphocytes.
C) They typically occur with the first exposure to an antigen:
This statement is incorrect. Type IV hypersensitivity reactions usually require sensitization upon initial exposure to an antigen, and subsequent exposures elicit the delayed hypersensitivity response. This is similar to types I, II, and III hypersensitivity reactions, which also involve sensitization upon initial exposure.
D) Delayed reactions are characterized by cytokine release:
This statement is partially correct. Type IV hypersensitivity reactions are characterized by a delayed onset (typically 24 to 72 hours after exposure) and involve the release of cytokines from activated T-lymphocytes, leading to inflammation and tissue damage. However, other types of hypersensitivity reactions may also involve cytokine release, so this feature alone does not differentiate Type IV from other types of reactions.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A) Blockage of retinal capillaries causing ischemic damage of the central macular area:
Correct. Blurry central vision that worsens over time can be indicative of macular ischemia, often caused by blockage of retinal capillaries leading to ischemic damage of the central macular area. This condition can occur in diseases such as diabetic retinopathy or retinal vein occlusion.
B) Opaque spoke-like lines developing in the periphery of the lens to the center:
This description is more characteristic of cataracts, which cause visual disturbances such as glare or halos around lights rather than blurry central vision.
C) Tears in the retina that detach from the lining of the posterior eyeball:
Retinal tears and subsequent detachment can cause visual disturbances, but they typically present as sudden onset of floaters, flashes of light, and a curtain-like shadow over the visual field rather than blurry central vision.
D) An increase in intraocular pressure with loss of peripheral vision:
This description is indicative of glaucoma, which can lead to loss of peripheral vision (visual field defects) rather than blurry central vision. Glaucoma-related visual field loss usually begins peripherally and progresses inward, affecting central vision in later stages.
Correct Answer is B
Explanation
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra of the basal ganglia. This degeneration leads to a deficiency of dopamine, a neurotransmitter involved in the regulation of movement and coordination. The inability to express oneself, as seen in the client's mumbling, can be attributed to the motor symptoms of PD, particularly bradykinesia (slowness of movement) and hypomimia (reduced facial expression), which result from dopaminergic neuron degeneration.
A) Damage to Broca's area in the temporal lobe of the brain:
Damage to Broca's area typically results in expressive aphasia, which is characterized by difficulty speaking and forming coherent sentences. While speech difficulties can occur in PD, they are primarily due to motor dysfunction rather than damage to specific language centers in the brain.
B) Degeneration of dopaminergic neurons of the basal ganglia:
Correct. Degeneration of dopaminergic neurons in the basal ganglia, particularly the substantia nigra, is the primary pathological factor in Parkinson's disease. This degeneration leads to motor symptoms such as bradykinesia, tremor, and rigidity, which can affect the client's ability to speak clearly and express himself.
C) Brain atrophy with diffuse amyloid plaques disposition:
This description is more characteristic of Alzheimer's disease, a different neurodegenerative disorder characterized by brain atrophy and the deposition of amyloid plaques. While cognitive impairment can occur in PD, the primary motor symptoms are related to dopaminergic neuron degeneration rather than amyloid plaque deposition.
D) Paralysis of the pharyngeal and epiglottal area:
Paralysis of the pharyngeal and epiglottal area can lead to dysphagia (difficulty swallowing) rather than difficulty expressing oneself verbally. While dysphagia can occur in PD, it is not typically the primary factor contributing to speech difficulties in this condition.
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