What is the inherent rate of the AV (atrioventricular) node area?
40 to 60.
20 to 40.
60 to 80.
80 to 100.
The Correct Answer is A
The atrioventricular (AV) node is an essential component of the cardiac conduction system responsible for transmitting electrical impulses from the atria to the ventricles. The inherent rate of the AV node refers to its intrinsic ability to generate electrical impulses in the absence of external influences.
Here's a breakdown of each option:
A) 40 to 60:
Correct. The inherent rate of the AV node is typically 40 to 60 beats per minute (bpm). This rate is slower than that of the sinoatrial (SA) node, which has an inherent rate of 60 to 100 bpm. The AV node acts as a backup pacemaker, ensuring that the ventricles receive electrical impulses even if the SA node fails to function properly.
B) 20 to 40:
This range is not consistent with the typical inherent rate of the AV node. A rate of 20 to 40 bpm would be unusually slow and could indicate significant conduction system abnormalities rather than the normal functioning of the AV node.
C) 60 to 80:
This range is more characteristic of the inherent rate of the SA node rather than the AV node. The SA node is the primary pacemaker of the heart, and its inherent rate is typically 60 to 100 bpm.
D) 80 to 100:
Similar to option C, this range is more consistent with the inherent rate of the SA node rather than the AV node. The SA node typically has a faster intrinsic rate compared to the AV node.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
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.
Correct Answer is B
Explanation
Otosclerosis is a condition characterized by abnormal bone growth in the middle ear, specifically involving the stapes bone. This abnormal bone growth interferes with the transmission of sound vibrations from the middle ear to the inner ear, resulting in conductive hearing loss. Here's a breakdown of each option:
A) Presbycusis:
Presbycusis refers to age-related hearing loss, typically involving sensorineural components such as the degeneration of hair cells in the inner ear or changes in the auditory nerve. While presbycusis is a common cause of hearing loss in older adults, it is not directly related to otosclerosis or previous ear surgeries.
B) Conductive:
Correct. Otosclerosis primarily affects the middle ear by causing abnormal bone growth around the stapes bone, which can immobilize it and interfere with sound transmission to the inner ear. As a result, individuals with otosclerosis often experience conductive hearing loss, where sound is not effectively conducted from the outer or middle ear to the inner ear.
C) Endolymphatic:
Endolymphatic hydrops, also known as Ménière's disease, involves abnormal fluid accumulation in the inner ear, leading to symptoms such as vertigo, tinnitus, and fluctuating sensorineural hearing loss. While inner ear disorders like endolymphatic hydrops can cause sensorineural hearing loss, otosclerosis primarily affects the conductive components of hearing.
D) Sensorineural:
Sensorineural hearing loss occurs due to dysfunction or damage to the inner ear (cochlea) or auditory nerve pathways leading to the brain. This type of hearing loss is typically permanent and can result from various factors, including age-related changes, noise exposure, and certain medical conditions. While sensorineural hearing loss can coexist with conductive hearing loss in some cases, otosclerosis primarily causes conductive hearing loss rather than sensorineural hearing loss.
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