A client who has asthma (a reactive airway disease) asks the nurse about the role of leukotrienes in this process. Leukotrienes have which immune response?
Produce the sensation of Itching.
Tighten airway and produce mucous.
Causes formation of bradykinin.
Serves as receptor for antigen.
The Correct Answer is B
Leukotrienes are inflammatory mediators derived from arachidonic acid metabolism, primarily produced by leukocytes (white blood cells) such as mast cells, eosinophils, and basophils. In the context of asthma, leukotrienes play a significant role in the pathophysiology of the disease by contributing to airway inflammation and bronchoconstriction. Here's a breakdown of their immune response:
A) Produce the sensation of itching:
Leukotrienes are not directly involved in producing the sensation of itching. Itching is often associated with histamine release rather than leukotrienes.
B) Tighten airway and produce mucous:
Correct. Leukotrienes are potent bronchoconstrictors that cause smooth muscle contraction in the airways, leading to narrowing (constriction) of the bronchioles. Additionally, they stimulate the secretion of mucus from goblet cells in the airway epithelium, contributing to airway obstruction and mucus production, which are characteristic features of asthma exacerbations.
C) Causes formation of bradykinin:
Bradykinin is a peptide mediator that is generated from the plasma protein kininogen and is involved in vasodilation, pain sensation, and inflammation. Leukotrienes are not directly responsible for the formation of bradykinin.
D) Serves as a receptor for antigen:
Leukotrienes do not serve as receptors for antigens. Instead, they are lipid mediators released in response to various stimuli, including allergens, infections, and irritants, and they act on specific receptors (e.g., leukotriene receptors) to exert their effects, such as bronchoconstriction and inflammation
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A) Increased preload that results in generalized peripheral edema:
This statement is incorrect. Decreased blood volume due to hemorrhage leads to decreased preload, not increased preload. Generalized peripheral edema is more commonly associated with conditions such as heart failure or kidney disease, where fluid retention leads to increased preload.
B) The lowered blood pressure results in a reduction of the heart rate:
While it's true that a decrease in blood pressure can trigger compensatory mechanisms such as an increase in heart rate (tachycardia), the specific response mentioned in this option is not entirely accurate. The primary compensatory response to hemorrhage-induced hypotension is typically an increase in heart rate, not a reduction.
C) Decreased preload that can lead to decreased cardiac output:
Correct. With decreased blood volume (preload), there is less blood returning to the heart during diastole. This leads to decreased ventricular filling and subsequently decreased stroke volume and cardiac output. Decreased cardiac output can contribute to hypotension and inadequate tissue perfusion.
D) Increased peripheral resistance resulting from poor renal perfusion:
While poor renal perfusion can trigger mechanisms to increase peripheral resistance (such as activation of the renin-angiotensin-aldosterone system), this option does not directly address the primary effect of decreased preload on cardiac output. Increased peripheral resistance alone does not adequately compensate for decreased preload to maintain cardiac output.
Correct Answer is D
Explanation
The loop of Henle, a critical structure within the nephron of the kidney, plays a key role in the concentration of urine through the process of countercurrent multiplication. Here's why option D is the correct choice:
A) Calyx:
The calyx is a structure in the kidney that collects urine from the renal papillae and channels it into the renal pelvis. It does not directly participate in the concentration of urine.
B) Proximal convoluted tubule:
The proximal convoluted tubule primarily reabsorbs water, electrolytes, and nutrients from the glomerular filtrate, but it does not contribute significantly to the concentration of urine.
C) Renal pelvis:
The renal pelvis is a funnel-shaped structure that collects urine from the calyces and funnels it into the ureter. It is not directly involved in the concentration of urine.
D) The loop of Henle:
Correct. The loop of Henle is the nephron segment responsible for generating a hypertonic medullary interstitium, which creates the osmotic gradient necessary for urine concentration. The loop of Henle achieves this through countercurrent multiplication, where the descending limb allows passive reabsorption of water, while the ascending limb actively pumps out sodium and chloride ions. This creates an osmotic gradient that allows for further water reabsorption in the collecting ducts, leading to concentrated urine.
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