Which blood vessels lack elastic tissue?
muscular arteries and arterioles
venules and veins
capillaries and venules
arterioles and capillaries
The Correct Answer is C
A. Muscular arteries and arterioles: Both muscular arteries and arterioles contain smooth muscle and some elastic tissue within their walls. These elastic components help them withstand pressure changes and regulate blood flow. Because they possess measurable elasticity, they cannot be categorized as vessels lacking elastic tissue.
B. Venules and veins: Veins and venules do contain small amounts of elastic fibers, even though they are far less elastic than arteries. These fibers help accommodate changes in blood volume and allow the vessel walls to stretch as they act as capacitance vessels. Since elastic tissue is present, they do not fit the criterion of lacking elasticity.
C. Capillaries and venules: Capillaries lack elastic tissue entirely because their walls consist of only a single layer of endothelial cells to allow rapid exchange of gases and nutrients. Venules, especially the smallest ones, also have minimal to no elastic tissue, consisting mainly of endothelium and a thin connective layer. This combination makes them the best match for vessels lacking elastic fibers.
D. Arterioles and capillaries: Arterioles possess smooth muscle and contain elastic tissue that allows them to regulate resistance and control blood flow into capillary beds. Capillaries alone lack elastic tissue, but arterioles do not.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Pulmonary trunk:The pulmonary trunk carries deoxygenated blood from the right ventricle to the lungs for oxygenation. It does not contain oxygenated blood at any point before reaching the pulmonary circulation.
B. Lobar arteries:Lobar arteries are branches of the pulmonary arteries that also carry deoxygenated blood to specific lobes of the lungs. Their role is in transporting blood to the lungs, not returning oxygenated blood.
C. Pulmonary veins:Pulmonary veins carry oxygenated blood from the lungs back to the left atrium of the heart. They are unique among veins in that they transport oxygen-rich blood rather than deoxygenated blood, making them the correct choice.
D. Pulmonary arteries:Pulmonary arteries carry deoxygenated blood away from the right ventricle toward the lungs. Despite being arteries, they do not carry oxygenated blood, as their function is to deliver blood for gas exchange.
Correct Answer is C
Explanation
A. Emotions:Emotional states, such as stress or anxiety, stimulate the sympathetic nervous system, increasing heart rate and thus affecting the pulse rate. Emotional fluctuations can cause measurable changes in pulse readings.
B. Activity:Physical activity raises heart rate to meet the increased oxygen and nutrient demands of tissues. Pulse rate typically rises during exercise and decreases with rest, making activity a significant factor.
C. The vessel selected to palpate:The choice of vessel (e.g., radial, carotid, brachial) does not inherently alter the actual heart rate; it only provides a site to detect the pulse. Pulse readings reflect heart rate regardless of which accessible artery is used.
D. Postural changes:Changes in body position, such as standing or sitting, can temporarily influence heart rate due to shifts in venous return and baroreceptor responses. This makes postural changes a relevant factor in pulse rate variability.
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