Doctors suggest that during long periods of sitting, you should flex and extend your feet at the ankles periodically and squeeze your calf muscles to assist with blood circulation.
Why would non-exercise muscle contraction affect blood flow and cardiovascular health?
Contraction of muscles stimulates the arteries to vasodilate, reducing blood pressure.
Contraction of muscles itself increases heart rate and burns calories, keeping the heart strong and assisting in maintaining a healthy weight.
Contraction of the leg muscles stimulates baroreceptors to signal the autonomic nervous system and decrease blood pressure and heart rate from multiple fronts.
Contraction of the leg muscles squeezes leg veins, which function as a pumping mechanism to return deoxygenated blood to the heart.
The Correct Answer is D
This helps prevent blood pooling and clotting in the lower extremities, which can lead to deep vein thrombosis and pulmonary embolism.
It also reduces the workload on the heart and improves blood circulation throughout the body.
Choice A is wrong because contraction of muscles does not stimulate the arteries to vasodilate, but rather causes vasoconstriction in the inactive tissues to divert blood flow to the active muscles.
Choice B is wrong because the contraction of muscles itself does not increase heart rate significantly unless it is part of an aerobic exercise that elevates the metabolic demand.
Burning calories and keeping the heart strong are benefits of regular physical activity, not occasional muscle contraction.
Choice C is wrong because contraction of the leg muscles does not stimulate baroreceptors, which are pressure-sensitive receptors located in the walls of the arteries.
Baroreceptors respond to changes in blood pressure and signal the autonomic nervous system to adjust heart rate and vascular resistance accordingly.
Contraction of the leg muscles does not affect blood pressure or heart rate directly but rather assists with venous return.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Persons with type AB blood are sometimes called universal recipients, not donors. This means they can safely receive a blood transfusion using any other blood type. Choice A is wrong because it confuses type AB blood with type O negative blood.
Type O negative blood is considered the universal donor type because it has no antigens on the surface of red blood cells and can be given to people of any blood type.
Type AB-positive blood is also considered the universal plasma donor type because it has both A and B antigens and can be given to patients with any blood type.
Plasma is the liquid part of blood that carries cells and proteins throughout the body.
The presence or absence of antigens and the Rh factor determine how a person’s immune system reacts to a blood transfusion or organ transplant.
Antigens are substances that can trigger an immune response if they are foreign to the body.
The Rh factor is a protein that can be either present (+) or absent (-) on the surface of red blood cells.
Correct Answer is B
Explanation
This means that the electrical activity that causes the atria to contract starts from the sinoatrial node and spreads across the atria.
The P wave on the ECG reflects this atrial depolarization.
Choice A is wrong because repolarization of atrial muscle fibers is not visible on the ECG, as it occurs during the QRS complex when the ventricular depolarization masks it.
Choice C is wrong because the depolarization of ventricular muscle fibers is represented by the QRS complex on the ECG, not the P wave.
Choice D is wrong because the repolarization of ventricular muscle fibers is represented by the T wave on the ECG, not the P wave.
Normal ranges for the P wave are:
Duration: less than 0.12 seconds (less than 3 small squares)
Amplitude: less than 2.5 mm (0.25 mV) in the limb leads, less than 1.5 mm (0.15 mV) in the precordial leads
Axis: between 0° and +75°12
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