Explain why long periods of standing promote development of varicose veins.
What will be an ideal response?
Answer: Pressures driving flow in the veins are generally low, reducing flow toward the heart, and in the legs, gravity works against the transport of blood through the veins up to the heart, further reducing flow. One-way valves assist the movement of blood toward the heart. Contractions of the leg muscles squeeze the veins, pushing blood toward the heart. If a person is standing without walking (muscle contractions) blood tends to pool in the veins of the legs, pushing on the walls and valves. Failure of the valves and stretching of the walls of the veins can contribute to the development of varicose veins.
You might also like to view...
t was often rumored that one of our deceased presidents was suffering from Addison's disease (inadequate synthesis of mineralocorticoids and glucocorticoids). What symptoms may have led to the diagnosis of this condition?
What will be an ideal response?
If a small blood clot passes through the heart and heart vessels, where is it most likely to cause damage if it becomes immobilized?
A) the aorta B) the left ventricle C) the right atrial chamber D) the left coronary artery E) Severe damage could occur if a small blood clot became immobilized at any of these positions.
If a section is made that separates the brainstem from the rest of the brain, the cut is between the
A) medulla oblongata and pons. B) pons and midbrain. C) midbrain and diencephalon. D) thalamus and cerebrum. E) medulla oblongata and spinal cord.
Starches and sugars are examples of
A. carbohydrates. B. lipids. C. proteins. D. vitamins. E. minerals.