A blood vessel has the following characteristics: outer layer of connective tiss

Question

A blood vessel has the following characteristics: outer layer of connective tissue, a thick layer of smooth muscle with elastic fibers, no valves. It is which of the following A) a vein B) a venule C) an artery D) a capillary E) a portal vessel Which of these are involved in the early stages of blood clotting? A) low-density lipoproteins B) immunoglobulins C) erythropoietin D) epinephrine E) platelets Which of the following features do all gas exchange systems have in common? A) The exchange surfaces are moist. B) They are enclosed within ribs. C) They are maintained at a constant temperature. D) They are exposed to air. E) They are found only in animals. Which of the following is an example of countercurrent exchange? A) the flow of water across the gills of fish and that of blood within those gills B) the flow of blood in the dorsal vessel of an insect and that of air within the its tracheae C) the flow of air within the primary bronchi of a human and that of blood within the pulmonary veins D) the flow of water across the skin of a frog and that of blood within the ventricle of its heart. E) the flow out of arterial end of a capillary and that of fluid back into the venous end of the same capillary An oil-water mixture is used as a spray against mosquitoes. How might this spray also affect gas exchange in other insects? A) The oil might coat their lungs. B) The oil might block the openings into the tracheal system. C) The oil might interfere with gas exchange across the capillaries. D) Only A and B are correct. E) A, B, and C are correct Which of the following occurs with the exhalation of air from human lungs?

Explanation / Answer

7-ans-C

Arteries wall is thicker and muscular wall helps to absorb the pressure which is generated by the heart and transmitted through blood.Arteries have smaller lumens than veins helps to maintain the pressure of blood.

8 ans-E platelets

also called thrombocytes,platelets from the circulating blood is attracted to the injured surface and by the process of hemostasis cause the bleeding stop,

9 ans-C

the exchange surfaces are moist because gases dissolve in water before diffuse in out and are able to maintain the diffusion gradient.

10- ans A The flow of water across the gills of the fish and that of blood within those gills

In the gills, oxygen transfer from the water to the blood and water and blood flow in opposite directions

11 ans-the oil might block the openings into the tracheal system

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