Capillary walls consist of a single layer of epithelial cells, and they exchange substances in the blood for substances in the tissue fluid surrounding body cells.
True
False
The Correct Answer is A
Capillary walls consist of a single layer of epithelial cells, and they exchange substances in the blood for substances in the tissue fluid surrounding body cells.
This single layer of cells is called the endothelium and it forms the barrier between the blood and the interstitial fluid.
The endothelium can be either continuous or fenestrated, depending on the tissue type and function.
The capillaries are very thin and allow red blood cells to flow through them single file.
The capillaries also have a layer of a glycoprotein called the glycocalyx that covers their luminal surface.
Choice B. False is wrong because it contradicts the definition and structure of capillaries.
Capillaries are not made of multiple layers of cells, nor do they prevent the exchange of substances between the blood and the tissue fluid.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
The pancreas is an organ that has both endocrine and exocrine functions.
As an endocrine gland, it secretes hormones such as insulin and glucagon that regulate blood sugar levels.
As an exocrine gland, it releases substances that neutralize stomach acid and digestive enzymes that break down proteins, fats, and carbohydrates.
Choice A is wrong because the thyroid gland is only an endocrine gland.
It secretes hormones such as thyroxine and calcitonin that regulate metabolism and calcium levels.
Choice C is wrong because the anterior pituitary is only an endocrine gland.
It secretes hormones such as growth hormone, prolactin, and adrenocorticotropic hormone that regulate growth, lactation, and stress response.
Choice D is wrong because the liver is mainly an exocrine gland. It produces bile that helps digest fats and detoxifies the blood.
The liver also has some endocrine functions, such as producing insulin-like growth factor 1 and angiotensinogen, but these are not its primary roles.
Correct Answer is B
Explanation
This is because fibrinogen is a soluble protein in the blood plasma that is converted to insoluble fibrin strands by the enzyme thrombin during blood clotting. Fibrin forms a mesh-like network that traps platelets and other blood cells to form a clot.
Choice A is wrong because thrombin is not converted to prothrombin, but rather prothrombin is converted to thrombin by another enzyme called prothrombinase.
Choice C is wrong because vitamin K is not converted to prothrombin, but rather vitamin K is required for the synthesis of prothrombin and other clotting factors in the liver.
Choice D is wrong because fibrin is not converted to fibrinogen, but rather fibrinogen is converted to fibrin as explained above.
Normal ranges of fibrinogen in the blood are 200 to 400 mg/dL.
Normal ranges of prothrombin time (a measure of how long it takes blood to clot) are 11 to
13.5 seconds.
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