Explain how the structure of the alveoli facilitate their function in gas exchange.
What will be an ideal response?
Answer: Alveoli are tiny air-filled spheres, surrounded by a very thin membrane, encircled by capillaries. The alveoli are the site of diffusive gas exchange in the lungs with the blood. Diffusion is faster when the surface area is greater, and the diffusion distance is short. Because they are very tiny (remember surface: volume ratio is high in small spheres), and there are many of them, the combined total surface area of alveoli is huge (roughly the size of a tennis court). This extensive surface area and the thinness of the barrier permits the rapid exchange of large quantities of oxygen and carbon dioxide by diffusion.
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. An erection is the result of parasympathetic innervation, and ejaculation is the result of sympathetic innervation
Indicate whether this statement is true or false.
Spinal nerves exiting the cord from the level of L4 to S4 form the ________
A) lumbar plexus B) sacral plexus C) thoracic plexus D) femoral plexus
Design an experiment to test whether molecular weight does indeed influence the rate of diffusion. Be sure to list all controlled variables.
What will be an ideal response?
Match the following:
A) Helper T cells B) Regulatory T cells C) APCs D) Complement E) Interferon 1) Small proteins secreted by virus-containing cells. 2) Major innate mechanism that mediates destruction of foreign substances in the body. 3) Stimulate the proliferation of other lymphocytes. 4) Dampen the activity of both T cells and B cells. 5) Present the double activation signal to T cells.