Which of the following is true of tight junctions?
A. They contain channels of diffusion of solutes from one cell to the next.
B. They seal off intercellular space and prevent substances from passing between cells.
C. They are formed by connexons.
D. They are patch-like connections that are abundant in the epidermis and serve to keep cells from pulling apart.
E. They are patches that are formed when J-shaped proteins protrude toward the plasma membrane from the cytoskeleton.
Answer: B
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Apoptosis has been implicated in a great number of disease states. Which of the following is probably not a consequence of errors in apoptosis?
A)A cell population that is triggered to undergo apoptosis would be diminished. An example is that HIV signals apoptosis in an important immune cell called the T helper cell. The reduction in T helper cells leads to the diminished immunity in Acquire Immunodeficincy Disease (AIDS). B)Failure of apoptosis in menstruating women could lead to cells that persist beyond their normal monthly cycle. A condition similar to this would be endometriosis. C)Excessive apoptosis would lead to cancerous growth of cells. An example is the inhibition of tumor suppressor genes like p53. D)Removing the tissue between fingers and toes during development relies on apoptosis. Thus, failure of apoptosis could lead to webbed toes.
Which of the following would a neurologist use to determine the specific point of damage on the spine?
a. Spinal fracture test. b. Dermatomes. c. Motor reflex test. d. Meridians.
Which muscle (sometimes called the boxer's muscle) allows you to punch a punching bag?
A. Serratus anterior B. Pectoralis major C. Deltoid D. Latissimus dorsi
Platelets are best described as
A. lymphoid cells. B. giant, multinucleated cells. C. cytoplasmic fragments of cells. D. immature leukocytes.