The bacterium that causes tetanus produces a toxin that affects the central nervous system and skeletal muscles, producing powerful tetanic contractions of the skeletal muscles. The toxin probably acts by
A) Increasing the amount of acetylcholinesterase in the synapse.
B) Making the cells less permeable to sodium ions.
C) Increasing the amount of potassium ion in the intercellular fluid.
D) Making the cell membranes more permeable to calcium ion.
E) Competing with acetylcholine for receptors at the motor end plate.
D) Making the cell membranes more permeable to calcium ion.
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Potent platelet aggregates that attract more platelets to the site of an injury are ________ and ________.
Fill in the blank(s) with the appropriate word(s).
Which of the following hormones is regulated by a positive feedback mechanism?
A) oxytocin B) slow-acting hormone that works through a second-messenger system C) TSH D) thyroxine E) TRH
The process of ultrafiltration
a. is movement of protein-free plasma from the capillaries into the interstitial fluid b. occurs when capillary blood pressure plus interstitial fluid osmotic pressure exceed blood-osmotic pressure plus interstitial fluid hydrostatic pressure c. occurs when capillary blood pressure plus plasma osmotic pressure exceed interstitial fluid hydrostatic pressure plus interstitial fluid osmotic pressure d. is both a and b e. is both a and c
Heat, one sign of inflammation, is caused by:
a. increased blood flow to the inflamed area b. increased vessel permeability c. increased white blood cell concentration d. all of the above