Platelets
a. are small cell fragments derived from large megakaryocytes in the bone marrow
b. lack nuclei
c. contain high concentrations of actin and myosin, which enable them to contract
d. have all of the above characteristics
e. have only characteristics a and b
D
You might also like to view...
When a depolarizing graded potential makes the axon membrane depolarize to threshold,
a) ligand-gated Ca+2 channels close rapidly. b) voltage-gated Ca+2 channels open rapidly. c) ligand-gated Na+ channels close rapidly. d) voltage-gated Na+ channels open rapidly. e) none of these choices occur.
Nervous tissue relies almost exclusively on __________ as fuel
Fill in the blank with the correct word.
Where in the nephron does secretion occur?
A) loop of Henle B) distal convoluted tubule C) glomerulus D) proximal convoluted tubule
There are special lymphatic vessels called ____ that absorb fats and transport them from the digestive tract to the blood
a. capillaries b. lacteals c. chyle d. arterioles