Low Levels of Calcium Within Cells Are Maintained by

question 105

Multiple Choice

Low levels of calcium within cells are maintained by

• A) a high number of voltage-gated and leakage channels for calcium in cell membranes.
• B) frequent exocytosis and endocytosis of calcium-containing vesicles.
• C) pumps that move calcium out of cells or into the sarcoplasmic reticulum.
• D) osmosis of large amounts of water into cells that have any calcium within them.

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Definitions:

Chorionic Villi

Microscopic, finger-like projections that emerge from the chorion to provide nutrient transfer from maternal blood to the fetus.

Amniotic Cavity

The fluid-filled space between the embryo or fetus and the amniotic sac, providing protection and facilitating movement.

Gastrulation

A phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula.

Germ Layers

The three primary layers of cells (ectoderm, mesoderm, and endoderm) in the early embryo that give rise to all organs and tissues in the body.