1. Describe cellular processes and alterations within cellular processes.
Movement. Muscle cells can generate forces that produce motion. Muscles that
... [Show More] are attached to
bones produce limb movements, whereas those that enclose hollow tubes or cavities move or
empty contents when they contract. For example, the contraction of smooth muscle cells
surrounding blood vessels changes the diameter of the vessels; the contraction of muscles in
walls of the urinary bladder expels urine.
Conductivity. Conduction as a response to a stimulus is manifested by a wave of excitation, an
electrical potential that passes along the surface of the cell to reach its other parts. Conductivity
is the chief function of nerve cells.
Metabolic absorption. All cells take in and use nutrients and other substances from their
surroundings. Cells of the intestine and the kidney are specialized to carry out absorption. Cells
of the kidney tubules reabsorb fluids and synthesize proteins. Intestinal epithelial cells reabsorb
fluids and synthesize protein enzymes.
Secretion. Certain cells, such as mucous gland cells, can synthesize new substances from
substances they absorb and then secrete the new substances to serve as needed elsewhere. Cells
of the adrenal gland, testis, and ovary can secrete hormonal steroids.
Excretion. All cells can rid themselves of waste products resulting from the metabolic breakdown
of nutrients. Membrane-bound sacs (lysosomes) within cells contain enzymes that break down,
or digest, large molecules, turning them into waste products that are released from the cell.
Respiration. Cells absorb oxygen, which is used to transform nutrients into energy in the form of
adenosine triphosphate (ATP). Cellular respiration, or oxidation, occurs in organelles called
mitochondria.
Reproduction. Tissue growth occurs as cells enlarge and reproduce themselves. Even without
growth, tissue maintenance requires that new cells be produced to replace cells that are lost
normally through cellular death. Not all cells are capable of continuous division.
Communication. Communication is vital for cells to survive as a society of cells. Pancreatic
cells, for instance, secrete and release insulin necessary to signal muscle cells to absorb sugar
from the blood for energy. Constant communication allows the maintenance of a dynamic steady
state.
2. What is the impact of the genetic environment on disease? [Show Less]