Nurs 6501 Midterm Exam Review Guide (Weeks 1-6)
Cellular Processes and the Genetic Environment
1. Describe cellular processes and alterations within
... [Show More] cellular processes.
Movement. Muscle cells can generate forces that produce motion. Muscles that 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?
Genetic diseases caused by single genes usually follow autosomal dominant, autosomal
recessive, or X-linked recessive modes of inheritance. The recurrence risk for autosomal
dominant diseases is usually 50%. Germline mosaicism can alter recurrence risks for genetic
diseases because unaffected parents can produce multiple affected offspring. This situation
occurs because the germline of one parent is affected by a mutation but the parent's somatic cells
are unaffected. Skipped generations are not seen in classic autosomal dominant pedigrees. Males
and females are equally likely to exhibit autosomal dominant diseases and to pass them on to
their offspring. Penetrance may be age-dependent, as in Huntington disease and familial breast
cancer. Most commonly, parents of children with autosomal recessive diseases are both
heterozygous carriers of the disease gene. In this case, the recurrence risk for autosomal [Show Less]