Biomedical Engineering Reference
In-Depth Information
9
8
+
7
++
6
+
5
4
0
20 40
Mean Population Doublings
60
80
100
100
+
80
+
60
40
+
20
0
0
20 40
Mean Population Doublings
60
80
100
FIGURE 6.11
Primary experimental data showing the shortening of telomere length with increasing cellular
doubling in cell culture.
From [5].
However, the time scales that relate cellular activities with tissue function are relatively
long, and therefore their importance tends to be overlooked. As examples, some cellular-
level activities that underlie dynamic states of tissue function fall
into the following
categories:
1.
Hyperplasia:
Cell replication or proliferation resulting in an increase in cell number due
to complete cell division (both DNA synthesis and cytokinesis).
2.
Hypertrophy:
DNA synthesis not accompanied by cytokinesis and instead results in an
increase in the cell volume.
3.
Cell maturation and differentiation:
Changes in gene expression and the acquisition of
particular functions, with the changes occurring in a maturationally lineage-dependent
pattern.
4.
Cell apoptosis:
Aging cells undergoing “programmed cell death,” a process
distinguishable from necrosis.
5.
Cell adhesion:
The physical binding of a cell to its immediate environment, which may be
a neighboring cell, an extracellular matrix, or an artificial surface.
6.
Cell motility:
The motion of a cell into a particular niche or location.
