Cellular basis of disease (cell injury, cell death, and adaptations) Adaptations Hypertrophy, Atrophy, Hyperplasia, Metaplasia

1. CELLULAR
BASIS OF
DISEASE
(Cell Injury, Cell Death, and
Adaptations
Prof. Mark Anthony I. Jose, MSc.

2. Overview of Cellular Responses
to Stress and Noxious Stimuli
– Cells are active participants in their environment, constantly
adjusting their structure and function to accommodate changing
demands and extracellular stresses.
– Cells tend to maintain their extracellular milieu within a fairly
narrow range of physiologic parameters; that is they maintain
normal homeostasis.
– The principal adaptive responses are hypertrophy, hyperplasia,
atrophy, and metaplasia.

5. Adaptation VS Injury

6. Cellular Adaptation to
Stress

7. HYPERTROPHY
– Hypertrophy is an increase in the size of
individual cells, in response to a stimulus or
injury. Increased workload leads to increased
protein synthesis & increased size & number of
intracellular organelles which, in turn, leads to
increased cell size. The increased cell size leads to
increased size of the organ.

11. HYPERPLASIA
– Is an increase in the absolute number of cells, in
response to a stimulus or persistent cell injury. It
can lead to an increase in the size of the organ. It
is usually caused by hormonal stimulation. It can
be physiological as in enlargement of the breast
during pregnancy or it can pathological as in
endometrial hyperplasia.

12. Two (2) forms of Physiologic
Hyperplasia
Hormonal Hyperplasia
– Exemplified by the proliferation of
the glandular epithelium of the
female breast at puberty and
during pregnancy.
Compensatory Hyperplasia
– Occurs when a portion of the
tissue is removed or diseased.
– For example, when a liver is
partially resected, mitotic activity
in the remaining cells begin as
early as 12 hours later, eventually
restoring to its normal weight

14. ATROPHY
– Shrinkage in the size of the cell (with or without accompanying
shrinkage of the organ or tissue). Atrophied cells are smaller than
normal but they are still viable. Atrophy can be caused by:
A. Disuse
B. Undernutrition
C. Decreased endocrine stimulation
D. Denervation
E. Old age

17. METAPLASIA
– A reversible change in which one mature/adult cell type (epithelial
or mesenchymal) is replaced by another mature cell type of the
same category. Metaplasia is the replacement of one
differentiated tissue by another differentiated tissue. There are
different types of metaplasia.

21. Osseous Metaplasia