1. CELLULAR ADAPTATIONS
Dr. Suhad Faisal Hatem

2. CELLULAR ADAPTATIONS
Adaptations are reversible changes and are divided into physiologic &
pathologic adaptations. Physiologic adaptations usually represent responses
of cells to normal stimulations e.g., the hormone-induced enlargement of the
breast and uterus during pregnancy. Pathologic adaptions, on the other hand,
can take several distinct forms.
Types of cellular adaptation:
The types of cellular adaptation include(atrophy,hypertrophy, , hyperplasia
& metaplasia).

3. A. Atrophy
Atrophy is a decrease in both the number and size of the cells. This can lead to decreased size
of the organ.Atrophy results from decreased protein synthesis together with increased
protein degradation in the affected cells.It can be Physiological atrophy, Example: uterus
after labour and atrophy of the ovary after menopause orPathological atrophy Example:
 a-Ischemic atrophy: due to decrease of blood supply e.g. atherosclerosis.
 b- Pressure atrophy: due to long continued pressure on a tissue leading to decrease in its
blood supply with atrophy of its cells.
 d-Decreased work load:e.g. immobilized limbas treatment for a bone fracture or after
prolonged bed rest. muscular strength is reduced, When normal activity resumes, the
muscle's size and function return.
 c-Neuropathicatrophy:e.g. when a motor nerve supplying a muscle is affected as in
poliomyelitis .
 d-Starvation: leading to generalized atrophy.
 e-Loss of endocrine stimulation: as in postmenopausal endometrial atrophy (due to
decrease in the levels of estrogen after menopause) and testicular atrophy (due to decrease
in the production of LH & FSH as in hypopituitarism.

5. B-Hypertrophy:
Hypertrophy is enlargement of individual cells without increase in the
number of cells. Increased workload leads to increasedprotein synthesis , size
& number of intracellular organelles. This increased in cell size leads to
increased size of theorgan.Examples: the enlargement of thepregnant
uterusdue to estrogen-stimulated smooth muscle, skeletal muscleof athletes
and heart muscles.

6. C. Hyperplasia
Hyperplasia is an increase in the number of cells. It can lead to an
increase in the sizeof the organ. It is usually caused by hormonal
stimulation. It can be physiological as inenlargement of the
breastglandular epithelium during pregnancy or it can pathological
as in endometrialhyperplasia.Endometrial hyperplasia: this results
from persistent or excessive estrogen stimulation of the
endometrium. This hyperplasia is a common cause of abnormal
uterine bleeding

8. D. Metaplasia
Metaplasia is the replacement of one differentiated tissue by
another cell type of the same tissue. Metaplasia is thought to arise
by genetic deprogramming" of epithelial stem cell or of
undifferentiated mesenchymal cells in connective tissue. There
are 2 different types of metaplasia:

9. 1- Squamous metaplasia
It is replacement of adultepithelium cell by another type of epithelium e.g.
squamous epithelium. Forexample:pseudostratified ciliated columnar respiratory
epithelium due to chronic irritation by habitual cigarette smoking , transitional
epithelium of urinary bladder, ureter or renal pelvis due to chronic irritation by
bilharziasis or stones.
2- Osseous metaplasia
This replacement of a connective tissue by bone, for example at sites of injury.
Note:If the influences that induce metaplastic transformation of the epithelium
are persistent, they may lead to cancer transformation in the metaplastic
epithelium, e.g. squamous metaplasia of transitional epithelium of the urinary
bladder by bilharziasis will lead to squamous cell carcinoma.
Note:If the influences that induce metaplastic transformation of the epithelium
are persistent, they may lead to cancer transformation in the metaplastic
epithelium, e.g. squamous metaplasia of transitional epithelium of the urinary
bladder by bilharziasis will lead to squamous cell carcinoma.

11. Pathologic calcification
Calcification is abnormal tissue deposition of calcium,iron and mineral salts. This
buildup can harden and disrupt your body’s normal processes. Calcium is
transported through the blood stream. It is also found in every cell. As a result,
calcification can occur in almost any part of the body.
about 99 percent of your body’s calcium is in your teeth and bones. The other 1
percent is in the blood, muscles, fluid outside the cells, and other body tissues.
Some disorders cause calcium to deposit in places where it does not typically
belong. Over time, this can add up and cause
problems.

12. Causes of calcification
Many factors have been found to play a role in calcification,These include:
•infections
•calcium metabolism disorders that cause hypercalcemia (too much calcium in
the blood)
•genetic or autoimmune disorders affecting your skeletal system and connective
tissues
•persistent inflammation
there are two type of calcification
dystrophic calcification is deposition of calcium in degeneration or dead
tissues, though serum levels of calcium remain normal(normal calcium
metabolism). This type of calcification is seen in:
a-areas of necrosis ,dying and dead tissue.
b-atherosclerotic plaques
c- aging or damaged heart valves.

13. Metastatic calcification is deposition of calcium salts in normal living tissue, with
elevated serum levels of calcium, which can occur because abnormal calcium
metabolism(hypercalacemia). This type of calcification happens when there is body
but principally affects the interstitial tissues of the vasculature, kidneys, lungs, and
gastric mucosa.
These differences in pathology also mean that metastatic calcification is often found
in many tissues , whereas dystrophic calcification is localized.
Pathogensis of calcification
The calcium in the surface of cell member will bind with phospholipid, phosphates
enzyme lead to the calcium,phosphates deposite as amicro crystal in the tissue
causing calcification.
Microscopically
Two type of calcification are appear as intracellular and /or extra cellular(bluish)
deposites as seed surrounding with ca+ layers.

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