2. Adaptation in animals
Walrus has thick
skin to protect
against cold
condition
Duck has
webbed feet
Nostrils on the
top of the
snout
3. The polar bear has small ears &
tail. This adaptation minimizes
heat loss.
Long & bushy
eyelash to
keep out the
sand & sun
Slit like nostrils
they are able
to open & close
to prevent sand
Hill like humps –
for storing fat, so
that they can go
without eating
long time
16. Examples:
1) Physiological-
A)Hormonal ( functional capacity)
Proliferation of glandular epithelium of
female breast at puberty & during pregnancy
B) Compensatory ( Tissue mass after damage/partial resection)
Regeneration of liver after partial hepatectomy
Unilateral nephrectomy
17. 2) Pathological Hyperplasia
• Endometrial Hyperplasia
• Benign prostatic Hyperplasia
Androgen induced
Ques : Which 1 has more chance of malignancy?
18. • Skin wart (HPV) CT proliferation in wound
healing
20. • Examples :
1) Physiological
• Notochord , Thyroglossal duct atrophy during fetal development.
• Involution of uterus after parturition.
21. 2) Pathological-
↓workload (Disuse atrophy) :
• Complete bed rest
(When fracture bone is immobilized in a plaster cast
prolonged disuse
Skeletal muscle fiber↓ in number , as well as size.)
22. Loss of innervation (Denervation atrophy) -
damage to nerve leads to atrophy.
↓ Blood supply- due to arterial occlusion-
Senile atrophy
Progressive brain atrophy.
23. Inadequate nutrition-
• PEM (Marasmus) +++ muscle wasting.
Loss of endocrine stimulation
Hormone responsive tissue (breast, reproductive organ)
depends on hormone for normal metabolism & function.
After menopause, loss of estrogen atrophy of endometrium, vaginal epithelium
& breast.
27. Epithelial Metaplasia
1) Squamous metaplasia-
Respiratory Tract
Ex– Habitual cigarette smoker
Vit A deficiency
• Pathogenesis-
Chronic irritation Normal ciliated columnar epithelium of trachea &
bronchi are replaced by stratified squamous epithelium.
28. Stones in the ducts of salivary gland, pancreas and bile duct
• Chronic irritation
Secretory columnar epithelium are
replaced by stratified squamous epithelium.
29. 2) Columnar metaplasia
• Barrett esophagus
Reflux gastric acid squamous epithelium
is replaced by
intestinal like columnar epithelium
• Adenocarcinoma may arise.
30. Connective Tissue Metaplasia
• Formation of cartilage , bone/ adipose tissue ( mesenchymal ) in
tissues that do not contain these element.
• Example-
Myositis ossificans – Bone formation in muscle, occasionally occurs after
intramuscular hemorrhage.