Cell adaptations

Hypoxia

Physical Agents

Chemicals

Infections

Immunological Reactions

Genetic Errors

Nutritional Imbalances

Hyperplasia

Hypertrophy

Atrophy

Metaplasia

Non dividing cells

Physiological

Pathological

Cells not capable of replication

Mechanisms

mechanical triggers

trophic triggers

Ex :hypertrophy of heart

uterus in pregnancy

Skeletal muscle in body builders

Increased production of structural proteins

Switch of contractile proteins from adult to fetal

Expression of fetal genes

Cells capable of replication

Increase in no of cells

Increase in size of the organ

Physiologic and pathologic

Hormonal

Compensatory

Mechanisms of hyperplasia

local production of growth factors

activation of intra cellular pathway

stem cells

Excessive hormonal stimulation

Bph , endometrial hyperplasia

Fertile soil for cancerous proliferations

Shrinkage in cell size by loss of substances

Organ shrinkage

Physiologic or pathologic

Physiologic Atrophy

Ex : 1. Development – notocord , thyroglossal duct

2. uterus after parturition

Decreased workload

Loss of innervation

Diminished blood supply

Inadequate nutrition

Loss of hormonal stimulation

Senile atrophy

Imbalance between protein production and utilization

Ubiqutin proteosome pathway

Reversible change

Replacement of one adult cell by other type

Mc – columnar to squamous

Seen in respiratory epithelium

Ducts of glands impacted by stones

Vitamin A deficiency

Malignant transformation on chronic stages

Barrets esophagus

Connective tissue metaplasia

Cervical metaplasia

Stem cell reprogramming

Uncoordinated growth factors

Vit A deficiency

Cytostatic drugs

Virus