Cell aaaadaptation

1. Cell Adaptation
Submitted To
Sir Ihsaan Mohsin

2. Definition:
In response to environmental stress the change in cell
shape, size, pattern of growth and metabolic activity in
order to escape and protect themselves from injury is called
cellular adaptation.
OR
The group of changes within cell in response to
environmental stress is called cellular adaptation.
OR
Cellular adaptation refers to those adjustments that a cell
makes in response to alterations in the environment in
which it must live.

6. Control of cell population
•Cellular adaptations refer to the changes made by cells in
response to various stimuli or changes in their local
environment. This can involve changing the number of
cells or their morphological appearance. It can
be physiological, where it occurs in normal tissues or organs,
or pathological, i.e. occurring in disease states.
•In this article, we will consider how the sizes of cell populations
are controlled, how cells and tissues can adapt in response to
stressors and how these processes can result in disease.

7. Cont ...
•Control of cell populations
•The size of cell populations depends on the rate of 3 factors:
•Cell proliferation
•Cell differentiation
•Cell death by apoptosis
•Increased cell numbers are therefore seen with
either increased cell proliferation or decreased cell death.

8. Cont ...
•Cell proliferation occurs both in both physiological and
pathological conditions. Physiological cell proliferation is
primarily regulated by chemical signals which either promote
or inhibit proliferation. Signalling may be via hormones, local
mediators such as growth factors or direct cell to cell contact. If
cell proliferation becomes uncontrolled, and cells no longer
respond to inhibitory signals, cancer can develop.
•Growth factors act on cell surface receptors, stimulating
transcription of genes that regulate the cell cycle. Examples of
growth factors include epidermal growth factor, vascular
endothelial growth factor and platelet-derived growth factor.

9. Cont ...
•Ultimately, cell signalling results in one of four outcomes:
•Cell survival, i.e. resistance of apoptosis
•Cell division – cell enters the cell cycle
•Cell differentiation – cell takes on specialised form and function
•Cell death via apoptosis

12. Types of Cell Adaption:
•Five major types of adaptation
•include
•Atrophy,
•Hypertrophy,
• Hyperplasia,
•Dysplasia,
•Metaplasia.

13. • Cellular Adaptations
Size Number Type
Atrophy
1.Disuse
2.Loss of
endocrine
stimulation
3.Denervation
4.Inadequate
nutrition
5.Ischemia
Hyperplasia Dysplasia
Intracellu
lar
Accumulat
ions
Calcifications
Dystrophic Metastatic
Hypertrophy Metaplasia

15. Physiologic Atrophy :
• Most instances of involution are the result of withdrawal of an endocrine
stimulus
Examples :
• breast after cessation of lactation
• uterus after parturition
• thyroid after puberty
Bring more example for the next class??????

18. Physiologic
Hypertrophy
Pathologic
Exercise Adaptive Compensatory

21. Mechanism of Hypertrophy:
The increased size due to synthesis of more structural
components.
cells capable of division may respond to stress by undergoing
both hyperplasia and hypertrophy, whereas in nondividing cells
hypertrophy occurs. Find Example
Nuclei in hypertrophied cells may have a higher DNA content
than in normal cells, probably because the cells arrest in the cell
cycle without undergoing mitosis.

26. Metaplasia :
• Cells that are normally columnar or stratified may change to squamous.
• Examples:
• With continued smoke exposure, ciliated columnar cells are changed
to stratified squamous cells
• Cervical cells change when exposed to STDs or HPV
• Think metamorphosis or change from one form to another
• Continued exposure may predispose to cancerous
transformations.
stratified cell change
to squamous cells

30. Cellular changes Summary: