Cellular adaptations, injury and death.. Lecture 1

Chapter I: Cellular responses to stress and

toxic insults: Adaptation, Injury and Death

GENERAL PATHOLOGY

CHAPTER I

CELLULAR RESPONSES TO STRESS AND TOXIC INSULTS

ADAPTATION, INJURY AND DEATH

Email: [email protected], Website: www.pathologybasics.wix.com/notes

Introduction to this lecture series

Welcome to series of lectures through ppts

on General pathology

I, Dr. Ashish Jawarkar am a practising

pathologist based in India.

The very idea behind this came from my

own experience, the difficulty I faced in

understanding general pathology concepts.

Chapter I: cellular responses to stress and


2

http://www.pathologybasics.wix.com/notes


mailto:[email protected]?subject=query: chapter1



Introduction to this lecture series

The first seven chapters of Robbins have

immense weightage not just for exams, but

for understanding pathology as a whole.

I will try here to be brief and precise yet

cover all important aspects with full use of

pictures and multimedia links.

I hope this will help students in becoming

thorough with pathology concepts.Chapter I: cellular responses to stress and


3






OVERVIEW

1. Homeostasis and other definitions

2. Adaptations of cellular growth and differentiation

3. Cell injury and cell death

4. Apoptosis

5. Intracellular accumulations

6. Pathologic calcification

7. Cellular aging



4






Definitions

1. Homeostasis

2. Adaptations

3. Cell injury

4. Cell death

5. Intracellular accumulations

6. Cellular aging



5






Definitions

Homeostasis

– A normal cell achieves a steady state of

functioning due to its

• Differentiation (genetic)

• State of metabolism

• Effects of neighbouring cells

• Metabolic substrates

– This is called normal homeostasis



6






That was for the definition

Robbins tries to explain, but still do we get

it? No?

After every definition I will try to explain

the concept in an easier way

So lets understand homeostasis through a

few pictures



7






nd



8






a



9






For further understanding see the following

youtube video

https://www.youtube.com/watch?v=XZxu

Qo3ylII



10





https://www.youtube.com/watch?v=XZxuQo3ylII


Hope that clears your mind..

Homeostasis done.. Lets move on..



11






What happens when a cell in

homeostasis is subjected to stress or

injury



12






Definitions

Adaptation

– When a cell in homeostasis is subjected to

stress, there is a functional and a structural

response from the cell

– It consists of hypertrophy, hyperplasia,

atrophy or metaplasia

– Due to this it achieves a new steady state

– It is a reversible response (see above chart)



13








14






Definitions

Cell injury

– When cells are exposed to stress/injury and

limits of adaptation are exceeded, a sequence

of events follows termed cell injury

– It is reversible up to a certain point, then

becomes irreversible (cell death)

– Irreversible injury is in form of necrosis or

apoptosis



15








16






Definitions

Intracellular accumulations

– Some types of stresses which are chronic and

sublethal in nature may lead to certain changes

in cells apart from adaptations, necrosis or

apoptosis

– It may lead to accumulation of a number of

different substances including proteins, lipids

or carbohydrates



17








18






Definitions

Pathologic calcification

– Calcium is often deposited at sites of cell

death



19








20






Definitions

Cellular aging

– There is a progressive decline in cellular

function and viability caused by genetic

abnormalities and accumulation of cellular and

molecular damage due to effects of exposure

to exogenous influences



21








22






That was an overview of what is in store

for us in this chapter…

Now lets look at each topic one by one..in

detail…

I will try to be as explanatory as possible

For any queries you can get back to me at

[email protected]



23





mailto:[email protected]?subject=Query:chapter1


ADAPTATIONS



24






Hypertrophy

Definition

Examples

Molecular Mechanisms



25






Hypertrophy

Definition

– Increase in size of the cells

– due to increased synthesis of structural

components

– Happens when non dividing cells such as

myocardium and skeletal muscle cells are

exposed to stress



26






Hypertrophy

Examples

– Pathological hypertrophy

• Myocardium in hypertension

• Skeletal muscle in response to exercise

– Physiological hypertrophy

• Growth of uterus during pregnancy



27








28








29








30






Pathological HypertrophyMechanism



31








32








33






Physiological HypertrophyMechanism

Due to cell growth in response to estrogen



34






HypertrophyMolecular mechanism



35






Hyperplasia

Definition

Examples

Molecular Mechanisms



36






HyperplasiaDefinition

Increase in number of cells in the organ



37






HyperplasiaExamples

Physiologic hyperplasia

– Hormonal

• Glandular epithelium of the breast during puberty and pregnancy

– Compensatory

• Liver regeneration

Pathologic hyperplasia

– Hyperplasia of endometrium due to excess estrogen

– Benign prostatic hypertrophy

– Skin warts (papilloma virus)



38






HyperplasiaExamples



39






HyperplasiaMolecular mechnism



40






Atrophy

Definition

Examples

Molecular mechanism



41






AtrophyDefinition

Atrophy is decrease in size of the organ

due to decrease in cell size and number



42






AtrophyExamples

Physiologic atrophy– Fetal organs – like notochord and thyroglossal duct

– Uterus after parturition

Pathologic atrophy– Disuse atrophy after immobilization in fracture cast

– Denervation atrophy

– Ischemic atrophy

– Senile atrophy – heart

– Inadequate nutrition – marasmus, cachexia

– Loss of endocrine stimulation – vaginal, endometrial and breast atrophy after menopause

– Pressure atrophy – in areas surrounding the tumor



43








44








45








46






AtrophyMolecular mechanism



47






Metaplasia

Definition

Examples

Molecular mechanism



48






MetaplasiaDefinition

It is a reversible change occuring in a

differentiated cell

One cell type is replaced by another cell

type due to stress/injurious stimuli

It is always pathological

If it becomes irreversible, it is called

dysplasia – leads to cancer



49






MetaplasiaExamples



50








51






That’s all for this lecture…we shall

continue with remaining part of this

chapter in the next lecture

Keep visiting

facebook.com/pathologybasics for

updates..

Chapter I: Cellular responses to stress and


52





Cellular adaptations, injury and death.. Lecture 1

Health & Medicine

Transcript of Cellular adaptations, injury and death.. Lecture 1