2. objective
• Understand the process of regeneration and
degeneration occurs
• Able to differentiate between regeneration
and degeneration biochemical process.
3. REGENERATION
Maintain proper structure of tissue
The replacement of cell can happen in
two ways:
by regeneration: the necrotic cells are
replaced by the same tissue as was
originally there.
by repair: injured tissue is replaced with
scar tissue.
Most organs will heal using a mixture of
both mechanism.
4. • In order for an injury to be healed by
regeneration, the cell type that was
destroyed must be able to replicate.
• Most cells have this ability, although it is
believed that cardiac muscle cells and
neurons are two important exceptions.
• Cells also need a collagen framework along
which to grow.
5. • Alongside, most cells there is either a
basement membrane or a collagenous
network made by fibroblasts that will guide
the cells growth.
• Proliferation of original cell occur from the
margin of injury.
• Since ischaemia and most toxins do not
destroy collagen, it will continue to exist
even when the cells around it are dead.
6. • Local factors that interfere with the
healing process such as:
• 1. Presence of inert foreign bodies in the
wound
• 2. Occlusion of blood vessels
• 3. Malnutrition
7. DEGENERATION
Loss of function of the cell, tissue or organ.
Degeneration and infiltration are retrogressive
changes in cells and tissues characterized by
abnormal structural changes and decreased
functions.
They are nonspecific responses of cells and tissues
following a variety of injuries.
Some of these processes may be reversible if the
injury is mild. If the injury is severe and persistent,
it may progress to the point where the involved
cell dies.
8. • The distinction between the point where
the cells would recover and the point
where the process is irreversible and
leads to cell death is arbitrary.
• In theory, the difference between the two
processes is vague.
• Most literatures however define these
two processes as:
• Degeneration: the accumulation of
metabolites or other substances in a cell
damaged by preceding injury.
9. • Infiltration: the overloading of
previously normal cells by materials
which are abnormal in either type of
quantity.
• Following these definitions, the
changes in the cells in both
degeneration and infiltration may
appear similar, and many consider the
two processes as identical.
10. • The patterns of cellular degeneration and
infiltration used by pathologist are
grouped according to the dominant
expression of injury as:
1) water overload
2) metabolite overload
3) Storage overload
11. • 1. Water overload – cellular swelling.
• 2. Metabolite overload which involves
excessive accumulation of normal
metabolic products such as fat, glycogen,
or protein (hyaline or proteinaseous).
• 3. Storage loading which involves
overloading by non-degradable products
such as pigments, minerals, and
exogenous substances.
12. • The causes of impaired energy production
in the mechanism of cellular
degeneration are:
• 1. Hypoglycemia – glucose is the main
substrate for energy production in most
tissue and sole energy source in brain
cells. – low glucose level = deficient ATP
production.
• 2. Hypoxia – oxygen carried by blood.
Lack of oxygen in the cells may cause =
ischemia, anemia, respiratory
obstruction, alteration of hemoglobin.
13. • 3. Enzyme inhibition- chemical interfering
with a vital enzyme. Ex= cyanide inhibit
cytochrome oxidase final enzyme in the
respiratory chain causing acute ATP
deficiency in all cells and cause rapid death.
• 4. Uncoupling of oxidative phosphorylation -
occur either through chemical reactions or
through physical detachment of enzyme from
mitochondrial membrane. Ex= mitochondrial
swelling is common changes associated with
injury.
14. Effects of defective energy
production
• Failure of energy production will first affect
those cells with the highest demand for O2 –
high basal metabolic rate.
• The earliest clinical sign of hypoxia and
hypoglycemia are disturbance of the normal
consciousness such as :
• A) intracellular accumulation of water and
electrolysis
• B)changes in organelles
• C) switch to anaerobic metabolism.
15. Effects of the defective energy production
are:
i. Intracellular accumulation of water and
electrolysis
Earliest detachable biochemical evidence-
diminished availability of ATP is dysfunction
of sodium pump on plasma membrane
Influx of water and sodium into cell
Swollen and cloudy cell
May lead to enzyme inhibition.
Early and reversible effects of cell injury
16. • ii. Changes in organelles
• Endoplasmic reticulum distend
• Ribosomes detached
• Interfere protein synthesis
• Mitochondrial swelling
17. • iii. Switch to anaerobic metabolism
• Production of lactic acid, low the
intracellular pH
• Chromatin to clump in nucleus
• Lysosomal membrane disrupt leading to
release of enzymes into cytoplasm,
damage the vital intracellular molecules.
• Cellular degeneration becomes
irreversible – result in necrosis.
