-----------------HC1 Pathology – Cell injury, cell death and
adaptations----------------
Pathology is to understand causes of disease.
The definition of disease is dysfunction of an
organ/tissue due to damage to the cells.
Etiology is the cause of disease, which is often
multifactorial, so why a disease occurs. For
example: ischemia is when a vessel is blocked
by a blood clot and will lead to cell death of that
specific tissue.
Pathogenesis is the sequence of cellular –
biochemical – molecular events, which will lead
to abnormalities in cells/tissues, so how a
disease occurs. During pathogenesis there are
biochemical and structural changes.
Diagnosis is made based on: clinical finding,
macroscopy, light macroscopy, electron
microscopy, molecular biology.
An organism with all its cells needs to maintain
homeostasis. Cells will be triggered by injurious stimuli
(stress, toxic stuff etc.). This leads to reversible injury so the
cell will adapt. But if the stimuli is severe and progressive,
then irreversible injury will occur. The consequence is cell
death: necrosis or apoptosis.
Causes of cell injury (etiology)
Causes: hypoxia and ischemia, toxins, infection, abnormal
immune reactions (allergy), genetic abnormalities, nutritional
imbalance, physical agents (UV, radiation).
For example: due to radiation a missense mutation
different nucleotide different amino acid
malfunctioning of a protein a
sequence of events will happen now.
1
, First there is a healthy cell (A) then injury will occur,
then the cell will swell (B). Swelling is due to less ATP
so failure of Na/K/ATP-pump so osmotic disbalance so a
lot of water into the cell. This process is reversible. If
this happens for a while, then there is irreversible
damage (C). Irreversible damage is characterized by 3
things:
1. Inability to restore mitochondrial dysfunction
2. Altered structure and loss of function of the
plasma and intracellular membranes
3. Loss of structural integrity of DNA and chromatin
When the cells leak there
will be an immune
response and then
necrosis.
3 types of cell death:
Necrosis
Apoptosis
Autophagy
Necrosis
The falling apart of cell membranes leads to leakage of enzymes leads to
inflammation reaction. Necrosis is always the result of an exogenous stimulus and is
pathogenic. Some severe injuries result in the death of many/all cells in a
tissue/organ. There are several morphological distinct patterns of tissue necrosis
which provide clues about the underlying cause (etiology):
- Coagulative necrosis: when an artery is blocked tissue behind it will
become ischemic which leads to injury of structural proteins and enzymes
(tissue will be yellow and firm). The tissue architecture/shape is intact for a
few days after injury and afterwards it will be degraded by leukocytes due to
post inflammatory response. Organs: heart, kidney, spleen.
2
adaptations----------------
Pathology is to understand causes of disease.
The definition of disease is dysfunction of an
organ/tissue due to damage to the cells.
Etiology is the cause of disease, which is often
multifactorial, so why a disease occurs. For
example: ischemia is when a vessel is blocked
by a blood clot and will lead to cell death of that
specific tissue.
Pathogenesis is the sequence of cellular –
biochemical – molecular events, which will lead
to abnormalities in cells/tissues, so how a
disease occurs. During pathogenesis there are
biochemical and structural changes.
Diagnosis is made based on: clinical finding,
macroscopy, light macroscopy, electron
microscopy, molecular biology.
An organism with all its cells needs to maintain
homeostasis. Cells will be triggered by injurious stimuli
(stress, toxic stuff etc.). This leads to reversible injury so the
cell will adapt. But if the stimuli is severe and progressive,
then irreversible injury will occur. The consequence is cell
death: necrosis or apoptosis.
Causes of cell injury (etiology)
Causes: hypoxia and ischemia, toxins, infection, abnormal
immune reactions (allergy), genetic abnormalities, nutritional
imbalance, physical agents (UV, radiation).
For example: due to radiation a missense mutation
different nucleotide different amino acid
malfunctioning of a protein a
sequence of events will happen now.
1
, First there is a healthy cell (A) then injury will occur,
then the cell will swell (B). Swelling is due to less ATP
so failure of Na/K/ATP-pump so osmotic disbalance so a
lot of water into the cell. This process is reversible. If
this happens for a while, then there is irreversible
damage (C). Irreversible damage is characterized by 3
things:
1. Inability to restore mitochondrial dysfunction
2. Altered structure and loss of function of the
plasma and intracellular membranes
3. Loss of structural integrity of DNA and chromatin
When the cells leak there
will be an immune
response and then
necrosis.
3 types of cell death:
Necrosis
Apoptosis
Autophagy
Necrosis
The falling apart of cell membranes leads to leakage of enzymes leads to
inflammation reaction. Necrosis is always the result of an exogenous stimulus and is
pathogenic. Some severe injuries result in the death of many/all cells in a
tissue/organ. There are several morphological distinct patterns of tissue necrosis
which provide clues about the underlying cause (etiology):
- Coagulative necrosis: when an artery is blocked tissue behind it will
become ischemic which leads to injury of structural proteins and enzymes
(tissue will be yellow and firm). The tissue architecture/shape is intact for a
few days after injury and afterwards it will be degraded by leukocytes due to
post inflammatory response. Organs: heart, kidney, spleen.
2
