Cell injury and tissue death Flashcards
Definition: Cell injury
The biochemical and/or morphological changes that occur when the steady state is perturbed (unsettles) by adverse inflences
What is hyperplasia?
The increase in the number of cells
What is hypertrophy?
The increase in the cells size
What 2 things can increase cellular activity?
Either hyperplasia or hypertrophy
What is atrophy?
When the cell shirnks either in size or number due to a decreased demand
What is metaplasia?
When cells change their shape/morphology, which consequently changes their function (for example this occurs in the cervix)
What is anoxia?
No O2 supply
What is ischemia?
Inadequate blood supply to an organ or part of the body
Physical trauma can damage cells. An example of this is extremes of temperatures.
Ice crystals can disrupt cell membranes.
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What is an exotoxin?
Toxins released by a living bacterial cell into its SURROUNDINGS
What is a endotoxin?
A toxin present INSIDE a bacterial cell that is released when it disintegrates
What is cell lysis?
Disintegration of a cell by rupture of the cell wall or membrane.
It is caused by a virus hijacking the cell
How does ionising radiation (irradiation) damage cells?
Ionising radiation will knock off an electron, which generates a free radical. This free radical will bind to macromolecules (molecules containing a large number of atoms, for example proteins or nucleic acids).
Often, free radicals can generate more free radicals, which can cause a chain reaction.
What type of enzyme detoxifies free radicals?
Superoxide dismutase, and also the vitamins A, C and E
In what example is free radical injury useful?
Neutophils and macrophages generate free radicals inside the phagosomes to kill the bacteria
List 3 parts of the body which has a high sensitivity to free radicals?
Bone marrow
Gonas
Intestines
List 3 parts of the body which has a low sensitivity to free radicals?
Uterus, pancreas and the adrenal glands
Mitrochondria function is often a target of cell injury.
If the mitrochondria are damaged, ATP production is decreased which will cause problems within the cell.
Give 3 examples.
- An increase in glycolysis will call a decrease in the amount of glycogen within the cell. This will cause a decrease in pH. This decrease will cause clumping of nuclear chromatin
2.
The Na+ pump can be targeted. If this stops working there will be an influx of Ca2+, H20 and Na+. This will also cause a efflux of K+.
The cell will swell (mostly due to the influx of H20) and the microvilli will be lost.
3.
There will be decreased protein synthesis and consequently lipid deposition (an example of this is fatty liver disease)
What is necrosis?
Necrosis is cell death due to disease, injury or failed blood supply.
It is a passive process which causes an inflammatory response
What are the 4 types of necrosis?
- Coagulation necrosis
- Colliquative necrosis
- Caseous necrosis
- Gangrenous necrosis
What is coagulation necrosis?
It is the denaturation of intracytoplasmic protein (proteins within the cytoplasm). This causes these proteins to become firm and swollen.
This is typical of ischaemic injury (except in the brain) and can cause the cellular proteins to leak into the blood. Therefore to test if coagulation necrosis
What is colliquative necrosis?
When the tissue completely liquefies.
The site is shown as a cyst
What is caseous necrosis?
It is characteristic of TB, and is when the tissue turns cheese like.
The cellular detail is destroyed and the cells are surrounded by granulomatous inflammation.
What is gangrenous necrosis?
This is localised death and decomposition of body tissue, resulting from obstruction to circulation or bacterial infection.
What are the 2 types of gangrenous necrosis?
- Dry (occurs in the peripheries)
2. Wet (common on the internal parts of the body)
Is apoptosis active or passive?
Active- it requires energy
What occurs in apoptosis?
The nucleus shrinks and the cell fragments
Does apoptosis OR necrosis cause an inflammatory response?
Only Necrosis
How does AIF (apoptosis initiating factor) and cytochrome C initiate apoptosis?
AIF and cyrochrome C are normally isolated within the mitochondria. However, if they are released into the cytosol they activate CASPASES.
Caspases are the effector molecules of apoptosis, and so therefore cause programmed cell death.
What is P53s role in apoptosis?
P53 is activated by DNA damage.
It causes apoptosis.
Mutations in P53 are common in malignant tumours.
What is Bcl-2 role in apoptosis?
Bcl-2 is normally isolated within Cytochrome C
(Remember cytochrome C is normally isolated within the mitochondria, but if it is released into the cytosol it will activate capases which cause apoptosis)
Bcl2 can prevent apoptosis by blocking the cytochrome C release from mitrochondria.
Mutations in Bcl-2 can cause it to be overexpressed which allows tumours to proliferate uncontrollably.
In necrosis what happens to the cell size?
They are enlarged
In apoptosis what happens to the cell size?
They are reduced
In necrosis AND/OR apoptosis is the plasma membrane disturbed?
Necrosis: yes
Apoptosis: No, it remains intact
What happens to the nucelus during necrosis?
Pyknosis> Karyorrhexis > karyolysis
Pkynosis= irrevesible condensation of chromatin
Karyorrhexis= destruction via fragmenation of the nucleus
Karyolysis= Dissolution of the cell nucleus
