Lecture One: Cellular Injury Flashcards
(12 cards)
What are the four causes of cell injury?
- Capacity for adaption exceeded
- Exposure to toxic or injurious agents
- The cell is deprived of nutrients.
- Mutation disrupts metabolism
Is cellular injury reversible or irreversible?
It will be reversible to a point
Irreversible if there is a severe or persistent injury.
May lead to cell death.
What are the two ways in which cell dies and what is the key difference between the two?
- NECROSIS: inflammatory process
- APOPTOSIS: non inflammatory process
Is necrosis reversible or irreversible?
Necrosis is characterised by cytoplasmic,swelling, irreversible damage to the plasma membrane and organelles breakdown leading to cell death.
What are the five stage of reversible cell injury?
- CELLULAR SWELLING:
- this is one of the most important forms of reversible injury.
- hydropic change = water accumulation in cell
-hard to identify under a microscope
-results in a reduction of sodium and potassium ion pumps.
- FATTY CHANGE:
found in the systems which heavily metabolise fats.
systems which heavily metabolise fats: liver, heart, skeletal muscle
lipid vacuoles appear in cytoplasm. - MITOCHONDRIAL SWELLING
- MEMBRANE BLEBBING
membrane blebbing is caused by a disruption of the cytoskeleton. - DILATION OF ENDOPLASMIC RETICULUM:
How does endoplasmic reticulum?
The ribosomes will detach from the endoplasmic reticulum.
This would lower protein synthesis.
This is polysomal detachment
Polysome =cluster of ribosomes
What are the two changes which occur during irreversible cell injury? (in necrosis)
- MEMBRANE DAMAGE:
-contents leak
-causes inflammation
-serum detection of cell content (troponin, lipase)
-calcium dependent phospholipases
- RAPTURE OF LYSOSOMES
-enzymes degrade cellular contents
What are the three classic nuclear changes in irreversible cell injury?
- KARYOLYSIS (loss of basophilic/dark colour)
- PYKNOSIS (nuclear shrinkage)
- KARYORRRHEXIS -(fragmented nucleus)
What are four mechanism of injury?
- ATP DEPLETION
- CALCIUM
- MITOCHONDRIAL DAMAGE
- FREE RADICALS
What are the causes of ATP depletion? What does it cause?
Causes of ATP depletion:
1. reduced oxygen supply
2. mitochondrial damage
3. direct effect some toxins
ATP depletion results in:
- loss of membrane pumps
- loss of protein synthesis
How does calcium effect the injury of the cell?
Normally: calcium inside of the cell would be low compared to the outside of the cell.
- hallmark of injury- this is when there is an influx of calcium
Calcium is released from the intracellular space
This high amount of calcium will then influx across the cell membrane.
This would cellular injury when you have a high amount of calcium.
- calcium dependent phospholipases
when there is a high amount of increased calcium they would be activated.
breakdown of membrane phospholipids.
when there is a breakdown of membrane phospholipids this then damage the mitochondria
How does mitochondrial damage cause cell injury?
-lack of oxygen
-reactive oxygen species
-hypoxia reduces aerobic oxidative respiration
-this decreases electron transport in mitochondria
-this results in reduction in mitochondrial membrane potential
-increased reactive oxygen species generation
-enhanced nitric oxide (NO) synthase
MTP - this is a protein which is found in the inner membrane of the mitochondria and are certain pathological conditions.
can lead to pathological condition such as traumatic brain injury and stroke.
opening means an increase in the permeability of the mitochondrial membranes.
induction of the permeability transition pole.
this can lead to mitochondrial swelling- this would lead to cell death through apoptosis and necrosis.
this is dependent on the biological setting.
mtp is one of the major causes of cell death.
MPT causes cell death in condition such as:
-neuronal cell death in excitotoxicity
-damage caused by ischaemia
-underlie cell death induced by Reye’s syndrome.
