Week 2 (1) Cell Injury and Death Flashcards
(25 cards)
What are the causes of CELL INJURY?
- oxygen deprivation
- physical, chemical agents and drugs
- infectious agents
- immunological reactions
-
Biochemical Mechanisms that cause injury
- ATP depletion
- oxygen adn oxygen dervived free radicals
- intracellular calcium and loss of calcium homeostasis
- defects in membrane permeability
- irreversible mitochondrial damage
Primary Targets (that are injured?)
- mitochondria
- cell membranes
- cytoskeleton
- cellular DNA
What happens in REVERSIBLE cell injury?
- Oxygen and ATP DROP
- anaerobic glycolosis
- lactic acid and pH drop
- the Na pump fails
- Na and water in cytoplasm
- protein synthesis is inhibited
What happens in IRREVERSIBLE cell injury?
- Ca activates certain enzymes such as phospholipases, proteases, ATPases and endoneculases =
STRUCTURAL DAMAGE
- rupture of lysosomes
- lysis of ER
- defects in cell membranes
- mitochondrial swelling
What happens to the NUCLEUS in irreversible cell injury?
Either:
- Pyknosis - becomes smaller, condensed with haemotoxylin
- Karyorrhexis - fragmentation of nuclei
- Karolysis - complete breakdown
What FREE RADICALS are there
- Superoxide anion
- hydroxyl radical
- hydrogen peroxide
What do FREE RADICALS do?
- peroxidation of lipid membranes
- attack thiol groups on proteins
- breakdown DNA
- NADPH depletion of mitochondria leads to Ca in cytosol
What do FREE RADICALS react with?
- cell membranes
- proteins
- DNA
- Mitochondria (thus releasing Ca into cytoplasm)
How do the cells PROTECT themselves from FREE RADICALS?
* Antioxidants e.g. Vit E
* Glutathione peroxidase
* Superoxide
* Catalase
What is the MORPHOLOGY of NECROSIS?
* cellular swelling
* nuclear amd cytoplasmic degradation
*coagulative
*Liquidifactive
*Caseous
*Fatty
Patterns of NECROSIS (MACRO) Hint - the different appearences of the cells when necrosis occurs
Coagulative Necrosis: outline of the cells and tissues can stil be seen
Liquefactive Necrosis: semi-liquid as the result og hydrolytic enzymes
Caseous Necrosis - dead tissue that resembles cream chees - characteristic of teberculosis
Fat Necrosis - can occus after liberation of pancreatic enzymes and after trauma to fat tissues
What is APOPTOSIS and why does it occur?
Defined: Programmed cell death
Why: Maintains cell populations, defence against invading pathogens, removes damaged cells, occurs as a part of natural ageing and during development
What part of the body does APOPTOSIS during DEVELOPMENT involve?
The fingers: e.g. webbing is removed before birth
Also: Occurs during ADULT development e.g. menstraual cycle, breast after weening.
What does APOPTOSIS involve during HOMEOSTASIS?
* regulation of cells e.g. the intestine
* tumour killing
* removal of viral infections
* removal of injured cells e.g. viral hepatitis
*Atopy of organs e.g. obstruction of pancreas and kidney
What are the FIVE (5) types of possible CELL ADAPTION?
1. HYPERTROPHY: increase in cell SIZE
2. HYPERPLASIA: increase in cell NUMBER
3. METAPLASIA: change in cell PHENOTYPE
4. DYSPLASIA: change to abnormal cell phenotype
5. NEOPLASIA: uncontrolled growth of abnormal cell phenotype
Hypertrophy:
What is it?
Examples?
“an increase in the size of exisiting cells”
- NO cell division.
- each cell’s structural components synthesis is increased
E.G ARNIE ;)
Hyperplasia:
What is it?
Examples?
“an increase in cell NUMBERS”
Example:
- callus
So, like, why is there a difference between hypertrophy adn hyperplasia?
Different types of cells —>
It depends on whether each cell can DIVIDE or not
Cells can be either:
LIABLE or STABLE: can undergo division –> HYPERPLASIA
PERMANENT: cannot divide after birth so therefore cannot undergo hyperplasia BUT can undergo hypertrophy
What is ATROPHY?
Cells DECREASE in size and activity.
Why?
- insufficient nutrition
- disuse
- loss of endocrine stimulation
- diminished blood supply
NOTE: THE CELLS HAVE DIMINISHED FUNCTION BUT THEY ARE NOT DEAD –> removing what causes the atrophy will revert the tissue/cells to normal :)
METAPLASIA
What is it?
is the reversible replacement of one differentiated cell type with another mature differentiated cell type.
Some examples of METAPLASIA include
- changes to the epithelium when SMOKING
- Barrett’s Oesophagus
Example - columnar to squamous
How does METAPLASIA occur?
- STEM cells are present in most epithelia
- These cells are UNDIFFERENTIATED
- These cells respond to SIGNALS to change
Intracellular Accumulations:
What are they?
Examples?
“one of the manifestation of METABOLIC disturbance of material within cells”
Example = FATTY LIVER
- toxins
- protein malnutrition
- diabetes mellitus
- obesity
- anoxia
- BOOOOOOZE!
