Week 2 (1) Cell Injury and Death

Question 1

What are the causes of CELL INJURY?

Answer 1

• oxygen deprivation
• physical, chemical agents and drugs
• infectious agents
• immunological reactions

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Question 2

Biochemical Mechanisms that cause injury

Answer 2

• ATP depletion
• oxygen adn oxygen dervived free radicals
• intracellular calcium and loss of calcium homeostasis
• defects in membrane permeability
• irreversible mitochondrial damage

Question 3

Primary Targets (that are injured?)

Answer 3

• mitochondria
• cell membranes
• cytoskeleton
• cellular DNA

Question 4

What happens in REVERSIBLE cell injury?

Answer 4

• Oxygen and ATP DROP
• anaerobic glycolosis
• lactic acid and pH drop
• the Na pump fails
• Na and water in cytoplasm
• protein synthesis is inhibited

Question 5

What happens in IRREVERSIBLE cell injury?

Answer 5

• 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

Question 6

What happens to the NUCLEUS in irreversible cell injury?

Answer 6

Either:

1. Pyknosis - becomes smaller, condensed with haemotoxylin
2. Karyorrhexis - fragmentation of nuclei
3. Karolysis - complete breakdown

Question 7

What FREE RADICALS are there

Answer 7

• Superoxide anion
• hydroxyl radical
• hydrogen peroxide

Question 8

What do FREE RADICALS do?

Answer 8

• peroxidation of lipid membranes
• attack thiol groups on proteins
• breakdown DNA
• NADPH depletion of mitochondria leads to Ca in cytosol

Question 9

What do FREE RADICALS react with?

Answer 9

• cell membranes
• proteins
• DNA
• Mitochondria (thus releasing Ca into cytoplasm)

Question 10

How do the cells PROTECT themselves from FREE RADICALS?

Answer 10

* Antioxidants e.g. Vit E

* Glutathione peroxidase

* Superoxide

* Catalase

Question 11

What is the MORPHOLOGY of NECROSIS?

Answer 11

* cellular swelling

* nuclear amd cytoplasmic degradation

*coagulative

*Liquidifactive

*Caseous

*Fatty

Question 12

Patterns of NECROSIS (MACRO) Hint - the different appearences of the cells when necrosis occurs

Answer 12

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

Question 13

What is APOPTOSIS and why does it occur?

Answer 13

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

Question 14

What part of the body does APOPTOSIS during DEVELOPMENT involve?

Answer 14

The fingers: e.g. webbing is removed before birth

Also: Occurs during ADULT development e.g. menstraual cycle, breast after weening.

Question 15

What does APOPTOSIS involve during HOMEOSTASIS?

Answer 15

* 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

Question 16

What are the FIVE (5) types of possible CELL ADAPTION?

Answer 16

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

Question 17

Hypertrophy:

What is it?

Examples?

Answer 17

“an increase in the size of exisiting cells”

• NO cell division.
• each cell’s structural components synthesis is increased

E.G ARNIE ;)

Question 18

Hyperplasia:

What is it?

Examples?

Answer 18

“an increase in cell NUMBERS”

Example:

• callus

Question 19

So, like, why is there a difference between hypertrophy adn hyperplasia?

Different types of cells —>

Answer 19

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

Question 20

What is ATROPHY?

Answer 20

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 :)

Question 21

METAPLASIA

What is it?

Answer 21

is the reversible replacement of one differentiated cell type with another mature differentiated cell type.

Question 22

Some examples of METAPLASIA include

Answer 22

• changes to the epithelium when SMOKING
• Barrett’s Oesophagus

Example - columnar to squamous

Question 23

How does METAPLASIA occur?

Answer 23

• STEM cells are present in most epithelia
• These cells are UNDIFFERENTIATED
• These cells respond to SIGNALS to change

Question 24

Intracellular Accumulations:

What are they?

Examples?

Answer 24

“one of the manifestation of METABOLIC disturbance of material within cells”

Example = FATTY LIVER

• toxins
• protein malnutrition
• diabetes mellitus
• obesity
• anoxia
• BOOOOOOZE!