Lecture 5

Question 1

What are the 5 types of cell death?

Answer 1

Oncosis/Necrosis,
Necroptosis,
Pyroptosis,
Apoptosis,
Autophagic Cell Death

Question 2

What occurs in oncotic cell death?

Answer 2

The cell loses control of the composition of its ions due to trauma resulting in swelling causing lysis and cell death resulting in inflammation

Question 3

What occurs in Necroptosis?

Answer 3

Death ligands activate receptors which turn on protein kinases RIP 1/3 causing mitochondrial dysfunction leading to a build up in reactive oxygen species resulting in lipase activation and messy cell death

Question 4

What is tumour necrosis factor?

Answer 4

A death ligand

Question 5

What is a necrostatin?

Answer 5

A competitive inhibitor for RIP 1 protein which can be used to suppress inflammation

Question 6

What occurs in pyroptosis?

Answer 6

Bacterial products activate the inflammasome, which activates the caspase-1 protease resulting in cell lysis and inflammation

Question 7

What is an inflammasome?

Answer 7

An internal danger sensor of cells causing inflammation ad cell death

Question 8

What is the purpose of pyroptosis?

Answer 8

To product against the intracellular replication of bacteria and to alert the immune system to the presence of invaders

Question 9

What occurs in apoptosis?

Answer 9

This is a more natural and clean way of removing cells that are old and need to be turned over, or if they are in excess to requirements. This is a process which retains an intact cell membrane stopping inflammation provided the budding off apoptopic bodies are phagocytosed before they degrade

Question 10

What occurs in Autophagic cell death?

Answer 10

Double membrane vacuoles enclose cytoplasm or organelles to form autophagosomes, these then fuse with a lysosome to form an autolysosome

Question 11

What is the normal purpose of autophagy?

Answer 11

To remove misfolded proteins and damaged organelles but the process can result in cell death if the cell is placed under tooo much stress

Question 12

In the case of anoxia what is the mechanism of oncosis? (Hint there are 9 steps)

Answer 12

1. Reduced ATP results in failure of the Na/K ATPase causing build up of Na+
2. Use of glycosis due to lack of Oxygen results in increase in lactic acid and a decrease in intracellular pH
3. The Na/H exchange is activated to restore pH but this results in an even higher conc. of Na+
4. Na+ Concentration is reduced through a Na+/Ca2+ transporter resulting in accumulation of Ca2+
5. Due to a lack of ATP the Ca2+ pump can not remove Ca2+
6. High Ca2+ conc. activates phospholipases releasing lysophospholipids and fatty acids that damage the cell membrane
7. Ca2+ acitvates proteases destroying the cytoskeleton
8. The cell lyses
9. The spilled contents induce inflammation

Question 13

What are the 5 causes of apoptotic death?

Answer 13

Engagement of a death ligand with is receptor,
Damage to DNA,
Absence of required growth factors,
Anoikis,
Stresses that activate p53

Question 14

What is Anoikis?

Answer 14

When a call loses its attachment to the extracellular matrix

Question 15

What does both DNA damage and death ligands activate?

Answer 15

Apoptotic Caspases

Question 16

What is the effect of an apoptotic caspase?

Answer 16

Pores are opened in the outer mitochondrial membrane releasing Cytochrome C, Apoptotic protease activating factor and a caspase casade

Question 17

What are Caspases?

Answer 17

Proteases activated by oligomerisation and proteolytic cleavage, which cleaves proteins after any aspartate residue resulting in apoptosis

Question 18

What are the signals that apoptotic cells release?

Answer 18

Find me ATP signal and eat me Phosphatidylserine on the outside of the cell

Question 19

What do phagocytosing cells express after ingesting an apoptotic body and what is its function?

Answer 19

Phosphatidylserine which supresses the release of the inflammatory protein Tumour Necrosis Factor and releases the anti-inflammatory protein transforming growth factor

Question 20

What can result from a loss of normal apoptosis?

Answer 20

Cancers and autoimmune diseases as lymphocytes which target ‘self’ are not removed

Question 21

What is the result of excessive apopotosis?

Answer 21

ischaemic injury, heart failure, neure degeneration, beta pancreatic cells in diabetes, lymphocytes in AIDs

Question 22

What are four types of necrotic lesions?

Answer 22

Coagulative necrosis, Colliquative necrosis, gas gangrene and dry gangrene

Question 23

What is Coagulative Necrosis?

Answer 23

Dead tissue is firm, retain its initial shape until removed by inflammatory cells and replaced with scar tissues. This can result in lesions that persist for years due to inaccessibility

Question 24

What is Colliquative necrosis?

Answer 24

Occurs when a cerebral blood vessel has been blocked, which results in digestion of brain tissue and cyst being formed by glial cells

Question 25

What is Gas Gangrene?

Answer 25

Deep wounds stop blood flow resulting in bacterial growth which releases and alpha toxin destroying an rotting cells while affected tissues turn black as haemoglobin is destroyed to provide iron for bacterial growth

Question 26

What is the bacteria that grows in gas gangrene?

Answer 26

Clostridium perfringens

Question 27

What is Dry Gangrene?

Answer 27

Arteries are slowly narrowed by atherosclerosis leading to tissue death through dessication and black colour formation due to blood breakdown

Question 28

What are the two forms of necrosis associated with infection?

Answer 28

Suppurative necrosis and Caseous Necrosis

Question 29

What is suppurative necrosis?

Answer 29

Bacterial infections cause necrosis resulting in neutrophils liquefying tissues to from an abscess

Question 30

What is Caseous necrosis?

Answer 30

As seen in tuberculosis, when chronic inflammation has resulted in dead cells forming a cheese like debris rich in lipids and proteins

Question 31

What occurs in acute haemorrhagic pancreatitis?

Answer 31

Fat necrosis resulting in Proteases and phospholipases digest membranes, lipases digest triglycerides causing release of soap