Pathology 6 - Cell ageing and death

Question 1

Mechanism that allow cells to cope with stress? (3)

Answer 1

HypertrophyHyperplasiaMetaplasia

Question 2

What happens when stress becomes too much for a cell?

Answer 2

Cell death occurs

Question 3

What are the 2 options of cell death?

Answer 3

NecrosisApoptosis

Question 4

Does necrosis require energy?

Answer 4

No

Question 5

Is necrosis physiological and/or pathological?

Answer 5

Always pathological

Question 6

What are the 3 main types of necrosis?

Answer 6

Coagulative necrosisLiquefactive necrosisCaseous necrosis (mixture of the above 2)

Question 7

What is coagulative necrosis?Usually caused by?What are dead cells consumed by?where is it often seen?

Answer 7

Type of necrosis where the cell outline is preserved for at least a couple of days usually caused by ischaemia or infarctiondead cells are consumed by various enzymatic processes and cells (microenvironment too toxic for proteolysis, etc.)Often seen in cardiac muscle - MI

Question 8

What is liquefactive necrosis?Usually caused by?

Answer 8

Liquefactive necrosis (or colliquative necrosis) is a type of necrosis which results in a transformation of the tissue into a liquid viscous mass (no cell structure contains)Tissue is turned into pussOften it is associated with focal bacterial or fungal infections.Necrosis within the brain

Question 9

What is another name for caseous necrosis?What is it usually associated with?What can it be considered as?

Answer 9

Cheesy necrosis - looks like cream cheeseTBA combination between coagulative and liquefactive necrosis

Question 10

What is the characteristic appearance of TB?

Answer 10

Granulomatous inflammation with central caseous necrosis

Question 11

What should be done if someone mentions caseous necrosis?

Answer 11

Think TB!!Ask for culture, PCR and look for result of Ziehl Neelson stain

Question 12

What is apoptosis?

Answer 12

Programmed cell death in response to specific signals

Question 13

Does apoptosis require energy?

Answer 13

Yes - it requires energy

Question 14

What is necrosis?

Answer 14

the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply.

Question 15

Is apoptosis physiological and/or pathological?

Answer 15

Physiological - we sometimes need cells to die off, it may be part of normal growthCan also be pathological

Question 16

Example of physiological apoptosis? (apoptosis required for health)

Answer 16

Fingers initially start off webbed and then apoptosis creates distinct digits

Question 17

Example of apoptosis related to immune system?

Answer 17

Removal of self reactive lymphocytes(another example of physiological apoptosis is hormone-dependant involution)

Question 18

Examples of pathological apoptosis? (6) - sign of disease

Answer 18

In response to injuryRadiation (including UV light)ChemotherapyViral infection - hepatitisCancersGraft versus host disease

Question 19

What are capsases?

Answer 19

Protease enzymes which play an essential role in apoptosis and inflammation

Question 20

What are the 2 possible pathways for activating capsases?

Answer 20

ExtrinsicIntrinsic

Question 21

What is the extrinsic pathway for activating capsases?

Answer 21

Death receptor (a TNF receptor/ Fas receptor) is activated when its ligand bindsWhen a number of these come together they form another receptor for a protein which also has a cytoplasmic “death domain” e.g. fas-associated death domainThis activates caspase

Question 22

What is the purpose of Fas ligand?

Answer 22

Fas is a type of TNFSome cells of the body express a Fas ligand and activated T lymphocytes always express the Fas receptor meaning if they join, capsase is activated = apoptosis

Question 23

What type of conditions do patients with Fas mutations often get?

Answer 23

Autoimmune diseases

Question 24

What is tumour necrosis factor?

Answer 24

A cytokine released by many leukocytes which is involved in many processes such as inflammation and can cause cell death

Question 25

What is another name for the intrinsic pathway of activating capsases?What is involved in this?

Answer 25

Mitochondrial pathwayGrowth signals promote anti-apoptotic molecules in the mitochondrial membraneWhen the growth signals are removed, they are replaced with apoptotic regulators (Bax or Bak)These increase the permeability of the mitochondria which causes the release of proteins, e.g. cytochrome C, that stimulate capsases

Question 26

What are capsases?

Answer 26

Any number of compounds consisting of haems bound to a protein

Question 27

What is p53?

Answer 27

A tumour supressor protein which binds to DNA and stimulates genes involved in suppressing division halting the cell cyclep53 binds to damaged DNA and if it can’t be repaired it induces apoptosis

Question 28

What type of conditions can occur if there is too little apoptosis?

Answer 28

CancersAutoimmune disease

Question 29

What type of conditions can occur if there is too much apoptosis?

Answer 29

Neurodegenerative disorders

Question 30

What is the name for thethe irreversible condensation of chromatin in the nucleus of a cell undergoing necrosis or apoptosis?

Answer 30

Pyknosis

Question 31

What morphological changes occur during apoptosis?

Answer 31

Pyknosis - Chromatin condensationCytoplasmic blebs (cytoplasm breaks up)Macrophages come in to hoover everything up

Question 32

What is oxidative stress?

Answer 32

essentially an imbalance between the production of free radicals and the ability of the body to counteract or detoxify their harmful effects through neutralization by antioxidants

Question 33

What causes cellular ageing?

Answer 33

Oxidative stress - free radical damageAccumulation of metabolism by-products e.g. lipofuscin

Question 34

What is the name given to finely granular yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or “wear-and-tear” pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells and ganglion cells?

Answer 34

Lipofuscin

Question 35

What is the name of the structure at the end of a chromosome?What is the purpose of these?What do they consist of?What happens with every division?

Answer 35

TelomeresProvides protection and stops chromosome ends from degradation and fusionTTAGGG repeatsWith every division the number of repeats get smaller

Question 36

What are somatic cells?

Answer 36

Any cell other than reproductive cells

Question 37

Why do stem cells not die?

Answer 37

They contain telomerase that keeps adding more TTAGGG after its lost (telomerase is not active in somatic cells)

Question 38

What is one factor that case stem cells to become immortal?

Answer 38

They reactivate telomerase