1 - Cell Death Flashcards
Influx of which ion into injured cells seems to mark the “point of no return” between reversible and irreversible injury?
Calcium / Ca2+
What is the correct term for cell death in the living organism?
Necrosis
What is the correct term for self-digestion of cells by their own lysosomal enzymes after death?
Autolysis
What is the correct term for decomposition of dead cells (generally by bacteria) with the production of foul-smelling compounds?
Putrefaction
Match each term (letters) with its correct definition (numbers):
(a) Autolysis
(b) Necrosis
(c) Putrefaction
(1) Cell death in the living organism
(2) Decomposition of dead cells (generally by bacteria) with the production of foul-smelling compounds
(3) Self-digestion of cells by their own lysosomal enzymes after death
(a)-(3); (b)-(1); (c)-(2)
What does the term necrosis mean in its correctly used form?
Cell death in the living organism
Pathologic cell death is seen in which of the following processes?
(a) Apoptosis
(b) Necrosis
Both (a) and (b)
Physiologic cell death is seen in which of the following processes?
(a) Apoptosis
(b) Necrosis
(a) only [apoptosis]. Necrosis is always a pathologic change.
Which process - apoptosis or necrosis - best fits with the following statement?
“It stimulates inflammation.”
Necrosis
Which process - apoptosis or necrosis - best fits with the following statement?
“It does not stimulate inflammation.”
Apoptosis
Which process - apoptosis or necrosis - best fits with the following statement?
“It is always pathologic.”
Necrosis
Which process - apoptosis or necrosis - best fits with the following statement?
“It can be pathologic or physiologic.”
Apoptosis
Which process - apoptosis or necrosis - best fits with the following statement?
“Cells swell before death.”
Necrosis
Which process - apoptosis or necrosis - best fits with the following statement?
“Cells shrink before death.”
Apoptosis
Which process - apoptosis or necrosis - best fits with the following statement?
“It is an important part of embryogenesis and organogenesis.”
Apoptosis
Plasma membrane blebs are a feature of which of the following processes?
(a) Apoptosis
(b) Necrosis
Both (a) and (b)
Leakage of cellular components is a feature of which of the following processes?
(a) Apoptosis
(b) Necrosis
(b) Necrosis
Myelin figures are a feature of which of the following processes?
(a) Apoptosis
(b) Necrosis
(b) Necrosis. Myelin figures are cellular inclusions representing damaged phospholipid membranes.
Chromatin condensation is a feature of which of the following processes?
(a) Apoptosis
(b) Necrosis
(a) Apoptosis
In programmed cell death, what is the term for extruded, membrane-bound cellular components?
Apoptotic bodies
Why do apoptotic cells not stimulate inflammation as they disintegrate?
During apoptosis intracellular components are never leaked to the interstitial space, which would attract inflammatory cells. Instead, disintegrating cellular components remain wrapped in plasma membranes in the form of apoptotic bodies, which are “shielded” from recognition by the immune system and so do not attract inflammatory cells.
What are apoptotic bodies?
Membrane-bound cellular components extruded from cells undergoing apoptosis. They are destined for phagocytosis by macrophages.
The nucleus of a necrotic cell may be shrunken and dark. The term for this is:
(a) Karyolysis
(b) Karyorrhexis
(c) Pyknosis
(c) Pyknosis
The nucleus of a necrotic cell may be swollen and pale. The term for this is:
(a) Karyolysis
(b) Karyorrhexis
(c) Pyknosis
(a) Karyolysis
The nucleus of a necrotic cell may be fragmented. The term for this is:
(a) Karyolysis
(b) Karyorrhexis
(c) Pyknosis
(b) Karyorrhexis
Describe the appearance of a pyknotic nucleus in a necrotic cell.
The nucleus is shrunken and dark.
Describe the appearance of a karyolytic nucleus in a necrotic cell.
The nucleus is swollen and pale.
Describe the appearance of a karyorrhectic nucleus in a necrotic cell.
The nucleus is fragmented.
You are examining injured tissue under the microscope and see numerous nuclei that are shrunken and dark, swollen and pale, or fragmented. What process does this suggest is taking place?
Necrosis
You are examining injured tissue under the microscope and see that cell outlines are indistinct and that cytoplasm is hypereosinophilic (dark pink to red) and amorphous (smudged). What process does this suggest is taking place?
Necrosis
You are examining injured tissue under the microscope and see that individual cells are shrunken, and have condensed chromatin and fragmented cytoplasm. Adjacent cells contain small intracellular eosinophilic inclusions sometimes with dense nuclear fragments. What process does this suggest is taking place?
Apoptosis. (The small intracellular eosinophilic inclusions with dense nuclear fragments in adjacent cells are phagocytosed apoptotic bodies.)
What is the name for the family of protease enzymes playing essential roles in apoptosis?
Caspases
What are caspases?
Members of a family of protease enzymes playing essential roles in apoptosis.
What types of enzyme are activated by executioner caspases?
Latent cytoplasmic ENDONUCLEASES and PROTEASES that degrade nuclear and cytoskeletal proteins. This results in a cascade of intracellular degradation, including fragmentation of nuclear chromatin and breakdown of the cytoskeleton.
What, in terms of apoptosis is/are the function(s) of members of the Bcl-2 family of proteins?
Different members of the Bcl-2 family have opposite functions. Some are anti-apoptotic, and some are pro-apoptotic.
Prevention or promotion of apoptosis is a constant balancing act between production of anti-apoptotic and pro-apoptotic molecules. Many of these molecules belong to the same family, despite having opposite functions. What is this family’s name?
Bcl-2 family
Many cellular insults can trigger apoptosis by the intrinsic pathway. Regardless of the type of insult, they all have a common effect on one particular organelle. (1) What is the organelle, and (2) what is the effect of these insults?
(1) Mitochondrion; (2) Leakage of cytochrome C. [This leads to activation of caspases and subsequent apoptosis via the intrinsic pathway.]
What are the two most well-recognized ligands that can activate death receptors and trigger apoptosis via the extrinsic pathway?
(1) TNF (tumor necrosis factor)
(2) FasL (Fas ligand)
Leakage of cytochrome C from mitochondria triggers apoptosis via which pathway?
Via the INTRINSIC pathway of apoptosis
Binding of cellular death receptors by ligands triggers apoptosis via which pathway?
Via the EXTRINSIC pathway of apoptosis
Fas ligand (FasL) and tumor necrosis factor (TNF) trigger apoptosis by binding to what type of cellular surface receptor?
Death receptors
Reduced exposure to cell survival factors (e.g., growth factors) may trigger apoptosis via which pathway?
Via the INTRINSIC pathway of apoptosis
DNA damage in a cell may trigger apoptosis via which pathway?
Via the INTRINSIC pathway of apoptosis
What are four commonly recognized types of necrosis?
(1) Coagulative necrosis
(2) Liquefactive necrosis
(3) Caseous necrosis
(4) Gangrenous necrosis
Myocardial infarction typically causes what type of necrosis?
Coagulative necrosis
Renal infarction typically causes what type of necrosis?
Coagulative necrosis
Ischemia typically causes what type of necrosis in non-CNS tissues?
Coagulative necrosis
Ischemia typically causes what type of necrosis in the brain?
Liquefactive necrosis
Ischemia typically causes what type of necrosis in the spinal cord?
Liquefactive necrosis
Which type of necrosis is associated with preservation of tissue architecture?
Coagulative necrosis
Why does hypoxic or ischemic tissue injury typically cause coagulative necrosis, rather than another type of necrosis?
The hypoxic injury denatures not only structural proteins, but also proteolytic enzymes. This delays the dissolution of the tissue and means that tissue architecture and cellular outlines are preserved.
What is the characteristic appearance of tissue that has undergone coagulative necrosis?
Tissue architecture and cellular outlines are preserved. The colour and texture may be different (e.g., paler).
What is the characteristic appearance of tissue that has undergone caseous necrosis?
Dead tissue becomes a granular, friable, crumbly or semi-liquid mass. (Think of cottage cheese [Caseous = “cheese-like”]).
What type of necrosis (in mammals) is often associated with specific bacteria whose lipid cell walls are not easily digested?
Caseous necrosis
What type of necrosis is most commonly seen in birds and reptiles?
Caseous necrosis
Tuberculosis, caseous lymphadenitis and tularemia in mammals are associated with what type of necrosis?
Caseous necrosis
What is the characteristic appearance of tissue that has undergone liquefactive necrosis?
Complete destruction of tissue produces a thick liquid composed of cellular debris.
What type of necrosis is most commonly associated with the presence of pyogenic (= “pus-forming”) bacteria?
Liquefactive necrosis
Caseous necrosis is most commonly associated with which type of bacteria?
(a) Bacteria whose lipid cell walls are not easily digested
(b) Pyogenic (= “pus-forming”) bacteria
(a) Bacteria whose lipid cell walls are not easily digested (e.g., Mycobacterium bovis, Rhodococcus equi)
Liquefactive necrosis is most commonly associated with which type of bacteria?
(a) Bacteria whose lipid cell walls are not easily digested
(b) Pyogenic (= “pus-forming”) bacteria”
(b) Pyogenic (= “pus-forming”) bacteria (e.g., Streptococcus spp., Arcanobacter spp.)
Liquefactive necrosis is typically associated with the presence of pyogenic bacteria. The exception to this is in which body system (where sterile ischemic or hypoxic injury also causes liquefactive necrosis)?
Central nervous system
Necrotic tissue that is soft, moist, red-black and possibly containing gas pockets is described as …
Gangrenous
Describe the appearance of gangrenous tissue (non-dry form).
Tissues are soft, moist, red-black and possibly contain gas pockets
What genus of bacterium is typically associated with development of gas gangrene?
Clostridium species
What are two distinct causes of dry gangrene?
(1) Frostbite
(2) Plant toxins (e.g., ergot) that cause ischemia in the extremities
What form of gangrenous necrosis is seen with frostbite?
Dry gangrene
What form of gangrenous necrosis is seen with plant toxins (e.g., ergot) that cause ischemia in the extremities?
Dry gangrene
