Patho final lec 2 Flashcards
What is the difference between apoptosis and necrosis?
Apoptosis is programmed cell death due to irreversible damage to the cell. The cell shrinks and membranes stay intact. The cell then buds into smaller fragments called apoptotic bodies (blebbing). The cells of the immune system remove these apoptotic bodies without the induction of inflammation.
Apoptosis is precisely controlled and can be manipulated by chemotherapeutic agents in cancer treatments.
Necrosis is unprogrammed cell death. The cell and the organelles swell due to fluid accumulation (reversible if stressor is removed). If stressor remains, the cell will start budding then lyse, releasing its contents, thereby activating inflammation. Necrosis is rapid and uncontrollable.
What are some morphological changes when cells are damaged reversibly?
-Organ swelling due to cell swelling (hydropic change)
-Fatty change (steatosis), abnormal accumulation of triglycerides, mainly in hepatocytes leading to dysfunction.
why do damaged cells swell up?
Sodium-Potassium pump stops working, increasing cellular sodium concentration and osmolarity.
Which organs are more likely to become fatty due as they are damaged?
Organs that deal with fat metabolism like hepatocytes, the organ looks yellowish while the cells look white because of fat droplets.
What are some microscopic changes to cells when they are damaged?
-Fatty change (steatosis)
-Swelling
-Blebbing (budding)
-Mitochondrial swelling and black spots appear
-Dilation/swelling in ER
-Detachment of ribosomes from ER
-Clumping of chromatin
-Cytoplasmic myelin figures (thin stacker membranous layers)
What makes irreversible damage irreversible?
-Mitochondrial dysfunction means that no ATP can be made for the cell
-Loss of membranes, especially the plasma membrane will cause enzyme leakage (can be detected in blood)
-Loss of DNA and chromatin structural integrity
What are some morphological changes in necrotic cells and why do they occur?
-Increased cytoplasmic eosinophilia (more denatured proteins in cytoplasm and less RNA production because enzymes are nonfunctional resulting in less basophilia)
-Dilation of ER and mitochondria
-Mitochondrial densities
-Myelin figures
Nuclear changes:
-Pyknosis
-Karyorrhexis
-Karyolysis
Overall, basophilia decreases in necrosis while increasing in apoptosis (turns into dense apoptotic bodies instead of following the necrotic changes).
What do these terms mean and when do they happen?
1-Pyknosis
2-Karyorrhexis
3-karyolysis
They are all nuclear changes in necrotic cells damaged irreversibly.
1- pyknosis is the shrinkage and increased basophilia of the nucleus
2- karyorrhexis is the fragmentation of nuclear material
3-karyolysis is the degradation of nuclear material, resulting in less basophilia
What are causes of necrosis vs apoptosis?
Necrosis:
1-Severe disturbances
2-ischemia, toxins, virulent infections, and traumas
Apoptosis:
1-Less severe injuries
2-Genetic pathways, activated by specific stimuli
What is necroptosis?
A mixture of both apoptosis and necrosis
What are the chronological trends when a cell is damaged?
1- Cell begins to lose functionality (reversible)
2- Cells begin to die
3- Ultrastructural changes
4- Light microscopic changes
5- Gross morphological changes
How is necrosis clinically detected?
Checking the blood for intracellular enzyme leakage (gives tissue specific information depending on enzymes found)
How can we detect a myocardial ischemia or myocarditis?
Detecting cardiac enzymes in the blood
How can we detect a hepatic injury?
by detecting the hepatic enzymes AST & ALT (ALT only found in liver) in the blood
What are the types of necrosis?
1-coagulative
2-liquefactive
3-gangrenous
4-caseous
5-Fat
6-Fibrinoid
What is coagulative necrosis and some of its features?
Necrosis usually due to ischemia to solid organs like the spleen, spleen, and heart (infarction). Tissue architecture is preserved initially until inflammation occurs and leukocytes and phagocytes infiltrate using lysosomes.
Enzymes are dysfunctional, preserving architecture, and the cells are without nuclei and show eosinophilia and look pale pink on LM.
The area affected by necrosis usually has a wedge shape due to lack of blood supply.
Doesn’t happen to the brain
What is liquefactive necrosis and its features?
A necrosis that usually affects the CNS due to ischemia or focal (localized) infections by fungi or bacteria. The center of the tissue liquefies and usually forms a pus. The necrotized tissue is removed by phagocytosis.
Macroscopically, it is characterized by cavitary lesions (can be found in the lung or CNS).
Microscopically, many inflammatory cells, mainly acute ones (neutrophils) are found.
What is gangrenous necrosis and its features?
A clinical term for coagulative necrosis usually caused by severe ischemia or bacterial infection. It usually affects levels of tissue instead of 1 tissue layer (an entire foot can be necrotized instead of just a part of it). It can be dry or wet.
Dry gangrenes often follow ischemia and look dry and dark, without bacterial infection. Wet gangrenes occur when there is bacterial infection in addition to ischemia, leading to tissue decay. It looks moist, swollen, and greenish or purplish in color with foul odor.
What is caseous necrosis and its features?
A necrosis that doesn’t preserve tissue architecture, its center has no cells and is usually enclosed by macrophages (granuloma). It has a cheese-like appearance.
Most often associated with tuberculosis
What is fat necrosis and its features?
Necrosis of adipocytes that can occur in pancreatitis due to release of pancreatic lipase, leading to focal (localized) fat destruction. Release fatty acids combine with Ca2+ in a process called saponification to produce a whitish chalky appearance. The outlines of the adipocytes are be observed sometimes.
What is Fibrinoid necrosis and its features?
A type of necrosis seen only microscopically. It consists of Ag-Ab complexes with fibrin, usually found in arterial walls. It can be seen in vasculitis that is caused autoimmune diseases such as polyarteritis nodasa (PAN). It also leads to severe hypertension.
Under the microscope, it can be seen as a pink ring-like structure composed of fibrin in the arterial wall.
