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what is hypertrophy?

increase in the size of cells
NO new cells
physiologic or pathologic


what is hyperplasia?

increase in the number of cells
cells MUST be able to replicate
can occur alongside hypertrophy
physiologic or pathologic
response remains CONTROLLED (i.e. not cancer)


Examples of physiologic & pathologic hyperplasia

--hormonal- increase in breast size at puberty
--compensatory- residual tissue growth after removal (i.e. liver regrowth)
--papilloma virus causing warts
--abnormal menstrual bleeding because of hormone imbalance


what is atrophy?

cell shrinkage
cells DONT DIE


causes of atrophy

1- decreased workload
2- loss of innervation
3- decreased blood supply
4- inadequate nutrition
5- loss of endocrine stimulation
6- aging


mechanisms of atrophy

1- protein synthesis dec. because dec. metabolic activity
2- ubiquitin-proteasome pathway
3- increased autophagy


what is autophagy?

process in which a starved cell eats its own components to survive


what is metaplasia?

-reversible cell change
-switch one adult cell type with another adult cell type
-influences that induce metaplastic change may predispose a malignant transformation of epithelium
-EX: smokers respiratory epithelium goes from ciliated columnar to stratified squamous


what are the two types of cell death?

necrosis and apoptosis


what is necrosis and its characteristics?

-severe damage to membranes causing enzymes to leak out of lysosomes, enter the cytoplasm and digest the cell
-host response occurs (inflammation)
ALWAYS pathologic


what is apoptosis and its characteristics?

-programmed cell death
-occurs when a cell is deprived of growth factors or DNA/proteins are severely messed up
-nuclear dissolution without complete loss of membrane integrity
-pathologic or physiologic
-NO host response


injurious stimuli to cells include...

1-oxygen deprivation
2-chemical agents
3-infectious agents
4-immunologic rxns
5-genetic factors
6-nutritional imbalances
7-phsical agents


what occurs first: morphologic changes of a cell, cellular function or cell death?

cellular function may be lost long before cell death occurs and the morphologic changes of cell injury/death lag far behind both


what two phenomena consistently characterize irreversible cell injury?

1-inability to correct mitochondrial dysfxn
2-profound disturbances in membrane fxn


what are the morphologic correlates of reversible cell injury and what are they caused by?

cellular swelling caused by failure of energy-dependent ion pumps in the plasma membrane=no ionic or fluid homeostasis
fatty change occurs in hypoxic, toxic or metabolic injury


what parts
of a cell show changes with necrosis?

cytoplasm- increased pink staining
nucleus- DNA breaks down, either karyolysis, pyknosis or karyorrhexis


fates of necrotic cells

may be digested, persist for some time or be calcified


what is coagulative necrosis?

-underlying tissue architecture is preserved for several days
-structural proteins and enzymes are denatured
-characteristic of infarcts except in brain


what is liquefactive necrosis

-seen in bacterial or fungal infections
-hypoxic death of cells within the CNS evokes this
-dead cells are completely digested and eventually removed
- creates 'pus'


what is gangrenous necrosis

-refers to the condition of a limb (typically lower leg) that has lost its blood supply and has undergone coagulative necrosis
-Wet gangrene- gangrenous necrosis with a bacterial infection too


what is caseous necrosis

-found with TB infections
-has distinct histological appearance
-often enclosed by a distinctive inflammatory border: granuloma


what is fat necrosis

-focal areas of fat destruction
-typically from the release of pancreatic lipases
-occurs with acute pancreatitis
-has distinct histological appearance


what is fibrinoid necrosis

- visible by light microscopy
-complexes of antigens and antibodies are deposited in the walls of arteries
-fibrinoid: a bright pink amorphous appearance caused by the immune complexes and fibrin


what allows detection of tissue-specific necrosis using blood or serum samples?

leakage of intracellular proteins through the damaged cell membrane and ultimately into the circulation


The cellular response to injurious stimuli depends on what three things?

type of injury, its duration and its severity


What characteristics of an cell determines how it responds to injurious stimulus?

type, status, adaptability and genetic makeup


What essential cellular components are disrupted with cellular injury?

1-mitochondria and their ability to generate ATP and ROS under pathologic conditions
2- disturbance in calcium homeostasis
3-damage to cellular membranes
4- damage to DNA and misfolding of proteins


what are the major causes of ATP depletion in a cell?

-reduced supply of oxygen and nutrients
-mitochondrial damage
-actions of some toxins (i.e. cyanide)


which cell would survive longer if ATP was depleted: brain or liver. Why?

liver because it has greater glycolytic capacity than a brain cell.


what two cations accumulate inside an injured cell and lead to more injury?

Na+ and Ca++