Pathology Flashcards
hypertophy definition and example
increased cell size; same cell number
E.g. Weightlifter muscles are larger than if they didn’t lift weights
[ὑπέρ (hupér, “over”); τροφή (trophḗ, “nourishment”]
hyperplasia definition and example
increased cell number; +/- increased size
an adaptive response
E.g. Liver regeneration occurring after a portion is injured or removed is hyperplasia
[ὑπέρ (hupér, “over”); πλάσις (plásis, “formation”]
atrophy definition and example
reduction in size d/t decrease in cell size and/or number
E.g. Uterus decreases in size in postpartum women after delivery; Brains are smaller in elderly compared to those in younger individuals
[ἀ- (a-, “not”); τροφή (trophḗ, “nourishment”)]
metaplasia definition and example
one differentiated cell type is replaced by another; tissues will assume the phenotype that gives the best protection from the insult
E.g. Respiratory stratified columnar epithelium replaced by squamous metaplastic epithelium in smokers
[μετα (meta, “change”; πλάσις (plásis, “molding, formation”]
reversible adaptations to stress as seen in tissue
hyperplasia metaplasia dysplasia hypertrophy atrophy
dysplasia definition
lack of normal maturation which may become an invasive carcinoma
[δυσ- (dus-, “bad”); πλάσις (plásis, “formation”]
hyperplasia causes
altered endocrine milieu, AKA hormonal stimulation (e.g. puberty)
increased functional demand (e.g. going to higher altitudes -> inc in erythropoietin lvls)
chronic injury (e.g. callus d/t repeated trauma)
hyperplasia basic mechanism
stimulation of resting cells (Gₒ to G₁) and entry into cell cycle
molecular mechanism of metaplasia
replacing the expression of one set of differentiation genes with another by reprogramming stem cells to differentiate along a new pathway
can become malignant over time and important normal protective mechanisms are lost
dysplasia cause
response to persistent injury
physiologic examples of atrophy during neonatal development
notochord (tail), which is present during the development of babies and goes away before birth
causes of pathologic atrophy
decreased workload (disuse atrophy)
loss of innervation (denervation atrophy)
diminished blood supply (ischemic atrophy)
inadequate nutrition
loss of endocrine stimulation
pressure (pressure atrophy
pressure atrophy
tissue compression for a length of time leads to atrophy of surrounding normal tissues
E.g. brain adjacent to a tumor; soft tissue over bone in bed ridden patients
cachexia
muscle wasting
disuse atrophy example
bed rest without using muscles leads to initial decrease in muscle fiber size (atrophy) and later decrease in number of muscle fibers (due to apoptosis) and decrease in muscle size (more atrophy)
denervation atrophy
skeletal muscle fiber size and strength are dependent on nerves; with nerve injury, there will be denervation atrophy of the muscle supplied by the nerve
ischemic atrophy
a gradual decrease in blood supply (atherosclerosis) leads to atrophy of supplied tissue (feet lose hair and skin appendages and skeletal muscle fibers); brain atrophies due to atherosclerotic vascular disease
mechanism of atrophy
reduced metabolic activity -> decreased protein synthesis and increased degradation
cellular protein degradation follows the ubiquitin-proteasome pathway: nutrient deficiency and disuse may activate ubiquitin ligases which would target these proteins for degradation in proteasomes
may have an increase in autophagy: starved cell eats its own components in order to survive with reduced nutrient demand
hypertrophy causes
Occurs in cells with terminal differentiation and relative inability for mitoses (skeletal muscle, cardiac muscle) and in cells that can divide as well as increase in size (liver, thyroid, etc)
an adaptive response to increased workload or to increased neurohormonal stimuli
the most consistent features of irreversible injury
profound membrane damage
inability to restore mitochondrial function
severe DNA or protein damage
necrosis vs apoptosis
necrosis is cell death that WILL incite an inflammatory reaction. Cytoplasmic contents WILL leak out
apoptosis is cell death that WILL NOT incite an inflammatory reaction. Cytoplasmic contents WILL NOT leak out
necrosis overview
‘accidental’ death because of something such as ischemia or hypoxia or toxic insult of some type
cell contents are released outside of the cell and an inflammatory response will be elicited
apoptosis overview
cell death triggered by extracellular or intracellular stimuli and performed thru organized cellular signaling pathways (cascades)
an inflammatory response is not elicited
coagulative necrosis
a type of necrosis that preserves the tissue architecture for a span of at least a few days
it is the pattern associated with hypoxia in all organs except the brain
localized areas of coagulative necrosis called infarcts; further characterized as pale or red depending on the presence of collateral vasculature
