Lecture 6: Pathology Flashcards
what is an adaptive response
reversible functional and structural changes
leads to the development of new cellular state but most importantly allows cell to ADAPT and SURVIVE the stimulus
what is a maladaptive response
usually occurs in response to cellular injury and when the cell is severely stressed that they can no longer adapt
what is hypertrophy and what can it allow
swell leading to increase in size
Cells make more intercellular structures
Response to specific stimuli
what is atrophy
tissue shrinkage leading to decrease in size
what is hyperplasia
increase in number of cells
what is metaplasia
one cell type replaced by another in a reversible change
what is hypertrophy usually in response to
increased demand functionally or due to specific stimuli
what is atrophy due to
decreased work load
diminished blood supply
pressure
what is hyperplasia driven by
growth factors or increased output of new cells from tissue derived STEM CELLS
what is physiologic hyperplasia in response to
hormones
what is the most common metaplasia
columnar to squamos epithelium
what does metaplasia replacement mean
cell type sensitive to stress replaced by one that is able to withstand the adverse pressure
what is metaplasia thought to be
reprogramming of differentiation
what is hypoxia defined as
oxigen deficiency interfering with aerobic respiration
what happens when there is hypoxia
genes are upregulated to drive the hypoxic response but sever oxygen deprivation leads to cell injury
what are major causes of hypoxia
ischemia
anaemia
cardiorespiratory failure
what are some chemicals and drugs that drive cell injury
various poisons
herbicides
nitrogen dioxide
what are infectious agents caused by
bacteria
viruses
fungi
helminths
parasites
what can genetic defects lead to
loss of protein function or accumulation of damaged DNA or misfolded protein
what do ultrastructural changes include
changes in cell membrane
e.g. changes in mitochondria or nuclear changes
what are light microscope changes
visible by microscopy
e.g. cell swelling or fat accumulation
what are gross morphological changes
irreversible
e.g. cytoplasmic changed such as increased eosinophilia
what is coagulative necrosis
Maintains architecture of dead tissue for several days
Injury denatures everything in the cell
Leukocyte recruitment to clear dying cells by phagocytosis
what are liquefactive necrosis
Changes the tissue into a viscous liquid mass i.e., complete destruction
Usually during infection where leukocytes stimulated to drive liquefaction
Liquid appears a yellow colour due to the accumulation of dead leukocytes and is called PUS
what is apoptosis
regulated form of cell death
serves to eliminate dying cells and minimise cellular damage
where does apoptosis occur
embryogenesis and organogenesis
in hormone dependent tissue
eliminated of harmful self reactive leukocytes
cell loss in tissues that rapidly proliferate
what is the key hallmark of apoptosis
activation of specific cysteine proteases called caspases
what can apoptosis be activated by
DNA DAMAGE->various agents can cause breakdown of DNA and
induce apoptosis
ACCUMULATION OF MISFOLDED PROTEINS e.g. Alzheimer’s disease
INFECTIONS e.g. HIV
OBSTRUCTION OF GLANDS OR DUCTS e.g. in pancreas or kidneys
what are key structural features of apoptosis
Cell SHRINKAGE
Chromatin CONDENSATION
CYTOPLASMIC BLEBS and APOPTOTIC BODIES
Phagocytosis of these apoptotic bodies->EFFEROCYTOSIS
what is autophagy
A form of cannibalism where the cell eats itself and recycles
the contents to create new structures and provide nutrients
when does autophagy happen
when nutrients are deprived
wjat are the three major categories of autophagy
chaperone mediated
microautophagy
macroautophagy
