Wk 1 CSB520 Notes
myocytes= muscle cells
Exocrine = glandular that goes into duct
endocrine = glandular that goes into blood
secretes mucous = goblet cells
Tissue types
Labile: continuously dividing
stabile: can divide when stimulated
permanent: non-dividing. If you injure them, they are irreplaceable
cardiac myocytes
skeletal myoctes
neurons
skin
GIT
reproductive
bladder
lining of exocrine ducts
liver
kidney
lung
pancreas
smooth muscle cells
endothelial cells of blood vessels (when there is inflammation
benign cells: still well-differentiated but abonrmal
Tissues need nerve innervation, blood and lymphatic supply
cell communication
autocrine (to itself)
paracinre (signal from neighbouring cells)
endocrine (into blood stream)
if cells lose these signals, they may undergo apoptosis
hypoxia = lack of oxygen
ischaemia = lack of blood supply
reperfusion: restoration of blood following period of ischaemia
Outcomes of cell stress
impaired function
mutation
death (both irreversible)
apoptosis
necrosis
adaptation
autophagy
hyperplasia: increased number of cells
metaplasia: change from one differentiated cell into another from environment change.
programmed cell death or suicide
neighbouring cells undergo necrosis
contents spill out and whole area undergoes infarct
stimulation of acute inflammation
the same stressor can stimulate either form depending on
duration
severity of application
how young/healthy the cell is
self-eating
mitochondria can be responsible for triggering cell death
phagocytosis
recognition
attachment
engulfment
killing and degradation by lysosomes
remove dodgy organelles (mitochondria), only way
way to resist and survive stressful situations
some cells are more resistant to stress
young cells choose to shrink to need less oxygen and nutrients
can come back to original size
in older people, autophagy is inhibited and cell will undergo apoptosis
loss/reduced tissue function
only ever pathological
physiological or pathological
active dismantling of cell
form apoptotic bodies (membrane bound)
no inflammation or scarring
one cell can die without impacting others
Physiological: embryonic development, tissue homeostasis, removal of redundant cells, immune function
pathological: pathological atrophy to stop necrosis, transplant rejections, auto-immune diseases, infections
is an active proces
is a passive process
Atrophy
combination of autophagy and apoptosis
decreased cell size
decreased cell number
reversible? depends on type of cell. If the cell can divide it can.
cells that have shrunk can get bigger
ones that can't divide can't be replaced
Lesser degree of stress is needed to start necrosis
sudden severe stress is always necrosis no matter how healthy the cell is
decrease in cell size
opposite of hyperplasia and hypertrophy
hyperptrophy: no cell division, but cells get larger
take away the stress, the adaptation is reversible
all active processes
involution: tissue returns to normal size from reduced hormone levels
increased workload on left ventricle: sustained increase in HR or force of contraction
caused by over-activation of SNS, valve disease, hypertension
right: heart defect, increased pressure in pulmonary circuit from congestion, loss of vasculature
reduces reserve capacity of heart so more likely to fail