wk 1- cell adaptation, stress and death Flashcards
LO: give examples of cell types that are considered under epithelial, connective tissue and others
- epithelial- 1) simple squamous; 2) simple cuboidal; 3) simple columnar; and 4) pseudostratified
- connective tissue- myocytes (muscle cells) - in skeletal muscle, smooth muscle, cardiac, fibroblasts, collagen and fat cells, endothelium, cartilage, bone.
- Others- mesothelial cells, melanocytes, germ cells, haemopoeitic cells,
LO: what is meant by labile, stable and permanent cells, give examples
- labile (continuously dividing) - epithelial cells, haemopoietic stem cells
- stable (quiescent) - epithelial cells, smooth muscle/fibroblasts, endothelial
- permanent (non-dividing) - cardiac, skeletal myocytes, CNS neurons (if cells don’t divide, no primary cancers- secondary cancers can migrate)
what occurs after stress on the cell?
cell adaptation or inability to adapt leads to cell injury and then (nercrosis or apoptosis) - cell death
LO: define types of cellular adaptation and understand when these processes are not possible/reversible
- autophagy- self eating, engulfs damaged or dangerous material to remove
- hypertrophy- increased size of cell
- hyperplasia- increased number of cells
- metaplasia- the change from one cell type to another cell type where it is not normally found
all reversible except atrophy in permanent tissue (cell death)
what is apoptosis definition
apoptosis- a programmed cell death, cell suicide so that neighbouring cells are not induced and inflammation does not occur
what is nercosis? and what does it cause
necrosis- a sudden, messy death due to lack of supply etc (contents spilled out) causing:
1. neighbouring cells induced to undergo nercosis also (area of nercotic tissue - infarct
2. stimulation of acute inflammation
3. loss/reduced function of tissue (scarring, calcification, death
LO: describe the main differences between apoptosis and necrosis 4
- apoptosis occurs in physiology and pathology, nercosis is pathological
- apoptosis is active (requires energy), necrosis is passive
- a single cell can die by apoptosis, a necrotic cell kills neighbouring cells
- apoptosis doesnt cause inflammation, necrosis does
LO: what is an infarct and how does it occur?
Infarction is tissue death or necrosis due to inadequate blood supply to the affected area. It may be caused by artery blockage, rupture, mechanical compression, or vasoconstriction
LO: what determines whether a stimulus causes atrophy or infarction?
atrophy- slow, gradual stress on cells (apoptosis/autophagy)
infarction- sudden severe stress. eg complete blockage of blood.
depends on stressor
LO: what effect does aging have on cells and organs?
less likely to undergo autophagy, therefore more cell death occurring as a result
what cellular adaptations would occur in a pregnant uterus?
epthithial layer (endometrium) undergoes HYPERPLASIA- increased number of cells
the deeper smooth muscle layer (mypmetrium) undergoes HYPERTROPHY- increased size of cells
what cellular adaptations would occur in the uterus post menopause
apoptosis - active programmed cell death leading to atrophy of the tissue
during embryogenesis, what cellular adaptation occurs and does it lead to inflammation
apoptosis and no, active programmed cell death so it is contained
after birth of a child what cellular adaptations would the uterus undergo?
the epithelial cells that has undergone hyperplasia would undergo apoptosis- programmed cell death
the deeper smooth muscle cells that had undergone hypertrophy would undergo autophagy- decrease in cell size
necrosis is (4)
passive form of cell death- doesnt use energy to contain
kills neighbouring cells from an infarct
does not occur in physiology
stimulates an acute inflammatory response
apoptosis is (4)
active form of cell death
contained death that doesn’t kill neighbouring cells
occurs in physiology and pathology
does not cause acute inflammation
where is the prostate gland located and what are its functions
epithelial gland that surrounds the male uretha just below the bladder.
the secretions from the prostate gland form part of the ejaculate, which provide nutrients to the sperm and show antibacterial properties
what cellular processes can occur within the prostate gland and bladder?
prostate- believed to originally be prostatic hyperplasia, however it is now believed to be failure of apoptosis. old cells that should be dying are being kept alive leading to an increase in size of the gland.
bladder- the enlarged prostate causes contriction on the uretha leading to urinary retention within the bladder. hypertrophy occurs in the bladder due to this.
what could cause the testicle to atrophy and what cellular adaptations are involved?
cyst, tumour, arterial disease atherosclerosis, hormonal abnormalities
anything that slowly puts pressure on the tissue to reduce blood or nerve supply, this will cause the cells to shrink through autophagy and die by apoptosis
what type of cell type are most metaplasia cells turning into and why
stratified squamous as they are more resistant to irritation
is metaplasia an active and passive process
active
is metaplsia reversible?
yes if the environment changes back or the stress is removed
what is the difference between young and old people and tissue atrophy
for young it often includes both autphagy and apoptosis, whereas old its just apoptosis
if a permanent cell type organ atrophies, can it be reversed?
no, the cells are unable to proliferate, therefore the cells lost through apoptosis will not be replaced
however, the cells that had shrunk through autophagy could undergo hypertrophy to restore the size of the organ, but will not have the same functional reserve it once had. this is also dependent on age if autophagy occurs.
what tissues in the human body atrophies with age?
all but the prostate gland in men
senile atrophy
senile atrophy is caused by
reduced hormones/growth factors and is exacerbated by vascular disease
why is pathological hypertrophy of the heart a bad thing?
the heart is less dynamic and there is further for
oxygen, nutrients and wastes to diffuse to get to and from cells.
As hypertrophy increases, muscle
contraction becomes less efficient and the valves of the heart may malfunction all of which
increases the risk of myocardial infarction &/or failure
what is the difference between this and an exercise induced hypertrophied heart?
more uniformly hypertrophied across the chambers.
increases in cardiac output during their workout but their resting heart rate is usually lower than average. increase in elastic fibres, capillary density,
mitochondrial number and energy efficiency
atrophy is
tissue/organ shrinkage through cellular apoptosis or apoptosis and autophage (opposite of hypertrophy)
what is autophagy
cell reduces in size by eating itself (still alive, not cell death)
infarction is
area of necrosis
ischaemia
lack of blood supply, might be partial or complete.
partial can be reversed
examples of permenant tissues/non dividing cells
cardiac/skeletal myocyctes, CNS neurons
examples of stable tissues
some epithelial cells: eg liver, kidney, lungs and pancreas
smooth muscle cells,
fibroblasts, endothelial cells
examples of labile tissues
some epithelial cells eg lining of skin, GIT, reproductive and urinary tracts
haemopoietic stem cells
what cellular adaptations lead to an increase in overall size of an organ
hyperplasia and hypertrophy
when is atrophy not reversible?
in permanent cells
what cellular adaptations lead to a decrease in overall size of an organ
apoptosis and autophagy
what is the term given to secretory epithelial cells
glandular
what type of epithelium is best at withstanding physical stress
straitified squamous epithelium
what cellular adaptation will occur in a heart that is forced to work harder
hypertrophy
will there be an inflammatory response if an infarct occurs to the heart or brain
yes if theyre still alive
when cells undergo metaplasia are they conidered normal or abnormal
theyre still normal cells
