Cell injury Flashcards
What could lead to adaptation of myocytes?
Physiological -exercise
Pathological - high BP
Both of these cause hypertrophy - more myofilaments needed to cope with increased demand of work
What are the two different types of cell injury?
Lethal - will cause death
Sub-lethal ~ produces injury not amounting to cell death
may be reversible or progress to cell death
Describe the the two pathways in which cell injury can occur.
Injured stimulus > cell injury > cell death
Stress > increased demand > inability to adapt > cell injury >cell death
What could lead to cell death in myocytes?
Myocardial infarction
What are the 8 causes of cell injury?
Oxygen deprivation - hypoxia, ischaemia, infarction Chemical agents - drugs Infectious agents - virus, bacteria Immunological reactions - hypersensitivity/`allergies Genetic defects Nutritional imbalances Physical agents - temp, UV light, force Aging
Why can high BP lead to cell injury?
Pathological- body cannot support hypertrophy- if they have high blood pressure- they probably have atherosclerosis too and so body cannot adequately supply the extra oxygen and nutrients- often leading to build up of toxic products which can eventually lead to lethal injury
What are the three things cellular response to injury depends on?
Type of injury
Duration
Severity
What do the consequences of an injurious stimulus on cells depend on?
Type of cell
Cells status
What are the 4 key intracellular systems that are particularly vulnerable to injury?
- Cell membrane integrity
- ATP generation
- Protein synthesis
- Integrity of the genetic apparatus
If a cell cannot synthesise proteins or divide, how does this affect the integrity of the cell?
No protein synthesis
No synthesis of proteins involved in generation of ATP
No cell membrane stability - needed for Na/K+ pumps
Why will ischaemia to the bone have a longer duration to ischaemia of the brain?
It is not metabolically active
What is cellular adaptation?
The ability of cells to respond to various types of stimuli and adverse environmental changes
What is atrophy?
What can it be caused by?
Shrinkage in the size of the cell, loss of cell number too Disuse Atrophy (immobilization after surgery) Denervation injuries (nerves supply nutrients to muscles).
What is hypertrophy?
What can it be caused by?
Increase in size of the cells and consequently the organ
caused by increased functional demand (hypertension) or specific hormonal stimulation (uterus in pregnancy)
Give an example of atrophy.
Cerebral atrophy in dementia
Why are muscles cells more associated with hypertrophy?
Muscle cells can’t divide so to meet demand they must enlarge
What is hyperplasia?
Increase in the number of cells in an organ
What is a physiological example of hyperplasia?
Physiological - in oestrogenic phase the endometrial cells in the uterus increase in number
What is a pathological example of hyperplasia?
Pathological - excessive growth factor or hormomal stimulation, excessive signals to divide can often cause cancer
What is metaplasia?
A reversible change in which one adult cell type is replaced by another
Is metaplasia reversible?
Yes
Give an example physiological metaplasia
During puberty, the cervix will expand, opening the endocervical canal.
This will expose the columnar epithelium to vaginal acid.
The low pH causes the columnar epithelium to transition into squamous epithelium.
Give an example of pathological metaplasia.
Baretts oesophagus, bottom end of oesophagus is exposed to stomach acid and goes from squamous epithelium to columnar epithelium
What is dysplasia?
Precancerous cells which show the genetic and cytological features or malignancy but not invading the underlying tissue
