Cell Pathology Flashcards
Define atrophy
- Shrinkage in the size of a cell and consequently the size of a whole organ, by the loss of cell substance
- We see a decrease in weight of an atrophic organ
Define hypertrophy
- Increase in the size of a cell and consequently the size of a whole organ
- Physiological or pathological
- important because muscle cells (skeletal and cardiac) cannot divide so an increase in cell size is the only way in which an organ can get bigger
Define hyperplasia
- Increase in the number of cells in an organ
- Physiological or pathological
Define metaplasia
- Reversible change in which one normal adult cell type (mature cell) is replaced by another (normal adult cell replacement)
- Physiological or pathological
Define dysplasia
- Precancerous cells which show the genetic and cytological features of malignancy but do not invade the underlying tissue (does not invade through the basal lamina)
- bridge between normality and cancer
Examples of atrophy
- Gastric atrophy causing pernicious anaemia (anaemia resulting from vitamin B12 deficiency)
- Posterior cortical atrophy from the loss of neurones in Alzheimer’s disease
Examples of hypertrophy
Physiological: muscle hypertrophy in the uterus during pregnancy
Pathological: left ventricular hypertrophy in response to hypertension
Examples of hyperplasia
Physiological: oestrogen-induced endometrial hyperplasia
Pathological: benign prostatic hyperplasia, carcinoma
Examples of metaplasia
Physiological: metaplasia in the cervix
Pathological: Barrett’s Oesophagus (columnar lined oesophagus)
Examples of dysplasia
- Cervical intraepithelial neoplasia
- Patients with Barrett’s oesophagus are associated with a much greater oesophageal cancer risk because metaplasia is typically followed by dysplasia
Light microscopic changes associated with reversible cell injury
- fatty changes (fat accumulation in cells=fatty globules)
- cellular swelling (ballooning)
Light microscopic changes associated with irreversible cell injury
-The different types of necrosis
Define coagulative necrosis
- substance changes but the shape of the molecule does not change
- tissue retains structure after coagulation and can be recognised (nuclei gone and inflammatory cells present)
- myocardial infarction example
Define liquefactive necrosis
- tissue broken down leaving empty space which fills with fluid (tissue is totally liquefied)
- identification only from cells surrounding it (empty space)
- old cerebral brain infarct example
Define caseous necrosis
-form of granulomatous inflammation
-characteristic ‘cheesy’ appearance where
necrotic area becomes granular
-tissue cannot be recognised from structure
-associated with pulmonary tuberculosis
Define fat necrosis
- breakdown of fat cells by lipase release or trauma (significantly severe fat trauma)
- release of lipases digests the fat and hydrolyses the triglycerides into free fatty acids and glycerol
- free fatty acids combine with calcium in ECF forming calcium fat salts which deposit themselves
- associated with acute pancreatitis
Define necrosis
Confluent cell death associated with inflammation
Define apoptosis
Programmed cell death of single cells, not associated with inflammation
-normal in organism’s growth and development
Features of apoptosis
- active (energy dependent=requires ATP hydrolysis)
- physiological and pathological
- not associated with inflammation (no bystander damage to healthy tissue)
Features of necrosis
- cellular reaction of inflammation
- not just single cells (areas)
- not energy dependent
- always pathological
Define necroptosis
Programmed cell death associated with inflammation
Features of necroptosis
- energy dependent
- halfway between apoptosis and necrosis
- many causes including viral infection
- generally occurs in pathological circumstances
Causes of cell injury
G=genetic defects
I=infectious agents (bacteria, viruses, multicellular parasites)
N=nutritional imbalances
C=chemical agents (includes iatrogenic injury resulting from the drugs/medication doctors give)
H=hypoxia
A=aging
P=physical agents (eg: gunshot wound, trauma etc)
I=immunological reactions (autoimmune disease where the body attacks itself=conditions include rheumatoid arthritis)
What causes cell adaptation?
- stress on cells of increased demand/load
- cell remains in equilibrium but works in newly adapted state
What causes cell injury?
- respond to injurious stimuli (stress which is harmful)
- stress exceeds the cell’s adaptive capability
Define lethal cell injury
Produces cell death
Define sublethal cell injury
Injury does not amount to cell death(injury does not kill the cell/organism)
Define reversible cell injury
Within certain limits, the cell can return back to normal
Define irreversible cell injury
Progresses to cell death
Intracellular mechanisms/systems vulnerable to cell injury (linked systems so damage to one will impact the others)
- cell membrane integrity
- ATP generation
- protein synthesis
- integrity of the genetic apparatus
List the 5 adaptive responses of cells
- Atrophy (growth)
- Hypertrophy (growth)
- Hyperplasia (development)
- Metaplasia (development)
- Dysplasia (development)
Define degenerative
Change to a tissue to a lower or less functionally active form
Define ulcer
Local defect or excavation of the surface of an organ or tissue, produced by the sloughing of necrotic inflammatory tissues
Explain Barrett’s Oesophagus
Normal epithelial tissue lining of the oesophagus converts from stratified squamous to columnar (resembles the lining of the small intestine)
- Cause: acid reflux
- Reversal: PPI’s to inhibit acid production (Proton Pump Inhibitors)
Explain metaplasia in the cervix
-Endocervix is lined with columnar epithelium
-Ectocervix is lined with stratified squamous epithelium
-Columnar of endocervix is converted to stratified squamous
Cause:At puberty/during pregnancy, the cervix expands and fragile columnar epithelial lining of the endocervical canal is exposed to harsher more acidic environments in the vagina
Reversal: cervix contracts and closes up
Factors affecting the cellular response to injurious stimuli
- type of injury
- duration of the injury
- severity of the injury
Factors affecting the consequences of an injurious stimuli
- type of cell (some cell types are naturally more resistant to injury than others=example of bone, fat, brain and heart to oxygen deprivation)
- Cell status (more vulnerable to various agents if dividing)
- adaptability of the cell
- genetic makeup of the cell
Define infarction
Tissue death due to ischaemia
Causes of cell death
- Stress is too severe
- Prolonged/persistent stress
Physiological effects
-result of a normal stressor (healthy people)
Pathological effects
-result of an abnormal stressor (diseased state)
Hypertrophy causes
- Increased functional demand
- Specific hormonal stimulation (seen in pregnancy)
Physiological hyperplasia causes
- Hormonal(eg: Oestrogen causes wave of proliferation of the endometrium=inner lining of the uterus)
- Compensatory (tissue previously lost)