Week 3- Cell adaptations + damage Flashcards
What is cell adaptation? When may it happen & what can change to preserve cell vitality?
Reversible change in cells in response to environment
Stimuli may arise under physiological or pathological conditions
Cell number
Cell size
Cell type
What are the three classes of proliferative cells? Give examples
1) Labile
eg: skin, epithelial
2) Stable
eg: bone
3) Permanent
eg: brain
What are the different types of cell adaptation?
Hyperplasia
Hypertrophic
Meterplasia
Atrophy
Define Hyperplasia. What is the cell type? Give examples of physiological & pathological hyperplasia including causes
Increase in cell number
Labile/ stable cells
Physiologically:
1) Hormonal → Endometrium
2) Compensatory → Partial hepatcetomy
Pathologically:
- Excessive growth hormone
- Chronic irritation
Can occur alongside hypertrophy
Increased risk of tumour development
Define Hypertrophy. What cells can it occur in? Give examples of physiological & pathological hypertrophy including causes
Increase in cell size. More cellular structural proteins
All cells, most common: permanent cells
Physiologically:
1) Increased functional demand → Skeletal muscle
2) Hormonal/ growth factor → Uterine muscle pregnancy
Alongside hyperplasia
Pathologically:
Increased functional demand → Cardiac muscle (LV hypertrophy/ aortic stenosis)
Define Atrophy. What are the causes of atrophy?
Shrinkage in cell size with self-digestion of organelles
1) Reduced workload
2) Loss nerve supply
3) Blood supply loss
4) Inadequete nutrition
5) Loss endocrine stimulation
6) Ageing
Define Metaplasia. Talk about it- why it happens, what can happen, what it usually involves. Give examples of physiological & pathological metaplasia
Change in cell type from adult cell to another
Talk:
New cell type better adapted to the stimulus
Ground for the later development of cancer
Usually involves epithelium
Physiological:
1) Growth/ development → Glandular to squarmous eputhelium in pubertal cervix
Pathological:
1) Abnormal environemnt → Squarmous to glandular epithlium in GORD
What are the different types of developmental abnormalities?
Agenesis: Failure to form
Aplasia: Failure to differentiate into organ specific tissue
Dysgenesis: Failure of tissue to strucurally organise themselves into organ
Hypoplasia: Failure of organ to grow to full size
What are the types of abnormal growth?
Dysplasia
Neoplasia
What is dysplasia? Talk about it. Where can it occur?
Presence of cellular atypia, increased cell growth, altered differentiation premelignant condition
Ocurrs:
- Cervix
- Bladder
- Stomach/ oesophagus
What is Neoplasia? What are the types?
Abnormal growth of cells which persists after stimulus removed and has escaped normally regularatory processes
Benign
Malignant
What is cell injury caused by? Is it reversible?
Inhrently injurous stimuli OR when the cell adaptability is exceeded.
Reversible if stimuli is removed, damage is minor + tx given
What are the causes of cell injury/death?
GINPIOC
Genetic derrangements
Infectious agents
Nutritional imbalance
Physical agents
Immune response
Oxygen deprivation
Chemicals/ toxins
What are the two types of cell death?
Apoptosis → Programmed
Necrosis → Unprogrammed
Talk about Cell Death Necrosis:
(6)
What type of cell death?
What are the causes?
What happens to the cell?
Pathological cell death- external factors
Hypoxia, Chemical toxins
Damage to cell physiology
Degredation of cell strucutre
Influx of ions & water
Cellular organelles swell & rupture
What is Cell Death by Apoptosis?
Programmed or Physiological
Constituent genes –> Cell death
What are the Morphological feature of Necrosis?
Cell membrane integrity is lost & lysosomal hydrolase are released resulting in:
- Small condensed nuclei
- Deeply stained nuclei
- Nuclei fragments in particles
- Cytoplasm becomes deeply stained
- Typically affects a large group of cells
- Enzymatic digestion of cellular contents possible- may leak out
- Frequent adjacent inflammation
- Plasma membrane disrupted
What are the Morphological Feature of Apoptosis?
- Organelles remain intact
- Nucleus and cytoplasm condense to form apoptotic bodies
- Intact membranes surrounding apoptotic bodies
- Apoptotic bodies phagocytosed by macrophages
- No inflammatory response
- Typically affects isolated cells
What are the types of Necrosis?
Liquefactive
Fat Necrosis
Caseous
Coagulative
Gangrenous
Fibrinoid
What is Liquefactive Cell Necrosis?
Tissue is replaced by liquefied material
Accompanied with enzymatic digestion of the tissues
What is Fat necrosis Cell Necrosis?
Enzymatic digestions of tissue
What is Caseous Cell Necrosis?
Dead tissue looks like cottage cheese (seen in TB infections)
[Midway in appearance between liquefactive & Coagulative]
What is Coagulative Cell Necrosis?
- Cells are non-vital i.e. the nucleus is not identifiable but the structure of the tissue still visible histologically
- Reflects cell death WITHOUT enzymatic digestion of the tissues
- Commonly seen in ischaemic injuries (except in the brain)
What are the mechanisms of cell damage?
- Free Radicals
- Loss of calcium homeostasis
- Oxidative stress
- Defects in membrane permeability
- Depletion of ATP
- Mitochondrial damage
