Cell adaptation Flashcards
What are the 3 ways cells react to injury?
Adaptation - new physiological state
Injury - sublethal state
Cell death - not capable of recovering
What causes cells to adapt into a new physiological state?
Prolonged stimulus, e.g.
Excessive physiological stress
Pathological stimuli
Cellular adaptation affects growth/differentiation of cells. What can it cause?
Atrophy Hypertrophy Hypoplasia Hyperplasia Aplasia Metaplasia
What is atrophy?
Decrease in size and number of cells and organ
Atrophy can be pathological. Give an example of when pathological atrophy might occur
Disuse of muscle e.g. due to fraction
Reduce organ perforation
Inadequate nutrition
Compression
Why does atrophy occur after disuse/reduced perforation/other pathological causes?
Decreased metabolism
Reduced organelles
Reduced cell volume
What disassembles non-required/damaged organelles?
Autophagic vacuoles
Contains lysozymes
Give examples of when involution or physiological atrophy may occur
To uterus after parturition
Thymus after puberty
What is hypoplasia?
Decreased organ volume due to incomplete cell proliferation (less cells)
What is aplasia?
Organ absence due to defective cell proliferation
What is hypertrophy?
Increased organ size due to increased size of cells
What causes hypertrophy?
Give examples of when this might occur
Increased functional demand
Can be physiological e.g. muscle in body builders
Can be pathological e.g. cardiomyocytes with overload
What is hyperplasia?
Increased organ size due to increased number of cells
What causes cell number to increase in hyperplasia?
Cells undergo mitosis in response to hormones and growth factors
Hyperplasia can be physiological. Give examples of the 2 types of physiological hyperplasia
Physiological hyperplasia - hormonal e.g. mammary glands during pregnancy
Compensatory hyperplasia - loss of parenchyma
Give examples of what can cause pathological hyperplasia
Excessive hormonal stimulation/growth factors on target cells
E.g. attempt of regeneration, viral infections like papilloma
What is metaplasia?
Stem cells reprogram themselves to another mature cell type
Or differentiated cells transform to another differentiated cell
Is metaplasia permanent or reversible?
Reversible
Give an example of metaplasia
Replacement of respiratory epithelium to squamous epithelium due to irritation
What are intracellular accumulations? What is it due to?
Accumulations of various substances in abnormal amounts
Metabolic abnormalities in cell
What processes cause cause intracellular accumulation?
Normal production but increased removal of endogenous substances
Transport of normal endogenous substances
Abnormal exogenous substances
What are the 3 categories of intracellular accumulation?
Normal cell constituents (water, lipid, protein, carbs)
Abnormal exogenous and endogenous substances
What is lipidosis?
Abnormal accumulation of triglycerides in parenchymal cells (liver)
What does lipidosis cause?
Toxin production
Protein malnutrition
Diabetes
Obesity
What morphological changes happen to the liver during lipidosis? What causes the swelling?
Liver turns yellow
Becomes fatty, oily and swollen
Swelling due to large vacuoles in adipocytes
What happens to free fatty acids from intestines and adipose tissue?
Chylomicrons transport them in the blood
Stored as lipoproteins for use in other cells
What causes protein accumulation? (2 main ways)
- Excess synthesis, excess protein presented to cell, reabsorption in renal tubules, excessive amounts of secretory protein
- Defects in protein folding
What may cause defects in protein folding?
Genetic mutation Aging Environmental factors Amyloidosis TSE
Excess protein can be caused by excess amounts of secretory proteins. Give an example of a secretory protein
Russell bodies in plasma cells
What causes an abnormal accumulation of glucose/glycogen?
Diabetes
Glucocorticoid hepatopathy
Glycogen storage diseases
When might there be an accumulation of calcium salts? Does this affect calcium serum levels?
Non-viable, dying or necrotic tissues
Calcium serum remains normal
What is dystrophic calcification?
Abnormal deposition of calcium due to tissue damage
What process happens to normal tissues with hypercalcaemia?
Metastatic calcification
What are the 2 phases of pathogenesis for dystrophic calcification?
- Initiation - calcium accumulates in mitochondria of dying cells and phospholipids in vesicles of dying cells
- calcium binds to phospholipids high causes calcium depolarisation. Microcrystals perforate membrane
Abnormal substances can accumulate due to exogenous or endogenous causes. Give examples of each
Exogenous - mineralas, products of infectious agents
Endogenous - abnormal synthesis/metabolism
What causes pigmentation in normal cells? What colour is this and what cells is it found in?
Melanin
Brown/black
Melanocytes
Pigmentation can be normal or abnormal. Give examples of when pigmentation can be exogenous or endogenous
Exogenous -anthrax causes inhalation of carbon
Endogenous - melanin, haemosiderin, bilirubin
What colour is lipofuscin? What is this?
Yellow/brain
Endogenous polymer of lipids and proteins
What is haemosiderin? What colour is it?
Stores iron from the breakdown of haem
Gold colour
What is heme broken down into to? Where is the iron stored?
Iron and biliverdin
Stored in haemosiderin
What is bilirubin? What is jaundice?
Major pigment in bile
Excess bilirubin in blood
Haem is broken down into biliverdin and iron. What happens to the iron?
Oxidised and stored in haemosiderin
Haem is broken down into biliverdin and iron. What happens to the biliverdin?
Biliverdin broken down by macrophages/monocytes to bilirubin
Bilirubin becomes bilirubin glucoronides in liver
Becomes urobilinogens
What colour is biliverdin? What about bilirubin?
Biliverdin - green
Bilirubin - blue/green
What colour is bile? Jaundice is due to high bilirubin in blood (bilirubinaemia). What causes this?
Yellow/green
Obstructed bile flow, excessive haemolysis
What does bile contain?
Water
Choletserol
Bile sals
Bile pigments from haemoglobin (bilirubin)
What is amyloidosis?
Abnormal build up of amyloid in organs and tissues
What is amyloid? What does it look like histologically?
Pathological protein deposited between cells
Soft, pink, fluffy
Where is amyloid associated protein synthesised? Does it contain Ig?
Hepatocytes
No Ig
What is amyloid light chain derived from? Does it contain Ig?
Plasma cells
Contains Ig
What disease cause deposition of beta amyloid protein?
Spongiform encephalopathies
Where is islet amyloid polypeptide deposited?
Pancreatic islets
Amyloidosis can be classed as systemic, localised, primary, secondary, hereditary or endocrine. What causes primary and secondary amyloidosis? What is endocrine amyloidosis?
Primary - immunocytic disorder
Secondary - complication of amyloid associated chronic inflammation
Endocrine - deposition of islet amyloid polypeptide
What is the most common type of amyloidosis - localised or systemic? Primary or secondary?
Systemic
Secondary
