Intracellular Accumulations Flashcards
(67 cards)
What is intracellular accumulation ?
Presence of abnormal amount of various substances
Substances Characteristics:
- They may be harmless or may cause injury
- They may be endogenous or be exogenous.
NOTE: endogenous: synthesised within the affected cells
Exogenous : produced elsewhere
Where does accumulation happen at a cellular level ?
- Within Organelles ( mainly lysosomes )
- In the nucleus
- In the cytoplasm
Pathways by which accumulation occurs :
- Abnormal metabolism
- Proteins Mutations
- Lack of enzymes responsible for breaking down certain compounds
- Ingestion of indigestible material
Example of abnormal metabolism :
Fatty change , In the liver
Proteins Mutation
- Mutations causes alterations in protein folding and transport
- defective protein accumulation , in the cytoplasm
-e.x : alpha 1-anti trypsin deficiency
Lacking of enzymes that are responsible for breaking down certain compounds
- Substrate accumulation , In the lysosome
- e.x : lysosomal storage diseases
Ingestion of indigestible materials
Carbon and silica accumulation
Fatty change Names :
Fatty change = steatosis = Fatty metamorphosis
What is steatosis?
Abnormal accumulation of triglycerides within parenchymal cells
How does steatosis occur ?
Defects at any step of uptake , catabolism and secretion ( from FA entry to lipoprotein exit )
What are these steps ?
- Free FAs from either adipose tissue or nutrition
- Transportation to hepatocytes
- Either : oxidation to form Ketones
Estrification to form triglycerides
Phospholipids and cholesterol - Triglycerides bind with apo-protein to form lipoprotein that can be transported within the circulation
Where fatty accumulation occurs mainly at organs level ?
1.liver 2. Heart 3. Skeletal muscles 4. Kidney
Why does fatty accumulation happen ? ( Cases )
Alcohol abuse , protein malnutrition , starvation , obesity , Diabetes mellitus , anaemia , anoxia and toxins
CCl4 and protein malnutrition :
Decrease the synthesis of apo-protein
Anoxia
Inhibits FA oxidation
Starvation
Increase Fatty acid metabolism from peripheral sources
Intracellular fatty accumulation severity effects : ( Mild , Moderate , Severe )
Mild accumulation : it has no effect on the cellular function
Severe accumulation : it may precede cell death
Moderate ( vital intracellular processes are NOT irreversibly impaired ) : it may transiently impair cellular function ……….. e.x : CCl4 poisoning
Effects of fatty change depend on :
- The cause of accumulation
- Severity of accumulation
Gross appearance of fatty change in the liver
- Mild accumulation : Has no effect in the gross appearance
- Severe accumulation : Liver apppears bright yellow , soft , greasy and enlarges ( reaches 3-6 kg weight )
Microscopic appearance of fatty change in the liver :
-Mild situation : small fatty vacuoles in the cytoplasm around the nucleus
-Severe situation : these vacuoles unite together and displace the nucleus to the periphery
Gross appearance of Mild fatty change in the heart :
- caused by prolonged moderate hypoxia as in severe anaemia
- focal intracellular fat deposits and trigger-like , tabby -cat pattern appearance ( specialised for the heart )
Gross appearance of severe fatty change in the heart :
- caused by : A) More Severe hypoxia
B) toxic myocarditis as diphtheria infection - diffuse fatty change ( occupancy of excess fats )
Cholesterol and cholesterol esters accumulation concept : (what is it ? )
Phagocytic Macrophages in contact with the lipid debris of necrotic cells may be stuffed with lipids ( cholesterol ) leading to foam appearance ( foam cells )