Intracellular Accumulation: Categories, Mechanism, Examples, Processes of Accumulation and MCQs for NEET, GPAT, CSIR NET JRF

INTRACELLULAR ACCUMULATION :- The normal cell accumulate abnormal amount of substance either for temporary or permanently which may be harmful to the cell and may cause injury. The sites of these accumulations are either in the cytoplasm ( phagolysosomes ) and nucleus. Accumulation may be transient and reversible or permanent.

THREE CATEGORIES OF ACCUMULATIONS :-

1.] Accumulation of constituents of normal cell metabolism :

• Fat
• Protein
• Carbohydrates

2.] Accumulation of abnormal substance of abnormal cell metabolism :

• Storage disease
• Inborn error of metabolism

3.] Accumulation of pigment :

• Endogenous pigments
• Exogenous pigments

MECHANISM OF ACCUMULATION :-

A.] Due to overproduction : Accumulation due to overproduction of normal endogenous at normal or increased rate but their metabolism is not adequate at the rate e.g. Fatty changes in liver.

B.] Due to inadequate metabolism : The accumulation of endogenous substance because they are not metabolized due to lack of enzymes that block the specific metabolic pathway.

C.] Lack of enzyme machinery to remove : Abnormal exogenous substance is deposited and accumulation due to lack of enzymatic machinery to degrade the substance or the ability to transport the other sites. Accumulation of carbon particles and non – metabolized chemicals like silica particles are an example.

SOME EXAMPLES ARE :-

A.] Fatty change in liver :

• Normal substances are produced at normal or increased state.
• Metabolism is inadequate to remove it.
• Accumulation.

B.] Storage disorder :

• Normal endogenous substance.
• Enzyme deficiency.
• Accumulation.

C.] Accumulation of carbon in lungs :

• Exogenous substance.
• No enzymatic activity for its degradation or transport.
• Accumulation.

PROCESSES OF ACCUMULATION :-

There are four steps involved in the processes of intracellular accumulation :

• Production of normal endogenous substance at normal or increased rate, but the rate of metabolism is inadequate to remove it. Example fatty liver, reabsorption of protein droplets in tubules of kidney.
• Accumulation of an abnormal endogenous substance (product of mutated gene) due to defect in protein folding, transport and inability to degrade abnormal protein effectively. Example accumulation of mutated protein in liver cell.
• Accumulation of an normal endogenous substance due to inherited defect in enzymes required for the metabolism of the substance. Example are lipid and glycogen storage disease.
• Accumulation of abnormal exogenous substance due to unavailability of enzymatic and transport mechanism to degrade and transport it to other site. Example are silicosis and anthracosis.

MULTIPLE CHOICE QUESTIONS [MCQs] :-

1.] The site of accumulation in the cell is ?

a. Cytoplasm

b. Phagoglysosomes

c. Nucleus

d. All of the above

2.] Pigmentation in the liver is caused by all except ?

a. Lipofuscin

b. Malarial pigment

c. Wilson’s disease

d. None of the above

3.] Wear and tear pigment in the body refers to ?

a. Lipochrome

b. Melanin

c. Anthracotic pigment

d. Hemosiderin

4.] Brown atrophy is due to ?

a. Fatty necrosis

b. Hemosiderin

c. Lipofuscin

d. Aruloplasmin

5.] All is true about metaplasia except ?

a. Slow growth

b. Reverse back to normal with appropriate treatment

c. Irreversible

d. If persistent may induce cancer transformation

6.] Examples of hypertrophy is ?

a. Breast in puberty

b. Uterus during pregnancy

c. Ovary after menopause

d. Liver after resection

7.] “Fatty change in the liver” is due to ?

a. Inadequate metabolism

b. Lack of enzyme machinery to remove

c. Overproduction

d. All of the above

8.] “Accumulation of carbon of lung” is an example of ?

a. Lack of enzyme machinery to remove

b. Overproduction

c. Inadequate metabolism

d. None of the above

9.] Accumulation of abnormal substance of abnormal cell metabolism causes ?

a. Storage disease

b. Inborn error of metabolism

c. Both (a) and (b)

d. None of the above

10.] Which of the following is an endogenous pigment ?

a. Hemosiderin – multiple transfusion

b. Lipofuscin – aging pigment

c. Bilirubin – hepatocytes

d. All of the above

SOLUTIONS :-

1.] (d)

2.] (d)

3.] (a) lipochrome

4.] (c) lipofuscin

5.] (c) irreversible

6.] (b) uterus during pregnancy

7.] (c) overproduction

8.] (a) lack of enzyme machinery to remove

9.] (c)

10.] (d)

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REFERENCES :-

1.] Textbook Of Pathology By Harsh Mohan; 7th edition; Page no. 19 – 21

2.] Robbin’s Basic Pathology; 5th edition; Page no. 24 – 30