Introduction to Pathological Concepts Flashcards
What is a cyst
- A cyst is a cavity lined by epithelium
- Secretion varies with the type of lining epithelium.
- Watery fluid if the lining epithelium was serous
- Mucus if the lining epithelium was mucus secreting columnar epithelium.
What is an abscess
- Lined by granulation tissue
- Contain pus (dead/dying neutrophil leukocytes)
- Similar to cyst as they both contain a cavitating lesion
What is a cavitating lesion
Gas or fluid filled space
What is a granulation tissue
Repair tissue that consists of newly formed blood vessels and myofibroblasts
What is a granuloma
Chronic inflammation tissue consisting of localised collection of modified macrophages called epithelioid histiocytes
- there may be central area of necrosis
- Lymphocytes and plasma cells can also be present
- Pathogenesis Type 4 hypersensitivity
What is apoptosis
- Cell death that is tightly regulated by intracellular programming.
- Cells activate enzymes that degrade the cells’ own DNA, nuclear and cytoplasmic proteins.
Apoptosis process
1) Loss of specialised surfaces
2) Cell volume reduction
3) Chromatic condensation - chromatin aggregates peripherally under nuclear membrane
4) Formation of cytoplasmic blebs and apoptotic bodies
5) Phagocytosis of apoptotic bodies usually by macrophages
What is necrosis
Spectrum of morphologic changes that follow cell death in living tissue, largely resulting from the progressive degradative action of enzymes on the lethally injured cells
What are the different subtypes of necrosis
Coagulative necrosis
Liquefactive necrosis
Suppurative necrosis
Caseous necrosis
Fat necrosis
Gangrene
Histology of Apoptosis
Single cells affected within living tissue (tissue structure is unaffected)
Histology of Necrosis
Sheets of cells dying together
Tissue architecture is disrupted
Cytology of Apoptosis
Cells contract
Increased density of cytoplasm and nucleus
Cytology of Necrosis
Cell swell (oedema)
Loss of intracellular features
Ultrastructure of Apoptosis
Plasma membrane and mitochondria remain intact
Ultrastructure of Necrosis
Plasma membrane and internal membranes ruptured
Mitochondria swell
Apoptosis - effects in the tissue
No inflammation
Rapid removal of dead cell leaving tissue architecture undisturbed
Necrosis - effect on the tissue
Evokes an acute inflammatory response.
Major disturbance of surrounding tissue
What is hyperplasia
Increase in the number of cells which is under negative feedback control
i.e., tissue/organ goes back to normal when the initial stimulus is withdrawn
What is neoplasia
Increase in number of cells which is not under negative feedback
(i.e., tissue/organ do not go back to normal even when the initial stimulus is withdrawn. These cells continue to multiply as some genetic control on cell proliferation is lost, usually by mutation in the oncogenes or tumour suppressor genes)
What is hyperplasia (pt. 2)
The organ responds to this increase in demand by increasing the number of cells because these cells are able to multiply (labile cells) like the epithelial cells of the gut.
What is hypertrophy
The organ responds to increase in demand by acquiring more organelles in cell cytoplasm thereby increasing the size of cells because these cells are not able to multiply like muscle cells.
What is aplasia
Involved organs do not develop at all from birth (e.g., finger or appendix)
What is atrophy
This organs fully develop first and then due to some reason like denervation or lack of activity (immobilisation after fracture) there is a reduction in cell size, thereby shrinkage of organ size.
What is metaplasia
Adaptation to cell environment. There is a change in one adult cell type to another cell type. E.g., squamous metaplasia in cervix and bronchus and Barrett’s metaplasia of oesophagus.
