L2: Cellular adaptation & degeneration Flashcards
Developmental abnormalities of cell growth
Occurs due to defective fetal development in uterus.
They manifest at birth or shortly after.
Either hereditary or congenital.
What are the causes of developmental abdnormalities of cell growth?
Hereditary abnormalities:• Inherited from the parents. e.g. Genetic disease
Congenital abnormalities:• Due to affection of the normal fertilized ovum by adverse factors as infection, chemicals, irradiation or an increased maternal age.
What are the congenital disorders of cell growth?
Agenesis Aplasia Hypoplasia Atresia Heterotobia(choristoma) Hamartoma
What is agenesis?
Congenital absence of an organ e.g. solitary kidney.
What is aplasia?
The organ is represented by a rudimentary structure
What is hypoplasia?
The organ is a normal structure but fails to reach adult size e.g. kidney.
What is atresia?
- Absence of a normal opening
* Failure of canalization of hollow organ e.g. intestine
What is Heterotobia(choristoma)?
• Presence of normal tissue in abnormal sites
• e.g pancreatic tissue in stomach or thyroid tissue in
the base of the tongue.
What is hamartoma?
• Formation of a mass of mature tissue of the locality, but in abnormal arrangement or quantity as pigmented nevi.
What are the cellular adaptations to stress?
Reversible changes in the number, size, phenotype, metabolic activity, or functions of cells.
What are the types of cellular adaptations to stress?
Physiologic adaptations:-
In response to normal stimulation e.g. by hormones
Pathologic adaptations:-
In responses to stress
What are acquired disorders of growth?
1- Atrophy 2- Hypertrophy 3- Hyperplasia 4- Metaplasia 5- Dysplasia
What is the definition of atrophy?
Decrease in organ size by decrease in size and/or the number of its cells.
What is the classification of atrophy?
Physiological and pathological
What are the types of physiological atrophy?
- General (Senile): It is an aging process.
- Local: Involution of an organ due to loss of its physiologic function. and its causes are (After labor: ↓ uterus, After child weaning: ↓ breast size)
What are the types and causes of pathological atrophy?
-General (Senile)
-Causes
Starvation.
Toxic.
Hormonal.
Local
-Causes Disuse Atrophy. Neurogenic atrophy. Ischemic atrophy. Pressure atrophy. Thermal.
What is the gross morphology of atrophy?
General Atrophy All organs are affected to a variable extent: 1. Skin is wrinkled 2. Loss of fat of adipose tissue 3. Wasting especially of liver, muscles 4. Brown atrophy of heart.
Local Atrophy
The organ is decreased in size and weight.
What is the microscopic morphology of atrophy?
1- Reduction of cytoplasmic mass.
2- The nucleus is apparently normal.
3- Spaces created by atrophied cells are occupied by fibrous tissue or fat.
What is hypertrophy?
Increase in organ size due to increase in the size of its constituent cells.
What is the classification of hypertrophy?
Pathological and physiological
What are examples of physiological hypertrophy?
➢ In response to hormones: Smooth muscles of the pregnant uterus.
➢ Excess functional demand: skeletal muscles in manual workers and
athletes.
What are examples of pathological hypertrophy?
Hormonal:
- Occurs with an excess growth hormone of the anterior pituitary, leading to gigantism and acromegaly.
Excess functional demand:
1- To overcome distal resistance: in hollow organs
2- Compensatory hypertrophy: in paired organs.
What is hyperplasia?
Enlargement of the organ due to an increase in the number of its component cells.
What are the types of hyperplasia?
a. Physiological Hyperplasia
b. Pathologic Hyperplasia
What are the types of physiological hyperplasia?
Hormonal:
- Hyperplasia of female breast at puberty and lactation.
- Smooth muscles of gravid uterus
Excess demand:
- Thyroid gland in girls at puberty and pregnancy.
What are the types of pathological hyperplasia?
Hormonal: Due to excessive hormonal stimulation (Cushing syndrome)
Compensatory hyperplasia: Liver cells proliferation after partial surgical excision or destruction
Irritative hyperplasia: Occurs in response to local irritation e.g. lymphoid tissue.
What is metaplasia?
Transformation of a differentiated tissue into another differentiated tissue of the same category i.e. epithelial to epithelial and connective tissue to connective tissue.
What are the types of metaplasia?
- Epithelial metaplasia.
- Connective tissue metaplasia.
- Mesothelial metaplasia.
What are the causes of epithelial metaplasia?
The adaptive mechanism by which the cells which are more sensitive to stress are replaced by another cell type with better ability to withstand the adverse environment as occurs in Chronic irritation.
What are the forms of epithelial metaplasia?
Squamous metaplasia:
➢ in response to chronic irritation:
➢ E.g. trachea, gall bladder, and uterine cervix
Glandular metaplasia
➢ Barret’s Esophagus.
➢ Metaplasia of the gastric mucosa to
the intestinal epithelium.
What is connective tissue metaplasia?
Connective tissue as fibrous, myxomatous, cartilage, bone, or fat can be changed to each other.
What is mesothelioma metaplasia?
Affects flattened cells that line the serous sacs.
Chronic irritation may change them to cubical, columnar, glandular, or stratified squamous.
What is the definition of Dysplasia?
It is disordered but nonneoplastic cellular proliferation Characterized by :
- loss of individual cell uniformity
- loss of normal arrangement within the tissue.
What are the sites of dysplasia?
a. Skin
b. Mucous membranes
c. Liver
What are the causes of reversible cell injury?
1- Oxygen deprivation (hypoxia, ischemia)
2- Oxygen free radicals.
3- Physical agents (heat, cold, radiation, trauma).
4- Chemical agents e.g. drugs, toxins
5- Infectious organisms.
6- Immunologic reactions.
7- Genetic derangements.
8- Nutritional imbalances e.g. starvation, obesity
What is the role of mitochondria in cell injury?
• Mitochondria is concerned with cell respiration and the production of ATP which is responsible for important vital functions of cell:-
1- Cellular osmolarity (Na/K )
2- membrane transport process.
3- Protein synthesis.
What is the pathogenesis of cell injury?
➢ Mitochondrial oxidative phosphorylation is disrupted first → Decreased ATP →
1. Decreased Na/K pump → gain of intracellular Na → cell swelling
- Altered metabolism → depletion of glycogen (anaerobic respiration with glycogenolysis).
- Lactic acid accumulation → ↓ pH & ↑ intracellular osmotic pressure → ↑intracellular H2O → cell swelling.
- Release of mitochondrial protein →↑ cytoplasmic osmotic pressure and helps intra-cellular water accumulation
What is the morphology of cloudy selling?
LM
➢ Occurs in organs rich in mitochondria e.g. renal tubules, cardiac muscles, and hepatocytes.
Grossly
➢ The organ is enlarged, soft, pale with tense capsules and rounded borders.
➢ C/S is bulging.
M/E
➢ Swollen cells
➢ Granular cytoplasm.
➢ Nucleus is NORMAL
What is hydronic degeneration?
A severe form of cloudy swelling.
Cytoplasm accumulates vacuoles of water.
The nucleus is still normal
What is the definition of fatty change(stenosis)?
Abnormal accumulation of intracellular neutral fat that occurs in parenchymatous organs most commonly liver, kidney, and heart.
What are the causes of fatty change?
As other causes of cell injury
What is the mitochondrial theory?
Mild prolonged or severe short injury leads to injury of mitochondria with the release of its fat that accumulates in the cytoplasm (fatty degeneration).
What are the causes of fatty change in the liver?
- Increased fatty acids entry to the liver (Obesity, starvation & cortisone therapy).
- Increased Fatty acid synthesis in the liver from acetate (alcoholism).
- Decreased oxidation of fatty acids (hypoxia, anemia, respiratory failure).
- Increased esterification of fatty acids to TGs (DM, alcoholism)
- Decreased formation of apoprotein (protein malnutrition, alcoholism, and CCL4 toxicity)
What is the gross morphology of fatty change?
Grossly:
Size: enlarged
Shape: Preserved
Surface: Smooth
Capsule: Tense
Consistency: Soft, greasy
Cut surface: Bulging
Color: Pale yellow
Borders: Rounded
What is the M/E of fatty change?
a. liver cells accumulate fat which appears in H&E stained section as clear vacuoles.
b. These vacuoles are first small (microsteatosis).
c. Later on the vacuoles fuse to form one large vacuole which pushes the nucleus to one side of the cell.
d. The nucleus becomes flattened (signet ring cell).
What are the fat stains for fatty change?
➢ During routine staining of sections by Hx and E fat is dissolved during preparation by the organic solvents.
➢ For a demonstration of fat, frozen sections are used and stained by
- Sudan III & oil red O →Orange-red
- Osmic acid →Black
What are the patterns of fatty change in the liver?
Focal
Zonal
Massive or diffuse
What is focal fatty change?
➢ Random single or small clusters
➢ e.g. in viral hepatitis C.
What is zonal fatty change?
➢ Centrizonal (zone 3) →hypoxic injury →away from the blood supply.
➢ Peripheral zonal ( zone 1) →toxic injury →first area to meet blood.
What is massive or diffuse fatty change?
➢ Reye syndrome
What are the types of fatty changes in the heart?
Localized
Diffuse
What are examples of localized fatty change in the heart?
In moderate cases Mostly due to anemia
What is the morphology of localized fatty change in the heart?
Gives yellow streaks alternating with dark brown fibers (tigroid or tabby cat appearance).
What is the examples of diffuse fatty change in the heart?
In severe toxicity e.g. diphtheria.
What is the morphology of diffuse fatty change in the heart?
- leads to toxic myocarditis & acute heart failure.
- If the patient survives, myocytes are replaced by fibrous tissue.
