W5 Lecture 1: Disorders of Growth Flashcards
What’s the complete failure of growth called?
- agenesis
What’s the partial failure of growth called?
- hypoplasia
What is hyperplasia?
- Is an increase in the size of tissue due to an increase in the number of its constituent cells
When does the hypertrophy or hyperplasia effects cease?
When the stimulus triggering and promoting their action is removed
What mechanisms within the body cells lead to hyperplasia?
- Transcription be turning on genes including those responsible for production of growth factor receptors
- Increase in levels of growth factor receptor receptors on cells
- Increase in local production of growth factors
- Activation of intracellular signaling pathways
Which organs see hyperplasia as a result of hormones or endocrine system??
- Breasts during puberty and pregnancy(stimulated by hormone estrogen)
- Thyroid gland at puberty and during pregnancy (stimulated by thyroid stimulating hormone from the pituitary gland)
What is compensatory hyperplasia, and why do we see it?
- It’s a form of hyperplasia that results from an increased functional demand of a specific tissue or organ.
When do we commonly see compensatory hyperplasia?
- On bone marrow:
-Due to an increased demand of RBC (erythropoiesis) when on high altitude or coz of blood loss;
-And due to an increased demand for granulocytes if microbial infection is evident. - On a liver:
-Following liver hepatectomy
A growth disorder resulting from chronic irritation of oral mucosa due to ill fitting denture, or callus on feet due to small shoes
Hyperplasia
A growth disorder resulting from chronic inflammation in the bronchi of smokers, also termed chronic bronchitis
- Hyperplasia
What is hypertrophy?
Is an increase in size of tissue due to an increase in size of its constituent cells
An important growth disorder on permanent cells, cells that cannot divide: skeletal, cardial myocytes, brain…
Hypertrophy
When do skeletal muscle hypertrophies?
-When there is an increased functional demand which is through:
- exercise
What a condition that forces the left ventricle, supplying oxygenated blood to the body to undergo hypertrophy?
Hypertension.
*Blood be moving with high pressure from the left ventricle to the body
Right ventricular hypertrophy is a result of ________
- Pulmonary hypertension
or pulmonary vulvar disease
*Blood be moving with great pressure from the lung to the right ventricle.
When does cardiac failure result from hypertrophy action of the heart ventricles?
- When the heart reaches the limit beyond which enlargement of muscle
mass is no longer able to compensate for increased burden.
Which hollow organs with smooth muscle undergo hypertrophy?
- Urinary Bladder- in urinary outflow obstruction
- Prostate- on elders
- Media of muscular arteries in hypertension
What are the 5 disorders of growth?
- Hyperplasia
- Hypertrophy
- Atrophy
- Metaplasia
- Dysplasia
- Neoplasia
What abnormal growth is anticipated on thyroid gland and on the breast during puberty/pregnancy?
Hyperplasia
A hormonal induced abnormal growth seen on the smooth muscle fibers of a pregnant uterus
hypertrophy
What is the normal cellular mechanism which induces atrophy
apoptosis
With respect to physiological and pathological atrophy, Which organs see physiological atrophy as we grow from embryonic stage to alders?
- Embryo and foetus:
*Part of process morphogenesis e.g. branchial clefts, notochord,
thyroglossal duct, Mullerian duct (males), Wolffian duct (females) - Infant :
*Closure of ductus arteriosus, umbilical vessels - Adolescence:
*Involution of thymus - Late adulthood & old age:
*Uterus, endometrium, testes, bone (particularly females),
cerebrum, lymphoid tissue
With respect to physiological and pathological atrophy, What exposes humans to pathological atrophy? What factors drive or perpetuates it so it happens?
- Malnutrition:
*Generalised atrophy due to starvation / malabsorption
*Also wasting from chronic inflammation / malignancy - Disuse atrophy:
*E.g. limb immobilised in a plaster cast>muscular atrophy - Neuropathic atrophy:
*Denervation- loss of muscle mass and function as a result of damage to the nerves supplying the muscle. - Ischaemic atrophy:
*Loss of muscle mass and function due to a decreased blood flow to the muscle
*E.g. partial limb ischaemia due to atherosclerosis - Pressure atrophy:
*Results from continuous pressure
*Probably due to ischaemia
What is metaplasia?
A change from one differentiated cell type to another type of
differentiated cell, which is usually less specialised
*maybe a reversible change
What cells are mostly impacted by metaplasia?
- Epithelial cells of mucosal lining
- and Mesenchymal cells (connective tissue cells)
What is the significance of metaplasia in human body?
The new group of cells replace original cells; giving rise to a tissue type better able to withstand adverse environmental conditions
When should we expect to see metaplasia in the organ/tissue epithelium?
Metaplasia is seen in the setting of chronic cellular injury and repair.
What are the 2 common metaplasia seen in the body tissues?
- Squamous cell metaplasia: Where epithelium layer of a tissue changes from maybe being columnar to being squamous.
- Columnar metaplasia:
Where epithelium layer of a tissue changes from maybe being squamous or cuboidal, to being columnar.
Which organs see squamous cell metaplasia?
- Ciliated columnar respiratory epithelium of trachea & bronchi in smokers
- Ducts of salivary glands, pancreas, bile duct with stones
- Urothelium of bladder, ureter, renal pelvis in cases of renal stones & Schistosoma haematobium infection
- Squamocolumnar junction of uterine cervix - puberty &
pregnancy (physiological phenomenon
Which organs see columnar metaplasia?
- The pseudostratified ciliated respiratory epithelium change to simpler mucus-secreting columnar epithelium
- In oesophagus, chronic reflux of gastro-duodenal contents –squamous epithelium is replaced by intestinal-like columnar cells
= Barrett oesophagus
*Barrett’s esophagus is a condition in which the lining of the lower esophagus undergoes changes that make it more similar to the lining of the intestine.
With respect to epithelial and mesenchymal metaplasia, where, like which body organs see mesenchymal hyperplasia?
Bone
What is dysplasia?
*also called atypical hyperplasia or intra-epithelial neoplasia
A premalignant condition characterised by increased cellular proliferation with features of atypia
*Atypia: Abnormal number, size, shape & orientation of epithelial cells which fall short of true malignant change
What is a potential cause of dysplasia?
- Longstanding irritation & injury of tissue(chronic inflammation)
- Exposure to carcinogenic
substances
*Severe dysplasia is a reflection of underlying DNA damage
What are the features of dysplasia?
- Increased growth:
-ncreased epithelial thickness &
-increased numbers of mitoses - Cellular atypia
- Pleomorphism (variation in size & shape of cells & their nuclei)
- Large, hyperchromatic nuclei, high nuclear:cytoplasmic ratio,
increased DNA content (more darkly staining nuclei)
