Disorders of Growth and Differentiation Flashcards
define auxetic growth of a cell
growth of a pre-existing cell (in size)
Define: accretionary growth of cells
ECM grows and cells do not
Physiological Hypertrophy in Muscle
Increase in cell size but not number
What pathologies cause pathological cell hypertrophy?
The right ventricle in cardiac dysfunction
What are some examples of physiological cell hyperplasia?
Adaptation to Altitude: Raised RBC count
Lactation: alveolar buds increase during pregnancy and lactation
Tissue Repair: Angiogenesis, Wound Healing, Liver Regeneration, Scarring
What are some examples of pathological hyperplasia?
Psoriasis: autoimmune skin disease
Keloid Scarring
Liver regeneration leading to cirrhosis, fatty change, or alcoholic hepatitis
Physiological Atrophy
Reduced Cell Size or Number or Both
What are some examples of Physiological Atrophy?
The thymus gland atrophies with age
Atrophy is a common part of ageing
What are some examples of pathological atrophy?
Muscles after trauma
Nerves in Paraplegics
Pressure from Bedsores
Diet in Anorexia Nervosa
What is Turner Syndrome?
Lack one chromosome containing the SHOX gene, resulting in 45XO
Results in Short Stature
What is the function of the SHOX gene?
Allows Chromosomes to realign and recombinate
Where is the SHOX gene located?
In the pseudoautosomal region of the X chromosome (tip), so it escapes X-inactivation
Expressed in chondrocytes of the human growth plate
Why does Turner Syndrome cause short stature?
Mutated/Missing SHOX gene
Beckwith-Wiedemann Syndrome
Inheritance of two copies of a chromosome from 1 parent and none from the other
Increased expression of IGF-II; Decreased expression of H19
Causes overgrowth in early childhood
Pituitary Gigantism
Increased IG1 and Growth Hormone, often from pituitary tumours
What mutation is present in the majority of cases of achondroplasia?
G80 Mutation
What is the function of the FGFR3 gene?
Inhibits growth in the proliferative zone and has most effect in chondrocytes, particularly in long bones
Metaplasia
Change of differentiated cell type as a response to altered cellular environment; this most often happens in epithelial or mesenchymal cells
Dysplasia
Increased cell proliferation, decreased differentiation, and expansion of malignant cells
Often a sign of premalignancy
Agenesis (Disorder of Differentiation)
Complete failure to develop an organ or structure
Atresia (Disorder of Differentiation)
Failure to develop a lumen
Hypoplasia (Disorder of Differentiation)
Failure of an organ to develop to a normal size
Ectopia/Heterotopia
small areas of mature tissue from one organ are present in another (eg endometriosis)
Maldifferentiation
Failure of Normal Differentiation with persistence of primitive embryological features
