Disorders of Growth and Differentiation Flashcards
Name four different types of growth
Multiplicative
Auxetic
Accretionary
Combined pattern
What is auxetic growth?
Growth in cell size as opposed to cell number
What is accretionary growth?
A cell secretion to increase the volume of the extracellular spaces.
What is a combined pattern of growth?
A mix of any of the other types of growth
What are the different types of increased growth?
Hyperplasia - An increase in the amount of organic tissue that results from cell proliferation
Hypertrophy - An increase in mass of a cell, tissue, or organ without cellular proliferation
Combined hypertrophy and hyperplasia
What is an example of physiological hypertrophy?
Athletes muscle
What is an example of pathological hypertrophy?
Right ventricular hypertrophy
Abnormal enlargement of the cardiac muscle surrounding the right ventricle - when the heart has to work harder
What is an example of physiological hyperplasia?
Adaptation to altitude
Psoriasis
What is an example of hyperplasia in tissue repair?
- Angiogenesis
- Wound healing
- Liver regeneration
- Heart
Give an example of physiological atrophy?
The thymus goes through regressive alterations with age
Ageing in general
Give an example of pathological atrophy
- Muscle – fractures
- Nerves - paraplegics
- Blood supply – circulatory problems
- Pressure – bedsores
- Diet - anorexia
What is Turner’s Syndrome?
Occurs in females with a missing X chromosome
Puberty will not occur or only partially occur
Females are shorter than average by 20 inches, only 5 with HRT
can live normal lives with regular chechup
What is SHOX?
Short stature homeobox gene present on X and Y chromosomes
If mutated or one is missing it is associated with shortened stature syndrome
Where is SHOX expressed?
SHOX is expressed in chondrocytes of the human growth plate
What gene is linked to Down syndrome?
Trisomy 21
What is Down syndrome associated with?
- Small stature
- Hypotonia
- Heart Defects
- Learning difficulties
How may Down syndrome be identified?
Flattened nose and face, upward slanting eyes
Single palmar crease, short 5th finger that curves inward
Widely separated first and second toes + increased sole skin creases
What is Beckwith-Wiedemann syndrome?
- Inheriting two copies of a chromosome from one (paternal) parent and none from the other is bad news
- Increased expression of IGF-II
- Decreased expression of H19
- Overgrowth in early childhood
What is pituitary gigantism?
• Increased IGF-1
• Increased growth hormone
• Often from pituitary tumours
You grow real big
What are some disproportionate alterations of skeletal growth?
- Achondroplasia (dominant allele)
* FGFR3
What does loss of FGFR3 do?
Loss of FGFR3 increases growth
As
FGFR3 suppresses growth
Where does mutation of FGFR3 have most effect?
Mutation of FGFR3 has most effect in chondrocytes
What is metaplasia?
- Change of differentiated cell type
- Response altered cellular environment
- Often epithelial or mesenchymal cells
Give an example of metaplasia
• Epithelium of trachea and bronchi in smokers
