Disorders Of Growth Flashcards
What are the two categories within growth disorders?
Developmental or acquired
What are develpomental disorders with too little growth?
- agenesis
Failure of organ/structure development
Eg red cell aplasia - atresia
Failure of lumen in tubular epithelium structure development
Eg salivary gland duct- lumen can’t travel through duct - hypoplasia
Less tissue formed, normal structure
Eg enamel hypoplasia, less enamel formed by ameloblasts giving absence of enamel from tooth surface
What are examples of developmental disorders with too much growth? - hamartoma tumour-like growth
- pigmented naevi (moles), basal cell layer
- haemanngioma- blood vessels (normally present at birth), areas correlate to an area supplied by a distribution of nerve branches
- lymphangioma- non-cancerous fluid filled cyst- tongue, most cavernous (big)
- odontoma- hamartoma of dental hard tissues
What is ectopia?
Developmental disorder in wrong place
- normal tissue
- eg mickel’s diverticulum- out punching of small intestine which can contain gastric type mucosa
- eg ectopic tooth- a normal tooth in the wrong position
What are acquired disorders of growth a result of?
Adaptation of cells to environmental stresses, may be reversible, may not be
What is atrophy?
Cells become smaller than normal
What is hypertrophy?
Cells become larger than normal
What is hyperplasia?
Number of cells increases but size stays the same
What is metaplaisa?
Cells change from one type to another
What is dysplasia?
A change in the maturation and growth pattern of the cells
What are the categories which can cause atrophy?
- physiological (normal growth and development, under hormonal influence)
- pathological
What are possible causes of atrophy?
- reduction in structural components of the cell
- imbalance of cell loss and production can cause atrophy in organs
- may involve apoptosis
What can cause localised atrophy?
- ischaemic
- pressure (tumours)
- disuse (muscle shrink from being immobile)
- autoimmune
- idiopathic (cannot identify cause)
What are causes of generalised atrophy?
- inadequate nutrition (body breaks down tissues to access nutrients) eg starvation
- senile- occurs in older age group, imbalance between cell production/loss
- endocrine- endocrine disturbances
Atrophic mandible
Mandible bone loss leading to ease to fracture
Osteoporosis
- physical activity, ageing, hormones
- oestrogen has inhibitory effect on osteoclasts
What is hyperplasia?
- increase in cell numbers
- size of cell stays same
- increases tissue size and function
- normally occurs in those cells capable of division (labile cells eg epithelial cells eg and stable cells)
- normally a response to a stimulus and may regress after stimulus is removed
- pathological or physiological, both can be hormonal or compensatory
- eg gingival hyperplasia
What are examples of pathological hyperplasia?
- endocrine stimulation by hormone producing organs (hyperplasia of target organs)
- chronic injury and inflammation stimulated by inflammatory cytokines- growth factors hyperplasia of bone marrow and lymphoid tissue eg wart/ squamous cell carcinoma both caused by HPV
- controlled hyperplasia means it can regress
What are causes of hyperplasia?
- growth factors (driven proliferation of cells)
- Increased output of cells from stem cells
Eg liver regeneration after donor surgery
What is hypertrophy?
- increase in cell size due to increased intracellular structural components
- often occurs with hyperplasia
- seen in cells with limited mitosis ability eg muscle cells
- in muscle cells, hypertrophy can be physiologic or pathological
Skeletal muscle via exercise (physiological)
Smooth muscle via pregnancy (physiological hormonal)
Cardiac muscle via LVH in hypertension (pathological)
What happens to the myocyte during increased workload?
They can adapt via hypertrophy
- increased number of myofilaments making the cell larger
Infarction
Irreversible cell injury
What is a goitre?
- result in iron deficiency in diet
- decreased synthesis of thyroid hormone
- competency increase in thyroid cells (hyperplasia and hypertrophy)
What is metaplasia?
- change from one differentiated form of a tissue to another
- adaptive response
- results from changes in environmental demand
Epithelial: - squamous metaplasia
- mucous metaplasia
Mesenchymal - osseous
What are examples of metaplasia?
- in smokers- ciliated columnar epithelium to squamous
- barret’s oesophagus- squamous to columnar
What is dysplasia?
- disordered growth
- can occur in metaplastic tissue
- mostly seen in epithelia
- severity may indicate that there is potential for malignant change
What is neoplasia?
- abnormal mass of tissue
- growth of which is excessive
- uncoordinated growth
- growth persists after the stimulus is removed
- includes benign and malignant tumours
