Growth Disorders Flashcards
What are disorders of too little growth?
agenesis (aplasia)
atresia
hypoplasia
What is agenesis?
failure of development of a organ or a structure within an organ
What is atresia?
failure of development of a lumen in a tubular epithelial structure
What is hypoplasia?
less tissue formed, normal structure
What are disorders of too much growth? (hamartoma disorders)
pigmented naevi (moles)
haemangioma
lymphangioma
odantoma (dental hard tissues)
When do hamartoma disorders occur in a person’s life?
only during growth period but excessively
What is haemangioma?
excessive growth of blood vessels - usually present at birth mostly in the head and neck area
What syndrome is haemangioma a part of?
Sturge-Weber Syndrome
What can haemangioma present as?
Capillary – made up of tiny capillaries
Cavernous – large blood filled spaces
What is lymphangioma?
excessive growth of lymph vessels
What does lymphangioma mostly present as?
Cavernous - large lymph fluid filled spaces
What is the commonest area for lymphangioma to occur?
tongue
What is lymphangioma from birth called?
cystic hygroma
What is naevus?
a mole
large amount of melanocytes present in the dermis
What is ectopia?
normal tissue in abnormal location
What are examples of ectopia and what tissue are they?
Mickel’s diverticulum, an outpouching of the small intestine.
Gastric type tissue in SI
Fertilised egg in Fallopian tube instead of uterus
Teeth in palate
What are acquired growth disorders?
adaptation of cells to environmental stress - not always reversible
What are examples of acquired growth disorders?
atrophy
hypertrophy
hyperplasia
metaplasia
dysplasia
What is atrophy?
reduction in size and number of cells
What is an example of physiological atrophy?
ageing under hormonal influence (menopause)
What is cellular atrophy?
reduction of organelles of a cell
What is organ atrophy?
cell loss is larger than cell production - may be caused by apoptosis
What are reasons localised atrophy may happen?
- ischaemic
- pressure (tumours)
- disuse/ denervation (immobile for long period)
- autoimmune
- idiopathic
What are reasons generalised atrophy may happen?
- Inadequate nutrition
- senile (ageing - cell loss ^)
- endocrine
What happens in mandible atrophy?
mental foramen and mental nerve get closer to alveolar ridge as mandible recedes
Why can osteoporosis occur?
menopause, ageing, physical activity, corticosteroids
What effect does oestrogen have on osteoclasts?
inhibits effect
What happens to oestrogen after menopause?
decreases therefore increased oestoclast activity
What is hyperplasia?
increase in cell numbers resulting in increased tissue size and function
What cell types can become hyper-plastic?
labile and stable
What can cause gingival hyperplasia?
medications (anti-epileptic) in combination with poor oral hygiene
What cell is proliferated in gingival hyperplasia?
fibroblasts
What are causes of pathologic hyperplasia and what are examples of each?
- endocrine (hormonal) stimulation by hormone producing organs hyperplasia of target organs - benign prostatic hyperplasia
- chronic injury and inflammation
stimulated by inflammatory cytokine - growth factors hyperplasia of bone marrow and lymphoid tissue
- HPV can induce hyperplasia of epithelium
What is controlled hyperplasia?
regresses when stimulus is removed
By which mechanisms can hyperplasia occur?
- Growth factor-driven proliferation of cells
- Increased output of cells from stem cells.
What is an example of beneficial hyperplasia?
liver regeneration
What is hypertrophy?
increased cell size due to intracellular components
What does hypertrophy often occur with?
hyperplasia
Where is pure hypertrophy seen?
in cells with poor division (mitotic) ability
muscle
When is muscle hypertrophy pathologic and when is it physiological?
- skeletal–exercise (physiologic-increased function)
- smooth–pregnancy (physiologic-hormones)
- cardiac – LVH in hypertension (pathologic)
In ventricular hypertrophy, what does the increased workload of BP cause?
increased number myofilaments in a myocyte
When cell death occurs in cardiac muscle what does this cause?
infarction
What causes goitre? (hypertrophy of the thyroid gland)
iodine deficiency
What does iodine deficiency cause and why does this cause hypertrophy?
decreased synthesis of thyroid hormone
compensatory increase in thyroid stimulating hormone
thyroid follicular cell hypertrophy and hyperplasia together
What is metaplasia?
change from one type of tissue to another (e.g. squamous > columnar)
Why does metaplasia occur?
adaptive to changes in environmental demands (e.g. trauma)
What are the common epithelium changes that occur?
changes to squamous as withholds more trauma
and mucous
What are the mesenchymal changes that can occur?
osseous (calcification)
What are examples of metaplasia?
- in smokers : ciliated columnar epithelium to squamous (squamous metaplasia)
- Barrett’s oesophagus : squamous to columnar (columnar metaplasia)
What is dysplasia?
disordered growth that has potential for malignant change
Where is dysplasia mostly seen?
epithelia
What is neoplasia?
an abnormal mass of tissue with excessive growth
uncoordinated with that of normal tissues
persists after the provoking stimulus is removed
What does neoplasia include?
benign and malignant tumours
