Disorders Of Growth

Question 1

What are the two categories within growth disorders?

Answer 1

Developmental or acquired

Question 2

What are develpomental disorders with too little growth?

Answer 2

• 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

Question 3

What are examples of developmental disorders with too much growth? - hamartoma tumour-like growth

Answer 3

• 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

Question 4

What is ectopia?

Answer 4

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

Question 5

What are acquired disorders of growth a result of?

Answer 5

Adaptation of cells to environmental stresses, may be reversible, may not be

Question 6

What is atrophy?

Answer 6

Cells become smaller than normal

Question 7

What is hypertrophy?

Answer 7

Cells become larger than normal

Question 8

What is hyperplasia?

Answer 8

Number of cells increases but size stays the same

Question 9

What is metaplaisa?

Answer 9

Cells change from one type to another

Question 10

What is dysplasia?

Answer 10

A change in the maturation and growth pattern of the cells

Question 11

What are the categories which can cause atrophy?

Answer 11

• physiological (normal growth and development, under hormonal influence)
• pathological

Question 12

What are possible causes of atrophy?

Answer 12

• reduction in structural components of the cell
• imbalance of cell loss and production can cause atrophy in organs
• may involve apoptosis

Question 13

What can cause localised atrophy?

Answer 13

• ischaemic
• pressure (tumours)
• disuse (muscle shrink from being immobile)
• autoimmune
• idiopathic (cannot identify cause)

Question 14

What are causes of generalised atrophy?

Answer 14

• 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

Question 15

Atrophic mandible

Answer 15

Mandible bone loss leading to ease to fracture

Question 16

Osteoporosis

Answer 16

• physical activity, ageing, hormones
• oestrogen has inhibitory effect on osteoclasts

Question 17

What is hyperplasia?

Answer 17

• 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

Question 18

What are examples of pathological hyperplasia?

Answer 18

• 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

Question 19

What are causes of hyperplasia?

Answer 19

• growth factors (driven proliferation of cells)
• Increased output of cells from stem cells
  Eg liver regeneration after donor surgery

Question 20

What is hypertrophy?

Answer 20

• 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)

Question 21

What happens to the myocyte during increased workload?

Answer 21

They can adapt via hypertrophy
- increased number of myofilaments making the cell larger

Question 22

Infarction

Answer 22

Irreversible cell injury

Question 23

What is a goitre?

Answer 23

• result in iron deficiency in diet
• decreased synthesis of thyroid hormone
• competency increase in thyroid cells (hyperplasia and hypertrophy)

Question 24

What is metaplasia?

Answer 24

• 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

Question 25

What are examples of metaplasia?

Answer 25

• in smokers- ciliated columnar epithelium to squamous
• barret’s oesophagus- squamous to columnar

Question 26

What is dysplasia?

Answer 26

• disordered growth
• can occur in metaplastic tissue
• mostly seen in epithelia
• severity may indicate that there is potential for malignant change

Question 27

What is neoplasia?

Answer 27

• abnormal mass of tissue
• growth of which is excessive
• uncoordinated growth
• growth persists after the stimulus is removed
• includes benign and malignant tumours