Growth Disorders Flashcards
What does agenesis mean?
An organ does not develop at all (genetic defect)
- Pretty rare - on occasion person might be born with no salivary glands at all
What does aplasia mean?
An organ fails to develop normal structure from primitive embryonic structure
- Tissues present but don’t get development of normal structure
What does hypoplasia mean?
Less tissue formed than normal structure
- Tissue is there but amount formed is much less than it normally should be
What does hamartoma mean?
- Normal tissue but size and structure much greater than normally would be
- Tumour-like growth
- Only grows in patient’s growth period, but excessive - will stop at a certain age
What are examples of hamartomas?
- Pigmented naevi (moles)
- Haemangioma - arises in blood vessels
- Lymphangioma - arises in lymphatic tissues
What does a haemangioma look like under a microscope?
- Does not have a fibrous tissue capsule - a benign tumour does
What types of lymphangioma are there?
- Most are cavernous
- Tongue
- Cystic hygroma
What is a naevus?
A mole
What does ‘ectopia’ mean?
Normal tissue in an abnormal site
What is an example of ectopia (normal tissue in an abnormal place)?
Mickel’s diverticulum - an outpouching of the small intestine. Can contain gastric type mucosa (should not have this in the small intestine)
What is meant by ‘atrophy’?
When cells become smaller than normal - decrease in size or number of cells
What is meant by ‘hypertrophy’?
Much larger cell than normally would be
What is meant by ‘hyperplasia’?
Many more cells than should be but same size
What is meant by ‘metaplasia’?
Change of tissue from one type to another type as long as it is the same group - epithelial tissue cannot change into connective tissue
What is meant by ‘dysplasia’?
Abnormal change in cells which makes them become more susceptible to become malignant
What are the 2 types of atrophy?
- Physiological - normal growth and development; under normal influence
- Pathological - As part of a certain disease process
What are the mechanisms of atrophy?
- Reduction in structural components of the cell (organelles)
- Imbalance of cell loss and production
- May involve apoptosis (atrophy of an organ)
Atrophy may be localised. What are the possible reasons for this?
- Ischaemic: Inadequate blood supply to an organ or part of the body
- Pressure (tumours)
- Disuse/denervation
- Autoimmune
- Idiopathic: Do not know the reason why tissue is becoming smaller
Atrophy may be generalised. What are the possible reasons for this?
- Nutritional: malabsorption
- Senile: atrophy occurring due to advanced aging
- Endocrine
How is an atrophic mandible produced?
If a person has no teeth then the transmission of forces is lost so the bone of the mandible is lost over a period of time
- The younger a person is when they get their teeth extracted, the more of the mandible they will lose as they get older
What is osteoporosis and what is it related to?
- Bones become brittle and fragile from loss of tissue (affecting most of the bones of the skeleton)
- Related to physical activity, aging, hormones - oestrogen has inhibitory effect on osteoclasts
What are the causes of pathological hyperplasia?
- Endocrine (hormonal) stimulation by hormone producing organs
Chronic injury and inflammation - stimulated by cytokines; growth factors hyperplasia of bone marrow and lymphoid tissue HPV can induce hyperplasia of epithelium
What are the mechanisms of hyperplasia?
- Growth factor driven proliferation of cells
- Increased output of cells from stem cells
What is liver regeneration?
Not actually regeneration - stem cells start to divide and start to produce more liver cells
Which cells have pure hypertrophy?
- Cells with limited mitotic ability
What is Goitre?
- Result of dietary iodine deficiency
- decreased synthesis of thyroid hormone
- Compensatory increase in TSH
- Thyroid follicular cell hypertrophy and hyperplasia together
What are the 2 epithelial types of metaplasia?
- Squamous
- Mucous
What is mesenchymal metaplasia?
- Osseous: consisting of or turned into bone
What happens to the epithelium in smokers with metaplasia?
- Ciliated columnar epithelium to squamous metaplasia
What happens to the epithelium in Barrett’s oesophagus?
- From squamous to columnar
Where is dysplasia mostly seen?
In epithelia
- Severity may indicate that there is a potential for malignant change
What is ‘neoplasia’?
An abnormal mass of a tissue
- A growth that is excessive AND is uncoordinated with that of normal tissues AND persists after the provoking stimulus is removed
- Includes both benign and malignant tumours
