disorders of growth

Question 1

What can go wrong?

Answer 1

Too much/too little/wrong type/wrong place

Question 2

How does cell stress lead to cell death?

Answer 2

Cell stress placed affected by dose intensity and cell vulnerability

Cell may adapt (metabolic/structural) +/ lead to injury

Injury may be reversible but at a certain point becomes irreversible leading to cell death

Question 3

What is atrophy?

Answer 3

Decrease in cell size/number

Question 4

What is hypertrophy?

Answer 4

Increase in cell size

Question 5

What is hyperplasia?

Answer 5

Increase in cell number

Question 6

What different cells are there in relation to the cell cycle?

Answer 6

Continuously cycling LABILE cells
Eg. Epidermis, GI tract epithelium

QUIESCENT, stable cells
Eg. Hepatocytes

PERMANENT cells
Eg. Neurons, cardiac myocytes

Question 7

How might you get too much growth?

Answer 7

Developmental/congenital
~hamartoma

Reactive/adaptive
~hyperplasia
~hypertrophy

Neoplasia

Question 8

What is hamartoma?

Answer 8

Tumour like overgrowth
Grows in patients growth period
Tissues normal for site but excessive
Eg. Congenital pigmented naevi (moles), haemangioma (collections of blood vessels), odontomes (overgrowth of teeth)

Question 9

What is hyperplasia?

Answer 9

Increase in cell no
Response to stimulus
Regression once stimulus removed
Increased size and function

-Endocrine
~physiological- normal growth, puberty and pregnancy
~pathological- parathyroids and thyroid 
-Chronic irritation/inflam
-Bone marrow, lymphoid tissue

Question 10

How does thyroid hyperplasia (goitre) occur?

Answer 10

Shortage of iodine
Iodine needed for thyroid hormones

No iodine= no thyroid hormones
Signals sent to pituitary to release thyroid stimulating cells
Tells cells to grow and divide in attempt to get hormones

Question 11

What is hypertrophy?

Answer 11

Increase in cell size
Usually occurs w hyperplasia

Pure hypertrophy- muscle (skeletal in exercise, smooth in pregnancy, cardiac in hypertension [left ventricular hypertrophy])

Question 12

What is a neoplasia?

Answer 12

Growth which is uncontrolled and doesn’t stop after the stimulus is removed

Question 13

How might you get too little growth?

Answer 13

Developmental
~agenesis
~aplasia
~hypoplasia

Question 14

What is achondroplasia

Answer 14

aCHONDROplasia

Chondro= cartilage

Too little cartilage

Question 15

What is enamel hypoplasia?

Answer 15

Fluorosis

Ameloblasts damaged so don’t produce enough enamel

Question 16

What is atrophy?

Answer 16

Decrease in size after growth
~size/no of cells
~can be physiological (embryo)

Imbalance of cell loss and production
~reduced proliferation
~increased cell loss
~reduction in structural components of cell

Generalised atrophy (nutritional, age related, endocrine, bone-osteoporosis)

Localised (ischaemic, pressure, disuse, neuropathic/denervation, immune mediated, idiopathic)

Question 17

What is metaplasia?

Answer 17

Change from one differentiated tissue to another
~within same germinal layer
~due to changes in environmental demands

Epithelial- (mucous metaplasia, squamous metaplasia [in smokers])

Mesenchymal (bony metaplasia)

With acid reflux- gastric metaplasia

Question 18

How is metaplasia related to cancer?

Answer 18

Smokers- lung cancer in squamous meta plastic epithelium in bronchi

Oesophageal cancer in meta plastic gastric epithelium in lower oesophagus

Pancreatic cancer due to inflammation- acinar-ductal metaplasia

Question 19

What is dysplasia?

Answer 19

Abnormal growth and differentiation in tissue w abnormal abnormal cell/tissue architecture
May be premalignant

Question 20

What is ectopia?

Answer 20

Developmental abnormality
Normal tissue
But abnormal site