Abnormalities of growth

Question 1

Decreased growth - Developmental

Answer 1

Agenesis and Hypoplasia

Question 2

Agenesis (developmental decrease growth)

Answer 2

Complete failure to develop

E.g. renal (Potter’s syndrome)/ pulmonary (surprisingly asymptomatic)

Question 3

Hypoplasia (developmental decrease growth)

Answer 3

Partial failure
E.g. testes - Klinefelter’s syndrome
Ovaries - Turner’s syndrome

Question 4

Decreased growth - progressive

Answer 4

Physiological and pathological

Question 5

Physiological (progressive decrease growth)

Answer 5

E.g. themes at puberty
At thymus T-lymphocytes educated (differentiate)
Thymus structure change over time, grad. lose capacity to mature T-cells

Question 6

Pathological (progressive decrease growth)

Answer 6

General affecting many diff. tissues (e.g. cachexia - ongoing muscle wastage due to starvation or malignant disease)
Tissue-specific (e.g. osteoporosis - loss of bone density)
Local atrophy = tissue grad. waste away
Result of:
Disuse (e.g. muscle and bone of limb in plaster cast)
Pressure from cyst/tumour/aneurysm
Ischaemia (lack blood supply) due vascular disease
Neuropathy (nerve damage) due to polio
Idiopathy (unknown cause e.g brain atrophy in Parkinson’s)

Question 7

Increase growth

Answer 7

Hypertrophy and hyperplasia
Response to ext. stimuli
Often normal histology, extra function
Usually self limiting and reversible

Question 8

Hypertrophy (increased growth)

Answer 8

Increase cell size NOT number, no progression through cell cycle
Permanent tissues (esp. muscle)
E.g. skeletal muscle - response to exercise
May be feature of disease

Question 9

Myocardial hypertrophy (clinical)

Answer 9

Adaptive response to pressure/volume stress
Common consequence of heart disease
Response of difficulty supplying blood to arteries

Question 10

Hyperplasia (increased growth)

Answer 10

Typical for renewing tissues
Increase cell no. but maintain size (balanced growth)
Physiological e.g. liver regeneration after partial resection and increase erythropoiesis (produce RBC) at high altitude, skin to abrasion
Feature of disease

Question 11

Hyperplasia of thyroid (clinical)

Answer 11

Graves’ disease
Autoimmune antibodies against TSH receptor - respond to thyroid stimulating hormone
= hyperthyroidism

Question 12

Neoplasia

Answer 12

Tumour growth 
XS proliferation of 1 cell type 
= cumulative genetic + epigenetic changes
Abnormal, unbalanced histology 
NO USEFUL FUNCTION

Question 13

Benign tumours

Answer 13

Grow by local expansion (increase proliferation)
Not invade adj. tissue, basement membrane or spread to distant sites (localised)
Differentiation resemble normal tissue (e.g. wart - polarity of epithelium maintained, more tissue than normal)
May cause harm through pressure, obstruction, secrete hormones
May progress to malignancy

Question 14

Malignant tumours

Answer 14

Grow by invasion x adj. tissue, basement membrane
Spread to distant sites (metastasis)
Differentiation incomplete (pleomorphism, anaplasia)
Large nuclei, aneuploid (abnormal no. chromosomes), mitotic abnormalities