It is an acquired condition and is defined as diminution in
size of organ due to decreased in number of cells , size of the cells without
any degenerative change and little amount of replacement by fibrosis .
There are two
types of atrophy
1.. General atrophy
–
a) Senileatrophy
- This is a physiological atrophy .
there will be atrophy of different organs and tissue like endocrine glands ,
sex organ , bones , muscle ., skin during sensility . Atrophy of breast and
uterus in female take place at the age of menopause . In long continued wasting
disease and in old age , the heart becomes a smaller in size , myocardium is
slightly thinned out and nutmeg brown in appearance . Microscopically , the
myocardial fibres show accumulation of small fat globules and lipochrome
granules which are called wear and tear pigment . Such type of atrophy is
called Brown atrophy of heart .
b) Starvation
atrophy – This type of atrophy is found
in famine , carcinoma of oesophagus , anorexia , nervosa , attended with loss
of appetite etc . In these condition , less nutrition is the main cause and
there will be utilization of stored sources of energy metabolism like
carbohydrate . fat , protein . Cachexia or generalized wasting is seen in
tuberculosis or carcinoma due to malnutrition .
2… localized atrophy or pathological atrophy ----
i)
Ischaemic atrophy –there will be atrophy of the
affected part due to diminution of blood supply .
ii)
Pressure atrophy – There will be atrophy of individual
cells due to persistan t pressyure of some substance like intercellular
infiltration of amyloid , glycogen or due to pressure of tumour .
iii)
Disuse atrophy – This ty,pe of atrophy is seen due to
the restriction of the use of a part followed by diminished metabolic activity
. This is particularly observed in the muscle fibres . Whre there is immobility
of the limbs as in ankylosis of a joint or hemiplegia .
iv)
Neurophagic atrophy – This is due to destruction of
neuromuscular activity where the nutruition
of tissue is not properly maintained as a result there will be presence
of feature of atrophy as found in poliomyelitis , tabes dorsalis ,
syringomyelia , facial herniatrophy , lower motor neurone paralysis etc .
v)
Endocrine atrophy – If pituitary gand destroyed the
dependent endocrine glands like adrenal gland , thyroid gland and gonads may
undergo atrophy as this trophgic harmonic stimulation diminishes .
vi)
Atrophy due to over work – Proper nutrition and over
work may lead to the hypertrophied condition of muscle but less nutrition and
over work will produce atrophy of the muscle .
