Cellular adaptations simple Flashcards
In response to physiological and pathological stimuli, cells can
undergo changes which make them more suited for their environment.
Hypertrophy
is the increase in the size of a tissue via the enlargement of cells
physiological cause of hypertrophy
increased skeletal muscle mass gained through anabolic metabolism following exercise
smooth muscle hypertrophy occurs in the uterus stimulated by hormonal changes
pathological cause of hypertrophy
hypertension causes pathological hypertrophy of the cardiac tissue-increased strain on the ventricles and atria fo the heart
too much cardiac hypertrophy results in
the muscular walls of the heart being too thick to effectively pump blood through the body causing heart failure
Hyperplasia
is the increase in the size of a tissue by an increase in the number of cells in that tissue.
physiological cause of hyperplasia
1) Occurs in the endometrium of the uterus upon stimulation of oestrogen during the menstrual cycle.
2) Hyperplasia is also the method by which the liver restores itself from a partial resection.
pathological cause of hyperplasia
can occur in overstimulation of endometrial tissue with oestrogen, for example in women taking unopposed oestrogen (without progesterone) for hormone replacement therapy after the menopause. The increased cell replication increases the chance of dysplasia (discussed later), and then neoplasia, taking place.
atrophy
is the opposite of hyperplasia and hypertrophy, in essence, it is the shrinkage of tissue.
This can happen by a decrease in cell number and/or cell size.
physiological atrophy
involution
involution
when a tissue reduce in size after having increased in size.
example of involution
For example, the uterus and breasts both reduce in size post-pregnancy.
another example of physiological atrophy
Atrophy will also occur with old age. When an individual gets older, most systems and tissues undergo some level of atrophy.
pathological cause of atrophy
malnutrition (catabolic metabolism)
inactivity
pressure
ischaemia
chronic inflammation.
malnutrition (catabolic metabolism) cause
caused by diseases such as cancer or by nutritional deficit.
Metaplasia
is the transformation of tissue from one type of cell to another, for example a squamous epithelial cell to a cuboidal epithelial cell.
example of physiological metaplasia
squamous metaplasia that occurs in the cervix.
squamous metaplasia that occurs in the cervix.
When the cervix everts, the columnar epithelium that lines it meets the acidic environment of the vagina. The epithelium undergoes metaplasia to become stratified squamous epithelium like the rest of the vagina as this is better suited to the conditions. The area where this metaplasia happens is called the transformation zone.
pathological metaplasia occurs in response to
chronic stimulation from chemical or physiological factors
metaplastic cells r often considered to be
precancerous since they can progress to form malignant cells
metaplasia is a …… process
reversible
there is a chance that the cells will regress to their original type of the stimulus is removed
examples of pathological metaplasia
- cigarette smoking
- barretts oesophagus
metaplasia and cigarette smoking
Transformation of the pseudostratified columnar epithelium of the bronchi to stratified squamous epithelium in smokers due to cigarette smoke.
Barrets oesophagus
Stratified squamous epithelium at the bottom of the oesophagus transforms to gastric glandular epithelium with persistent acid reflux.
- can occur due to a gastric hernia
Dysplasia
is disordered growth of epithelium characterized by frequent mitotic figures and loss of cell orientation and uniformity (size, shape).
dysplasia can progress to become
malignant (known as carcinoma in situ
difference between dysplasia and neoplasia (cell that is cancerous) is that
dysplasia is reversible if the stimulus is removed,w while neoplasia is not
example of cause of dysplasia
human papilloma virus (HPV) can cause dysplasia of the cervix int he transformation zone
anaplasia
Anaplasia is the progression of dysplasia to the point where the cells have mutated so much, they are no longer morphologically distinct from other differentiated cells types.
aplasia
Complete failure of specific tissue or organ to develop
aplasia is what sort of disorder
embryological developmental disorder
e.g. thymic aplasia and kidney aplasia
hypoplasia
Underdevelopment or incomplete development of tissue or organ at embryonic stage- inadequate number of cells
why is hypoplasia not the opposite of hyperplasia
hypoplasia is a congenital disorder and hyperplasia is not
atresia
No orifice- failure for opening to form
congenital
examples of atresia
pulmonary valve
anus
vagina
small bowel