Disturbance of Growth Flashcards
Throughout the embryonic and
postnatal development of an animal,
tissues grow mainly by the process of?
cellular division
could also be increased by an increase in cell size
tissue mass
In the skin, for instance, there is continual replacement of cells at the surface that become keratinized by?
proliferation of basal cell
produces epidermal cells, and liver cells produces liver cells and soon
epidermal cell proliferation
The
sequence of events
comprising mitosis is called
cell cycle
The cell cycle consists of four
stages, what are these?
✓ G1 phase
✓ S phase
✓ G2 phase
✓ M phase
In this phase, the cell
cytoplasm and nuclei become enlarge and the nucleoli become prominent,
and there occur active production of
proteins and ribonucleic acid (RNA).
G1 Phase
in this phase, it is marked by active synthesis of
deoxyribonucleic acid (DNA) and occupies about 30-40% of the cycle.
S phase
wherein other preparations for cellular division takes place, and
occupies another 10 - 20% of the cycle.
G2 Phase
In this phase, daughter cells are
produced which undergo terminal
differentiation and are no longer
capable of cellular division.
M phase
may result in either excess or a deficit of
tissue, or may produce an abnormal pattern of development
disturbances in growth
During the growth and development of an organ or tissue in the early fetal developmental stage, malformation may occur as a result
of?
genetic or nongenetic influences
These malformations are
present at birth and are saidto be
congenital
Certain types of developmental abnormalities represent growth abnormalities and these include
✓ agenesis
✓ aplasia
✓ hypoplasia
suggests a complete failure of that tissue or organ to develop and is therefore absent.
agenesis
implies failure of the tissue or
organ to grow and therefore a
rudimentary organ is present
aplasia
is also used to refer to failure of a tissue to renew itself, such as that occurring in bone marrow
leading to aplastic anemia
aplasia
refers to failure of an organ to reach its normal size.
hypoplasia
occurs in many tissues as part of the normal involution of tissues and organs
physiological atrophy
Common examples of psychological atrophy include;
✓ involution of the thymus as the animal matures
✓ the reduction in the
mammary glands of males of species
✓ the postpartum changes in the uterus
✓ the reduction in fetal structures
such as the umbilical vessels and
ductus arteriosus.
is also termed as complete atrophy
involution
occurs whenever there is deprivation of blood supply,nutritional
requirement,
or hormonal stimulation as a result of some disease thatproduces trophic hormone.
pathological atrophy
Types of pathological atrophy includes the following:
✓ Nutritional Atrophy
✓ Vascular Atrophy
✓ Disuse Atrophy
✓ Pressure Atrophy
✓ Endocrine/Hormonal Atrophy
✓ Miscellaneous Atrophy
due to inadequate dietary intake or in
chronic starvation
nutritional atrophy
as a result of long-standing ischemia
vascular atrophy
due to reduced functional activity such as those occurring in paralyzed limbs or those held immobile for some time
disuse atrophy
due to long standing pressure that creates inefficient vascular supply to tissues
pressure atrophy
due to loss of trophic hormones such
as that seen in pituitary disease
resulting to generalized somatic
atrophy.
endocrine/hormonal atrophy
as a result of certain diseases.
miscellaneous atrophy
Some Classical Example of Atrophy;
✓ Withered or shrunken limb
✓ Involution of the normal corpus
luteum
✓ Pressure atrophy
✓ Disuse atrophy
✓ Serous atrophy of fat
a classic response of muscle to denervation
withered or shrunken limb
may be considered complete atrophy
Involution of the normal corpus
luteum
pressure results in a slow localized loss of cells through degeneration and necrosis, as when and expanding
testicular tumor presses on
surrounding seminiferous tubules
pressure Atrophy
a very important lesion to recognize
during postmortem examination
because it is and indication of
emaciation
serous atrophy of fat
is most evident on the heart
and around the kidneys, as well as in
mesenteries
lesion
Limb kept in a cast. Due to inactivity it results to reduction in size of the organ
disuse atrophy
When there is an increase in
workload or endocrine stimulation to
an organ or tissue, they respond by
either increasing the size of its
component cells, or increasing the
number of constituent cells.
is the increase in the size of the tissue or organ due to an
increase in the size of individual cells. In its pure form, it
occurs only in muscles in response to
increased demand for work.
hypertrophy
is an increase in tissue mass or organ size due to an increase in the number of
constituent cells
hyperplasia
hypertrophy alone occurs
in those tissues that are incapable of
regeneration, such as?
cardiac muscles and nerve cell bodies
Types of hypertrophy and hyperplasia include the following:
✓ Endocrine
✓ Compensatory
✓ Functional
✓ Replacement
✓ Reactive
✓ Neoplastic
following
increased hormonal stimulation, as in mammary gland during lactation
endocrine
especially in paired organ when one is severely damaged, the other will
compensate for the lost function, e.g., when onekidney is hypoplastic or
surgically removed, the other will
enlarge.
compensatory
as a response
to increased functional demands, e.g.,muscles in repeated heavy exercise, and in left ventricular
myocardiumfollowing aortic stenosis
functional
as part of the repair process, e.g., healing of fractured bone, and healing of liver defect by regeneration
replacement
in response to chronic irritation or infection, e.g., skin thickening in mange mite infestation, enlargement of lymph nodes ininfections
Reactive
tumors are formed because of localized areas of increase in cells, and thus, tumors are pathological forms of hyperplasia.
neoplastic
With reference to hyperplasia
where there is an increase in the
number ofconstituent cells, the
additional cells form abnormal patterns as follows:
✓ nodular hyperplasia
✓ cystic hyperplasia
✓ papillary hyperplasia
✓ adenomatous hyperplasia
when the added tissue mass assumes
nodules,e.g., in liver tissue remodeling
nodular hyperplasia
when they form spaces lined with epithelia, e.g.,cystic prostatic hyperplasia
cystic hyperplasia
form frond like projections, e.g., hyperplasia oflining epithelia of tubular organs
papillary hyperplasia
when they form gland-like mass
resembling
neoplasm
adenomatous hyperplasia
NOTE!
Hypertrophy and Hyperplasia is
best differentiated by histological than
for gross lesion.
Metaplasia
✓ is an adaptive response in
which one type of mature
differentiated tissue is replaced by a
different but related tissue type
✓ This response is usually reversible
✓ most commonly seen as a
replacement from a specialized tissue
type to a less specialized one but
more resistant cell type, e.g., from
columnar or transitional epithelia to
squamous epithelia
occurs following prolonged irritation or chronic infection such as that occurring in urinary
stones where the bladder epithelia is changed, and innutritional deficiencies e.g.,vitamin A deficiency cause squamous metaplasia of esophageal glands and prostate gland
epithelial metaplasia
occurs in association with repair
processes (e.g., fibro blast retain their
mesenchymal ability to change into another
connective tissue types as bone, cartilage orfibrocartilage) .
connective tissue metaplasia
does not occur because of alterations in existing mature cells,rather it depends on the proliferation of germinal cells whose progenies undergo a modified differentiation
metaplasia
dysplasia means?
abnormal growth
it is used in a more restricted sense to describe a proliferative response accompanied by loss of regular differentiation and by
cellular atypia and tissue
architectural disarray
dysplasia
Cellular atypia is characterized by?
pleomorphism and hyperchromicity
variation in size and shape
pleomorphism
increased staining
hyperchromicity
is commonly observed in epithelia subjected to chronic irritation or inflammation.
dysplasia
dysplasia change is however
reversible but when left alone, may
progress to?
neoplasia
