2- Growth disorders, neoplasms Flashcards
What are the 8 normal processes of growth and differentiation
Environmental influence
Feedback mechanisms
Hormone regulation
Genetic control
Tissue growth
Organogenesis
Cell division
Cell differentiation
Environmental influence and feedback mechanisms
Evironmental Influence: External factors such as nutrition, physical activity, and exposure to stimuli can impact growth and differentiation.
Feedback Mechanisms: Feedback loops help maintain homeostasis and regulate growth processes in response to internal and external cues.
Hormone regulation and genetic control function
Hormonal Regulation: Hormones play a crucial role in coordinating growth and differentiation processes.
Genetic Control: Gene expression and regulation guide cell differentiation and tissue development.
What is the difference bewteen tissue growth and organogenesis
Tissue Growth: Cells proliferate and organize to form tissues with distinct structures and functions.
Organogenesis: Different tissues come together to form complex organs during development.
Cell division and cell differentiation
Differentiation- cell develops a specialised function or morphology which distinguishes it from its parent cell and takes on specific functions as tissues and organs develop.
Cell Division: Cells divide and replicate to increase their numbers during growth.
What are the two systemic and local abnormalities of growth
H H
hyperplasia and hypotrophy
What is carcinogenesis
Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells.
Characterized by; changes at the cellular, genetic, and epigenetic levels and abnormal cell division.
What is differentiation
cell develops a specialised function or morphology which distinguishes it from its parent cell.
Endocrine
factors in postnatal growth
GH,TH, I, IGFS, SS, C, PTH
Postnatal growth is governed by multiple endocrine factors:
Growth Hormone (GH): Secreted by the pituitary gland, it stimulates growth in tissues and bones and promotes the production of insulin-like growth factors (IGFs).
Thyroid Hormones (TH): Produced by the thyroid gland, these hormones are crucial for overall growth and development, including the maturation of the nervous system and bone growth.
Insulin: Produced by the pancreas, it has anabolic effects on muscle and tissue growth, apart from its role in glucose metabolism.
Insulin-like Growth Factors (IGFs): Mostly produced in the liver in response to GH; they are significant mediators of growth in cells and bones.
Sex Steroids: Including testosterone and estrogen, these hormones are responsible for the growth spurt during puberty and the development of secondary sexual characteristics.
Cortisol: A steroid hormone from the adrenal cortex that in high levels can impair growth but is needed in normal levels for tissue maturation and metabolism.
Parathyroid Hormone (PTH) and Vitamin D: These regulate calcium and phosphate metabolism, which is vital for bone growth and maintenance.
The interplay between these hormones ensures proper postnatal growth and development. Imbalances can lead to growth disorders, requiring careful medical attention.
Endocrine factors in foetal growth
-Small parents, racial origin and lower foetal insulin or occasionally insulin receptors
- if increased growth foetal hyperinsulinaemia (Maternal diabetes)
What are the major causes of endocrine abnormality
u/a, o/a, malfunction
1) Underproduction of a certain hormone
2) Overproduction of a certain hormone
3) A malfunction in the production line of a hormone or in its ability to function correctly.
What is morphopigenesis
a complex process of embryological development
Formation of shape and organisation of body organs
Involves growth, differentiation, and relative movement of groups of cells
Programmed cell death (apoptosis) removes unwanted cells
What is apoptosis and what is it controlled and stimulated by
Is a form of programmed cell death.
It is controlled by P53 and other parts. Also, its stimulated by growth factors needed for body processes
What is growth a balance between
cell division and apoptosis
What develops last in morphopigenesis
Head is one of the last things to develop in morphogenesis
Foetal pancreas and then thyroid develops
- placenta does it is the source for nutrients and removing waste products. Fetal pancreas and thyroid then develop
What is hyperplasia and what process is it controlled by
Increase in cell number by mitosis
Hypertrophy is an increase of____ without _____________
cell size
cell division
What is atrophy
decrease in
Decrease in size or wasting away of a body part or tissue. also : arrested development or loss of a part or organ incidental to the normal development or life of an animal or plant. atrophy.
Example of abnormal tissue growth
Benign neoplasms (tumour)
Types:
Benign bone tumors (osteomas).
Brain tumors such as meningiomas and schwannomas.
Gland tumors such as pituitary adenomas.
Lymphatic tumors such as angiomas.
Benign soft tissue tumors such as lipomas.
Uterine fibroids
How is cell differentiation controlled
Embryonic differentiation of cells is controlled by gene expression, systemic hormones, position within the foetus, local growth factors and matrix proteins.
Maintenance of differentiated state depends upon the persistence of some of these factors.
Differentiation and morphogenesis can be disrupted by environmental factors (e.g. teratogens)
Control by the genome
what can a single master gene do
A single master gene can switch other genes on and off
example; dolly the sheep- a sheep cloned in America
What is aptosis controlled and stimulated by
Aptosis controlled by P53 and other parts . Stimulated by growth factors needed fir body processes
What is post natal growth controlled by
G
GH-IGF-1 axis
What is pre natal growth controlled by
MN and HS
Maternal nutritional and hormonal state
What is hypoplasia
failure of…
Failure of development of an organ and morphogenesis
Process is related to atrophy
example; micropthalmia which affects infants and causes diploid/tetraploid
(46:92) chromosome mosaic
What is the principle of tetrogrens
A teratogen is any agent that causes an abnormality following fetal exposure during pregnancy.
Teratogens are usually discovered after an increased prevalence of a particular birth defect.
For example, in the early 1960’s, a drug known as thalidomide was used to treat morning sickness.
What environmental factor can disrupt differentiation and morphopigenesis
What, examples and what they cause
Teratogens
Teratogens are substances that cause congenital disorders in a developing embryo or fetus.
Examples- A teratogen is anything a person is exposed to or ingests during pregnancy that’s known to cause fetal abnormalities. Drugs, medicine, chemicals, certain infections and toxic substances are examples of teratogens.
Cause- risk for miscarriage, preterm labor or stillbirth.
What is the principle of tetrogenesis
Teratogenesis is a process that causes birth defects or malformations in an embryo or foetus.
Susepctibilty of drug induced malformation:
- genotype of conceptus
- the developmental stage at which exposure occurs
- the mechanisms of action of the drug,
- the access of the drug to developing tissues, and (5) the dose of the drug
What are some acquired disorders of growth and differentiation in single tissues
M N D
Metaplasia
Dysplasia
Neoplasia (tumours)
What is metaplasia
-acquired form of altered differentiation
-transformation of one mature differentiated cell type to another
-reversible response to altered cellular environment
Metaplasia can undergo further
indirect transformation to neoplasm via dysplasia
example; squamous cell carcinoma associated with squamous metaplasia in bronchi (smoker associated)
What is dysplasia
Causes increased cell growth e.g. more mitoses visible than normal and there is presence of atypical morphology e.g. abnormally large nuceli and decreased differentiation e.g. cellular immaturity
Dysplasia lesions are
dysplasia lesions are often pre neo-plastic
chronic physical or chemical injury but it can be reversible in the early stages
What is neoplasia (tumours)
Is characterised by abnormal, uncoordinated and excessive cell growth
it persists after initiating stimulus has been withdrawn
What can neoplasia cause
GA
genetic alterations
neoplastic cells can influence the behaviour of normal cells by the production of hormones and growth factors
Is neoplasia painful
It’s not usually painful
But it can be painful if nerves compressed, bone involved
Two classifications of neoplasms
L + M
location and morphology
Benign tumours features
-Slow growth rate
-Low mitotic activity
-Good histological resemblance to normal tissue
-Often normal nuclear morphology
-No invasion
-Never metastases
often circumscribed or encapsulated border
-Necrosis is rare
-Ulceration is rare
-Direction of growth on skin or mucosal surfaces is often exophytic
Malignant tumours growth and affects
-Rapid growth rate
-High mitotic activity
-Variable often poor histological resemblance to normal tissue
-Usually hyperchromatic, irregular outline, multiple nucleoli and pleomorphic nuclear morphology
-Can invade
-Frequent metastases
-Often poorly defined or irregular border
-Necrosis is common
-Ulceration is common on skin or mucosal surfaces
-Direction of growth on skin or mucosal surfaces is often endophytic
Metastases process is often
fatal and often kills the patient as that causes the cancer to come back
Are benign tumours self contained
Yes, and malignant tumors aren’t
Cancer grading is dependent on
The grade of a cancer depends on what the cells look like under a microscope.
Lower grade indicates a slower-growing cancer and a higher grade indicates a faster-growing one.
Cancer grading system 1,2,3
grade 1 – slow growth and normal cell appearance
grade 2 – fast growth and abnormal cells
grade 3 – aggressive growth and spread, abnormal appearance
Oncogenes cause
the cancer
TS genes suppress
cancer development
As differentiation decreases
malignancy increases
