Lecture 7 Flashcards
What are the 3 properties of every type of stem cell
Capable of dividing and renewing themselves for long periods
unspecialised
can give rise to specialised cells
explain the adult stem cell/somatic stem cell
Undifferentiated but amongst differentiated cells in a tissue or organ
can renew itself and differentiate into major cells types of tissues/organs- MULTIPOTENT depends on niche
primary role is maintenance and repair
explain embryonic stem cells
PLURIPOTENT- can become any cell type in the body
Define pluripotent and multipotent
multipotent- able to generate many types of cell but only within the niche theyre found in. If you move them to a different area of the body they won’t be able to change to fit the new environment
Pluripotent- able to generate all tissue types
Where are epidermis stem cells found and how do they work
In the bulge underneath the sebacous glands. They translocate to the basal layer of the epidermis and become the new cells
Where are the intestinal/GI stem cells found and how do they work
They are found in trenches of the lining the gi tract known as crypts. They differentiate into absorptive cells, goblet cell, paneth cells and enteroendocrine cells
What are the cell turnover rates for the skin and GI
Skin- 2 months
GI- a few days, this is due to the high friction
What are the 2 homeostatic mechanisms of environmental adaption of cells
Physiological conditions, such as friction and hormones- adaptation to normal changes
pathological conditions- to limit damage in response to disease progression
Define hyperplasia
Increased size of a tissue due to increased cell count. REVERSIBLE
Define hypertrophy
Tissue is bigger due to increased size of the existing cells. REVERSIBLE
Define atrophy
Decrease in size of tissue/organ. Cell atrophy is decrease in size while tissue atrophy can be the same or decrease in cell number. REVERSIBLE
Define metaplasia
A REVERSIBLE transition from one type of cell to another. Once mature a fully differentiated cell type will become a totally different type of cell
Define dysplasia
a REVERSIBLE presence of abnormal cells(happens in a result to a stimulus). Comes with an increased rate of cell division and incomplete maturation of cells
Define neoplasia
Uncontrolled growth of new cells without a stimulus, often time a type of cancer. Results in loss of differentiation
What are the 3 ways tissues can change their cells in response to a stimuli
Change in cell size, rate of division and differentiation. These allow us to adapt
Why might metaplasia occur
morphology changes in response to the cellular environment, therefore it could be an adaptive response to a negative stimuli (metaplasia is mainly in epithelial cells )
What happens when a cell cannot adapt and the stimulus is severe?
The cell is injured or entirely killed resulting in the tissue needing to renew or totally replace itself
What happens when the cell cannot adapt but the stimulus is mild or damages the DNA
Results in a change in the growth pattern, producing abnormal cells (dysplasia) in sever cases the cells will continue to mutate and grow from this damage(neoplasia)
Whats the difference between hyperplasia and neoplasia
Hyperplasia stops making more cells when the stimulus is removed while neoplasia continues regardless of stimulus
What happens to mutations in Neoplastic cells
They are passed on to all generations
Define a transformed cell
A cell that has developed a mutation and will begin neoplasia as it divides. Its division will cause the next generations to carry on the mutations and develop more. Each generation will have less differentiation if malignant
What are the 2 types of neoplasm
in-situ(local) and invasive(disrupts the BM)
What are the 4 steps needed for metastasis
1)A portion of the neoplasm break away from surrounding cells and needs to disrupt the BM due the accumulations weight, and the connective tissue. 2)It then needs to spread to a region of vasculature 3)where a portion will need to break off and 4)travel through the blood
What are the 4 ways neoplasms can spread
1) though blood
2) spread through local region
3) Spread through the lymphatic system
4) spread trans-coelomically/ through the body cavity of origin eg.pleural or peritoneal
