Cell Adaptations Flashcards
(37 cards)
Stable cell populations
Normally quiescent or proliferate slowly, but can proliferate when required
Permanent cell populations
Stme cells are present, but cannot mount an effective proliferative response to significant cell loss.
Labile Cell Populations
Cells present are short lived and so cells proliferate continually to replace those lost.
Define regeneration
Replacement of cell loss by identical cells (to maintain tissue size)
Define reconstitution. What does it require?
Replacement of a lost body part. This requires coordinated regeneration of different cells
What can induce regeneration?
Growth factors, cell to cell communication, nervous stimuli
What must happen for regeneration to occur in response to injury?
Harmful agent must be removed & site of damage mustn’t be too large
Give an example where slow/less efficient regeneration is advantageous
Influenza virus, new respiratory epithelia won’t initially have receptors for virus
Define hyperplasia
Increase in tissue size due to increase in cell number
What type of cells can hyperplasia occur in?
Labile or stable only
How is hyperplasia different from neoplasia?
It is reversible, under physiological control, occurs as a response to another cause whereas neoplasia is the cause of injury
What triggers hyperplasia?
Increased functional demand or stimulation
Give a physiological example of hyperplasia
Endometrium (in response to oestrogen), bone marrow makes more erythrocytes (in response to hypoxia)
Define hypertrophy
Increase in tissue size due to increase in cell size (NOT cell number)
Where is hypertrophy most likely to be seen?
Permanent cells
What is the usefulness of knowing regenerative capacity of different cells?
You can predict their response when put under increased demand
What can trigger hypertrophy?
Increased functional demand, hormonal stimulus.
What is the usefulness of having an increased amount of structural components in a cell after hypertrophy?
The increased workload is then shared by a greater mass of components and so becomes less of a task/burden
Why is cardiac hypertrophy a problem if pathological?
The cardiac muscle gets no rest from hypoxia. The number of capillaries does increase, but not enough to be able to meet the needs of the increased muscle mass–> exhaustion
Why isnt cardiac hypertrophy such a problem in pro athletes?
They allow time for their heart to rest, to become fully supplied before training again
Define Atrophy
Shrinkage of a tissue due to a decrease in cell number and/or cell size
Why can atrophy occur?
In response to disuse (eg skeletal muscle), loss of innervation/blood supply, loss of hormonal stimuli, decrease in growth factor, persistent muscle injury (as repair cant occur)
How does decreased function come to be a consequence of atrophy?
On a cellular level, the cells shrink, TF there are fewer cellular components, meaning the cells cannot do as much TF decreasing function
How does cell number decrease? And what happens to the cell remnants?
Apoptosis. If on an external or surface- lost to lumen. If internal- removed by phagocytosis
