Cell Repair Flashcards
what sets into motion the process of repair
inflammatory response
Cell Repair
the restoration of tissue ARCHITECTURE and FUNCTION after an injury
2 types of reactions for cell repair
- Regeneration - tissues return to a normal state
2. Scar Formation - repair by lying down connective fibrous tissue *usually accompanies CHRONIC inflammation
term for Scarring at Inflamed Sites
ORGANISATION
what determines which repair process will happen
- tissue type
2. nature of injury
what interaction is important in the repair process
that between the proliferating cells and the ECM
proliferating cells include…
- remnants of the injured tissue
- VASCULAR endothelial cells
- Fibroblasts
is cell proliferation controlled
yes; under tight control. uncontrolled proliferation may lead to cancer development
“Neoplastic Transformation”
cancer development
key processes involved in proliferation of cells
- DNA replication
- Mitosis
* controlled by the ‘Cell Cycle’
Define Cell Cycle
series of steps at which cell CHECKS accuracy of processes and instructs itself to PROCEED to the next step
4 phases of cell cycle
- The Presynthetic Growth Phase 1 (G1)
- DNA Synthesis Phase (S)
- The Premitotic Growth Phase 2 (G2)
- Mitotic Phase (M)
what promotes cells entering the cell cycle
GROWTH FACTORS
Role of CHECKPOINT CONTROLS
Prevent DNA replication OR mitosis of damaged cells
what determines ability of tissues to repair themselves
their PROLIFERATIVE CAPACITY.
*accordingly, tissues of the body divided into 3 groups
3 groups?
- Labile Tissues
- Stable Tissues
- Permanent Tissues
Labile Tissues
- continuously dividing tissues
- can readily regenerate after injury
eg. stratified squamous surfaces of skin and oral cav. - cuboidal epithelia of DUCTS DRAINING exocrine glands
- haematopoietic cells in bone marrow
Stable Tissues
- usually quiescent (period of inactivity) in the G0 stage
- minimal replicative activity in their NORMAL state
- yet, capable of proliferating IN RESPONSE TO INJURY or LOSS of tissue MASS
eg Stable Tissues
- the parenchyma of most solid tissues - kidney, liver, and pancreas
- endothelial cells
- fibroblasts
- smooth muscle
Permanent Tissues
- terminally differentiated
- nonproliferative in POSTNATAL life
- regeneration not possible, results in a scar
- NEURONS (brain)
- CARDIAC MUSCLE CELLS (heart)
Stem Cells - function
replenishment of tissue as its mature cells (short-lived) die through stem cell differentiation
2 properties of Stem Cells
- Self-renewal capacity
2. Asymmetric Replication
Asymmetric replication of stem cells?
after each DIVISION, some progeny enter differentiation pathway, OTHERS remain undifferentiated (retaining their self-renewal capacity)
Growth factors
=proteins
=stimulating cell division
=promoting cell survival
