unit 11

What is tissue repair

The process by which the body restores the integrity and function of damaged tissue

What two processes does tissue repair involve

Regeneration and Repair/Fibrosis

What is regeneration

Replacement of damaged cells with others of the same characteristics (100% functional tissue)

What percentage of functional tissue is associated with regeneration

100% functional tissue

What is a Repair or Fibrosis?

The replacement of the space occupied by damaged or dead elements by collagenous connective tissue

What does repair or fibrosis replace damaged or dead elements with

Collagenous connective tissue

What does repair or fibrosis produce

SCAR and CYCATRIZATION

Approximately how functional is tissue after repair or fibrosis

90% functional tissue

Both regeneration and repair/fibrosis depend on mechanisms involved in ….. what

cell migration, proliferation and

differentiation, as well as in cell-extracellular matrix (ECM) interaction.

Type of tissue repair depends on what

The tissue affected

When do epithelial tissues regenerate completely?

If only the epithelium is damaged

Another name for connective tissue

Mesenchymal tissue

How do connective (mesenchymal) tissues heal mainly?

By repair

Connective (mesenchymal) tissue mainly heals by repair and produces what

Fibrous tissue and a possible scar

What happens to the chance of scarring when the injury is deeper

Chance of scarring is greater

What happens when more connective tissue and thus a deeper injury has happened

Greater the chance of scarring

Epithelium = ?

Connective tissue= ?

1. Regeneration

2. Repair and scar formation

EPITHELIAL TISSUE

What do epithelial tissues form

Surface layers of organs and the lining of body cavities

EPITHELIAL TISSUE

What are they made of

Closely packed cells

EPITHELIAL TISSUE

What are the different types of epithelial tissue organisation

Simple and stratified

EPITHELIAL TISSUE

Functional

Protection secretion absorption

EPITHELIAL TISSUE

Regenerative capacity - EXAM

high regenerative capacity

EPITHELIAL TISSUE

What does Hight regenerative capacity mean

They can replace damaged cells quickly

CONNECTIVE (MESENCHYMAL) TISSUES

Where is it situated in comparison to epithelial tissue

Bellow

CONNECTIVE (MESENCHYMAL) TISSUES

What does it provide

Structural support and nutritional supply

CONNECTIVE (MESENCHYMAL) TISSUES

What is it composed of

Fibroblasts, collagen fibres and extra cellular matrix

CONNECTIVE (MESENCHYMAL) TISSUES

Function

Structural support and repair

CONNECTIVE (MESENCHYMAL) TISSUES

Regenerative capacity?

Lower regenerative capacity

CONNECTIVE (MESENCHYMAL) TISSUES

What happens because the CT has lose regenerative capacity

Healing occurs by fibrosis (scar formation)

CONNECTIVE (MESENCHYMAL) TISSUES

What is is it described as

Very dynamic tissue

What is stratum básale

Stem cells

What is the role of the Stratum Básale

It contains dividing cells - the stem cells that regenerate the epithelium

Look

Done

Answer

B

Answer

C

Answer

C

Epithelial regeneration

what is epithelial regeneration

a rapid and efficient process driven by high proliferative capacity of basal cells and their close interaction with the underlying connective tissue

Epithelial regeneration

what drives epithelial regeneration

high proliferative capacity of basal cells and their close interaction with underlying connective tissue

Epithelial regeneration

what happens in oral ulcers though epithelial regeneration

complete restoration of the epithelium within a few days, provided the mesenchyme remains intact

Epithelial regeneration

how quickly can the epithelium be completely restored in oral ulcers?

within a few days

Epithelial regeneration

what condition must be met for complete epithelial restoration in oral ulcers

the mesenchyme remains intact

Epithelial regeneration

what happens when damage is limited to the epithelium

full recovers, no scar

Epithelial regeneration

the three tissue are

labile tissues, permanent tissues and stable (quiescent) tissues

tell me which one is the most regenerative (1) and least (3)

1. labile tissues

2. stable (quiescent)

3. permanent tissues

Epithelial regeneration

what is the regenerative capacity of labile tissues and what does it mean

continuous regeneration, cells are constantly renewed

Epithelial regeneration

where does cell renewal start in labile tissues (IMPORTANT)

from progenitor stem cell

Epithelial regeneration

what is the cell cycle status of labile tissues

active cycle

(G1 → S→G2→M)

Epithelial regeneration

what are examples of labile tissues (4)

• epithelia (skin, mucosa)

• bone marrow

• internal lining

• oral mucosa

Epithelial regeneration

what is the regenerative capacity of stable (quiescent) tissues - and what can happen if stimulated

• limited regeneration

• can proliferate if stimulated

Epithelial regeneration

what is the cell cycle status of stable (quiescent) tissues

Reversible G0

Epithelial regeneration

what are examples of stable tissues (4)

• liver

• fibroblasts

• renal tubules

• endothelium

Epithelial regeneration

what is the regenerative capacity of permanent tissues, and what is loss replaced by

no regenerative capacity and loss replaced by fibrosis

Epithelial regeneration

what is the cell cycle status of permanent tissues

irreversible G0

Epithelial regeneration

what are examples of permanent tissues

neurons

cardiac muscle

skeletal muscle

READ

done

Epithelial regeneration

what characterises Labile cells (labile tissues)

constant cell activity

Epithelial regeneration

where does cell renewal start in labile cells

from a progenitor stem cell

Epithelial regeneration

what happens after a labile cell cycle is completed

they initiated the next one (G1 to M)

Epithelial regeneration

what tissues have high cell renewal

labile tissues

Epithelial regeneration

what are examples of labile tissues

intestine

skin

Epithelial regeneration

what characterises quiescent cells (stable tissues) - to do with cell cycle stuff

normally reduced cell activity (G0) but upon appropriate stimuli they proliferate (G1)

Epithelial regeneration

in which phase are quiescent cells normally found

G0 phase

Epithelial regeneration

what happens to quiescent cells after appropriate stimuli

they proliferate (G1 phase)

Epithelial regeneration

quiescent cells are wat type of cells and found where?

parenchymal cells of glands

Epithelial regeneration

what are examples of quiescent tissues/cells?

liver, kidney, fibroblasts, smooth muscle cells

Epithelial regeneration

what characterises permanent cells (terminally differentiated cells)

differentiated cells

Epithelial regeneration

do permanent cells have the capacity to initiate a new cell cycle

no capacity to initiate a new cell cycle

Epithelial regeneration

what are examples of permanent cells?

nerve cells, striatal cells, cardiac cells

look

done

Epithelial regeneration

what is the cell cycle

the sequence of events that a cell undergoes to grow, replicate its DNA, and divide into two daughter cells

Epithelial regeneration

name the phases of the cell cycle in order

1. G1

2. S

3. G2

4. M

5. G0

Epithelial regeneration

what happens during G1

cell growth and protein syntheses, preparation for DNA replication

Epithelial regeneration

what happens during S phase

DNA synthesis (replication of genetic material)

Epithelial regeneration

what happens during G2 phase

DNA integrity check and preparation for mitosis

Epithelial regeneration

what happens during M phase (mitosis)

nuclear and cytoplasmic division - results in two daughter cells

Epithelial regeneration

what happens during G0

resting phase

cell leaves the cycle temporarily or permanently

look at the placement of the different tissues

done

Epithelial regeneration

there are 4 stages of epithelial regeneration process what are they

1. epithelial loss and exposure of underlying tissues

2. cell migration

3. proliferation

4. differentiation and maturation

Epithelial regeneration

what is the first phase

epithelial loss and exposure of underlying tissue

Epithelial regeneration

what is the second phase

cell migration

Epithelial regeneration

what is the 3rd phase

proliferation

Epithelial regeneration

what is the 4th and final stage

differentiation and maturation

Epithelial regeneration

what happens during phase 2 - cell migration

basal epithelial cells at the wound margins migrate over the residual basement membrane or fibrin clot

Epithelial regeneration

which cells migrate during epithelial regeneration

basal epithelial cells at the wound margins

Epithelial regeneration

what do basal epithelial cells migrate over during epithelial regeneration

the residual basement membrane or fibrin clot

Epithelial regeneration

what happens during stage 3 - proliferation

epithelial cells re-enter the cell cycle to increase cell numbers

Epithelial regeneration

what happens during stage 4 - differentiation and maturation

epithelial layers are resorted, keratinisation resumes, and the barrier function is re-established

Epithelial regeneration

where are epithelial stem cells located

basal layer

Epithelial regeneration

what does the basement membrane provide

structural support

Epithelial regeneration

what does the basement membrane contain

matrix proteins such as collagen IV and laminin

look

done

Epithelial regeneration

look at the cycle

done

Epithelial regeneration - proliferative capacity and cell cycle

what happens when there is cell injury

growth factors are secreted by damaged and adjacent cells

Epithelial regeneration - proliferative capacity and cell cycle

what do growth factors bind to

the cell surface (rGFs-RFCr)

Epithelial regeneration - proliferative capacity and cell cycle

what happens after growth factors bind to the cell surface

activation of the cytoplasmic protein cascade occurs

Epithelial regeneration - proliferative capacity and cell cycle

what happens after activation of the cytoplasmic protein cascade

induction in the nucleus of transcription factors (TFs)

Epithelial regeneration - proliferative capacity and cell cycle

what do the transcription factors activate

proto-oncogenes (c-myc, p53 and the retinoblastoma gene)

Epithelial regeneration - proliferative capacity and cell cycle

what must be activated for proliferation to begin

the cell cycle

Epithelial regeneration - proliferative capacity and cell cycle

what activated the cell cycle for proliferation

proteins that drive growth and division

Epithelial regeneration - proliferative capacity and cell cycle

why must cell proliferation be regulated

to prevent abnormal growth

Epithelial regeneration - proliferative capacity and cell cycle

place these in the correct order from an injury to cell proliferation

cytoplasmic signalling

growth factors

receptors

injury

new proteins

transcription

cell proliferation

1. injury

2. growth factors

3. receptors

4. cytoplasmic signalling

5. transcription

6. new proteins

7. cell proliferation