Repair of Injury在线视频

Hello everyone

China Medical University Han Yuchen

Now we will learn the repair of the injury together

The process of repair begins with tissue damage

Repair is the way in which the body regenerates parenchymal cells and fibrous connective tissue

The process of recovering from loss

Loss here refers to the aging and apoptosis of tissue cells under physiological conditions and the damage of tissue or cells under pathological conditions

There are two types of repair processes

One is regenerative repair or complete repair

It means that the tissue or the cell can completely return to its original normal tissue

The other is scar repair which can also be called fibrous repair

The process of repairing damaged tissue with fibrous connective tissue

Scar tissue is also known as incomplete repair

What is regenerative repair

Regeneration is the proliferation of the same cells that occurs by repairing lost substantive cells

The main three elements

The first element is a regenerative cell which is a proliferation of cells

The second element is that the essence of regeneration is to repair loss but non-absorptive necrosis and to eliminate inflammatory factors

The third element is that the regenerated cells are identical to the lost parenchymal cells

Regeneration is divided into physiologic regeneration and pathologic regeneration

Physiological regeneration refers to the continuous aging and apoptosis of cells and tissues under physiological conditions

Replenished by new cells and tissues of the same species

Maintain the original structure and function

For example the stratified squamous epithelial cells of the epidermis is constantly keratinized and exfoliated

Basal cells continue to proliferate differentiate and supplement

A process to supplement the loss of the epidermal cells

The regeneration of the endometrium during the menstrual cycle

The regeneration and regeneration of digestive tract epithelium are physiological regeneration

Pathological regeneration refers to the pathological state

Tissue necrosis or tissue or cell damage following a defect is less severe

And these cells or tissues have a strong ability to regenerate

By the surrounding residual tissue or cell of the same tissue or cell regeneration completely restored the original structure and function

For example blisters are common secondary degree burns to the skin

The epidermis except for the basal cells

After all the cells are damaged the basal cells regenerate and repair the original structure and function of the skin

For example viral hepatitis

After degeneration and necrosis of hepatocytes peripheral hepatocytes are regenerated

When the glandular epithelium is damaged

With the basement membrane intact

Regenerated from the remaining glandular epithelium

Restore the normal structure and function of the glands

There is bone necrosis or fracture

Under certain circumstances

It can also fully restore the original structure and function

Different cell types have different cycle lengths

The number of cells entering the cell cycle to proliferate per unit time is also different

The ability of different cells to regenerate is completely different

The G0 cells in the cell cycle can proliferate when be stimulated

Depending on the ability of different cell types to regenerate

They can be classified as labile cells

Stabile cells

Permanent cells

Labile cells are also called persistent dividing cells

These cells can continue to proliferate and divide throughout the cell cycle

Their regenerative ability are very strong

For example epidermal cells and the cells on the mucosa of the respiratory and digestive tract

The covering cells of the lumen of a reproductive organ

Lymphatic and hematopoietic cells and mesothelial cells and so on

Stable cells are also called quiescent cells

These cells are often at rest

When the are stimulated by injury

They can go into the cell cycle to proliferate and mitosis

So these cells have a strong potential for regeneration

They include glands in the respiratory or digestive tract

The parenchymal cells of an adenoid organ

Liver pancreas salivary gland endocrine gland

Sweat glands and sebaceous glands

Renal tubular epithelial cells

And primitive mesenchymal cells and the various cells that they differentiate from

For example we are familiar with the fibroblast

Endothelial cells and osteoblasts

Permanent cells are also called non-mitotic cells

They have no ability of regeneration

Including nerve cells

Cardiomyocytes and skeletal muscle cells are also poorly regenerated

These nerve cells include central neurons and peripheral ganglion cells

But not include nerve fibers

The ability of cardiomyocytes and skeletal muscle cells to regenerate is weak

They have no practical meaning of regenerative repair

It is usually replaced by scar repair

Let's introduce scar repair

Also called fibrous repair

Due to the damage of the tissues or cells is more severe

or with infection

It cannot be repaired in a completely regenerative manner

Instead granulation tissue consists of proliferating fibroblasts and capillaries

The process of becoming fibrous tissue for repair is called scar repair

It's an incomplete repair

The basis of scar repair is granulation tissue

So what is granulation tissue

Granulation tissue is a newly formed fibrous connective tissue rich in capillaries

Its main component is the fibroblast new capillaries and varying numbers of inflammatory cells

When granulation tissue is associated with a significant infection

The infiltrating inflammatory cells are mainly neutrophils

When there is no obvious infection

The infiltrating inflammatory cells in granulation tissue are mainly monocytes and lymphocytes

Morphological characteristics of granulation tissue

When viewed with the naked eye the surface appears as fine particles

Bright red soft and moist

Tissues bleed easily

Because there are no nerve fibers

So it feels no pain

and looks like tender meats

Under the microscope

Granulation tissue surface are covered with an inflammatory exudation and necrotic tissues

The lower part is a large number of capillaries arranged in parallel

Perpendicular to the surface

And they meet near the surface to form a arch

The anastomotic capillaries are interspersed with fibroblasts small amounts of collagen fibers and an indeterminate number of inflammatory cells

The deep part is a mature fibrous connective tissue composed of fibrous cells a large number of collagen fibers and a small number of small blood vessels

In high-power field we can see that the granulation tissue is composed of new capillary fibroblasts and inflammatory cells

Granulation tissue is used to protect wounds from infection to fill in wounds and other tissue defects to organize or wrap tissue necrosis thrombotic exudates and other foreign bodies

Organization is the process by which new granulation tissue absorbs and replaces various deactivated substances or foreign bodies

Encapsulation is an incomplete organization

The granulation tissue gradually matures into fibrous tissue separating necrotic material or foreign material from normal tissue

The outcome of granulation tissue

2 to 3 days after injury

Granulation tissue can grow up from the lower part of the damaged area

Or around the damaged tissue toward the center of the damaged tissue

Mature gradually after 1 to 2 weeks

This maturation process involves the gradual absorption of water and the gradual loss of inflammatory cells and the reduction of capillary occlusion

Fibroblasts mature into fibroblasts

Collagen fibers proliferate

Hyaline degeneration occurs

Gradually mature into fibrous connective tissue

It eventually turns into scar tissue

Scar tissue is fibrous connective tissue that changes from granulation tissue to aging

The characteristics of scar tissue

Microscopically we can see a large number of collagenous bundles distributed in parallel or interlaced

It showed homogeneous hyaline degeneration

Fibroblasts are very rare

The nuclei are slender and hyperchromatic

Small blood vessels are very rare

Visual observation of local contraction of scar tissue

Pale color or gray semitransparent

It's tough

inelastic

The role of scar tissue

On the plus side there is scar tissue

A damaged wound or other defect can be permanently filled and joined together

It can keep the tissues or organs completely

In addition scar tissue is more resistant to tension

Strong tensile strength than the granulation tissue

But it was much weaker than the original organization

And the lack of elasticity

Prolapse can cause scarring

You can have a hernia in the abdominal wall

A ventricular aneurysm can form in the ventricular wall

Scar tissue has a downside

For example we can all imagine that scar tissue constriction can cause obstruction

It can also appear scar adhesion

Or excessive scar tissue hyperplasia

Hypertrophic scar formation

Sometimes we can see this hypertrophic scar protruding from the surface of the skin

And spread irregularly to surrounding tissues

It is called as keloids

These are our introduction to repair damage

And we're done in this video

Thank you all