4- Injury, repair and regeneration Flashcards
Cellular injury can be
reversible or irreversible
Injury can be reversible or irreversible depending on…
- Nature of injury agent
- Duration of exposure
- Type of Cell
- Ability of cell to regenerate.
What are the causes of cellular injury
TTPDII
trauma
thermal injury (hot / cold)
poisons
drugs
infectious organisms
ionising radiation
What is direct injury
Damage cells and tissue causing cell death, bleeding and inflammation
What are some examples of direct injury
PCR
- Physical trauma
- Chemical injury
- Radiation injury – Damage DNA and other cellular components
What are examples of indirect injury
OII
- Oxidative stress – Damage DNA and cellular components
- Inflammation
- Immune-mediated injury – caused by autoimmune diseases and leads to the immune system attacking its own tissue
Radiation effects are dependent on
the dose, duration of exposure, and type of radiation
Harmful affects of radiation are
Acute radiation sickness
Cancer
Tissue damage
Radiation- acute radiation sickness
Exposure to high levels of radiation, with symptoms including nausea, vomiting
Radiation- cancer
Increase the risk of cancer development, as radiation damages DNA in cells and leads to mutations.
Radiation- tissue damage
damage tissues and organs, leading to tissue death and organ failure.
What are the benefits of radiation
Medical use
Sterilisation
Research
Medical use of radiation
Radiation is used in medical imaging and radiation therapy to diagnose and treat cancer and other medical conditions
Sterilisation use of radiation
Radiation is used to sterilize medical equipment.
Research use of radiation
Radiation is used in scientific research to study the properties of materials and molecules
Cell and tissue response injury (ICIAF)
- Inflammation.
- Cellular swelling
- Ischaemia Necrosis
- Apoptosis – Apoptosis can occur in response to certain signals or stimuli, such as DNA damage or activation of specific signalling pathways.
- Fibrosis.
What is ischaemia
alive cells with ____ ____
____ ______ is restricted
Alive cells but reduced function
Blood flow (and thus oxygen) is restricted or reduced in a part of the body
Can eventually lead to necrosis or ulcers.
What is necrosis
Death of tissues affecting multiple cells in an area. Resulting due to an injury or disease.
- cell nuclei break up and disappear– Caused by bacteria i.e Staph A or CNS after strokes
- Coagulation (Tissue initially swells then becomes firm) – Most common type
What are ulcers
type of tissue injury characterised by ________ ___ _________ or _______
Type of tissue injury characterized by a break in the skin or mucous membrane leading to open lesions.
Ulcers can occur in various parts of the body, including the stomach, intestines, skin, and mouth.
Types of ulcers
Ischaemic and necrotic
What are ischaemic ulcers
cause?
where does it happen?
Typically due to arterial disease or blockages. Often occur in the lower legs or feet and can be slow to heal, as the lack of blood flow limits the delivery of oxygen and nutrients to the affected tissue.
What are necrotic ulcers
Caused by prolonged pressure on the skin, typically due to immobility or being bedridden. Prolonged pressure can lead to ischemia and subsequent necrosis, particularly challenging to treat, as the lack of blood flow to the affected area can limit the delivery of topical treatments and impede the healing process.
What is repair and regeneration
The process of replacing injured or dead cells. Cell types vary in regenerative ability depending on type and location
Types of repair and regeneration cells
Labile cells- Very high regenerative ability and turnover (e.g. intestinal epithelium)
Stable cells- Good regenerative ability but low rate of turnover (e.g.hepatocytes (Kidney))
Permanent cells- No regenerative ability often replaced with scar tissue (e.g.neurones)
Complex tissue architecture cannot be reconstructed
Healing is seen as restorative and is aimed at
restoring structure and function of damaged tissue
Healing by the first intention…
is there a residual effect and what does it form
with no, or minimal residual defect e.g. superficial skin abrasion, incised wound. Results in formation of thin scar
Healing- skin
Exudation of ______ creates weak _____ join between edges of _____
The exudation of fibrinogen creates a weak fibrin join between the edges of the wound. Over time its replaced by a stronger collagen join, and epidermal regrowth occurs on top
Healing by second intention…
repair is necessary because _________ is lost and _________ ____ _______
where repair is necessary as this is tissue loss and edges of wound cannot be brought together.
Healing- organisation
_________is replaced by_____ then remodelled to form a _________
When granulation tissue is replaced by fibrous tissue, then remodelled to form a
scar. For specialised tissue its it the formation of scars to help it repair.
Healing of ulcers
IPR
Inflammation
Proliferation
Remodelling
Ulcer healing- inflammation
removes any …… or ………..
to remove any pathogens or debris that may be present and begins the process of preparing the wound for healing
Ulcer healing- proliferation
New formation of tissue – Granulation tissue
Ulcer healing- remodelling
Tissue replaced by new skin cells
Granulation tissue is NOT
Granulomas
Granulation tissue is
___________of highly vascularised newly formed ____________
A repair phenomenon of highly vascularised newly formed connective tissue
The new blood vessels bring oxygen and nutrients to injury site
Ensures new tissue is aligned and has correct mechanical properties.
- Loops of capillaries supported by fibroblasts.
- Inflammation may be present.
- Eventually scar constricts – this may cause problems.
What factors modify or impair healing
7
- Age (very young/very old)
- Loss/absence nerve supply
- Decreased immunity – Being on corticosteroids (Cushing’s Syndrome, therapeutic) or have local or systemic infections.
- Drugs.
- diabetes mellitus
- intercurrent disease (e.g. rheumatoid disease)
- irradiation
