Test Three Module 5 Flashcards
Tissues restore homeostasis with what two processes?
- inflammation
2. regeneration
The insults and injuries that can trigger inflammation include:(7)
- Blunt physical injury
- Penetrating physical injury (abrasions)
- Heat or frost burns
- Toxins
- Infection by pathogens
- Radiation
- Foreign bodies (dirt, debris)
What is acute inflammation?
Inflammation that occurs in response to a specific insult or injury
What is chronic inflammation?
Inflammation continues for a long time, beyond the time needed to repair damage
What are the 5 characteristic features that are noticed of inflammation?
- redness
- swelling
- heat
- pain
- loss of function
What are the 15 steps of inflammation?
- Inflammation starts when damaged cells start leaking contents.
- If cells are damaged sufficiently, their own lysosomes break open, releasing degradative enzymes that destroy the injured cell but also attack surrounding tissue (necrosis)
- The leaking cells release ions and signaling molecules into the surrounding interstitial fluid.
- The signaling molecules from the site of injury trigger mast cells in nearby connective tissue to release histamine and other signaling molecules.
- The signaling molecules from the mast cells trigger blood vessels in area to dilate (they signal the smooth muscles surrounding the vessels to relax).
- Increased blood flow to site of injury causes it to appear red and causes it to warm up.
- The signaling molecules from mast cells also cause blood vessels in the area to become leaky – fluid and cells from blood squeeze out between blood vessel epithelial cells.
- This causes site of injury to swell and delivers more immune cells to site, like macrophages and neutrophils.
- The swelling and signaling molecules trigger pain nerves to fire and this cause the sensation of pain
- The immune cells delivered to site by leaky blood vessels ingest & remove debris (and pathogens, if present)
- As white blood cells ingest debris, they die off – dead white blood cells & fluid surrounding them is pus (pus in an enclosed space is an abscess; pus within or under skin is a pustule or pimple.)
- As debris and pathogens are removed, signaling to mast cells decreases
- Mast cells eventually stop releasing their own signaling molecules
- Vessels in area constrict their smooth muscles (reducing blood flow to the area) and stop being leaky, reducing redness.
- INFLAMMATION ENDS
what is necrosis?
Uncontrolled, premature, unplanned cell death that can occur in response to infection, toxins, chemicals, injury, or lack of blood supply.
signal molecule do mast cells release?
histamine
The inflammation response _____ injuries and insults, but underlying tissue is still damaged and needs to be restored?
cleans up
What is regeneration?
Regeneration of tissues repairs and replaces the tissues lost of injury and starts to occur while inflammation is winding down
What is the process of regeneration?
- Fibroblasts move into damaged area from nearby connective tissue (whether or not damaged area is connective tissue or not)
- Fibroblasts lay down extensive collagen protein fibers as an extracellular matrix – more dense and more stiff than typical collagen fibers – binding the area together
- The region with the dense, stiff collagen fibers is not like the surrounding tissue – it is scar tissue (or fibrous tissue, a specialised dense regular connective tissue proper)
- Mesenchymal stem cells, muscle stem cells, or epithelial stem cells produce replacement cells for their tissues (if damaged) and some scars fade as they are replaced by new tissue.
- Epithelia, skeletal muscles, and connective tissues regenerate well but not all tissues do – cardiac cells and neurons do not regenerate (or regenerate poorly) and scar tissue remains.
What cells start the regeneration process after injury?
Fibroblasts
What is a scar?
Specialised connective tissue with excess collagen protein fibers at the site of tissue repair.
