3 - Healing and Repair Flashcards
What type of collagen is most abundant in bone, ligaments, tendon, dermis etc.?
“Type I. [There are > 20 forms of collagen (type I, type II …). Most tissues have a predominance of one collagen type.]”
In which of the four phases of wound healing is granulation tissue production an important feature?
The third phase: proliferation. [The four phases are: 1. Hemostasis; 2. Acute inflammation; 3. Proliferation; 4. Maturation and contraction (remodeling)]
Aside from wound features that predispose to second intention healing (gaping wounds, infection, foreign bodies etc.) name four other factors or conditions that can delay wound healing.
“The four Ds”: 1. Disease (e.g., specific collagen disorders, certain endocrine diseases); 2. Drugs (certain anti-cancer drugs); 3. Deficiencies (vitamin C deficiency in primates & guinea pigs); 4. Diet (starvation, malnutrition & cancer cachexia)
What provides the tensile strength of collagen?
(a) Conversion from its liquid to solid form over time;
(b) Cross-linking of collagen fibrils;
(c) Matrix metalloproteinases;
(d) Transforming growth factor beta;
(e) Vitamin C
(b) Cross-linking of collagen fibrils
What is the term for a mixture of proliferating fibroblasts and endothelial cells with minimal or no collagen deposition that quickly fills in tissue defects?
Granulation tissue
What are three features of a wound that will go on to heal by secondary intention?
- Wound edges are NOT apposed (due to extensive tissue loss, failure to suture gaping wounds or wound instability and repeat trauma)
- Infection is present
- Foreign bodies are present (exogenous, such as sticks or surgical sponges; endogenous, such as neoplasms and sequestra)
The presence of a bony sequestrum in a wound may impede healing. What is a bony sequestrum?
A bony sequestrum is a piece of devitalized (i.e., dead, having lost its blood supply) bone that the animal now recognizes as a foreign body
What are three features of a wound that will go on to heal by primary (first) intention?
- Wound edges are apposed
- There is no infection
- There are no foreign bodies present
How does the use of certain chemotherapeutic drugs, used to treat neoplasia, impair wound healing?
Certain chemotherapeutic drugs -> reduced cellular proliferation -> reduced fibroplasia -> impaired healing
Name 3 cell types that can produce matrix metalloproteinases (MMPs).
MMPs are produced by pretty much every cell type you can think of (fibroblasts, macrophages, neutrophils, endothelial cells, cancer cells …)
The extracellular matrix is composed of proteins, such as collagen, and a hydrated gel made of _______. [Fill in the blank]
Proteoglycans
You vaccinate a cat against rabies and several months later notice a large, fleshy subcutaneous mass at the injection site in the dorsal skin. What should you consider as the most likely diagnosis?
Post-vaccine fibrosarcoma. Fibroblasts are especially responsive to injury in cats and sometimes cross the line from hyperplasia into neoplasia. This is seen relatively commonly following subcutaneous rabies vaccination.
Place the following four steps of wound healing into correct sequence, from earliest to latest: (a) Acute inflammation; (b) Hemostasis; (c) Maturation and contraction; (d) Proliferation
- Hemostasis
- Acute inflammation
- Proliferation
- Maturation and contraction (remodeling)
Name two relatively common endocrine diseases that result in poor wound healing.
- Diabetes mellitus
- Hyperadrenocorticism / Hypercortisolism (Cushing’s disease)
What is the term for a mixture of proliferating fibroblasts and endothelial cells with minimal or no collagen deposition that quickly fills in tissue defects?
Granulation tissue
How does vitamin C deficiency in primates and guinea pigs impair wound healing?
Vitamin C is an essential co-factor in production of collagen alpha chains in ribosomes. Vitamin C deficiency -> reduced collagen synthesis -> poor wound healing (“scurvy”)
What are the most important inflammatory cells in the first 24-96 hours after a wound occurs?
Neutrophils and macrophages
In which animal types does vitamin C deficiency impair wound healing?
Primates and guinea pigs
How long does the proliferative phase of wound healing last, in general?
3-4 weeks depending on the size of the wound
What is the meaning of the term angiogenesis?
The formation of (1) new blood vessels from (2) preexisting vessels. [You need both parts to be fully correct. The formation of vessels de novo in, for example a developing fetus in NOT angiogenesis; it’s called vasculogenesis]
