Lecture 3 - Tissue Repair

Question 1

Labile cells

Answer 1

-continuously divide throughout life
-easily regenerate
Ex. skin, surface epithelium, epithelium of ducts and GI, hematopoietic cells

Question 2

Stable cells

Answer 2

-retain their ability to proliferate (divide) once organ is at adult size but have limited regeneration if damaged.
Ex. connective tissue (fibroblast, smooth muscle, parenchymal tissue, endothelial cells, liver)

Question 3

Permanent cells

Answer 3

-no regeneration once at adult state; “Terminally differentiated”
Ex. Neurons, cardiac muscle, (some skeletal muscles)

Question 4

Stem cells

Answer 4

self-renewing; continuously replicate. Asymmetric replication = 1 enters cycle to differentiate, 1 stays undifferentiated.
Two types: Tissue stem cells and embryonic stem cells

Question 5

Tissue stem cells

Answer 5

adult stem cells = help in healing process
- are already being used successfully in organ transplants.
Ex. hematopoeitic stem cells from bone marrow

Question 6

Embryonic stem cells

Answer 6

• pluripotent

- can turn into any cell

Question 7

Autocrine signaling

Answer 7

-cell sends signal from itself to stimulate itself

Ex. Lymphoid proliferation and liver regeneration

Question 8

Paracrine signaling

Answer 8

-signals produced by cells for other cells within the immediate vicinity.
Ex. recruiting calls in inflammation and wound healing

Question 9

Endocrine signaling

Answer 9

-produced by glands to signal distant cells

Ex. Hormones and tumors for stimulating cancer

Question 10

Angiogenesis

Answer 10

-formulation of new blood vessels

2 types: vasculogenesis and neovascularization

Question 11

Vasculogenesis

Answer 11

-formed via angioblasts while an embryo

Question 12

Neovascularization

Answer 12

• in adult tissue, vessels formed via new capillaries sent out from existing blood vessels.
• Leaky at first = cause inflammation/swelling

Question 13

First intention healing

Answer 13

-healing of a clean, uninfected surgical incision
-no large damage, no infection
-epithelial growth is predominant = less scar formation
Ex. paper cut

Question 14

Steps of 1st intention healing

Answer 14

-Fibrin clot and neutrophils fill wound
-Epithelial cells migrate
-granulation tissue migrates and epithelium covers surface
-granulation tissue fills wound
-inflammatory elements dissolve
== Minimal scar tissue

Question 15

Second intention healing

Answer 15

-healing of a large, infected wounds

Ex. Ulceration, large wounds, abscess formation, extensive inflammation and granulation tissue

Question 16

Dehisce

Answer 16

-mechanical factor (torsion, pressure) pulls wound apart

Question 17

Keloids

Answer 17

• over exuberant scarring
• growth on surface of skin is scar tissue
• hereditary and more common in black skin and really pale skin