Tissue Homeostasis and Repair Flashcards
Which layer of skin is responsible for cell proliferation?
strata basal
2 examples of permanent cell type
neurons + myocardial cell
permanent cells
always in G0 with no ability to differentiate
stable cells example
hepatocytes
stable cells
in G0 but able to divide if needed
ex: will divide if there is tissue damage
What are 3 ways that tissues can replace mass?
1) regnerate parenchyma
2) fibrosis
3) scarring
Difference between scarring and fibrosis
Fibrosis occurs in response to more chronic inflammation
Scarring occurs in response to acute injury
Similarity between fibrosis and scarring
both lay down connective tissue to replace mass
What 2 cell types can regenerate after tissue damage?
labile and stable
Difference between epidermis and dermis in healing from wound
epidermis can regenerate
dermis scars
example of fibrosis
HCV infection in the liver
chronic inflammation that leads to fibrosis
secondary provisional matrix
granulation tissue
granulation tissue
seen with scarring
lays the groundwork for connective tissue by bringing capillaries to area
what does granulation tissue secrete?
VGEF to make new capillaries
3 stages of liver regeneration
1) initation / priming
2) proliferation
3) termination
priming stage of liver regeneration
increase in growth factors like HGF and EGF
increase in blood flow + cytokines
What growth factor is downregulated during priming?
TGF-B
TGF-B is a negative growth regulator
proliferation stage of liver regeneration
increased proliferation of most cell types in liver
Termination stage of liver regeneration
return to homeostasis
increase in negative growth regualtors like TGF-beta
what is another way to describe liver regeneration?
compensatory hyperplasia
What occurs during HCV infection of liver?
combination of inflammation, parenchymal regeneration, deposit of collagen in form of fibrosis (regain liver volume through fibrosis)
2 types of sweat glands
1) apocrine glands: primarily respond to thermal regulation
2) eccrine glands: response to emotional regulation
what layer of skin is melanin found?
strata basal
what layer of skin has tight junctions?
strata granulosum
what is the dermis made of?
irregular, dense connective tissue
where are glands?
reticular dermis
hyperdermis
adipose tissue / good fat
primary provisional matrix
formation of fibrin clot
bring neutrophils to the acute inflammatory site
what happens after a couple days in epidermis regeneration?
the epidermis needs to migrate to fill in underneath the fibrin clot
where does epidermis regenerate?
underneath the eschar (scab)
what do you need for epidermis to migrate?
integrin for it to attach to
what do you downregulate during migration of tissues?
downregulate laminin production
downregulate desmosomes
laminin
component of basement membrane
do not want basement membrane when moving cells (want to be free)
when are neutrophils gone?
after 2 days
what does the redness surrounding a scab indicate?
VGEF / new blood vessels
what is happening to dermis a couple days following an injury?
scarring
lots of blood vessels for granulosum development
lots of myofibroblasts
how can you tell the scar in the dermis is mature?
type I collagen is replaced with type III collagen
3 phases of skin repair
inflammation, proliferation, maturation
myofibroblasts and maturation
pull the scarring in / contract
what phase of skin repair do you see lots of VGEF?
proliferation
keloid dermis
lots of type I collagen
hypertrophic scar dermis
type III collagen in parallel, organized arrangment
sclerosis
see more connective tissue
adhesion
form fibrin bridge
contracture after a burn
myofibroblasts over contract the whole wound
dehiscence
failure to form scar / granulation tissue
often seen in diabetes
*how to review lesions
*review slides from Mon, Nov. 20th with pictures
proud flesh
cannot get past granulation stage
dystrophic calcification
Ca2+ deposition on vessel
pretty common / normal
Ca2+ stains basophilic
metastatic calification
Ca2+ deposition with abnormal growth
stains basophilic
what happens to tissues after MI?
myocytes undergo scarring
