Healing .tissue regeneration and repair

Question 1

Describe the structure and function of platelets

Answer 1

Platelets are small colourless fragments that are anucelated and they assist in blood clotting when there is cut or damage to the skin barrier. It’s purpose is to reduce the amount of blood that is leaving the body to avoid to much blood escaping .Platelets are made in the bone marrow from megakaryocytes.

Question 2

Name 4 of the growth factors involved in tissue regeneration.

Answer 2

EGF-epidermal growth factor
TGF-transforming growth factor
VEGF-vascular endothelial cell growth factor
FGF-Fibroblast growth factor

Question 3

Describe the 5 stages of haemostasis

Answer 3

1) Vessel spasm
2) Primary haemostasis-platelet plug
3) Secondary haemostasis-formation of a clot
4) Clot retraction
5) Clot dissolution

Question 4

Describe the primary plug formation

Answer 4

1) Injury cause exposure of subendothelial collagen
2) The platelets start to bind to Von Willeband factor on the inside surface subendothelial
3) vWF binds platelets via Gp1b to the injured area and also to each other
4) Some Fibrinogen is released and this cause the platelet to also stick together causing a loose clot

Question 5

What happens when platelets are activated?

Answer 5

1) They become star shaped
2) They secrete thromboxane A2
3) Secrete granule content e.g ADP,
4) Gain the ability to bind to fibrinogen through a conformational change of GPIIB/IIIa

Question 6

What occurs in the secondary haemostasis?

Answer 6

its start as a loose coagulation and the fibrinogen is converted to fibrin the solidifies the platelets to form a secondary haemostatic plug or clot.

Question 7

Outline the major features of the clotting cascade

Answer 7

Pro-thrombin, thrombin ,fibrin and fibrogen

Question 8

What are some ways to switch off the clotting cascade?

Answer 8

Dilution
Anti-thrombin
Sheilding of vWF by healing Endothelial cells

Question 9

Classify stem cells based on their differentiation capacities

Answer 9

Totipotent-differentiate in any cell types
Pluripotent-Differentiate into cells from any of the three germ layers
Multipotent-Differentiate into limited range of cell type in one are e.g. hemopoietic cell regenerate al cell types in the blood
Oligopotent-differentiate into limited number of cells
Unipotent -differentiate into a single cell type (make copies of themselves.

Question 10

Describe in detail the stages that lead to the generation of a scar

Answer 10

1) Angiogenesis/haemostasis(clotting cascade)
2) Formation of granulation tissue (pink ,soft)(2-5 days)
3) Tissue remodelling
4) Scar

Question 11

Name some key growth factors that influence healing

Answer 11

VEGF,TGF beta,FGF & MMPs

Question 12

Describe healing by first and second intention

Answer 12

First intention-
Clean and uninfected
Surgical
Edges of wound are clear
Little loss of cells/tissue

Second intention-
Possibly infected
Larger wound
Unclear demarcation of edges
Open wound

Question 13

Describe the potential impacts of stem cells in clinical medicine

Answer 13

Neurons
Blastocyst
Red blood cells
Cardiac cells
Fat cell

Question 14

What are some components of granulation tissue?

Answer 14

1) remnants /residual of inflammatory cells(neutrophils)
2) fibroblast secreting collagen and extracellular matrix deposition
3) light bleeding because of new formation blood vessels
4) fibroblasts and endothelial cells undergoing mitosis

Question 15

What carries out tissue remodelling and collagen synthesis?

Answer 15

MMPs-matrix metalloproteinases(degrade collagen and ECM

TIMPs-tissue inhibitor of matrix metalloproteinases(inhibit MMPs)