4 Cell Proliferation And Tissue Regeneration

Question 1

Cell proliferation vs differentiation

Answer 1

The process of increasing cell numbers by mitotic division

The process whereby a cell becomes more specialized in the terms of structure and function

Question 2

Cell cycle

Answer 2

The duplicated chromosomes are appropriately aligned for distribution between two genetically identical daughter cells
4 phases G1 S G2 M

Question 3

G1 cycle

Answer 3

The post mitotic phase during which DNA synthesis ceases and RNA and protein synthesis and cell growth take place

Question 4

S phase

Answer 4

DNA synthesis takes place, giving rise to two separate sets of chromosomes, one for each daughter cell

Question 5

G2 phase

Answer 5

Is the premitotic phase DNA synthesis ceases and RNA and protein synthesis continues

Question 6

M phase

Answer 6

The nuclear division and cytokinesis

Question 7

Proliferation capacity of tissues.

Body tissues have three types

Answer 7

1. Continuously dividing
2. Stable
3. Permanent

Question 8

Continuously dividing or lability tissues are those in which cells continue to divide and replicate through out life replacing cells that are continually being destroyed. Which cells are these

Answer 8

Surface epithelial cells of the skin, oral cavity, vagina, and cervix, the columnar epithelium of the gi tract, uterus, and Fallopian tubes, the transitional epithelium and of the urinary tract, and bone marrow cells

Question 9

Stable tissues contain cells that normally stop dividing when growth ceases. Are in a g0 stage of cell cycle, but are capable of undergoing regeneration when confronted with an appropriate stimulus, are capable of reconstituting the tissue of origin, these are

Answer 9

Solid organs such as the liver and kidney, smooth muscle cells, vascular endothelial cells and fibroblasts,

Question 10

Permanent tissues do not proliferate, terminally differentiated and do not undergo mitotic division in postnatal life, these are

Answer 10

Nerve cells, skeletal muscle cells , and cardiac muscle cells. Once destroyed they are replaced with fibrous scar tissue that lacks functional characteristics of the destroyed tissue.

Question 11

What are stem cells?

Answer 11

Are reserve cells that remain quiescent until there is a need for cell replenishment, in which case they divide, producing other stem cells and cells that can carry out the functions of the differentiated cell. When it divides one daughter cell remains a stem cell an the other becomes a progenitor cell that undergoes a process that leads to terminal differentiation

Question 12

Stem cells have three properties?

Answer 12

Self-renewal means they can undergo numerous mitotic divisions while maintaining an undifferentiated state.
Asymmetric replication means that after each cell division, some progeny of the stem cell enter a differentiation pathway, while other remain undifferentiated, retaining their self-renewal capacity.
Differential potential is the term potency

Question 13

Totipotent stem cells are

Answer 13

Those produced by a fertilized ovum and can differentiate into embryonic and extra embryonic cells and give rise to pluripotent

Question 14

Pluripotent stem cells are

Answer 14

That can differentiate into the three germ layers of the embryo

Question 15

Multiipotent stem cells are

Unipotent stems cells are

Answer 15

Such as hematopoietic stem cells that give rise to a family of cells including red blood cells and all various types of leukocytes.

Produce only one cell type but retain the property of self-renewal

Question 16

Two basic stem cells categories

Answer 16

Embryonic are pluripotent cells derived from the inner cell mass of the blastocyst stage of the embryo. Have the capacity to generate multiple cell lines.

Adult stem cells or tissue stem cells are new with use for regenerative medicine can potentially be use bone marrow stem cells can replace blood cells, fat cartilage bone endothelial and muscle cells.

Question 17

Influence of growth factor is generally applied to small proteins that inc cell size and cell division. What else do they assist?

Answer 17

Regulating the inflammatory process, serve as chemoattractants for neutrophils, monocytes, fibroblasts, keratinocytes, and epithelial cells, stimulate angiogenesis and contribute to the generation of the ECM. Many are produced by leukocytes, parenchyma or stromal cells in response to injury or loss.

Question 18

Extracellular matrix and Cell-matrix interactions

Two basic forms of ECM

Answer 18

The basement membrane, which surrounds epithelial, endothelial, and smooth muscle cells.

Interstitial matrix, which is present in the spaces between cells in connective tissue and between the epithelium and supporting cells of blood vessels.

Question 19

three basic components of the ECM

Answer 19

Fibrous structural proteins (collagen and elastin fibres)
Water-hydrated gels (proteoglycans and hyaluronic acid)) that permit resilience and lubrication
Adhesive glycoproteins (fibronectin, laminitin) that connect the matrix elements to one another and to cells

Question 20

What are integrins?

Answer 20

Are a family of transmembrane glycoproteins that are the main cellular receptors for ECM components such as fibronectin and laminitis. They bind many ECM components, initiating signaling cascades that affect cell proliferation and differentiation

Question 21

Fibroblasts are?

Answer 21

Reside in close proximity to collagen fibres, are responsible for the synthesis of collagen, elastic, and reticular fibres, and complex carbohydrates in the ground substance.

Question 22

What does ECM do?

Answer 22

Provides Turgor to soft tissue and rigidity to bone, it supplies the substratum for cell adhesion, it is involved in regulation of growth, movement and differentiation of the cells surrounding it, and it provides for storage and presentation of regularity molecules that control the repair process. Also provides the scaffolding for tissue renewal

Question 23

Healing by connective tissue repair is the restoration of injured tissue to its normal structure and function by proliferation of adjacent surviving cells. When regeneration cannot occur?

Answer 23

Scar formation, fibrosis is often used to describe the extensive deposition of collagen that occurs in organs that are incapable of regeneration.

Question 24

Three phases of repair by connective tissue deposition?

Answer 24

1. Hemostasis, angiogenesis, and in growth of granulation tissue
2. Emigration of fibroblasts and deposition of extracellular matrix
3. Maturation and reorganization of the fibrous tissue

Question 25

What is granulation tissue and what does it do?

Answer 25

Is a glistening reed, moist connective tissue that fills the inured area while necrotic debris is removed. It is composed of newly formed capillaries, proliferating fibroblasts, and residual inflammatory cells. It involves the growth of new capillaries angiogenesis

Question 26

What is angiogenesis and what does it do?

Answer 26

Growth of new capillaries, is a tightly regulated process that includes migration of endothelial cells to the site of tissue injury, formation of capillary buds, and proliferation of endothelial cells, followed by fusion and remodeling of the endothelial cells in capillary tubes. Several growth factors induce it are VEGF (stimulates both proliferation and motility of endothelial cells, thus mitigating the process of capillary sprouting and basic FGF-2 ( participates by stimulating the proliferation of endothelial cells.

Question 27

Emigration of fibroblasts and deposition of extracellular matrix. Scar formation builds on the granulation tissue framework of new vessels and loose ECM. What are the two phases?

Answer 27

1. Emigration and proliferation of fibroblasts into the site of injury
2. Deposition of extracellular matrix by these cells.

Growth factors FGF-2 TGF-B are released from endothelial cells and from inflammatory cells that are present at the site of injury

Question 28

Cutaneous wound healing involves both epithelial cell regeneration and connective tissue scar formation and thus is illustrative of general principles that apply to all tissues. Depending on the extent of tissue loss, wound closure and healing occur by?

Answer 28

Primary intention is a sutured surgical incision.
Secondary intention is larger wounds that have a greater loss of tissue and contamination
Secondary is slower and results in the formation of larger amounts of scar tissue

Question 29

Three phases of healing are and what are they?

Answer 29

1. Inflammatory phase - of wound healing begins at the time of injury and is a critical period because it prepares the wound environment for healing then the cellular phase of inflammation follows and is evidenced by the migration of phagocytize wbc
2. Proliferative phase - begins within 2-3 days of injury and last as long as 3 was healing by primary intention, key cell is fibroblast is a connective tissue that synthesizes and secretes collagen and other intercellular elements. The final components is epithelialization - migration, proliferation and differentiation of the epithelial cells at the wound edges to form a new surface layer that is similar to the pat destroyed by the injury.
3. Remodeling phase - begins approximately 3 wks after injury and can continue for 6 moths or longer, depending on the extent of the wound. There is continued remodeling of scar tissue by simutaneous synthesis of colagen by fibroblasts and lysis by collagenase enzymes.

Question 30

What Factors that affect wound healing?

Answer 30

1. Nutritional status - depends in part on adequate stores of proteins, carbohydrates, fats, vitamins, and minerals.
2. Blood flow and oxygen delivery - must have adequate blood flow to supply the necessary nutrients and to remove the resulting waste, local toxins bacteria, and other debris.
3. Impaired inflammatory and immune responses- inflammation is the essential to the first phase, and immune mechanisms prevent infections that impair healing
4. Infection, wound separation and foreign bodies. Can delay healing and infection to begin