Tissues and tissue repair LO 5, LO7

Question 1

Formation of tissues

Answer 1

Cell differentiate from stem
cells into specialised cells to
form 4 primary tissue types

Question 2

Nervous tissue

Answer 2

• nervous tissue is the main component of the
  brain, spinal cord and nerves
• composed of neurons and supporting cells
• communication
• transmits electrical signals to regulate and control body functions

Question 3

Muscle tissue

Answer 3

• composed of muscle cells that contain contractile
  microfilaments
• specialised for contraction to allow movement
• skeletal muscle – voluntary skeletal movement
• cardiac muscle – involuntary and found in heart
• smooth muscle – involuntary in blood vessels, gut, bladder, uterus

Question 4

Epithelial Tissue

Answer 4

• epithelium is a sheet of cells that can
• cover the body
• line cavities and internal organs
• form glands
• oxygen & nutrients delivered by
  diffusion from connective tissue

Question 5

Connective tissue (CT)

Answer 5

• is the connecting tissue of the body
• specialised cells
• ground substance
• protein fibers
  classes include: CT proper, carliage, bone, blood

Question 6

ground substance CT

Answer 6

unstructured material that fills space between cells
and contains protein fibers
* holds large volume of water called interstitial fluid
* ranges from liquid to solid

Question 7

protein fibers CT

Answer 7

collagen fibers: tough fibers with high tensile strength to resist
twisting and pulling forces
* elastic fibers: long thin fibers for stretch and recoil
* reticular fibers: short fibers continuous with collagen fibers

Question 8

3 stages of repair

Answer 8

Stage 1: Inflammation
Stage 2: Organisation or proliferation
Stage 3: maturation or remodelling

Question 9

Stage 1: Inflammation

Answer 9

Function: prepares the wound for repair, eliminates invading microorganisms and removes debris and dead tissue.
* blood vessels become more permeable
➢ macrophages: engulf debris/invading microorganisms
➢ clotting proteins: produce a blood clot to stop blood loss, hold wound
together and prevent any further invasion of microorganisms
* signs: redness, pain, heat & swelling
* clot on surface dries and forms a scab

Question 10

Stage 2. Organisation or proliferative stage

Answer 10

• Function: extracellular matrix synthesis including collagen & restore a blood
  supply
• blood clot is replaced by granulation tissue composed of:
  ➢ capillaries that grow across the wound to
  restore blood supply, bring oxygen and nutrients required for healing
  ➢ fibroblasts → produce collagen fibers that bridge the gap
  ➢ macrophages → engulf cell debris, invading microorganisms and blood clot
• epithelial stem cells multiply and migrate
  over the granulation tissue

Question 11

Stage 3. Maturation or remodelling

Answer 11

Function: complete permanent skin repair by regeneration and fibrosis
* collagen is remodeled and contracts to pull wound edges together
* existing blood vessels are compressed, granulation tissue is replaced by
scar tissue → fibrosis
* scar tissue is avascular, tough but no elasticity or flexibility, no hair, sweat or
oil glands
* regeneration where epidermal stem cells multiply and grow under scab and regenerate
epidermis → scab falls off and skin reflects preinjury tissue
* if a major wound: scar tissue visible if repair only by fibrosis
* if a major wound: scar tissue invisible if repair by regeneration & fibrosis