Connective Tissue

Question 1

Fibroblasts

Answer 1

Most abundant connective tissue cell

Derived from mesenchymal cells

Fibrocytes: inactive fibroblasts

Question 2

Myofibroblasts

Answer 2

Intermediate between fibroblasts / smooth muscle cells

Abundant in areas of wound healing

Found in periodontal ligament - thought to be involved with tooth eruption

Question 3

Pericytes

Answer 3

Derived from mesenchymal cells
multipotential/pluripotential.
Surround endothelial cells of capillaries / small venules

Intermediate between endothelial cells / smooth muscle cells

Question 4

Types of collagen and examples

Answer 4

Type 1: Most widespread form, found in CT proper, bone, dentin, cementum

Type 2: found in cartilage

Type 3: Forms reticular fibers

Type 4: Found in basal lamina

Question 5

4 Categories of collagen

Answer 5

1. Collagen forms fibrils (type 1)
2. Fibril-associated collagens (bind fibrils to each other to other matrix componenets) - FACIT (fibril-associated collagens wwith interrupted triple helices)
   3.) Collagens forming anchoring fibrils (type VII collagen, binds basal lamina to reticular fibers)
   4.) Collagens forming networks (Type 4 collagen)

Question 6

Adipose cells & 2 types of fat cells

Answer 6

production of estrogen / leptin
synthesis / storage of triglycerides

Unilocular: one single lipid droplet fills entire cell (white fat)

Multilocular: Many small droplets in cytoplasm (brown fat) - heat generation

Question 7

Macrophages

Mononuclear phagocyte system

Answer 7

Phagocytosis of debris, bacteria, etc.

irregular shape, cytoplasm basophilic

mononuclear phagocyte system: arise from stem cells in bone marrow, become monocytes, mature into macrophages under M-CSF

Can fuse to form foreign-body giant cells

Question 8

Mast cells

Answer 8

ovoid, central spherical nucleus

cytoplasm filled with basophilic granules containing heparin, histamine, proteases, others

activated by binding of IgE to Fc receptors in response to presence of foreign antigens.

Question 9

Plasma cells

Answer 9

activated B lymphocytes

ovoid, intensely basophilic, lots of RER

produce antibodies

Question 10

Diapedesis

Answer 10

process where leukocytes escape from blood stream by squeezing between endothelial cells

Question 11

Reticular fibers

Answer 11

Very slender glycosylated fibers of type 3 collagen

form framework for liver, endocrine, lymphatic, hematopoietic tissues

Question 12

Elastic fibers

Answer 12

thinner than collagen fibers

made of elastin / microfibrils

Question 13

Ground substance composed of…

Answer 13

glycosaminoglycans, proteoglycans, adhesive glycoproteins

it is hydrated, amorphous

Question 14

embryonic connective tissues

Answer 14

mesenchymal connective tissue - formed of mesenchymal cells and gel-like ground substance with reticular fibers

mucous connective tissue - loose amorphous tissue found only in umbilical cord (wharton’s jelly)

Question 15

loose (areolar) connective tissue

Answer 15

abundant ground substance and tissue fluid

fibroblasts, adipocytes, macrophages, mast cells, undifferentiated cells

collagen, reticular and elastic fibers

Question 16

Dense connective tissue

Dense irregular, dense regular collagenous, dense regular elastic CT

Answer 16

more fibers, less cells and ground substance than loose CT

dense irregular CT: collagen fibers arranged in multiple orientations, serving to resist stress from all directions

dense regular collagenous CT: collagen bundles packed parallel to each other, resisitng tensile forces

dense regular elastic CT: contains mostly elastic fibers, with little collagen.

Question 17

Reticular connective tissue

Answer 17

contains type 3 collagen fibers forming a meshwork which supports the parenchyma of liver sinusoids, adipose tissue, bone marrow, lymph nodes, spleen, smooth muscle, islets of langerhans

Question 18

adipose tissue

Answer 18

made of adipocytes with supporting connective tissue