Connective Tissue

Question 1

Derived from what embryonic tissue?

Answer 1

mesenchyme (middle germ layer)

Question 2

ground substance

Answer 2

amorphous gel like substance. Part of extracellular matrix.

Question 3

Components of ground substance (3)

Answer 3

Glycosaminoglycans (GAG), proteoglycans, adhesive glycoproteins

Question 4

Glycosaminoglycans (GAG)

Answer 4

long inflexible unbranched polysaccharides

Question 5

proteoglycans

Answer 5

proteins and GAG. attracts water to make tissue bulky and resist compression/pressure. Slow movement of cells.

Question 6

Adhesive glycoproteins

Answer 6

large macromolecules with cell surface proteins (integrins). Fastens tissue components together.

Question 7

Collagen

Answer 7

most prevalent protein in body. Forms various structures for different functions (cables, sheets, etc)

Question 8

Collagen type 1

Answer 8

Location: dermis of skin, bone, capsules of organs, fibrocartilage, dentin, cementum, tendons. (places where there is siginificant force and tension.

Function: resists tension and pull

Question 9

Collagen type II

Answer 9

Location: hyaline and elastic cartilage

Function: resistance to pressure

Question 10

Collagen type III

Answer 10

AKA reticular collagen

Location: reticular fibers of spleen, liver, cardiovascular system, lungs, skin. (In organs having structural framework)

Function: structural support

Question 11

Collagen type IV

Answer 11

Location: basal lamina (structure associated with epithelial cells)

Function: support and filtration

Question 12

Collagen type V

Answer 12

Location: fetal tissues, placenta, dermis, bone, most interstitial tissues

Function: associated with type 1

Question 13

Collagen type VII

Answer 13

Location: skin

Function: anchors epidermal basal lamina to underlying dermis

Question 14

Collagen groups based on structures formed:

Answer 14

Fibrillar collagens: types I, II, III. Have subunits that aggregate to form large fibrils (can see on electron or light microscope)

Sheet forming collagens: type IV. To do with basement membrane. Subunits produced by epithelial cells. Major structural proteins of external laminae and basal lamina in epithelia

Linking/anchoring collagens (type VII): short collagens that link fibrillar collagens to one another and to components of ECM

Question 15

Elastic fibers

Answer 15

seen mostly in organs subject to bending/stretching

thinner than type 1 collagen. Form sparse network interspersed with collagen bundles

protein cross link holds elastin aggregates together

Question 16

Reticular fibers

Answer 16

mostly type III collagen

narrow, branching, don’t bundle

Question 17

Stroma

Answer 17

scaffolding/framework. Supporting tissue of epithelial organ, tumor, gonads

Question 18

Select fixed/resident cells

Answer 18

stay in connective tissue their whole lives

Question 19

Connective tissue cellular components (6)

Answer 19

Fibroblasts, active fibroblasts, inactive fibroblasts, myofibroblasts, adiposytes, pericytes

Question 20

Fibroblasts

Answer 20

originate locally from mesenchymal cells. Most abundant cell type. Active or quiescent state (fibrocytes)

Question 21

active fibroblasts

Answer 21

found in close association with collagen bundles. elongated fusiform cells. Large, granular, ovoid nucleus; well defined nucleolus.

Question 22

inactive fibrobalst

Answer 22

smaller than active. May differentiate into adipose cells, chrondrocytes, osteoblasts (under extreme stress/trauma)

Question 23

myofibroblasts

Answer 23

modified fibroblasts that demonstrate characteristics of both fibroblasts and smooth muscle cells. Not easily distinguishable by LM. Abundant where wound healing takes place. Also in periodontal ligament. Bundles of actin filaments and dense bodies similar to those of smooth muscle cells.

Question 24

Adipocytes

Answer 24

fully differentiated cells, function in synthesis, storage, and release of fat. Found throughout body in loose CT, concentrated along blood vessels. Masses form adipose tissue (15-20% of body weight)

Question 25

Adipocytes of white fat

Answer 25

large spherical cells, polyhedral when in adipose tissue. Store fat in single droplet. Unicellular. Energy reserve

Question 26

Adipocytes of brown fat

Answer 26

brown fat cells smaller and more polygonal than white fat. Stores fat in several small droplets. Lots of mitochondria so stains darker than white fat. Multicellular. Thermogenic, lose after infancy

Question 27

pericytes

Answer 27

surround endothelial cells of capillaries and small venules. Have characteristics of smooth muscle cells and endothelial cells. Long processes coming off that associate with small capillaries

Question 28

Transient cells

Answer 28

Come and go from CT. Plasma cells, leukocytes, macrophages, immune cells

Question 29

Functions of CT (4)

Answer 29

• structural support
• medium for nutrient exchange
• aiding in defense and protection of body (via immune cells and ‘cushioning’)
• site for fat storage

Question 30

Mesenchyme

Answer 30

derived mainly from mesoderm. Loosly packed stem cells in gel like extracellular matrix.

Question 31

Loose CT

Answer 31

abundant ground substance, below lining of internal body cavity. Surrounds parenchyma of glands. Very pliable and flexible

Question 32

Lamina propria

Answer 32

loost CT in GI tract that allows nutrients to diffuse to epithelium

Question 33

Dense irregular CT

Answer 33

abundant collagen fibers, resistant to stress, tightly packed and not well organized.

location: dermis of skin, lymph node capsule

Question 34

Dense regular CT (2 types)

Answer 34

Collagenous: abundant collagen fibers organized in parallel cylinders along lines of force/stress. Resistent to tensile stress.
Location: tendons, ligaments.

Elastic: abundant elastic fibers in parallel to form thin sheets. Resistant to tensile stress.
Location: large blood vessles