Fibrous Connective Tissue

Question 1

What are the functions of connective tissue?

Answer 1

Structural framework of the body (bones)
Protection
Supports and interconnect other tissues 
Energy storage (adipose)
Transport fluids, cells, and dissolved chemicals (blood)
Defense against invasion

Question 2

What are the 3 types of cells that makeup the fibrous component of the ECM?

Answer 2

Collagens= resist tension

Elastin= stretchable fiber

Reticular Fibers= supportive meshwork

Question 3

What is the most common type of collagen? What is its role in the ECM?

Answer 3

Type-1, see banding in electron micrographs

When cross-linked increase tensile strength
- alpha 1 and 2 trimers released as procollagen on the surface and crosslinked

Question 4

What makes up the Amorphous Ground Substance of the ECM?

Answer 4

Proteoglycans= protein + sugar covalently linked, neg charge so suck up water

• chondroitin sulfates
• heparan sulfates
• keratan sulfates

Hyaluronan= linke proteoglycans

Glycoproteins= cytokines, growth factors, structural proteins

Extracellular Proenzymes

Question 5

What are integrin receptors role in the ECM?

Answer 5

Bind specific ECM components and initiate intracellular signaling for Cell-ECM interactions

Co-receptor examples: Syndecans, CD44 (bind hylauronan), selectins, GF receptors, cytokine receptors

Question 6

What are structural features of embryonic connective tissue?

Answer 6

Rich in ECM= a lot of proteoglycans, well hydrated, not as many collagen or reticular fibers
Rich in mesenchymal stem cells

Question 7

What is embryonic connective tissue in the umbilical cord often referred to as?

Answer 7

Warton’s jelly

Question 8

What do adult mesenchymal stem cells differentiate into?

Answer 8

Fibrobalsts
Muscle cells
Osteoblasts
Chondroblasts
Adipocytes

Question 9

What are the 3 types of loose connective tissue? What are their defining characteristics?

Answer 9

Lots of proteoglycans

Areolar= low density with fixed and wandering cells, widespread

Adipose= fat

Reticular= mesh for holding free cells

Question 10

What are the 3 types of dense connective tissue? What are their defining characteristics?

Answer 10

Big bundles of collagen

Irregular= deposited in random pattern, dermis of skin

Regular= highly regular, tendons connecting skeletal muscle to bone

Elastic= rich in elastin fibers

Question 11

What cells are fixed cells in loose areolar connective tissue?

Answer 11

Fibroblasts
Adipocytes
Mesenchymal Cells

Question 12

What type of cells are wandering cells in loose areolar connective tissue?

Answer 12

Macrophages
Mast Cells
Leukocytes/Lymphocytes
Plasma Cells

Go in and out of CT through circulation

Question 13

What is the function of Loose Connective Tissue? Where are they found?

Answer 13

Support and bind tissues, hold body fluids, defend against infection

Found immediately beneath membranous epithelia and around blood vessels, muscles, and nerves

Question 14

Where is loose areolar connective tissue found?

Answer 14

SI villis

not very strong

Question 15

What is the role of adipose CT? Where is it found?

Answer 15

Abundant in adipocytes and sparse ECM, very well vascularized

Provides reserve energy source, insulates against heat loss
Supports and protects organs

Under skin and around organs
- kidney, eyeballs, abdomen, breast, buttocks

Question 16

What is the difference between white and brown fat?

Answer 16

White= energy storage, insulation, cushioning vital organs, hormone secretion

Brown= thermogenic tissue, abundant in newborns greatly reduced in adults

Question 17

What is the role of Reticular CT? Where is it found?

Answer 17

Forms open framework to create a labyrinth for holding free cells

Bone marrow, lymph nodes and spleen
- meshwork houses blood cells and immune cells outside the blood and lymphatic vessels

Question 18

What characterizes Dense Irregular CT? What is its principle cell type? Where is it found?

Answer 18

Tightly packed, interwoven collagen fibers running in a random pattern

Fibroblasts

Dermis of skin, capsules that surround internal organs, perichondrium (collagen) and periosteum (bone), fascia

Question 19

What characterizes Dense Irregular CT? What is its principle cell type? Where is it found?

Answer 19

Tightly packed regularly arranged collagen fibers

• resists pulling forces
• poorly vascularized

Fibroblasts

Tendons, ligaments, aponeuroses, dense fascia, joint capsules (places with lots of tension)

Question 20

What characterizes Dense Irregular CT? Where is it found?

Answer 20

High proportion of elastic fibers that allows the recoil of tissue following stretching

Found in blood vessel walls, bronchiole tubes, and special ligaments (ligamentum nuchae)

Question 21

What is Marfan’s Syndrome?

Answer 21

Autosomal dominant, mutation in fibrilin-1 gene

Targets ocular, skeletal, and cardiovascular systems
- life threatening cardio anomalies (dissecting aneurysms)
Tall with long arms and legs

Question 22

What is the role of a fibroblast?

Answer 22

With the BM functions to produce the collagen, elastin, reticular fibers, proteoglycans, and glycoproteins in the ECM

Question 23

What is the role of adipocytes?

Answer 23

Remove lipids from blood, store them, and then release them again when needed (energy reserve)

Very well vascularized
Closely packed with nuclei pushed to side because of fat droplet

Question 24

What is the role of macrophages?

Answer 24

Phagocytosis

Question 25

What is the role of mast cells?

Answer 25

secrete chemicals that mediate the allergic response and anti-coagulation, serine proteases chemoattractants

• normally around blood vessels
• filled with granules

Key feature= lobulated nuclei

Question 26

What is the role of Plasma Cells?

Answer 26

Differentiate from B-lymphocytes

Produce antibodies to mediate immunity