4. Introduction To Microanatomy: Connective Tissue

Question 1

1. Identify and describe the main components of connective tissue (objective)

Answer 1

Answer later

Question 2

2. Identify and describe the main types of connective tissue proper (objective)

Answer 2

Answer later

Question 3

Connective Tissue: Overview 1/5

Answer 3

Provides a matrix that serves as structural support and physically connects tissues and cells together to form organs

Question 4

Connective Tissue: Overview 2/5

Answer 4

Provides metabolic support to cells/serves as medium for diffusion of nutrients and waste products
-Important site for storage of water, electrolytes and lipids

Question 5

Connective Tissue: Overview 3/5

Answer 5

Plays a role in defense against foreign objects (gel-like consistency of matrix provides physical barrier, also home to inflammatory and immune cells)

Question 6

Connective Tissue: Overview 4/5

Answer 6

Helps regulate cell-cell signaling by binding signaling molecules (regulates growth and depth of tissues)

Question 7

Connective Tissue: Overview 5/5

Answer 7

Differs from other tissue types in structure: composed mostly of extracellular material with relatively few cells

Question 8

Cells of Connective Tissue: Mesenchymal Cells

Answer 8

Undifferentiated cells that produce all types of proper and specialized connective tissue and contain stem cells for other tissue (blood, muscle)

Give rise to fibroblasts and lipoblasts

Question 9

Cells of Connective Tissue: Fibroblasts

Answer 9

• Most common cells in connective tissue proper
• Produce and maintain collagen and elastin to form fibers
• Synthesize and secrete components of ground substance

Question 10

Cells of Connective Tissue: Lipoblasts

Answer 10

• Give rise to adipocytes (fat cells) specialized for cytoplasmic storage of lipid
• Tissue with large population of adipocytes also serve to cushion and insulate (skin, kidney)

Question 11

Cells of Connective Tissue: Macrophages

Answer 11

-Specialize in removal of dead cells and tissue debris, bacteria and other foreign material
-Can activate immune system and promote inflammatory response
-Secrete enzymes to break down dead tissue and growth factors to promote repair and healing
Ex. Removing E. Coli bacteria

Question 12

Cells of Connective Tissue:

Mast Cells

Answer 12

• Type of immune cell which stores chemical mediators important in localized immune response and tissue repair
• Often located near blood vessels, in tissue lining digestive and respiratory treat (areas where threats can be detected)

Question 13

Extracellular Matrix

Answer 13

-Contains structural proteins (collagen and elastin fibers) embedded in viscous gel made up of protein-polysaccharide complexes (proteoglycans), water, and adhesive glycoproteins that bind to matrix proteins and cell membrane proteins (laminin, fibronectin)

Question 14

Fibers 1/3

Answer 14

Formed from proteins secreted by fibroblasts

Question 15

Fibers 2/3

Answer 15

3 main types: 2 types made of collagen (collagen, reticular) and 1 type made of elastin (elastic)

Question 16

Fibers 3/3

Answer 16

Types of fibers distributed unequally among different types of connective tissue- predominate fiber type confers tissue properties

• Collagen/reticular: impart tensile strength (shearing), provide supporting framework
• Elastic: imparts elasticity and resilience, allows for deformation and recoil

Question 17

Collagens 1/2

Answer 17

• 30% of body (dry weight), most common protein type

- Family of proteins which are extremely strong and resistant to shearing/tearing forces

Question 18

Collagens 2/2

Answer 18

Categorized by formed structures:

• Fibrillar: Type I most abundant and widely distributed, forms collagen fibers of ECM), Type III forms reticular fibers
• Network/sheet-forming: Type IV major structural proteins of basement membranes
• Linking/anchoring: Type VII anchors layers of basement membrane to each other

Question 19

Collagen Fibers

Answer 19

Abundant in dermis, organ capsules, tendons and ligaments

Largest, thick pink bands on A&E, collagen, wavy and do not branch (run in bundles), strength, tendon/ligament

Question 20

Reticular Fibers

Answer 20

Forms delicate network of thin fibers that provide supportive stroma for bone marrow, lymph nodes, organs including liver and spleen
Can’t see on A&E, need Silver Stain

Smallest, reticulin, not wavy and branch/intersect, support, spleen/lymph nodes/bone marrow/inside organs

Question 21

Elastic Fibers

Answer 21

Form sparse networks interspersed with collagen bundles in tissue subject to stretching or bending (skin, vertebral ligaments, elastic arteries, vocal cords)
Elastic: medium, thinner pink bands on A&E, elastin, less wavy and branch (run singly), elasticity, lungs/aorta/blood vessels

Question 22

Connective Tissue: Classification

Answer 22

By ratio of components

• Loose: composed of cells, fiber, ground substance in equal amounts (if see ground substance in between clue)
• Dense: densely packed collagen fibers with fewer cells
• –Regular: fibers aligned in parallel
• –Irregular: fibers randomly interwoven

Question 23

Connective Tissue Proper: Loose (areolar)

Answer 23

Description: gel-like matrix with all three fiber types; cells: fibroblasts/macrophages/mast cells/some wbc’s
Function: cushion organs, phagocytize bacteria, inflammation, hold/conveys tissue fluid
Location: widely under epithelia, makes up LAMINA PROPRIA

Question 24

Connective Tissue Proper: Loose (adipose)

Answer 24

Description: matrix like areolar but very sparse; closely packed fat cells, have nuclei pushed to side of large fat droplets
Function: reserve food fuel; insulates against heat loss; supports/protects organs
Location: under skin; around kidneys and eyeballs; within abdomen; in breasts.

Question 25

Connective Tissue Proper: Loose (reticular)

Answer 25

Description: network of reticular fibers in typical loose ground substance, reticular cells lie on network
Function: fibers form soft internal skeleton (stroma) that supports other cell types (including wbc’s, mast cells, macrophages)
Location: lymphoid organs (lymph nodes, bone marrow, spleen)

Question 26

Connective Tissue Proper: Dense (dense regular)

Answer 26

Description: primarily parallel collagen fibers; few elastin fibers; major cell type is fibroblast
Function: attaches muscles to bones or to muscles; attach bones to bones; withstand tensile stress when pulling force is applied one direction
Location: tendons/ligaments/aponeuroses

Question 27

Connective Tissue Proper: Dense (dense irregular)

Answer 27

Description: primarily irregularly arranged collagen fibers; some elastic fibers; fibroblasts is major cell type
Function: withstand tension exerted in many directions; structural strength
Locations: fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract