Connective Tissue The Big Connection! Chapter 4 Anatomy and Physiology Mr. Knowles Liberty Senior High School

All C.T. have Three Parts 1. Specialized Cells 2. Extracellular Protein Fibers 3. The Fibers above and a ground substance - make up the Matrix that surrounds cells. (most of the volume of C.T.)

Differences Between C.T. and other Tissues

In general, C. T.... Found throughout the body Never exposed to outside environment Many C.T.s are highly vascular and/or have sensory receptors.

Functions of C.T. Structural framework for body. Transportation of fluids and materials. Protection of delicate organs.

Functions of C.T. Supporting and interconnecting other tissue types. Store energy reserves (lipids). Defending the body from pathogens.

1. The Cells Fibroblasts- most abundant, present in every C.T. Proper; they secrete polysaccharide and proteins-->ground substance (very viscous); also secrete extracellular fibers. Macrophages- part of immune system that engulfs pathogens and damaged cells.

Show me a macrophage!

1. The Cells Adipocytes- “fat cells”; store lipids in a huge droplet; number may vary from C.T. type. Mesenchymal Cells- stem cells that can differentiate into fibroblasts and macrophages.

1. The Cells Melanocytes- synthesize and store melanin (pigment). Mast Cells- small mobile cells of immune system; make histamine and heparin. Lymphocytes- migrating immune cells that produce antibodies.

2. The Fibers Collagen Fibers- long, straight, unbranched, fibers of fibrous proteins; rope-like, very flexible, yet strong. (Tendons and Ligaments)

Collagen Fibers

2. The Fibers Reticular Fibers- same protein subunits as collagen; branched network of fibers, thinner than collagen; form an interwoven network; resist forces from multiple directions; stabilize organs.

2. The Fibers Elastic Fibers- contain the protein elastin as a subunit; branched, thin and wavy fibers; after they stretch they return to original length; (elastic ligaments in vertebrae).

What would happen if a person’s elastic fibers were not properly formed?

Williams’ Syndrome- Abnormal Elastic Fibers

The Mind Traveler: Don’t Be Shy Mr. Sacks Williams’ Syndrome

3. Ground Substance Fills the space between cells and fibers. In C.T. Proper, it is clear and viscous; very thick due to proteoglycans and glycoproteins.(maple syrup)

3. Ground Substance Density slows the spread of pathogens. Ex. Of Deficiency: Marfan’s Syndrome (fibrillin glycoprotein)

Marfan Syndrome- Dominant Mutation Marfan’s Syndrome- mutation in the fibrillin gene (glycoprotein in connective tissue).

A Marfan’s Sufferer ?

Medical Mysteries: Giants Marfan’s Syndrome

I. C.T. Proper- A. Loose C. T. Areolar- “packing material” of the body. Fills spaces between organs, provides cushioning, and supports epithelia. Open framework with much ground substance to cushion shock.

A. Loose C. T. Loosely organized fibers- allow distortions. Elastic fibers- allow resilience Has extensive circulatory system. (site of injections, epithelia)

Areolar Tissue

1. Adipose Tissue Most of volume is adipocytes. Provide padding, cushions shock, act as insulator, energy storage. Under skin of buttocks, sides, and breasts, fills bony sockets behind eyes. Ex. Brown Fat in Infants.

A Bunch of Brown Fat

Adipose Tissue, Low Magnification

Adipose Tissue, High Magnification

Does the Cell Make Me Look Fat? Nucleus Stored Fat

1. Adipose Tissue Do adipocytes continually divide in adults? How do we acquire more fat tissue? Is liposuction a permanent solution? Answers on p. 124, Martini, 4 th Edition

Show me some adipose tissue! Discovery: Body Story Series- Baby (Brown Fat in an Infant) Oprah Video - Adipose from an Autopsy

2. Reticular Tissue Composed of reticular fibers. Create a complex, 3-D network (stroma) that supports the cells of an organ. In which direction is this C.T. strongest?

Reticular Tissue Reticular Fibers

B. Dense C. T. Most of the volume is fibers- collagen. Two Types: –Dense Regular C. T. –Dense Irregular C. T.

1. Dense Regular C. T. Collagen fibers are parallel (aligned with the forces applied to tissue).

1. Dense Regular C. T. a.) Tendons-cords that attach bone to skeletal muscle. b.) Ligaments- connect bone to bone. c.) Elastic Tissue-mostly elastic fibers (resilient); around blood vessels and elastic ligaments.

Dense Regular Tissue

2. Dense Irregular C. T. Form interwoven meshwork. (Function?) Strength and support. Skin its strength (cured leather). Capsule around organs- protection.

Dense Regular - Elastic Tissue

II. Fluid Connective Tissue A. Blood- specialized cells in fluid matrix; has soluble fibers normally! 1. Cells- a. Leukocytes (WBC’s) like neutrophils, eosinophils, lymphocytes-immune cells.

Neutrophil and Eosinophil

Leukemia

Blood b. Erythrocytes (RBC’s)- transport O 2 /CO 2 ; most common cell. c. Platelets- contain enzymes and other proteins for clotting.

Erythrocyte

Blood 2. Ground Substance- called plasma, mostly water and dissolved solutes and large proteins. 3. Extracellular Fibers- normally not present until needed to form blood clots.

Blood Clot

B. Lymph Lymph- interstitial fluid that enters the cardiovascular system. 1. Cells- lymphocytes. 2. Ground substance- water without large proteins. 3. Fibers- very little present.

III. Supporting Connective Tissue A. Cartilage- 1. Cells- chondrocytes-only cells of matrix; live in pockets called lacunae. 2. Ground Substance- thick gel of proteoglycans secreted by chondrocytes. 3. Fibers- are a proteoglycan + collagen or elastic fibers.

Characteristics of Cartilage Cartilage is avascular-chondrocytes secrete antiangiogenesis factor (cancer treatment drug). Cartilage is slow to heal. Why? Cartilage is surrounded by a perichondrium which is a C.T. Proper.

Types of Cartilage 1. Hyaline- most common; loosely packed collagen fibers; flexible but tough. Function: reduce friction between bony surfaces; covers bony surfaces. Ex. Ribs/sternum, articular cartilages.

Hyaline Cartilage- Low Mag.

Hyaline Cartilage- High Mag.

Types of Cartilage 2. Elastic- mostly elastic fibers; resilient and flexible. Function: provide support but resist distortion without damage. Ex. Tip of nose, pinna of ear, epiglottis.

Elastic Cartilage- Low Mag.

Elastic Cartilage- High Mag.

Types of Cartilage 3. Fibrocartilage- little ground substance; matrix mostly collagen fibers. Fibers are interwoven making it tough and durable. Function: resist compression and absorb shock between bone-to-bone contacts. Ex. Pads within knee joint, intervertebral discs.

Fibrocartilage- Low Mag.

Fibrocartilage- High Mag.

Examples of Stem Cell Research and Growing Cartilage and Bone Scientific American: November 1991 issue. Movie: Science Times Scientific Frontiers: Never Say Die

Bone (Osseous Tissue) G.S. = collagen fibers + calcium salts (CaPO 4 and some CaCO 3) Strong and flexible properties. Lacunae in matrix contain osteocytes.

Bone (Osseous Tissue) Lacunae organized around a central canal (Haversian canal) which contains blood vessels. Diffusion cannot occur through calcium salts. Cytoplasm of osteocytes extend to central canal by canaliculi.

A Basic Pattern in Bone Tissue Lacunae with osteocytes arranged around and connected to a central canal by radiating canaliculi- Osteon Many osteons in one bone.

Bone (Osseous Tissue) G.S. = collagen fibers + calcium salts (CaPO 4 and some CaCO 3) Strong and flexible properties. Lacunae in matrix contain osteocytes.

Rickets

Rickets X-ray

Bone (Osseous Tissue) Bone surfaces covered by periosteum- fibrous layer of C.T.; attachment for tendons and ligaments. Site of appositional growth of bone. Bone is constantly remodeled- grow thicker with stresses.

Osteon

Bone-Low Mag.

Bone-High Mag.

Bone

Can we ever grow tissue? What kinds of tissue can regenerate? Scientific American special issue, October 1999 Science Times: Tissue Regeneration video