1. CONNECTIVE TISSUE
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2. Connective Tissue Most widespread tissue
Fat, cartilage, rigid bones, fluid
Found in nearly every organ of the body
Made up mostly of matrix with relatively few cells
Qualities of the matrix and fibers largely determine the structural characteristics of each type of connective tissue

3. Classification of connective tissue
Fibrous
Bone
Cartilage
Blood

4. Fibrous connective tissue
Have extracellular fibers as their predominant feature
Strengthen and support CT
Arrangement of the fibers is what makes each type different

5. Fibrous connective tissue
3 Fiber types: collagenous, elastic, and reticular
Collagen=very strong, but flexible
Most abundant (bone, cartilage, and tendons)
Elastic=property of elasticity
Can stretch 150% from original shape without damage
Reticular=support tissues & organs
Frame soft organs (fat)

6. Fibrous connective tissue
Loose (areolar)
It forms the subcutaneous layer
Layer under the skin that connects skin to tissues and organs
Made of collagen, elastic, and reticular fibers
Fibroblasts: produce a gel-like substance
Creates the extracellular matrix
Macrophages: carry out phagocytosis

7. Loose CT Elastic fiber (black) Collagen fiber (Pink)
Fibroblast cells (purple)

8. Fibrous connective tissue
Adipose (fat)
Storage for excess food
Specialized for storage of triglyceride
Insulating material
Reduces heat loss through skin
Support and protection
fatty tissue layer over internal organs in anterior abdominal region

9. Fat storage area
Nucleus of adipocyte
Blood vessel

10. Fibrous connective tissue
Reticular (Loose CT)
Forms the framework of the liver, spleen, and lymph nodes
Help defend against invaders
Fibers in spleen filter and remove blood cells
Fibers in lymph filter and remove bacteria

11. Nucleus of reticular cell
Lymph Node
Reticular fiber

12. Fibrous connective tissue
Dense
Made mostly of fibers packed densely in the matrix
Regular: fibers are in parallel rows
Flexible, but great strength
Examples: tendons, ligaments
Irregular: the bundles are NOT parallel
Intertwine and form a thick material
Can withstand stress from any direction
Example: dermis and pericardium

13. Nucleus of fibroblast
Tendons
Collagen fiber
Periosteum – membrane surrounding bone
fibroblast
Collagen fiber

14. Bone connective tissue
One of the most highly specialized CTs
Osteocytes: mature bone cells
Contain Osseous Tissue: Spongy Bone or Compact Bone

15. Bone connective tissue
Function
Provide protection and support
Point of attachment for muscles
Helps move muscles
Serves as a mineral reservoir
Yellow marrow stores triglycerides
Blood production
Red marrow creates RBCs

16. Calcified extracellular matrix
Humerus
Lacuna (outer space of osteocyte)

17. Cartilage connective tissue
Chondrocyte (cartilage cells) – found in lacunaes
Avascular, so they receive nutrients through diffusion
No blood vessels = no blood supply
Perichondrium – membrane that allows for diffusion
Covers the surface of most cartilage
Heals very slowly if at all due to method of nutrient delivery

18. Cartilage connective tissue
3 types:
1. Hyaline: most abundant and weakest
very flexible and supportive, also reduces friction
2. Fibrocartilage: strongest
Serve as shock absorbers (ball & socket joints)
3. Elastic: contain very fine elastic fibers to add strength and flexibility (nose, ears, epiglottis, larynx)

19. trachea, nose, bronchi, etc
Hyaline:
trachea, nose, bronchi, etc
Elastic: Ear & Epiglottis
Fibro: Discs between vertebrate, menisci of knee, etc

20. Blood connective tissue
Most unusual connective tissue
contains neither ground substance nor fibers
Moves O2 and CO2 (RBCs)
Maintains body temp and regulates pH
Helps defend body (WBC)
Liquid part 55% (plasma)
Cells 45% (erythrocytes, leukocytes, thrombocytes)

21. Platelet
WBC
RBC
Plasma