Connective Tissue l l Includes the most abundant

Connective Tissue l l Includes the most abundant and widely distributed tissues Functions: l l l Binds body tissues together Supports the body Provides protection

Connective Tissue Characteristics l l l Most tissue types are well vascularized (bone, adipose, reticular, areolar) Some have poor blood supply or are avascular (cartilage, ligaments, tendons) matrix l Non-living material that surrounds living cells

Extracellular Matrix (cont. ) l Two main elements of matrix: l l 1. Ground substance – mostly water along with adhesion proteins and polysaccharide molecules 2. Fibers (3) – made by the cells § § § Collagen fibers (strongest) Elastic fibers Reticular fibers (delicate)

Connective Tissue Types l Bone (osseous tissue) l l Composed of: l Bone cells-(osteocyte) in lacunae (cavities) l Hard matrix of calcium salts l Large numbers of collagen fibers Used to protect and support the body Figure 3. 19 a

Connective Tissue Types l Hyaline cartilage l l Most common cartilage Composed of: l l Abundant collagen fibers Rubbery matrix Cells - chondrocyte Examples: entire fetal skeleton, ends of long bones Figure 3. 19 b

Connective Tissue Types l Elastic cartilage l l Provides elasticity Example: ear, wall of aorta

Connective Tissue Types l Fibrocartilage l l Highly compressible Example: cushion-like discs between vertebrae Figure 3. 19 c

Connective Tissue Types l Dense connective tissue l l l Main matrix element is collagen fibers Cells are fibroblasts Examples l Tendon – attach muscle to bone l Ligaments – attach bone to bone Figure 3. 19 d

Connective Tissue Types l Areolar (loose) connective tissue l l Most widely distributed connective tissue Soft, pliable tissue Contains all fiber types Ex. packs most of our organs Figure 3. 19 e

Connective Tissue Types l Adipose tissue (fat) l l l Matrix is an areolar tissue Storage, cushions, protects, insulates Examples? Figure 3. 19 f

Connective Tissue Types l Reticular connective tissue l l Delicate network of fibers Examples: l Lymph nodes l Spleen l Bone marrow Figure 3. 19 g

Connective Tissue Types l Blood l l Blood cells surrounded by fluid matrix (plasma) RBC’s, WBC’s and platelets Figure 3. 19 h

Muscle Tissue Types (3) l 1. Skeletal muscle l l l voluntary striated have more than one nucleus (multinucleate) Figure 3. 20 a

Muscle Tissue Types l 2. Cardiac muscle l l l Found only in the heart (involuntary) Cells attached to each other at intercalated disks striated One nucleus per cell Figure 3. 20 b

Muscle Tissue Types l 3. Smooth muscle l l Involuntary No visible striations (smooth) One nucleus per cell Ex. Lines hollow organs, blood vessels, reproductive tracts Figure 3. 20 c

Nervous Tissue l l Neurons and nerve support cells send impulses to other areas of the body Figure 3. 21

Tissue Repair (2 ways) l 1. Regeneration l l Replacement of destroyed tissue by the same kind of cells 2. Fibrosis (scar tissue) l l Repair by dense fibrous connective tissue (scar tissue) Tissues that are replaced largely with scar tissue: l Cardiac muscle l Nervous tissue within the brain and spinal cord l Joints (knee and elbow)

Developmental Aspects of Tissue l l With old age there is a decrease in mass and viability in most tissues (atrophy) Atrophy will also occur when tissues (muscles) are not used l Most prominent in muscles