Transcript
Section 2, Chapter 5
Connective Tissues
Characteristics of Connective Tissues (CT)
Cells are separated by non-cellular material, called the extracellular matrix
Most connective tissues have good blood supply
Most cells divide (to recover from injury)
nucleus of cell
Extracellular matrix
Elastic Cartilage
FibroblastsSecretes protein fibers into matrix
Mast CellsSecretes histamine & heparin into blood
Mast CellFibroblast
Cell Types
Examples of fixed cells
Cells of CT may either be fixed in place (resident cells) or they may be wandering cells
Wandering cells move throughout the tissues.
Example of a wandering cell: Macrophages
Macrophages actively move about during infection phagocytizing bacteria & debris.
macrophages
The matrix of most CT contains protein fibers & a non-protein ground substance
extracellular matrix of connective tissues
Protein FibersProtein fibers are secreted by fibroblasts.
3 types of protein fibers include elastic fibers, collagen fibers, and reticular fibers
1. Collagenous fibersThick bands of protein
Collagen fibers are flexible, but only slightly elastic
They exhibit great tensile strength that resists pulling
Collagenous fibers forms the bulk of ligaments & tendons
Most abundant protein in mammals
Protein Fibers
Ligaments connect bone to bone
Tendons connect muscle to bone
2. Elastic FibersComposed of a spring-like protein, called elastin.
Elastic fibers are weaker than collagen, but exhibit elastic recoil
Elastic fibers can be easily stretched or deformed and they retain their shape.
Locations: vocal cords, respiratory tract, blood vessels
Protein Fibers
Figure 5.17 Scanning electron micrograph of collagenous fibers and elastic fibers
3. Reticular FibersConsist of thin strands of collagen fibers
Reticular fibers form an interwoven matrix, called a reticulum.
Reticular fibers fill the spleen, liver, and lymph nodes
Reticular fiber
Protein Fibers
Types of connective tissue
Loose Connective Tissue Dense Connective TissueAreolar Dense Regular C.T.Adipose Dense Irregular C.T.Reticular Elastic C.T.
Connective Tissue Proper
Specialized Connective TissueCartilageBoneBlood
Connective tissue is often divided into two categories 1. CT proper 2. Specialized CT
Areolar tissue consist of a loose network of collagen and elastic fibers produced by fibroblasts.
Areolar tissue forms delicate membranes that loosely bind organs together
Locations subcutaneous layer of skin between muscles surrounds organs
Areolar Tissue
Functions anchors skin to underlying organs holds organs in place
LocationsBeneath the skin – subcutaneous fatWithin abdominal cavity – visceral fatSurrounds kidneys & eyeballsSurface of heart
Adipose Tissue (fat)
StructurePrecursor cells resemble fibroblasts, but as they accumulate fat droplets in the cytoplasm they become adipocytes.
Functions of adipose stores energy insulation cushions organs secretes estrogens
StructureReticular CT contains fibroblasts along with a network of thin collagenous fibers arranged into a reticulum.
Locations include the framework of Spleen LiverLymph nodes
Reticular Connective Tissue
Functions of reticular CT forms the framework of some organs
reduces the flow of fluid through an organ
Dense Regular Connective Tissue
Structure:Dense Regular CT contains relatively few fibroblasts with densely packed collagenous fibers in parallel arrangement.
Functions: Great tensile strength that withstands pulling forces especially in one direction
Locations:Tendons & Ligaments
Dense CT has a poor blood supply so they are slow to heal following an injury.
Dense Irregular Connective Tissue
StructureDense Irregular CT contains fibroblasts with a dense network of interwoven collagenous fibers
FunctionsDense Irregular CT withstands pulling forces in all directions
LocationDermis of skin
Dermis (deep layer) of skin
Elastic Connective Tissue
StructureElastic CT contains fibroblasts along with a dense arrangement of elastic fibers, with a few collagen fibers.
Functions Elastic recoil
Locations Walls of larger arteries and the respiratory tract
Cartilage Overview
Functions of cartilagesProvides attachmentsProtects tissue Structural model for developing bone
General structure of cartilagesMature cartilage cells are called chondrocytes
The extracellular matrix of cartilage consists of 1. An abundance of collagen fibers 2. a gel-like ground substance 3. Lacunae = cavities containing chondrocytes
In addition, each of the three types of cartilages have unique characteristics.
Hyaline Cartilage
StructureHyaline cartilage contains very fine collagenous fibers and the ground substance gives hyaline cartilage a glossy appearance.
FunctionsHyaline cartilage provides durable protection and supports movable joints
Locations end of bones embryonic skeleton costal cartilages of the ribs end of the nose
Elastic Cartilage
StructureElastic cartilage contains a dense network of elastic fibers in its extracellular matrix in addition to the gel-like ground substance and collagen proteins.
FunctionElastic cartilage provides flexible support that helps maintain the shape of the organs.
Locations framework of external ear and portions of the larynx
Fibrocartilage
Locations within intervertebral discs meniscus of the knees pubic symphysis
FunctionFibrocartilage acts like a shock absorber
StructureHyaline cartilage contains very fine collagenous fibers and the ground substance gives hyaline cartilage a glossy appearance.
Bone
Structure Bone is composed of 1. Cells called osteocytes within lacunae (cavities) 2. Collagen fibers that offer pliability to bone 3. Mineral Salts that provide hardness
Functions 1. support and protection 2. movement 3. blood cell production
Locations skeleton of the body
BloodStructureBlood is composed of red blood cells, white blood cells, and platelets suspended in a fluid matrix, called plasma.
Functions 1. RBCs – transport gasses 2. WBCs – fight infection and remove debris 3. Platelets – blood coagulation (clotting) 4. Plasma – transports nutrients, wastes, hormones, etc.
Location Within blood vessels
Overview of Connective Tissues
End Section 2, Chapter 5
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