Blood…why?

Connective Tissue

Plasma

Whiteblood cells

55

m

Red blood cellsCartilage

Chondrocytes

Chondroitin sulfate

10

0

m

Adipose tissue

Fat droplets

15

0

m

Bone

Centralcanal

Osteon

70

0

m

Nuclei

Fibrous connective tissue

Elastic fiber

30

m

12

0

m

Collagenous fiber

Loose connective tissue

Connective Tissue

• Most diverse tissue type• Binds together, supports and strengthens other

tissues.• Protects and insulates internal organs• Compartmentalizes structures – e.g. skeletal

muscles• Major transport system – ?• Store energy – ?• Immune response – ?• Two basic elements: cell and matrix – material

between the cells.• Matrix contains: protein fibers and ground

substance – the material between the cells and the fibers.

• Nerve supply -- ?• Usually highly vascular: Exceptions are cartilage

and tendons.

• Widely spaced – Not tight packed like epithelial cells.• Types of cells:

1. Fibroblasts that secrete the fibers and ground substance of the extracellular matrix

2. Macrophages that are involved in the immune system (fixed and wandering)

3. Mast cells produce histamine, a chemical that dilates small blood vessels as part of the inflammatory response – The body’s reaction to injury or infection.

4. Adipocytes are fat cells

Types of Cells

Extracellular Matrix• Two main elements

– Ground substance – mostly water along with adhesion proteins and polysaccharide molecules

– Supports cells– Binds cells together– Exchange of substances between blood and cells

– Fibers• Produced by the cells• Three types

– Collagen fibers– Elastic fibers– Reticular fibers

• The matrix is firm in some parts of the body, but hard in others. • Examples: ?

Fibers (this they should know)

Fibers• Collagen Fibers

– Made of protein called collagen– Strong yet flexible– Resist pulling forces– Found in:

• Bone• Cartilage• Tendons• Ligaments

Fibers• Elastic Fibers

– Thiner than collagen fibers– Made of the protein, elastin– Can be stretch without

breaking– Found in:

• Skin• Blood vessels• lungs

Fibers• Reticular Fibers

– Much thinner than collagen fibers

– Provide support for stroma (covering) of soft organs

– Found in:• Basement membrane• Nerve fibers• Muscles• Spleen• Lymph nodes

• There are three types of connective tissue fiber, all made of protein:

– Collagenous fibers provide strength and flexibility • Found in: tendon, ligament, skin, cornea, cartilage, bone, blood

vessels, gut, and intervertebral disc.

– Elastic fibers stretch and snap back to their original length• Found in: Skin, blood vessel walls, lung tissue

– Reticular fibers join connective tissue to adjacent tissues • Found in: liver, bone marrow, lymphatic organs, basement

membrane

Connective Tissue FibersSummary

Quiz1. Which type of protein are collagen fibers

made of?2. Which type of fiber provides support for soft

organs?3. Which type of protein are elastic fibers made

of?4. Which type of fibers can be found in blood

vessels?5. Which type of fiber provides the greatest

strength?

Ground Substance• Forms the material between the

cells and fibers of connective tissue.

• Made of water, proteins, and polysaccharides

• Instrumental in how tissues:• Develop• Migrate• Proliferate• Change shape• Metabolize

six major types of connective tissue: 1. Loose connective tissue2. Dense connective tissue3. Cartilage4. Bone5. Blood tissue6. Lymph

Connective Tissue Types

Loose Connective Tissue3 types of loose connective tissue

1. Areolar connective tissue2. Adipose connective tissue3. Reticular connective tissue

Areolar Connective Tissue• Forms the subcutaneous

layer – Attaches skin to the underlying tissues and organs

• Made of collagen, elastic and reticular fibers.

• Made of fibroblast, macrophages, plasma, mast cells and adipocytes (fat cells)

Figure 3.19e

Figure 3.19f

Adipose Tissue• Cells store fat.• Functions

– Insulates the body– Protects some organs– Serves as a site of

fuel storage• Does an obese

person have more blood vessels?

Reticular Connective Tissue• Delicate network of

interwoven fibers• Forms stroma of

lymphoid organs– Lymph nodes– Spleen– Bone marrow

• Bind together smooth muscle cells

• Filter worn out blood cells and bacteria.

Dense Connective Tissue• Dense connective tissue

– More and thicker fibers but fewer cells than loose connective tissue

– Main matrix element is collagen fibers

– Cells are fibroblasts– Examples

• Tendon – attach muscle to bone

• Ligaments – attach bone to bone Figure 3.19d

Dense Connective Tissue

• Dense Regular– Fibers arranged in parallel –

Regular– Tendons and most ligaments

• Dense Irregular– Fibers not parallel – Irregular– Heart valves

• Elastic– Can extend and return to

original length– Lungs, arteries

Connective Tissue Types• Bone (osseous tissue)

– Composed of:• Bone cells in cavities• Hard matrix of

calcium salts• Large numbers of

collagen fibers

– Used to protect and support the body

Connective Tissue Types

• Hyaline cartilage– Most common

cartilage– Composed of:

• Abundant collagen fibers

• Rubbery matrix– Entire fetal skeleton

is hyaline cartilage

Figure 3.19b

Connective Tissue Types

• Elastic cartilage– Provides elasticity– Example: supports the

external ear

Connective Tissue Types• Fibrocartilage

– Highly compressible– Example: forms

cushion-like discs between vertebrae

Figure 3.19c

Connective Tissue Types• Blood

– Blood cells surrounded by fluid matrix

– Functions as the transport vehicle for materials

Figure 3.19h