How are these cells different? A.A. B.B. C.C. D.D. pancake Circle, bricks, boxes Vertical, long,...

How are these cells different?

A.B.

C. D.

pancake Circle, bricks, boxes

Vertical, long, compact

Puzzle pieces, vertical

Connective Tissue

General Characteristics

• Support, protection, binding• Most diverse• Widely distributed within ECM

– Lots of distance between bone cells

• Vascularized– Exceptions: tendons/ligaments, Cartilage

• ECM = fibers/ground substance• Rigid (bone, cartilage) or loose (adipose, dense)

3 common features1. Cellular component

• Blast cells are responsible for secreting extracellular and fibrous components

2. Extracellular matrix: Non-living ground substance secreted by cellular component (see next slide)

• Ex: solid in bone is created by osteoblasts

3. Fiber component: usually produced by cellular component (fibroblasts)

a) Collagenb) Elastin

Extracellular Matrix

• ECM• Function: supports cells, binds them together,

stores water, provides a medium through which substances are exchanged between the blood and cells

Connective Tissue Fibers

Collagenous Fibers

Elastic Fibers

Made of what protein?

Collagen (thick threads)

Elastin

What shape? Long, parallel bundles

Thin, branch into networks

Strength Tensile (strong) Weaker

Flexibility Some, not like elastic

Stretch

Found where?

•Fibroblasts produce connective tissue fibers secreted in the extracellular matrix.

Connective TissueI. LooseII. AdiposeIII. DenseIV. CartilageV. BoneVI. Blood

I. Loose Connective Tissue

• First glance:

• Loose, gel-like ECM with collagenous and elastic fibers

• Function: Binds organs together, holds tissue fluids

• Where: – beneath skin– between muscles– beneath epithelial tissues

II. Adipose Tissue

• First glance:

• Adipocyte cells store fat in droplets• Enlarge around other cell types• Function: cushions, insulates, stores energy• Where: beneath skin, behind eyeballs, surface

of heart

III. Dense Connective Tissue

• First glance:

• Few cells, but they are closely packed; Blood supply is slow

• Thick collagenous fibers but also elastic: flexible but withstand pulling

• Function: Binds organs together• Where: tendons, ligaments, deeper layers of

skin• Why don’t Achilles tendon injuries repair

easily?– Blood supply is slow repair from blood is slow

IV. Cartilage

• First glance:

• Rigid• Function: support, frameworks, attachments;

protection; models for developing bones• Collagen fibers• Chondrocytes found in chambers called lacunae• Lacunae is surrounded by ECM with collagenous

fibers• Looks smooth, rubbery

Types of cartilage

Type depends on the ECMA. Hyaline: (Shown previously)

- Fine collagenous fibers in ECM- Important for bone growth- Where? End of bones, in joints, nose, rings of

resp. passages

B. ElasticC. Fibrocartilage

B. Elastic cartilage

• Elastic fiber network more flexible• Where? External ears, part of larynx

C. Fibrocartilage

• Many collagenous fibers• Absorbs shock for structures under pressure• Where? Pads between bones (discs in

vertebrae); cushions bones in pelvic girdle, knees

V. Bone

• First glance:

• Where? Bones of skeleton• Function? Support (internal body structures),

protect (cranial, thoracic cavities), provide framework (muscles attach)

• Rigid: mineral salts between cells• ECM has collagenous fibers: Flexible, reinforce

mineral salts in bone

• Lamellae: layers of bone matrix; concentric circles around canals

• Central canals: empty cavity at center

• Osteocytes: bone cells, found in lacunae

• Lacunae: house bone cells, evenly spaced between lamellae

• Osteocytes and EXM layers (concentric) for osteon– Many osteons cemented together form bone

• Each central canal has a blood vessel: gives nutrient supply

• Canaliculi: cellular processes that connect with membranes of nearby cells– Materials move rapidly between blood vessels and

bone cells– Bone is very active that heals faster than cartilage

VI. Blood

• First glance:

• Function: transports materials between interior body cells and those that exchange material with external environment– Ex: gas exchange in the lungs

• Maintains stable environmental conditions• Parts of blood: formed elements suspended in

ECM– ECM = blood plasma– Formed elements = red blood cells, white blood

cells, platelets

• Made in red marrow, hollow parts of bone