extracellular matrix

What does ECM stand for?

Extracellular matrix

What does extracellular mean?

Outside the cell

What is the extracellular matrix or ECM?

A network of proteins and other molecules that surrounds cells and tissues

What are the two main components of a tissue?

Cellular component and extracellular component

What is the cellular component of a tissue?

The actual cells

What is the extracellular component of a tissue?

The material outside and between the cells

Where is the ECM located?

Outside cells and in the spaces between cells in tissues

What is a simple way to think about the ECM?

It is the support network around cells

What structural role does the ECM have?

It provides structural support to cells

What cell processes can the ECM influence?

Cell division and cell growth and cell development

What is the ECM around cells often referred to as?

Connective tissue

How does connective tissue help organs?

It protects and supports organs

What property can ECM provide to tissues that need to stretch?

Elasticity

What is elasticity?

The ability to stretch and return toward the original shape

What tissues are examples of tissues that need elasticity from their ECM?

Blood vessels and lungs and skin

What does it mean that ECM acts as an adhesive?

It helps hold the cells of a tissue in place

What is adhesion?

The ability of structures to stick or attach to each other

What specialized structures can ECM form?

Cartilage and tendons and the basement membrane

What is another name used for the basal part of the basement membrane in the lecture?

Basal lamina

How does ECM help cell migration?

It provides a pathway or channel that cells can move through

What is cell migration?

Movement of cells from one location to another

How does ECM help cells communicate?

It contains and works with signaling molecules

What are signaling molecules?

Chemical messages that influence how cells behave

What important factors can be present in the ECM?

Growth factors and differentiating factors

What do growth and differentiating factors in the ECM regulate?

Development and migration and proliferation and metabolic functions of cells

What is proliferation?

An increase in cell number through cell division

What is differentiation?

The process by which a cell becomes more specialized

What is metabolism?

The chemical reactions occurring in cells

Is ECM involved only in normal processes?

No. It is involved in both normal and pathological processes

What does pathological mean?

Related to disease or abnormal changes

How can genetic disturbances involving collagen affect the ECM?

They can cause abnormal collagen synthesis and disease

What collagen related diseases are given as examples of genetic disturbances in the lecture?

Osteogenesis imperfecta and Ehlers Danlos syndrome

Does ECM change during aging?

Yes. Changes in ECM occur during the aging process

Can ECM respond to changes or injury?

Yes. ECM has the capacity to respond to changes

How is ECM involved in fracture and wound healing?

It participates in the repair and healing process

What should happen to a blood clot after an injury?

It should form rapidly at the correct location and later disperse as the injury is repaired

What is angiogenesis?

The generation of new blood vessels

When can angiogenesis occur?

In response to injury or tumor growth

How can angiogenesis help tumor growth?

New blood vessels can grow toward the tumor and support its continued growth

Is the amount of ECM the same in every tissue?

No. The amount and composition of ECM differ depending on tissue function

Which tissues contain abundant ECM?

Connective tissue and bone and cartilage and skin

Which tissues have relatively scanty ECM?

Epithelial tissue and muscle tissue

Where is ECM mainly confined in highly cellular tissues such as epithelium and muscle?

The basement membrane

Why does bone require a large amount of specialized ECM?

Bone must be calcified and strong

What does calcified mean?

Hardened by deposition of calcium containing minerals

Why does cartilage need specialized ECM?

It must resist compression and provide cushioning between bones at joints

What is compression?

A squeezing or pressing force

What does cartilage do between bones in a joint?

It provides cushioning and helps resist compression

What is the dermis?

The connective tissue layer of the skin beneath the epidermis

What does the dermis connect?

The epidermis to underlying tissues

What properties does the dermis provide?

Strength and elasticity

What is the basement lamina?

A thin supporting layer that allows cell attachment

Can the basement lamina have specialized functions?

Yes. It has specialized functions in places such as the kidney

What are the two major components of ECM?

Fibers and ground substance

What types of fibers are found in the ECM?

Structural fibers and adhesive fibers

What is ground substance?

The material filling the spaces between cells and ECM fibers

Into what three major groups of biomolecules can ECM composition be categorized?

Structural fibrous proteins and adhesive proteins and proteoglycans with GAGs

What is the major purpose of structural fibrous proteins in the ECM?

To provide tensile and compressive strength

What structural proteins are listed in the lecture?

Collagen and elastin and keratin

What is the purpose of adhesive proteins in the ECM?

They help cells attach and stick

What adhesive molecules are listed in the lecture?

Fibronectin and integrin

What does GP mean?

Glycoprotein

What is a glycoprotein?

A protein with carbohydrate attached

What is a proteoglycan?

A core protein with GAG chains attached

What does GAG stand for?

Glycosaminoglycan

What are glycosaminoglycans or GAGs?

Long chain carbohydrates

What electrical charge do GAGs have?

Negative charge

What do negatively charged GAGs attract?

Positively charged ions or cations

What important cation is attracted by GAGs?

Sodium ions or Na+

What happens after GAGs attract Na+?

Water is attracted into the ECM

What does the water attracted by GAGs help form?

A hydrated gel like substance

What major functions do proteoglycans and GAGs provide?

Compressive resistance and lubrication

Why can GAG rich ECM resist compression?

GAGs attract ions and water which produces a hydrated gel that resists pressure

What is the GAG compression sequence?

Negative GAG attracts Na+ then water is attracted then a gel forms then the gel resists compression

Where is resistance to compression especially important?

Cartilage in joints

What is the most abundant protein in the ECM?

Collagen

What type of fiber is collagen?

A strong and stretch resistant fiber

What is the major mechanical function of collagen?

It provides tensile strength and stability

What is tensile strength?

The ability to resist being pulled or stretched apart

What structures contain large amounts of collagen?

Tendons and ligaments

What is a tendon?

A structure that connects muscle to bone

What is a ligament?

A structure that connects bone to bone

What does collagen do in the skin?

It provides structural support

How is collagen involved in wound healing?

It helps heal wounds and forms scar tissue

What happens to collagen during scar formation?

Collagen rich connective tissue helps form the scar

What are the major classes of collagen mentioned in the lecture?

Fibrillar and fibril associated and network forming and anchoring and transmembrane collagens

What percentage of total collagen is fibrillar collagen according to the lecture?

About 90 percent

How many different collagen types are mentioned in the lecture?

More than 25

Why are there many different collagen types?

Different collagen types are adapted to the specific needs of different tissues

Which collagen types are especially common?

Types I and II and III and IV

Where is Type I collagen found?

Bone and dermis of skin and tendons and ligaments

What is the main memory idea for Type I collagen?

Strong structures such as bone and skin and tendons and ligaments

Where is Type II collagen found?

Hyaline cartilage and elastic cartilage and cornea

What is the easiest association for Type II collagen?

Cartilage

Where is Type III collagen found?

Reticular fibers and blood vessels

What does Type III collagen form?

Reticular fibers

What are reticular fibers?

Thin supporting fibers that form a delicate supportive network

Where is Type IV collagen found?

Basement membrane and lens capsule

What is the most important association for Type IV collagen?

Basement membrane

Which collagen type should you immediately think of when you hear basement membrane?

Type IV collagen