1. composed of proteins and polysaccharides 2. substance secreted by cells into their outside environment

1. flexible,strong resistant to stretching 2. main protein in the ECM 3. major body protein 4. made of 3 intertwining fibers: tropocollagen ( alpha helical)

L8. ECM Flashcards by Samantha Tan

What is the function of the ECM?

provide structural support for cells to organize into tissues
all tissues need ECM to assemble

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What is the ECM

composed of proteins and polysaccharides

2. substance secreted by cells into their outside environment

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What does the ECM do?

gives structural support
regulates growth and development of cell
regulates migration of the cell
signals that regulate cell survival
forms adhesive contacts with the cell
modifies cell shape and function
directs proliferative activity

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What are the 2 types of ECM?

Basement Membrane

2. Connective tissue

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What is the connective tissue composed of?

fibers

2. ground substance

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What is the function of ground substance in connective tissue?

resist compression

2. permits diffusion of nutrients and waste between cells

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What is the function of fibers in connective tissue?

provide structural support

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What are the 2 proteins that make fibers

collagen +elastin

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what is ground substance

kelly like

made up of water,electrolyte , polysaccharide and proteins

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How many collagen genes are there in humans

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Describe collagen

flexible,strong resistant to stretching
main protein in the ECM
major body protein
made of 3 intertwining fibers: tropocollagen ( alpha helical)

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Name 2 GAGs

heparin

2. hyaluronic acid

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What is hyaluronic acid?

huge and abundant GAG
only GAG that indirectly binds to proteins
good lubricant found in joints
involved in wound repair, cell migration, inflammation

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What causes MPS (mucopolysaccharidoses)

inability to break down GAGs

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What is fibronectin?

a GP; needed for blood clottting

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what is aggracan

PG ; found in cartilage

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draw how hyaluronic acid binds to collagen

associates with link proteins ( L8, pg 11b)

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what do fibroblasts secrete

they secrete precursors for BOTH collagen and the ECM.

What is the basement membrane

interface between the epithelial cells and the connective tissue

What are the 2 distinct parts of the basement membrane

basal lamina ( made by epithelial cells)

2. reticular lamina (made by CT)

What are the 2 layers of the basal lamina ?

lamina lucida

2. lamina densa

What is the lamina lucida, what does it contain

(part of the basal lamina of the basement membrane)

GP laminin and GP integrins

What is integrin

A Glycoprotein

Name some PG

aggracan, perlecan

Paul Gifted A Pelican

Name some GP

fibronectin,laminin, integrins | God Paul Licked Fido's Intestines

What is the lamina densa, consists of?

(part of the basal lamina of the basement membrane) collagen 4 PG perlecan GAG heparan

What is the functin of laminins

A GP that binds collagen and integrins - bridge between both layers

What does the reticular lamina contain?

collagen 1 and 3 anchoring fibrils GP fibrillin

Draw the relation between the BM, epithelial cells and CT ( add the basal lamina ( lamina lucida and lamina reticular) and the reticular lamina)

pg 14a

What are the functions of the BM?

1. provide structural support 2. anchor the epithelium ( firm +flexible) 3. molecular filter for the epithelium

What is alport syndrome?

lost of collagen 4

How is the ECM attached to cells

junctional anchoring transmembrane protein | link to cytsokeleton via cytoskeletal linkers with adhesion complex

What are the 2 types of integrin, how many of each

the 2 PG : alpha (18) and beta (8)

What composes a functional integrin

an alpha and beta integrin

What determines the function of the integrin heterodimer

the individual alpha beta subunits that compose the dimer

Draw the integrin adhesion complex

(pg 17a)

describe focal contacts, which cytoskeleton do they link to

link to actin filaments made up of integrins composed of a variety of integrin heterodimers

Describe hemidesmosomes, which cytoskeleton do they link to

feature of epithelial cells binds to lamina lucidia link to intermediate filament made up of a6b4 integrin

What are the 2 modes of integrin activation?

1. intracellular: integrin bind proteins inside the cell and convert it to high affinity 2. extracellular: integrin bind to ECM proteins converts it from low affinity to high affinity

What are the 4 functions of integrin?

1. cell migration - would healing - neuron path finding - immune function 2. cell signalling 3. cytoskeletal organization (because of link to junctional proteins) 4. stable adhesion - muscle tendon attachemnt - attachment to diff skin layers

What causes junctional epidermolysis bullosa?

loss of integrin

What is collagen 4 in the BM used for

- part of the lamina densa ( and part of reticular lamina)

What collagen makes anchoring fibrils

collagen 7