Tissue biochemistry –Extracellular matrix

Abdul Salam M. Sofro & Yulia SAbdul Salam M. Sofro & Yulia S

Faculty of MedicineFaculty of Medicine

YARSI UniversityYARSI University

Definition of Tissue

An aggregation of morphologically An aggregation of morphologically similar cells and associated similar cells and associated intercellular matter acting together intercellular matter acting together to perform one or more specific to perform one or more specific functions in the body. functions in the body.

Definition of organ

A group of tissues that perform a specific function or group of functions (www.biology-

online.org) A differentiated part of an organism, such

as an eye, wing, or leaf, that performs a specific function (http://www.thefreedictionary.com/organ).

Widely distributed tissues

Connective tissue Connective tissue Muscle tissue Muscle tissue Nervous tissue Nervous tissue Epithelial tissue Epithelial tissue Bone tissue Bone tissue Adipose tissue Adipose tissue

There are four basic types of There are four basic types of tissue: muscle, nerve, epidermal, tissue: muscle, nerve, epidermal, and connective. and connective.

Connective tissueConnective tissue

Traditional classification of Tissue

Connective tissue Connective tissue proper Specialized Connective tissue:

Epithelial tissue Muscle tissue Nervous tissue

Connective tissue

is one of the four types of is one of the four types of tissue in traditional in traditional classifications (the others being classifications (the others being epithelial, , muscle, and , and nervous tissue.) .)

All or most tissues in this category are All or most tissues in this category are similarly:similarly: Involved in structure and support. Involved in structure and support. Derived from Derived from mesoderm, usually. , usually. Characterized largely by the traits of non-living Characterized largely by the traits of non-living

tissue. tissue.

Blood, , cartilage, and , and bone are usually are usually considered connective tissue, but because they considered connective tissue, but because they differ so substantially from the other tissues in differ so substantially from the other tissues in this class, the phrase "connective tissue proper" this class, the phrase "connective tissue proper" is commonly used to exclude those three. is commonly used to exclude those three.

Collagen is the main protein of connective is the main protein of connective tissue in animals and the most abundant protein tissue in animals and the most abundant protein in mammals, making up about 25% of the total in mammals, making up about 25% of the total protein content.protein content.

ClassificationClassification

Connective tissue properConnective tissue proper Areolar (or loose) connective tissue holds holds

organs and epithelia in place, and has a organs and epithelia in place, and has a variety of variety of proteinaceous fibres, including fibres, including collagen and collagen and elastin. .

Dense connective tissue (or, less (or, less commonly, commonly, fibrous connective tissue) forms ) forms ligaments and and tendons. Its densely packed . Its densely packed collagen fibers have great tensile strength. collagen fibers have great tensile strength.

Specialized connective tissuesSpecialized connective tissues Blood functions in transport. Its functions in transport. Its

extracellular matrix is extracellular matrix is blood plasma, , which transports dissolved which transports dissolved nutrients, , hormones, and , and carbon dioxide in the in the form of form of bicarbonate. The main cellular . The main cellular component is component is red blood cells. .

Bone makes up virtually the entire makes up virtually the entire skeleton in adult vertebrates. skeleton in adult vertebrates.

Cartilage makes up virtually the entire makes up virtually the entire skeleton in skeleton in chondrichthyes. In most . In most other other vertebrates, it is found primarily , it is found primarily in in joints, where it provides cushioning. , where it provides cushioning. The extracellular matrix of cartilage is The extracellular matrix of cartilage is composed primarily of composed primarily of collagen..

Adipose tissue contains contains adipocytes, , used for cushioning, used for cushioning, thermal insulation, , lubrication (primarily in the (primarily in the pericardium) and ) and energy storage [fat] storage [fat]

Reticular connective tissue is a network is a network of reticular fibers (fine collagen, type III) of reticular fibers (fine collagen, type III) that form a soft skeleton to support the that form a soft skeleton to support the lymphoid organs ( organs (lymph nodes, , bone marrow, and , and spleen.) .)

Embryonic connective tissuesEmbryonic connective tissues Mesenchymal connective tissue Mucous connective tissue

Connective tissue

Connective tissueproper

Specialized Connective tissue

Areolar or loose CT – kolagen, elastin

Dense CT (fibrous CT) – ligaments & tendons

BloodBoneCartilageAdiposeReticular CT

Other classification of connective tissue

Supporting connective tissue (Gives strength, support, and protection to the soft parts of the body)

Cartilage. Example: the outer ear Bone. The matrix of bone contains

collagen fibers and mineral deposits. The most abundant mineral is calcium phosphate, although magnesium, carbonate, and fluoride ions are also present.

Binding connective tissue (It binds body parts together) (It binds body parts together)

TendonsTendons connect muscle to bone. The connect muscle to bone. The matrix is principally matrix is principally collagencollagen, and the , and the fibers are all oriented parallel to each fibers are all oriented parallel to each other. Tendons are strong but not elastic. other. Tendons are strong but not elastic.

LigamentsLigaments attach one bone to another. attach one bone to another. They contain both collagen and also the They contain both collagen and also the protein protein elastin. Elastin permits ligaments . Elastin permits ligaments to be stretched. to be stretched.

Fibrous connective tissueFibrous connective tissue

(It is distributed throughout the body. It (It is distributed throughout the body. It serves as a packing and binding material serves as a packing and binding material for most of our organs. Collagen, elastin, for most of our organs. Collagen, elastin, and other proteins are found in the and other proteins are found in the matrix). matrix). FasciaFascia is fibrous connective tissue that is fibrous connective tissue that

binds muscle together and binds the binds muscle together and binds the skin to the underlying structures. skin to the underlying structures. ElastinElastin is a major protein component. is a major protein component.

Adipose tissueAdipose tissue is fibrous connective is fibrous connective tissue in which the cells, called tissue in which the cells, called adipocytes, have become almost filled adipocytes, have become almost filled with oil. Fibrous and binding connective with oil. Fibrous and binding connective tissue is derived from cells called tissue is derived from cells called fibroblastsfibroblasts, which secrete the , which secrete the extracellular matrix. extracellular matrix.

Note: The extracellular matrix of cartilage Note: The extracellular matrix of cartilage and bone is secreted by specialized cells and bone is secreted by specialized cells derived from fibroblasts: derived from fibroblasts:

chondroblastschondroblasts for cartilage; for cartilage; osteoblastsosteoblasts for bone. for bone.

Disorders of connective tissue Various connective tissue conditions have Various connective tissue conditions have

been identified (can be both inherited and been identified (can be both inherited and environmental)environmental)

Marfan syndrome - a genetic disease causing - a genetic disease causing abnormal abnormal fibrillin. .

Scurvy - caused by a dietary deficiency in - caused by a dietary deficiency in vitamin C, leading to abnormal , leading to abnormal collagen. .

Ehlers-Danlos syndrome - deficient type III - deficient type III collagen- a genetic disease causing collagen- a genetic disease causing progressive deterioration of collagens, with progressive deterioration of collagens, with different EDS types affecting different sites in different EDS types affecting different sites in the body, such as joints, heart valves, organ the body, such as joints, heart valves, organ walls, arterial walls, etc. walls, arterial walls, etc.

Loeys-Dietz syndrome - a genetic disease - a genetic disease related to Marfan syndrome, with an emphasis related to Marfan syndrome, with an emphasis on vascular deterioration. on vascular deterioration.

Pseudoxanthoma elasticum - an autosomal - an autosomal recessive hereditary disease, caused by recessive hereditary disease, caused by calcification and fragmentation of elastic fibres, calcification and fragmentation of elastic fibres, affecting the skin, the eyes and the affecting the skin, the eyes and the cardiovascular system. cardiovascular system.

Systemic lupus erythematosus - a chronic, - a chronic, multisystem, inflammatory disorder of probable multisystem, inflammatory disorder of probable autoimmune etiology, occurring predominantly autoimmune etiology, occurring predominantly in young women. in young women.

Osteogenesis imperfecta (brittle bone (brittle bone disease) - caused by insufficient disease) - caused by insufficient production of good quality collagen to production of good quality collagen to produce healthy, strong bones. produce healthy, strong bones.

Fibrodysplasia ossificans progressiva - - disease of the connective tissue, caused disease of the connective tissue, caused by a defective gene which turns by a defective gene which turns connective tissue into connective tissue into bone. .

Spontaneous Spontaneous pneumothorax - collapsed - collapsed lung, believed to be related to subtle lung, believed to be related to subtle abnormalities in connective tissue. abnormalities in connective tissue.

Sarcoma - a - a neoplastic process process originating within connective tissue. originating within connective tissue.

Extracellular Matrix

Collagens Elastin Proteoglycans & glycosaminoglycans

(GAGs) Cell-adhesion molecules (fibronectin,

laminin, others)

Cell Membranes and Extracellular Matrix (ECM) www.recoveryeq.com/recovery_eq_technical_mono...

KOMPONEN UTAMA

Protein struktural ( kolagen, elastin, Protein struktural ( kolagen, elastin, fibrilin.)fibrilin.)

Protein khusus (fibrillin, fibronektin, Protein khusus (fibrillin, fibronektin, laminin)laminin)

Berbagai proteoglikan ( yg tdd rantai Berbagai proteoglikan ( yg tdd rantai panjang disakarida yg panjang disakarida yg berulang/glikosaminoglikan)berulang/glikosaminoglikan)

KOLAGEN Komponen utama pembentuk jaringan ikat.Komponen utama pembentuk jaringan ikat. Terdapat +/- 19 tipe kolagen yg berbeda dan Terdapat +/- 19 tipe kolagen yg berbeda dan

tersusun dari +/- 30 rantai polipeptida yg tersusun dari +/- 30 rantai polipeptida yg berlainanberlainan

Struktur kolagen: ( Gly-X-Y)n, dimana Struktur kolagen: ( Gly-X-Y)n, dimana 1/3nya ditempati asam amino Glisin1/3nya ditempati asam amino Glisin

+/- 100 aa X adalah Prolin+/- 100 aa X adalah Prolin +/- 100 aa Y adalah hidroksiprolin+/- 100 aa Y adalah hidroksiprolin Prolin dan hidroksiprolin memberikan sifat Prolin dan hidroksiprolin memberikan sifat

rigiditas pd molekul kolagenrigiditas pd molekul kolagen

KOLAGEN

Berbentuk triple heliks : 3 rantai Berbentuk triple heliks : 3 rantai polipeptidanya terpilin spt talipolipeptidanya terpilin spt tali

Jenis kolagen: ada 7-8 jenis gen rantai Jenis kolagen: ada 7-8 jenis gen rantai polipeptida ( polipeptida ( 1 (I), 1 (I), 2, 2, 1 (II), 1 (II), 1(III), 1(III), 1(IV), 1(IV), 1 (V), 1 (V), 2 (V).2 (V).

Molecular biology of Collagen, a major structural protein

Figure ©2000 by Griffiths et al.; All text material ©2005  by Steven M. Carr

ELASTIN

Bertanggungjawab atas sifat mulur dan Bertanggungjawab atas sifat mulur dan mengkerut scr elastis dlm suatu jaringan mengkerut scr elastis dlm suatu jaringan

Bentuknya berupa gelungan acakBentuknya berupa gelungan acak Tdp pd paru, pembuluh drh arteri besar, Tdp pd paru, pembuluh drh arteri besar,

bbrp ligamnetum.<< kulit dan kartilago bbrp ligamnetum.<< kulit dan kartilago telingatelinga

Hanya ada 1 tipe genetik untuk elastinHanya ada 1 tipe genetik untuk elastin

ELASTIN

Tidak terdapat struktur berulangTidak terdapat struktur berulang Tidak mengandung KH, maupun AA Tidak mengandung KH, maupun AA

Hidroksilisin.Hidroksilisin. Setelah terjadi ikatan silang dlm bentuk Setelah terjadi ikatan silang dlm bentuk

ekstraselnya, elastin mjd sangat tdk larut ekstraselnya, elastin mjd sangat tdk larut dan stabil.dan stabil.

Peny Peny Sindroma Williams ( Sindroma Williams ( kel. Perkembangan pd jar. Ikat dan SSP)kel. Perkembangan pd jar. Ikat dan SSP)

www.biomed.metu.edu.tr/.../image008.gif

FIBRILIN

Sebuah glikoprotein berukuran besar Sebuah glikoprotein berukuran besar ( 350 KDa) yg merupakan komponen ( 350 KDa) yg merupakan komponen struktural mikrofibril.struktural mikrofibril.

Disekresikan oleh fibroblasDisekresikan oleh fibroblas PenyPeny Sindroma Marfan:Sindroma Marfan:

Mutasi gen u/ fibrilin, autosom dominanMutasi gen u/ fibrilin, autosom dominan Dislokasi lensa ( ektopia lentis)Dislokasi lensa ( ektopia lentis) Hiperekstensibilitas sendi, aracnodaktili, Hiperekstensibilitas sendi, aracnodaktili,

dilatasi aorta desendensdilatasi aorta desendens

FIBRONECTIN

Adalah protein yang menghubungkan sel Adalah protein yang menghubungkan sel dengan serabut kolagen di matriks ekstrasel, dengan serabut kolagen di matriks ekstrasel, memungkinkan sel bergerak di matriks memungkinkan sel bergerak di matriks ekstrasel. ekstrasel.

Fibronectin mengikat kolagen dan integrins Fibronectin mengikat kolagen dan integrins permukaan sel, menyebabkan reorganisasi permukaan sel, menyebabkan reorganisasi sitoskeleton sel dan memfasilitasi sitoskeleton sel dan memfasilitasi pergerakan sel. pergerakan sel.

Fibronectins disekresi oleh sel dalam bentuk Fibronectins disekresi oleh sel dalam bentuk terurai terurai

Bila mengikat integrins molekul Bila mengikat integrins molekul fibronectin terbuka sehingga dapat fibronectin terbuka sehingga dapat membentuk dimer dan berfungsi.membentuk dimer dan berfungsi.

Fibronectins juga membantu di tempat Fibronectins juga membantu di tempat jejas dengan mengikat trombosit selama jejas dengan mengikat trombosit selama penggumpalan darah dan memfasilitasi penggumpalan darah dan memfasilitasi pergerakan sel ke area yang terkena pergerakan sel ke area yang terkena selama penyembuhan luka. selama penyembuhan luka.

LAMININ

Adalah protein yang dijumpai di lamina Adalah protein yang dijumpai di lamina basal semua hewan basal semua hewan

Laminin membentuk jejaring seperti Laminin membentuk jejaring seperti struktur jaring yang menahan daya tarik struktur jaring yang menahan daya tarik di lamina basal.di lamina basal.

Juga membantu dalam adhesi sel dan Juga membantu dalam adhesi sel dan mengikat komponen matriks ekstrasel mengikat komponen matriks ekstrasel lain seperti kolagen, nidogen dan lain seperti kolagen, nidogen dan entactin. entactin.

PROTEOGLIKAN

Merupakan protein yang mengandung Merupakan protein yang mengandung glikosaminoglikan dgn ikatan kovalen glikosaminoglikan dgn ikatan kovalen (sindekan, betaglikan, agrekan dll)(sindekan, betaglikan, agrekan dll)

Pada matriks ekstraseluler berikatan baik Pada matriks ekstraseluler berikatan baik dengan kolagen maupun elastin.dengan kolagen maupun elastin.

GLIKOSAMINOGLIKAN

Glikosaminoglikan : polisakarida tak Glikosaminoglikan : polisakarida tak bercabang yg tersusun dari mol. bercabang yg tersusun dari mol. Disakarida berulang dimana salah satu Disakarida berulang dimana salah satu komponennya selalu AA.komponennya selalu AA.

As. Hialuronat, kondroitin sulfat, keratan As. Hialuronat, kondroitin sulfat, keratan sulfat I dan II, heparin, heparan sulfat, sulfat I dan II, heparin, heparan sulfat, dermatan sulfat)dermatan sulfat)

PenyPeny MukopolisakaridosisMukopolisakaridosis

CELL ADHESION MOLECULES (CAM)

Kebanyakan CAMs termasuk dalam 4 Kebanyakan CAMs termasuk dalam 4 keluarga protein: Ig (keluarga protein: Ig (immunoglobulin) ) superfamily (IgSF CAMs), integrins, (IgSF CAMs), integrins, cadherins dan selectins. cadherins dan selectins.

Muscle tissueMuscle tissue

Muscles contain 3 types Muscles contain 3 types of protein fibers:of protein fibers:

microfilaments, microfilaments, microtubules, and microtubules, and intermediate filamentsintermediate filaments

MicrofilamentsMicrofilaments are polymers are polymers composed of globular unit monomers composed of globular unit monomers called called actinactin.  . 

MicrotubulesMicrotubules are polymers composed are polymers composed of two monomers, α and β of two monomers, α and β tubulintubulin.  .  These monomers contain the nucleotide These monomers contain the nucleotide guanineguanine instead of instead of adenineadenine.  They are .  They are involved in many cellular processes involved in many cellular processes including mitosis, cytokinesis, and including mitosis, cytokinesis, and vesicular transport vesicular transport

Intermediate filamentsIntermediate filaments contain other contain other polymers such as polymers such as keratinkeratin and don't and don't contain nucleotides in their monomers.  contain nucleotides in their monomers.  They compose structures inside cells but They compose structures inside cells but are more familiar in external forms such are more familiar in external forms such as as hair, nails, horns hair, nails, horns andand scales scales

Organization of Contractile Proteins in MuscleOrganization of Contractile Proteins in Muscle

Thick Thick FilamentFilament

Composed of hundreds of long, contractile myosin molecules Composed of hundreds of long, contractile myosin molecules arranged in a staggered side by side complex.arranged in a staggered side by side complex.

Thin Thin FilamentFilament

Composed of a linear array of hundreds of globular, actin Composed of a linear array of hundreds of globular, actin monomers in a double helical. arrangement.monomers in a double helical. arrangement.

SarcomereSarcomere The unit of contractile activity composed mainly of actin and The unit of contractile activity composed mainly of actin and myosin and extending from Z line to Z line in a myofibril.myosin and extending from Z line to Z line in a myofibril.

MyofibrilMyofibril End to end arrays of identical sarcomeres.End to end arrays of identical sarcomeres.

MyofiberMyofiber A single multinucleate muscle cell containing all the usual cell A single multinucleate muscle cell containing all the usual cell organelles plus many myofibrils.organelles plus many myofibrils.

MuscleMuscle Organized arrays of muscle fibers.Organized arrays of muscle fibers.

Diagrammatic breakdown of a typical muscle. Shows how actin thin filaments and myosin thick filaments are arranged to form the myofilaments of a sarcomere, continuing with the formation of myofibrils from many myofilaments.

Myofibril

Actin & myosin

Myosin is one of the most abundant Myosin is one of the most abundant proteins in the human body. proteins in the human body.

It is found in all the body's muscle It is found in all the body's muscle types, in the ears and eyes, in the blood types, in the ears and eyes, in the blood platelets, and is used in cytokinesis. platelets, and is used in cytokinesis.

Because of all the diverse functions of Because of all the diverse functions of myosin, it can be grouped into myosin, it can be grouped into anywhere from seven to fourteen anywhere from seven to fourteen unique categories. These categories unique categories. These categories are grouped by the properties of the are grouped by the properties of the head domains of the myosins.head domains of the myosins.

The most common type of myosin is The most common type of myosin is myosin class II. This is the type present myosin class II. This is the type present in muscle tissues. in muscle tissues.

Class II myosin is used to contract Class II myosin is used to contract muscle tissue, thereby giving an muscle tissue, thereby giving an organism mobility. Myosin II has this organism mobility. Myosin II has this function due to its complex function due to its complex configuration. Myosin II also plays a role configuration. Myosin II also plays a role enzymatically as it is an ATPase. enzymatically as it is an ATPase.

Myosin II is a component of the Myosin II is a component of the myofibers in skeletal, smooth, and myofibers in skeletal, smooth, and cardiac tissue cardiac tissue

Nervous Tissue

Supportive connective tissue cells Supportive connective tissue cells Neuroglia support and protect neurons Neuroglia support and protect neurons

in the CNS. Specific glial cells are in the CNS. Specific glial cells are phagocytes; others myelinate neuron phagocytes; others myelinate neuron processes in the CNS or line cavities. processes in the CNS or line cavities.

Schwann cells myelinate neuron Schwann cells myelinate neuron processes in the PNSprocesses in the PNS

Neurons Neurons All neurons have a cell body containing All neurons have a cell body containing

the nucleus and processes (fibers) of two the nucleus and processes (fibers) of two types; (1) axons (one per cell) typically types; (1) axons (one per cell) typically generate and conduct impulses away from generate and conduct impulses away from the cell body and release a the cell body and release a neurotransmitter, and (2) dendrites (one to neurotransmitter, and (2) dendrites (one to many per cell) typically carry electrical many per cell) typically carry electrical currents toward the cell body. currents toward the cell body.

Most large fibers are myelinated; myelin Most large fibers are myelinated; myelin increases the rate of nerve impulse increases the rate of nerve impulse transmission. transmission.

Schwann cells myelinate neuron processes in the PNS

Bone Tissue

http://images.google.co.id/imgres?imgurl=http://chrischamcl.files.wordpress.com/2009/10/osteoporos

Bone is formed through a lengthy Bone is formed through a lengthy process involving ossification of a process involving ossification of a cartilage formed from mesenchyme. cartilage formed from mesenchyme.

Two main forms of ossification occur in Two main forms of ossification occur in different bones, intramembranous (eg different bones, intramembranous (eg skull) and endochondral (eg vertebra) skull) and endochondral (eg vertebra) ossification. Ossification continues ossification. Ossification continues postnatally, through puberty until mid 20s postnatally, through puberty until mid 20s

http://images.google.co.id/imgres?imgurl=http://www.roche.com/pages/facets/11/bone_remodelling2

http://kcampbell.bio.umb.edu/December01/Bone2.gif

Osteoblasts manufacture bone and are derived from mesodermal in origin, arising from multipotential mesenchymal cells and further differentiate into bone-lining cells and osteocytes.

Osteoclasts resorb bone and are derived from hematopoietic precursor cells formed by the fusion of monocytic cells at the bone sites to be resorbed.

The marrow of bones is the site of The marrow of bones is the site of haematopoiesis, the generation of blood haematopoiesis, the generation of blood cells. At birth nearly all bones are a cells. At birth nearly all bones are a source of blood cells, this is restricted with source of blood cells, this is restricted with postnatal development to a few specific postnatal development to a few specific bones. Pluripotential stem cells reside in bones. Pluripotential stem cells reside in the marrow and are a self renewing the marrow and are a self renewing source of stem cells or commitment to a source of stem cells or commitment to a progenitor cell.progenitor cell.

Bone matrix and marrow

The organic matrix of bone consists of:The organic matrix of bone consists of: 95% Type I collagen 95% Type I collagen 5% proteoglycans and noncollagenous 5% proteoglycans and noncollagenous

proteins (osteopontin and osteocalcin). proteins (osteopontin and osteocalcin).

Epithelial Tissue

epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body.

Epithelium lines both the outside (skin) and the inside cavities and lumen of bodies. The outermost layer of our skin is composed of dead stratified squamous, keratinized epithelial cells.

http://en.wikipedia.org/wiki/Epithelial_tissue

Types of epithelium

Epithelial cells are often arranged in broad sheets or tube-like structures. Epithelium is commonly found on the

surfaces of the body and organs, and the lining of body cavities, tubes, and ducts - the boundary between the

body's internal and external environments.

Epithelial tissues are physically separated from Epithelial tissues are physically separated from underlying connective tissues by a underlying connective tissues by a basement basement membranemembrane (also called the basal lamina). (also called the basal lamina).

Epithelial tissues contain no blood Epithelial tissues contain no blood vessels. Cells receive nourishment by vessels. Cells receive nourishment by diffusion from a highly vascular area of diffusion from a highly vascular area of loose connective tissue just below the loose connective tissue just below the basement membrane called the basement membrane called the lamina proprialamina propria. .

Epithelial tissues are derived from all Epithelial tissues are derived from all three primary germ cell layers: three primary germ cell layers:

Ectoderm:Ectoderm: The epithelial cells of the skin The epithelial cells of the skin and oral cavity (epidermis) are derived and oral cavity (epidermis) are derived from ectoderm. Epithelial cells covering from ectoderm. Epithelial cells covering the cornea and lens, as well as sensory the cornea and lens, as well as sensory receptors of the eyes, ears, and nose, are receptors of the eyes, ears, and nose, are also ectodermal in origin. also ectodermal in origin.

Mesoderm:Mesoderm: The epithelial lining of blood The epithelial lining of blood vessels (endothelium) is derived from vessels (endothelium) is derived from mesoderm. The epithelial lining of the mesoderm. The epithelial lining of the pleural and peritoneal cavities pleural and peritoneal cavities (mesothelium) also originate from (mesothelium) also originate from mesodermal cells. mesodermal cells.

Endoderm: The epithelial lining of the respiratory system and digestive tracts - as well as the functional cells (parenchyma) of the liver, pancreas, gallbladder, thyroid, and parathyroid, are derived from endoderm.

FunctionsFunctions

BarrierBarrier Absorption Absorption SecretionSecretion SensorySensory ContractilityContractility

Adipose TissueAdipose Tissue

Adipose tissueAdipose tissue or or fatfat is loose is loose connective tissue composed of composed of adipocytes. Its main role is to store . Its main role is to store energy in the form of fat, although it also in the form of fat, although it also cushions and insulates the bodycushions and insulates the body

Two types of adipose tissue exist:Two types of adipose tissue exist: white adipose tissue (WAT) and white adipose tissue (WAT) and brown adipose tissue (BAT). brown adipose tissue (BAT).

Brown adipose tissue

Adipose tissue with microvessels

Adipose tissue also serves as an Adipose tissue also serves as an important endocrine organ by producing important endocrine organ by producing recently-discovered hormones such as recently-discovered hormones such as leptin, resistin and the cytokine TNFα. leptin, resistin and the cytokine TNFα. The formation of adipose tissue appears The formation of adipose tissue appears to be controlled by the adipose gene.to be controlled by the adipose gene.

Subcutaneous adipose tissue