Connective Tissue Flashcards
what is the role of connective tissue
Connective tissue provides structural metabolic and defensive support within other tissues and organs, thereofre they are sometimes called supporting tissue
name the different types of connective tissue
- Fibrocollagenous tissues
- Adipose tissue
- Cartilage
- Bone
- Blood
what is the characteristic of connective tissue
- Few cells compared to epithelia and other tissues
- Large amounts of extracellular matrix, usually made by its intrinsic cells
where are connective tissue cells derived from
mesodorm
- Some stem cells remain in the adult these are called mesenchymal cells
name the language of connective tissue
- Blast means immature
- Cyte means mature
- Fibroblast is the excpetion
what makes up the extracellular matrix
- Ground substance – in most types, this is a smei-lfuid gel though which metbaolites can diffuse through
- Structual glycoproteins
- Fibres – colllagen fibres for strength and support and elastic fibres for stretch
describe what the ground substance does
- Water to gel like
- Gives each connective tissue distinctive properites
what makes up the ground substance
- Made of GAGs and proteoglycans (bind via a linker to hyalurinc acid to form either larger complexes)
- Fluid components with dissolved substances including nutrients, electroyltes, gases and hormones
- Structural glycoproteins – molecules with different functions such as aiding fibre assembly, promoting cell adhesion or calcium deposition
describe GAGs
- Negatively charged
- Open conformations
- Retain water and postivie ions
- Make up extracellular fluid
- Forms a hydrated gel that allows selective passage of molecules
what is the role of structural glycoproteins
- Functional molecules
- Role in linking, organising, catalysing processes, folding of proteins and carriers of molecules
what are the different types of collagen
- Type 1 : thick bundles that are very strong
- Type II: thin, interwoven fibres that are only in cartilage
- Type III: delicate branching reticulin
- Type IV: forms meshwork – important in the basement membrane
what does collagen secrete
- precursor tropocollagen secreted
what are fibre precursors secreted by
connective tissue cells, fibres polymersie outside of the cell
describe elastic fibres
- Stretch and resiliency
- Tropoelastin secreted
- Elastin forms fibrils with fibrillin
- Fibres can be organised into sheets
- Higher amounts found in arteries, skin, lung, elastic and cartilage
how is fibrocollagenous tissue classed according too
- Number or amount of collagen fibres
- Organisation of collagen fibres
- Type of collagen fibres
describe the
- cell that makes the fibrocollagenous tissue
- the role it plays
- the types of the tissue
Cell: fibrobaslt – responsible for making the cells in the extracellular matrix in fibrocolllagenous tissues
Role: structural and supportive
Types; you can have loose, desne, and reticular (type of loose collagen III)
describe loose areolar connective tissue
- cell
- role
- example
- location
- Cells: Fibroblasts – also stem cells, adipocytes, lymphocytes, resident macrophages, mast cells
- relatively few collagen type I fibres bundles that are oriented in different directions, there are some type III fibres that are present
- Role – physical, metabolic and defensive support, plays role in inflammation, holds and conveys tissue fluid
- Example – lamina propria
- Location – distributed under the epithelial of the body, packages organs, surrounds capilaires
whats denser the submucosa or the lamina propria
although submucosa is loose CT the density of collagen fibres is higher than the lamina propria of the mucosa above it, the submucosa has a more supportive function and is more robust
describe dense connective tissue amount organisation type cell role examples
- Amount – many fibres, little ground substance
- Organisaiton – radom – desne irregular, structured – dense regular
- Type – type I collagen, mainly elastic fibres, reticulin
- Cells: fibroblasts primarly
- Role: mechanical support and tensile strength
- Examples: irregular – dermis (many directions), capsules, regular- tendon and ligament (one direction)
describe dense irregular
irregularly arranged collagen, some elastic fibers, major cell type is fibroblast
describe the function of dense irregular
can withstand tension exerted in many dreictions and provides structural strength
describe the location of dense irregular
fibrous capsules of organs and of joints; dermis of the skin
what is the dermis of the skin composed of
while the dermis of the skin is mainly composed of desne irregular fibrocollagenous tissues areas of lower density areolar type tissue are found just below the epithelium of the skin in the high vascular papillary layer
describe dense regular
primarily parallel collagen fibers, few elastic fibers, major cell type is fibroblast
describe function of dense regular
withstands great tensile stress when pulling force is applied in one direction
describe the location of dense regular
tendons, most ligaments and aponeuroses
describe reticular connective tissue e
- amount
- organisation
- type of collagen
- cells
- role
- examples
Fibres
- Amount – few fibres, little ground substance
- Orgaisation – fine network
- Type – type III collagen meshwork
- Cells – mainly fibroblasts and more speicliased cells in some tissues
- Role – structural support for epithelia in some hihgly cellular tissues, forma soft intenral skeleton that supports other cell types including WBC, mast cells and macrophages
- Exaples – lymph nodes, spleen, liver and other glands including the endocrine glands and liver
describe adipose tissue
- Adbunat in adipocytes
- Contains supporting loose connective tissue (with fibroblasts)
what are the two types of adipose tissue
white and brown
describe white adipose tissue
- Unilocular – one space for lipid
- Adult -
- Wide spread
- Enegry store, shock absorber, insulator, fat storage
- Description: matrix as in areolar but very sparse, closely packed adipocytes or fat cells have nucleus pushed to the side by large fat droplet
- Location – under the skin in hypodermis around kidenys and eyeballs, wihtin abdomen and in breasts
describe brown adipose tissue
- Multilocular – fats is stored in multiple, small droplets
- Newborn
- Restricted -mostly loss by adulthood
- Organised into lobules separated by fibrocollagenous septa – and carry larger blood vessels and sympathetic nerves that control heat production
- Heat source of newborns
- Description – nucleic are round and central, large amount of mitcohodnrial, use lipids to produce heat for the neonate who cannot shiver or otherwise act to seek warmth, similar to aerolar tissue
what are the three types of cartilage
hyaline
elastic
fibrocartilage
what is the role of cartilage
- structural - solid but flexible; resists compression
what forms cartilage and what maintains it
Fomred by chrondoblasts, mature cells that maintain the tissue are called chondrocytes
Cells appear to be in spaces which are called lacunae
describe unique ground substance that makes up cartilage
proteoglycans (aggrecan) containing chondrotin sulphate, and keratan sulphate linked to hyaluronic acid form large complexes and interacting with type II collagen fibres
describe the ECM in cartilage
- Abdunat ECM in caritlage has a predominance of sulfated GAG rich proteoglycan and hyaluroinic acid in its ground susbtance complexed to a fine collagen (type II mainly) fibre
- GAGs and proteoglycans are expanded molecules that are negatively charged and attract large amounts of water and positive ions which are mainly soidum
- cartilage contaisn up to 80% water this is responsible for the give in the cartilage during comrpession and allows diffusion of small molecules
what type of cartilage is hyaline cartilage
type II collagen
what type of cartilage is elastic cartilage
type II collagen and elastic fibres (same as hyaline but matrix contains more elastic fibres)
what type of cartilage is fibrocartilage
- type II and type I collagen (hybrid between dense fibrocollagenous tissue and hyaline cartilage
- high in proteoglycans
describer hyaline
firm matrix but clearly defined, collagen fibres form an imperceptible network, chondroblasts produce the matrix and when mature lie in lacunae
describe the function of hyaline
supports and reinforces, has resilient cushioning properites, reists compressive stress
describe the location of hyaline
forms most of the embyronic skeleton, covers the ends of long bones in joint cavities, forms costal cartilages of the ribs, cartilages of the nose, trachea and larynx
describe elastic
similar to hyaline cartilage but more elastic fibres in martrix
describe the function of elastic
maintains the shape of a strucutre while allowing great flexibility
describe the location of elastic
supports the external ear and the epiglottis
describe fibrocartilage
matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predomainate
describe the function of fibrocartilage
tensile strength with the ability to absorb compressive shock
describe the location of fibrocartilage
intervertebral discs; pubic symphysis; discs of knee joint
describe the perichondrium
- Cartilage does not contain blood vessels and must obtain its nutrietns from the surrounding tissues
- Spcialised layer of highly vascular fibrocollagenous tissue called the perichondrium is found surrounding the cartilage
- Nutrients from the capillaries in the perichondrium diffuse through the cartilage matrix to nourish the chrondrocytes
- Chrondroblasts are also found here and can be actiated to repair injruies
- In joints the hyaline cartilage is bathed by fluid which carries the nutrients and metabolites
describe the role of bone
structural, locomotion, supportive, protective, metabolic
Highly organised and metabolically active
describe the ECM in bone
- Ground susbtacen called osteoid
- Collagen type I fibres – layers in mature bone
- Mineralised
describe the cells in bone
- Osteocytes – maintain bone
- Osteoblasts – secrete osteoid, form bone
- Osteoclasts – reabsrob bone
describe
- the role of blood
- the ECM
- the cells
- Roles – metabolic support for transport of molecules and cells to and form tissues, defesive
ECM - ground substance fluid; plasma
- Fibres: fibrin of clots – made by liver as soluble fibrinogen
Cells - Circulating blood cells formed in bone marorw
