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Body logistics > Connective tissues proper > Flashcards

Connective tissues proper Flashcards

1
Q

define connective tissue

A

tissue that connects, support, binds or separates other tissues or organs, typically having relatively few cells embedded in an amorphous matrix, often with collagen or other fibres

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2
Q

components of connective tissue

A
  • cells mainly mature fibroblasts/fibrocytes, fixed adipocytes, reticular cells, melanocytes, mast cells, mesenchymal stem cells
  • fibres collagens, elastin, reticular fibres
  • ground substance proteoglycans, glucosaminoglycans
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3
Q

functions of connective tissue

A
  • binding and supporting holding skin, gut, lungs, bones etc. together
  • protection eg. bone protecting vital organs, fat as shock-absorber
  • insulation eg. fat underlying skin
  • storing reserve fuel and cells eg. bone marrow and fat tissue
  • transporting substances within body eg. blood and interstitium
  • separation of tissues eg. fascia and tendons/cartilage
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4
Q

what is the interstitium

A

space between tissues and organs of the body

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5
Q

types of connective tissue proper

A

loose connective tissue
- areolar

dense connective tissue
- regular
- irregular

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6
Q

structure of loose connective tissue (areolar)

A

contains multiple cell types
- fibroblasts, macrophages, white blood cells, mast cells, adipocytes

contains two main fibres
- collagenous
- elastic

gel-like ground substance
- proteoglycans, hyaluronic acid

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7
Q

functions of loose connective tissue (areolar tissue)

A
  • holds vessels that supply fluids
  • permits cell migration
  • involved in inflammation pathways
  • acts as packaging around organs
  • generally hold everything in place
  • cushions and stabilises organs
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8
Q

where is loose connective tissue found

A
  • under epithelial cell layers
  • around glands
  • surrounds capillaries, nerves and sinusoids
  • areas where bacteria/viruses that have breached the epithelial surface can be attacked and destroyed by the large number of immune cells present in the highly viscous loose connective tissue
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9
Q

histology of loose connective tissue

A
  • adipocyte large white droplet
  • mast cells large and darkly stained
  • collagen fibres thick strands
  • elastin fibres thin strands
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9
Q

function of fibroblasts

A
  • synthesise and secrete the fibres lying within ground substance (extracellular matrix)
  • important in wound healing process and responsible for formation of scar tissue
  • myofibroblasts contain actin and myosin and responsible for wound contraction when tissue loss has occurred
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10
Q

function of macrophages

A
  • derived from blood monocytes and move into loose connective tissue when there’s local inflammation
  • phagocytic so degrade foreign organisms and cell debris
  • professional antigen presenting cells
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11
Q

function of mast cells

A
  • look like basophils
  • contain abundant granules including histamine (inceases blood vessel wall permeability), heparin (anticoaguant), cytokines (attract eosinophils and neutrophils)
  • found in areolar connective tissue near blood vessels
  • absent from CNS to avoid damging effects of oedema
  • become coated with IgE molecules that bind allergens causing contents of granules to be released from cell
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12
Q

what are unilocular adipocytes (white)

A
  • single enormous lipid droplet with nucleus, cytoplasm and organelles squeezed to one side of cell
  • function is padding and shock absorber, insulation and energy reserve
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13
Q

what are multilocular adipocytes (brown)

A
  • multiple small lipid droplets with nucleus, cytoplasm and organelles squeezed to centre of cell
  • very few in adults
  • function is to provide insulation and energy reserves
  • main method of generating heat in neonates through non-shivering thermogenesis
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14
Q

white VS brown adipose tissue

A

white
- single lipid droplet
- normal number of mitochondria
- single peripheral nucleus
- lipid breakdown slow in adults so heat generated by shivering reflex

white
- multiple lipid droplets
- increased number of mitochondria
- single central nucleus
- lipid breakdown accelerated in young children so oxidative phosphorylation uncoupled to generate heat

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15
Q

what are adipose cells generated from

A
  • immature fibroblasts
  • mesenchymal cells
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16
Q

fibres of connective tissue

A
  • collagen flexible with high tenisle strength
  • reticular/reticulin supporting framework/sponge
  • elastic allows tissues to recoil after stretch or distension
17
Q

what is extracellular matrix

A

complex extracellular structural network consisting of ground substance and fibres

18
Q

types of collagen

A

type I
- most widely distributed type ~90%
- fibrils aggregate into fibres and fibre bundles eg. in tendons, skin dermis

type II
- fibrils do not form fibres
- in hyaline and elastic cartilage

type III (reticulin)
- fibrils form fibres around muscle and nerve cells and within lymphatic tissues and organs and tendons

type IV
- unique form present in basement membrane
- binds to proteoglycans

19
Q

examples of loose connective tissue

A
  • superficial fascia
  • submucosa of colon
20
Q

what is ground substance

A
  • viscous, clear substance with a slippery feel
  • high water content
  • composed of proteoglycans, glycosaminoglycans and glycoproteins
21
Q

what are proteoglycans

A
  • large macromolecules consisting of a core protein to which glycosaminoglycans (GAGs) are covalently bonded
  • GAGs attract water and form a gel that permits diffusion but resists compression
  • core proteins attached to the hyaluronate
  • sugar moieties attract water but make ground substance sticky and slippery at same time
22
Q

what is hyaluronic acid

A

unique GAG that’s bound to proteoglycans by a link protein to form giant hydrophilic macromolecules that resist compression without inhibiting flexibility so main GAG in cartilage

23
Q

mucoid connective tissue

A
  • cell: immature fibroblasts
  • fibres: thin collagen III fibres
  • main component: jelly-like ground substance - hyaluronic acid
24
Q

where is mucoid connective tissue found

A
  • umbilical cord
  • vitreous humour of eye
25
Q

how is collagen formed

A
  • fibroblasts secrete procollagen which is converted to collagen molecules outside the cell and aggregated to from final collagen fibrils
  • fibrils can group together to form collagen fibres that provide strength to the tissue eg. tendons, ligaments
26
Q

what are reticular fibres

A
  • type of fibre composed of type III collagen secreted by reticular cells
  • crosslink to form reticulin which acts as supporting mesh in soft tissues
27
Q

what are elastin fibres

A
  • elastin is the primary component which enfolds and is surrounded by microfibrils called fibrillin
  • occurs in most connective tissues but to varying degrees
  • allows tissues to recoil after stretch or distension
  • important in artery walls, dermis, lungs, elastic cartilage
28
Q

structure of dense connective tissue

A
  • few cell types - mostly fibroblasts
  • many collagen fibres
  • little ground substance
29
Q

two types of dense connective tissue

A

regular
- collagen fibres arranged in parallel bundles and densely packed
- fibroblasts between bundles
- designed to withstand stress in a single direction
- tendons, ligaments, aponeuroses

irregular
- collagen fibres arranged in bundles orientated in various directions
- fibroblasts between bundles
- designed to withstand stress in multiple directions
- submucosa of intestine, deep layers of dermis

30
Q

examples of dense regular connective tissue

A

tendon connects muscle to bone
- cylindrical mass of connective tissue at end of muscle
- collagen bundles in parallel, densely packed formation in line with tensile force exerted by muscle
- rows of elongated flattened fibroblasts between the collagen bundles so muscles can exert force onto bone and cause movement

ligament connects bone to bone
- collagen bundles densely packed in parallel arrangement
- not straight but undulate and arranged in fascicles that are separated by loose connective tissue

aponeuroses cover large areas of body and provide structural support
- flat sheet of regular connective tissue with bundles of fibres in one layer arranged at 90 degrees to those in adjacent layers
- tendon flattened into thin broad sheath

31
Q

example of dense irregular connective tissue

A

dermis underlying epidermis of skin
- collagen bundles densely packed but irregularly arranged and orientated in multiple directions
- skin can resist forces in multiple directions to prevent tearing
- elastic fibres allow stretch and restoration to original shape after skin bent or folded

32
Q

types of fascia

A
  • superficial
  • deep
  • visceral/parietal
33
Q

what is fascia

A
  • made up of fibrous (dense) connective tissue containing closely packed bundles of collagen fibres oriented in a wavy pattern parallel to direction of pull
  • fascia is flexible and able to resist great unidirectional tension forces until wavy pattern of fibres has been straightened out by pulling force
  • collagen fibres produced by fibroblasts within fascia
34
Q

why is vitamin C needed for collagen formation

A

vitamin C hydroxylates proline and lysine which helps form procollagen inside cell which can be oackaged, released and modified into collagen outside of cell

35
Q

what is scurvy

A

vitamin C deficiency
- synthesis of abnormal collagen that lacks usual strength
- poor wound healing and impaired bone formation

36
Q

symptoms and signs of scurvy

A
  • gum disease and tooth loss
  • bruising of skin
  • hair loss
  • bleeding
  • poor wound healing
  • weakness and fatigue
  • impaired bone development in young
37
Q

what is Marfan’s syndrome

A
  • autosomal dominant disorder
  • mutation in fibrillin 1 gene so elastic tissue is abnormal
38
Q

signs of Marfan’s syndrome

A
  • abnormally tall
  • arachnodactyly
  • frequent joint dislocation
  • greater span than length
  • risk of catastrophic aortic rupture
39
Q

what is osteogenesis imperfecta (“brittle bone disease”)

A
  • autosomal dominant disease
  • due to mutated collagen fibres and/or not enough collagen produced
40
Q

signs of osteogenesis imperfecta

A
  • weakened bones (fractures common)
  • short stature
  • blue sclera
  • hearing loss
  • hypermobility (loose joints)
  • flat or arched feet
  • poor teeth development
41
Q

what is Ehlers-Danlos syndrome

A
  • collagen fibre abnormalities of dermis and tendons
  • presents as joint dislocations and skin deformation

Body logistics (20 decks)

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