(01) Connective Tissue Flashcards
function of connective tissue
binds, supports, strengthens other tissue
blood = major transport system
stored energy reserves (fat / adipose)
features of CT, and exception
CT is not found on body surfaces
can be highly vascular
supplied by nerves
EXCEPT: cartilage - avascular + no nerves
tendons = little blood supply
CT “Equation”
CT = ECM + Cells
ECM “equation”
ECM = GS + Fibres
where do the protein fibres in ECM come from
protein fibres of ECM are secreted by the cells in ECM
What determines the functions of a type of connective tissue?
the structure of the ECM
eg. in cartilage, ECM = firm + rubbery
in bone, ECM = hard + inflexible
what three things make up GS?
GS = Water + Proteins + Polysaccharides (sugars)
like jelly! (gelatine = protein)
what are GAGS
glycosaminoglycans or mucopolysaccharides
= long unbranched polysaccharides (repeating disaccharide unit)
sugars found in GS
what is the structure of GAGs
long unbranched polysaccharides made of repeating disaccharide units
(many GAGs attach to a protein core with a glycoprotein head to make a proteoglycan which looks a bristled brush)
Polar and trap water
what are proteoglycans
protein + (sulphated) glycosaminoglycan (GAGS)
examples of sulphated GAG
dermatan sulphate
heparin sulphate
keratan sulfate
chondroitin sulfate
binds to proteins to form proteoglycans (PGs)
name one non-sulphated GAG
hyaluronic acid
does not bind directly (covalently) to protein backbone but joined to various PGs
how to glycosaminoglycans give the GS its form
GAGS trap water (like bottle brushes) to make the GS more jelly-like
what is hyaluronidase and what does it do?
an enzyme produced by white blood cells, sperm and some bacteria
breaks apart hyaluronic acid so the GS becomes more liquid + move more easily through it
what is hyaluronic acid and where is it found?
viscous slippery substance
binds cells
lubricates joints
maintains shape of eyeball
applications of chondroitin sulphate as ground substance
support + ADHESIVE features of cartilage, bone, skin, blood vessels
locations of keratan sulphate in GS
bone, cartilage, cornea of eye
locations of dermatan sulphate in GS
skin
tendons
blood vessels + heart valves
describe exophthalmus
protruding eyes as a result of autoimmune over-activation of thyroid
autoimmune action of fibroblasts in ECM of eye –> deposition of GAGS and influx of water
name the three different protein fibres found in ECM of CT
Collagen
Reticular
Elastic
describe what collagen fibres in ECM are made of, look like, and where they’re found
made of collagen
thicker, parallel bundles
strong and flexible, resist pulling forces
most abundant type - common in bone, cartilage, tendons and ligaments
describe reticular fibres - what they’re made out of, what they do, what they look like
collagen (fine bundles) with a coating of glycoprotein
made by fibroblasts
provide strength + support
forms part of the basement membrane
networks in vessels and through adipose tissue, muscle tissue, nerve fibres
describe elastic fibres - composition, appearance, functions, locations
protein ELASTIN surrounded by glycoprotein FIBRILLIN
thinner than collagen fibres, network
can be stretched 150%
skin, blood vessels, lung
what is Marfan syndrome
hereditary defect in elastic fibres - increase growth because Transforming Growth Factor beta (TGFb) does not bind normally to fibrillin
(TGFb makes you grow - binding to fibrillin makes it inactive)
long lived tall people with weakened heart valves / arterial walls
name two common connective tissue cell types
Fibroblasts
Adipocytes
features, function and location of fibroblasts
migratory
widely distributed in CT
secretes components of the matrix (fibres and GS)
where are adipocytes found and what do they do?
Fat cells
found under the skin and around organs
store fat (triglycerides)
name four cells (other than fibroblasts and adipocytes) found in Solid CT
Macrophages
Plasma cells
Mast cells
Leucocytes
what are macrophages?
a type of phagocytic cell (white blood cell, immune response)
capable of engulfing bacteria and cellular debris by phagocytosis
name and describe the two types of macrophages
fixed - reside in particular tissue
wandering - can move around tissue and gather at sites of infection / inflammation to carry out phagocytosis
what are plasma cells, what do they do
small blood cells that develop from B-lymphocyte (WBC)
secrete antibodies (proteins that attack and neutralise foreign substances)
locations of plasma cells
many CT sites
esp. gastrointestinal + respiratory tracts
salivary glands
lymph nodes, spleen
red bone marrow
what do mast cells produce
histamines
(which dilates vessels)
what are leukocytes and how to they function
white blood cells
not found in large quantities in normal CT, but in response to certain conditions they migrate from blood into connective tissue
name the two classifications of connective tissue
Embryonic
Mature
what is embryonic connective tissue?
formed in the embryo’s development
name and describe the two types of embryonic connective tissue
Mesenchyme - gives rise to all other connective tissues.
Mesenchymal cells + semi-fluid GS containing reticular fibres
Mucous - widely scattered fibroblasts embedded in gelatinous GS, supports umbilical cord + foetus
Name three broad categories of mature connective tissue
Connective tissue Proper
Fluid CT
Supporting CT
(both considered “specialised CTs”)
name and describe the two types of CT Proper
Loose - fibres create loose, open framework
many cells, few fibres
Dense - fibres densely packed
many fibres, few cells
name the three types of loose connective tissue
areolar
adipose
reticular
describe the structure, location and function of areolar CT
all three (collagen, reticular and elastic) fibres present
widely distributed
strength, elasticity, support
describe the structure, location and function of adipose CT
adipocytes for specialised storage of triglycerides as a large central droplet
found with areolar CT
insulation, energy source (white), temp control (brown)
describe the structure, location and function of reticular CT
network of reticular fibres and cells
forms STROMA (supporting framework) of organs
eg. liver, spleen, lymph nodes, BM, blood vessels and muscles
binds smooth muscle tissue cells
name the three types of dense connective tissue
Regular
Irregular
Elastic
describe the structure and appearance of dense Regular connective tissue
shiny white ECM
collagen fibres neatly arranged in bundles w/ fibroblasts in rows between
location and function of dense regular CT
tendons (muscle-bone)
ligaments (bone-bone)
aponeuroses (muscle-muscle)
provides strong attachment between structures, withstands tension
describe the healing of dense regular CT
collagen fibres not living tissue = slow healing
describe the appearance / structure of dense irregular CT
collagen fibres arranges irregularly with few fibroblasts
(looks like a slice of wagyu beef to me)
locations of dense irregular CT
often in sheets like fasciae, reticular of dermis etc (there are a lot more examples oop)
function of dense irregular CT
provides tensile (pulling) strength in MANY directions
structure of dense elastic CT
elastic fibres with fibroblasts between
unstained tissue is yellowish
locations of dense elastic CT
lung tissue
walls of elastic arteries
vocal cords / trachea / bronchi etc
functions of dense elastic CT
allows stretching of various organs
two types of supporting CT
cartilage
bone / osseous tissue
name three subtypes of cartilage
hyaline cartilage
fibrocartilage
elastic cartilage
what is cartilage
a dense network of collagen and elastic fibres
protects joints and bones
prefix associated with cartilage
chondro–
explain the -blasts suffix
means “to bud or sprout”
generally associated with immature cells
blast cells undergo cell division and secrete the ECM that is characteristic of the tissue
fibroblasts in dense / loose CT
chondroblasts in cartilage
osteoblasts in bone
explain the -cytes suffix
mature cells
reduced capacity for cell division / ECM production
mostly monitors and maintains ECM
what is the perichondrium
dense layer of fibrous connective tissue that covers the surface of most of the cartilage in the body
describe the structure of function of hyaline cartilage
chondrocytes contained within lacuna (empty spaces)
shiny (“glass”) resilient gel as GS (bluish white appearance)
surrounded by perichondrium
fibres not visible
what is the function of hyaline cartilage and where can it be found
most abundant
weakest cartilage, but offers flexibility and movement
respiratory cartilage - nose, trachea, bronchi
anterior ends of ribs
ends of long bones
structure of fibrocartilage
chondrocyte within visible thick bundles of collagen fibres within ECM
lacks perichondrium
function of fibrocartilage
support + joining structures together
strength + rigidity = Strongest type of cartilage
locations of fibrocartilage
intervertebral discs
pubic symphysis - hip bones join anteriorly
portions of tendon that insert into cartilage
menisci (cartilage pads) of knee
structure of elastic cartilage
chondrocytes in thread-like network of ELASTIC fibres
perichondrium present
function of elastic cartilage
strength + elasticity
maintains shapes of certain structures
locations of elastic cartilage
auricle (outer part) of ear
lid on top of larynx
name and describe the functions of the two types of bone tissue
Compact bone - made up of the basic unit of osteons (haversian systems)
stores Ca / P
Spongy bone - lacks osteons, stores triglycerides (yellow marrow), produces red marrow (RBC)
name the four bone cell types
Osteogenic cells
Osteoblasts
Osteocytes
Osteoclasts
define suffix -clast
a cell that destroys or reabsorbs
what are osteogenic cells
mesenchymal stem cells that start to lay down collagen
becomes trapped and becomes osteoblasts
what are osteoblasts
bone-forming cells (forms bone matrix)
lays down more collagen
mineralisation starts
what are osteocytes
mature bone cells
formed when osteoblasts become trapped in ECM
maintain bone tissue
exchange of nutrients / waste
have gap junctions
what are osteoclasts
large, multinucleated, ruffled border
formed from the fusion of blood monocytes (WBCs)
breaks down bone, resorption (breakdown of bone ECM)
name the four components of the osteon
lamellae
lacunae
canaliculi
central (haversian) canal
what are lamellae
concentric rings of mineral salts for hardness
(eg. Ca phosphate / OH –> hydroxyapatite)
and collagen for tensile strength
what are lacunae
“little lakes”
small spaces between lamellae containing osteocytes
what are canaliculi
“minute canals”
contain EC fluid and minute osteocytic processes
radiate from lacunae
= routes for O2, nutrients and waste
what is the central (haversian) canal
blood
lymph
nerves
cells involved with the healing of broken bone
osteoclasts reabsorb dead bone
chondroblasts lay down hyaline cartilage callus
osteoblasts lay down new bone
osteoclasts remodel new bone
name the two types of fluid CT
blood
lymph
composition of blood
blood plasma = liquid ECM
FORMED ELEMENTS = RBC (erythrocytes), WBC (leukocytes), Platelets (thrombocytes)
role of erythrocytes
RBC - transport oxygen and carbon dioxide
role of thrombocytes
platelets (come from megakaryocytic in red marrow) - clotting
name two types of leukocytes
granular and agranular leukocytes
name three types of granular leukocytes
Neutrophils
Basophils
Eosinophils
name three types of granular leukocytes
monocyte
T lymphocyte (T cell)
B lymphocyte (B cell)
function of neutrophils and monocytes
phagocytic - they engulf bacteria
functions of basophils and mast cells
release substances (eg. histamine) that intensify inflammatory reaction
function of eosinophils
effective against certain parasitic worms
acute allergic response
