Connective Tissue Flashcards
What is the extracellular matrix made up of?
Ground substance and fibres
What is the ground substance made of?
Hyaluronate proteoglycan aggregates
What kind of fibres can there be?
Collagen, reticular or elastic
Name the specialised types of connective tissue
adipose tissue, blood, cartilage, bone, lymphatic tissue and haemopoietic tissue
What kind of cells make up cartilage?
Chondrocytes
What kind of cells make up ligaments and tendons?
Fibroblasts
What cells form skeletal muscle?
Myoblasts
What is the embryonic origin of all the connective tissue?
Mesenchyme
What are the features of the mesenchyme?
tapering appearance to cells and abundant viscous ground substance
What is the mucous connective tissue in an embryo called?
Wharton’s jelly - from the umbilical cord
What does a proteoglycan monomer consist of?
A core protein of approximately 100 GAG units
GAG = glycosaminoglycan
What do proteoglycan form linear aggregates with?
Hyaluronic acid and collagen fibrils
What is the charge on GAGs and why is this good?
Negative charge
Attracts water so that a hydrated gel is formed
Which type of collagen is present in cartilage?
Type II
What is the other name for type III collagen?
Reticulin
What are the features of Type I collagen?
periodic banding, fibrils composed of staggered collagen molecules, triple helix of alpha chains and every third amino acid is glycine
What is Marfan’s syndrome?
Autosomal dominant disorder. Expression of the Fibrillin gene is abnormal so elastic tissue is abnormal. Sufferers are abnormally tall, exhibit arachnodactyly (long fingers and toes) and have frequent joint dislocation.
What are the 3 layers of a small elastic artery in order from inside to outside?
tunica intima: endothelial cells
tunica media: elastin lamellae
tunica adventitia: collagen
What do myotendinous junctions consist of?
Skeletal muscle fibres interdigitate with tendon collagen bundles
What does ligament join together?
Bone to bone
How is ligament arranged?
Into fascicles separated by loose connective tissue
What 2 cellular features will fibroblasts have?
Lots of RER and Lots of euchromatin
Which cells are primarily responsible for the formation of scar tissue?
Fibroblasts
Which cells are professional antigen presenting cells?
Macrophages
What substances do the granules in mast cells contain?
Heparin, Histamine and Cytokines
What is heparin?
An anticoagulant
What is the function of histamine?
To increase blood vessel permeability
What happens when allergens bind to mast cells?
The contents of the granules are rapidly released.
What are the functions of adipose tissue?
fuel reserve, thermal insulation and shock absorption
Why is brown adipose tissue brown?
Due to the rich vascular supply and abundant mitochondria
Name some places where cartilage is found
embryonic skeleton, ends of long bones, nose, trachea and larynx
What are the 3 major types of cartilage?
elastic, hyaline and fibrocartilage
Is cartilage vascularised?
No
It is an avascular tissue.
What is in the matrix of hyaline cartilage?
proteoglycans, hyaluronic acid and Type II collagen
What is found in the matrix of elastic cartilage?
proteoglycans, hyaluronic acid, Type II collagen and elastic fibres
What is the matrix of fibrocartilage made of?
proteoglycans, hyaluronic acid, Type II collagen and Type I collagen
Which type of cartilage is the precursor to bone?
Hyaline
Where is hyaline cartilage found?
parts of rib cage, nose, trachea, bronchi and larynx
What cells are in the perichondrium?
Fibroblasts (outer)
which can develop into chondroblasts (inner)
Why does the matrix stain darker around the chondrocytes?
The territorial matrix is more highly sulphated.
What kinds of signals affect the synthetic activity of the chondrocytes?
mechanical, electrical and chemical
What is different about elastic cartilage?
It does not calcify with age
Where would you find elastic cartilage?
pinna of ear, initial canal of ear, epiglottis and Eustachian tube
What are the features of fibrocartilage?
contains chondrocytes and fibroblasts, cells often distributed in rows and no perichondrium
Where would you find fibrocartilage?
Intervertebral discs, Sternoclavicular joint, Temporomandibular joint, Menisci of knee and Pubic symphysis
What are entheses?
Points of attachment of tendon and bone.
What is the structure of cancellous bone?
A network of fine, bony columns or plates. The spaces between them are filled with bone marrow.
Describe the placement of Haversian and Volkmann’s canals
Haversian - the centre of every osteon
Volkmann’s - perpendicular to the Haversian canals
How can you tell that bone is mature?
The osteocytes are arranged in concentric lamellae.
Which direction do resorption canals run?
Parallel to osteons’ long axes and Haversian canals
What are the 2 ways of viewing bone?
decalcify mature bone so it can be sectioned or grind bone down to a thin layer
How do osteoclasts break down bone?
They release H+ ions and lysosomal enzymes.
What is the sequence of healing for a long bone?
haematoma formation, granulation tissue forms a soft procallus, procallus is replaced with a harder fibrocartilaginous callus, bony trabeculae develop, ossification occurs then remodelling occurs
Define autograft
The donor of the bone is the recipient
Define homograft
The donor of the bone is another human
Define heterograft
The donor of the bone is a different species
What are the connective tissue functions?
provide substance and form to the body and organs
provide a medium for diffusion of nutrients and waste
attach muscle to bone and bone to bone
provide a cushion between tissues and organs
defend against infection
aid in injury repair
