Connective Tissue (1) Flashcards
Define a tissue
A collection of cells containing a predominant cell type that work together and perform the same function form a tissue.
Connective Tissue (CT) = network of fibres in a ground substance + cells in the following relative proportions which characterise a
CT:- few cells, large amount of extracellular matrix with many fibres and abundant ground substance
Define an organ
An organ is a collection of tissues joined in a structural unit to serve a common function
What 3 components make up a tissue?
cells + fibres + extracellular substance
Name the 4 basic (primary) tissues
What is the function of connective tissue?
Functions to ‘connect’ and mechanically support other tissues of the body. (Also called Support Tissue).
What are the 2 classifications of connective tissue?
CT ‘Proper’
Specialised CT
Define CT ‘proper’
provides mechanical support to tissues and organs whilst also carrying blood vessels and nerves to and from these.
Define specialised CT
bone, cartilage, blood, adipose tissue, ligaments and tendons. (Bone & cartilage to be given in separate lecture).
What are the 2 subclasses of CT ‘proper’?
loose (areolar) CT
dense CT
What can dense CT be subclassed into?
dense irregular and dense regular
What differentiates dense regular and regular?
dependent on arrangement of collagen fibres
What are the identifying characteristics of connective tissue?
- Few cells
- Cells apart from each other
- Spaces filled with fibres + ground substance + fluid = extracellular matrix (ECM)
- Connects and supports
What are the spaces between cells in connective tissue filled with?
ECM
What does the ECM define in CT?
defines structural and functional
e.g. solid to liquid connective tissue… bone and blood
Describe the appearance of loose (areolar) CT?
An aggregation of loosely arranged fibres and many cells of differing types.
Picture showing histology of skin
What is the role of loose CT?
Primary location beneath epithelia that cover surfaces or line tubes/cavities
What is the role of loose CT?
Initial site of defence against bacteria, so many transient cell types migrate to loose CT from local blood vessels.
What classification of CT does adipose tissue fall under?
specialised CT
What are the characteristics of adipose tissue?
Specialised Loose CT with abundant fat storing adipocytes
Single, large droplet of lipid pushes nucleus to one side and flattens cytoplasm to a thin rim
Rich blood supply
White fat (most adult) and brown fat (mostly foetal)
Mostly in CT under skin -insulation - and also for protection around organs and neurovascular bundles
What type of CT tissue is shown?
adipose tissue
Single, large droplet of lipid pushes nucleus to one side and flattens cytoplasm to a thin rim
C = capillaries
N = nucleus
Does adipose tissue have a rich blood supply?
YES
What is the difference between white and brown fat?
White fat (most adult) and brown fat (mostly foetal)
Where is adipose tissue located in the human body?
Mostly in CT under skin -insulation - and also for protection around organs and neurovascular bundles
Define fat
Fat = adipose cells in amongst some CT cells and fibres macroscopically has yellowish colour
What is adipose tissue abundant in?
Specialised Loose CT with abundant fat storing adipocytes
What is adipose tissue mainly made up of?
adipocytes (fat cells)
What bone marrow made up of?
red marrow, which produces red and white blood cells and platelets, and yellow marrow, which contains fat and connective tissue.
A = adipocytes
purple = capillaries
Describe dense irregular CT?
Thick collagen fibres that run in all directions
What is the function of dense irregular CT?
Able to withstand tension exerted in many directions; provides structural strength
What is the location f dense irregular CT?
Dermis of the skin; submucosa of digestive tract; fibrous capsules or organs and of joints
What CT is this?
dense irregular CT
What are structures A and B
dense irregular tissue
Describe dense regular tissue
closely packed collagen fibres all running in the same direction
poorly vascularised
Describe the function of dense regular tissue
attaches muscl;es to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction
What is the location of dense regular CT?
tendons and ligaments
What CT is this?
CT dense regular
Name fibres A and B
CT dense regular
What are the components of connective tissue?
CT = cells + ECM
What makes up ECM?
- Fibres - ‘rope-like’
- Ground substance - ‘jelly-like’
- Tissue fluid - liquid
What are the major fibres in the ECM?
collagen
reticular and elastin
What is the ground substance in the ECM?
carbohydrate linked to protein (e.g. hyaluronic acid - joints)
How would you describe fibres in the ECM?
rope-like
How would you describe ground substance in the ECM?
jelly-like
What fibre is this?
collagen protein
What fibre is this?
Reticular lymph
What fibre is this?
Elastic aorta
What is the most abundant fibre in CT?
collagen
Describe collagen in the ECM
Strong, flexible with good tensile strength
Exhibits ultrastructural periodicity
Describe the appearance of collagen fibres
LM looks like wavy structures of variable width and length
What fibre is this?
collagen
What fibre is this?
reticular fibres
Arrows indicate the reticular fibres supporting lymphoid tissue, eg. in lymph node, spleen, thymus
Describe the characteristics/structure of reticular fibres
Are collagen fibrils but only 20nm in diameter and greater amount of sugar
Do not form large bundles
Often found singly, dispersed in an extensive matrix of ground substance or in a mesh/network
In adults what do reticular fibres support?
In adults also the supporting stroma of haemopoietic and lymphatic tissue; in the liver and other glands
What fibre is the arrow pointing to?
elastic fibre
Are elastic fibres thinner than collagen?
YES
Are elastic fibres arranged more randomly than collagen?
yes
What is the property of elastic fibres?
elastic properties
What are the microfibrils like in elastic fibres?
straight and thin (12nm diameter)
How does the composition of elastic fibres change with age?
Composition changes with age (more microfibrils in youth, more amorphous elastin as we age)
Give 2 examples of where elastic fibres are located/involved in?
Elastic ligaments of the spinal column
Fenestrated lamellae in concentric rings in the walls of elastic arteries
