Connective Tissue Flashcards
Why is connective unusual to other major tissues
It consists of cells embedded in large quantities of extracellular matrix
What is extracellular matrix composed of
Protein fibres, amorphous ground substance and tissue fluid
Functions of connective tissue
Space filler, mechanical support, attachment, protection, highway for nutrients, main fat store, calcium store, and site of many immunological defence reactions
Three types of connective tissue
Soft connective tissue, herd connective tissue, and blood and lymph
Where so soft connective tissue found
Tendons, ligaments, mesentery, stroma of organs, and dermis of skin
Where is hard connective tissue found
Bone and cartilage
Resident cells of connective tissue
Fibroblasts, adipose cells, osteocytes, and chondrocytes
Fibroblasts structure
Elongated cells with tapered ends
Function of fibroblasts
Produce and maintain extra cellular matrix
What effect does damage have on fibroblasts
Causes them to proliferate
Adipose cell structures
Single giant fat droplet
What do adipose cells release
Fatty acid
What type of cells are the predominant cells of adipose tissue
Adipose cells
Where is brown fat found
Foetus and neonate
Structure of brown fat cells
Contain many small fat droplets and numerous mitochondria
When brown fat is oxidised what occurs
A large amount of heat is produced and this is known as non-shivering thermogenesis
Adipose tissue characteristics
Largest energy store in the body, in a constant state of turnover and is sensitive to both hormonal and nervous stimuli
Intermediate cell found during wound healing
Myofibroblast
What actions do myofibroblast carry out during wound repair
They cause wound contraction by producing collagen fibres and tugging on them to draw together the wound margins
What cells are immigrant cells
Leukocytes and mast cells
Types of leukocytes
Lymphocytes, plasma cells, granulocytes and macrophages
Where do leukocytes migrate from
The blood stream
What causes an increase in leukocytes
Inflammation or infection
What do mast cells contain
Granules of heparin, histamine and substances that stimulate inflammation and attract white blood cells
What is responsible for the symptoms of an allergic reaction
Histamine
What type of leukocyte leaves the blood stream in response to infection
Neutrophils
What type of leukocyte is found in increased number during allergic reactions and parasitic diseases
Eosinophils
What transient cells are found in connective tissue
Macrophages
Characteristics of macrophages
- Derived from monocytes in the bone marrow
- Transform into macrophages in the connective tissue
- Can proliferate locally
- Are phagocytic cells
- Have a body wide distribution
What does the presence of histamine cause
Increased permeability of small blood vessels and increased mucous production and smooth muscle contraction in airways
What is the smallest cell present in connective tissue
Lymphocytes
Composition of lymphocytes
Small nucleus with almost no cytoplasm
Where are large numbers of lymphocytes found
In the gut
What do B lymphocytes give rise to
Plasma cells
Where are plasma cells likely to be found
Site of infection
Composistion of plasma cells
Large oval cells, rich in rough ER and a basophilic cytoplasm
What is the function of plasma cells
To synthesis antibodies found in the blood stream
What actions are causes by plasma cells
Neutralise harmful antigens, render toxins harmless, promote phagocytosis and protect the body from micro-organisms
What are the fibres of the extracellular matrix made up of
Collagen, reticular and elastic fibres
What is ground substance
An amorphus space occupying material
What is ground substance made of
Unbranched polysaccharide molecules, glycoaminoglycands (GAGs), most of which are bound to a protein core to form glycoproteins
What synthesises collagen
Fibroblasts
Characteristics of collagen
Inelastic and the most common form (type I) has a tensile strength similar to mild steel, making a tissue which is both flexible and strong
Characteristics of reticular fibres
Thin fibres made of type II collagen that forms a support network in many organs
In which organs can you find reticular fibres
Liver, lymph nodes, spleen and bone marrow
Characteristic of elastic fibres
- Provide elasticity
- Made of elastin and the microfibril fibrilin
- Provide blood vessels with elastic recoil
Characteristics of GAGs
- Linear polysaccharides bound, covalently, to a protein core, forming a preoteoglycan molecule
- Intensly hydrophillic due to presence of hydroxyl, carboxyl and sulphate groups
- Trap water so are resistant to compression
What do GAGs provide for the extracellular matrix
Turgor and determine the diffusion of substances through the matrix
Function of structural glycoproteins
Bind molecules on the surface of cells as well as extracellular matrix components so establish structural continuity between cytoskeleton and extracellular matrix
Most common glycoproteins
Fibronectin, laminin, and chondronectin
Function of fibronectin
Bind ECM to ECM
Where is laminin found
Basal lamina
Where is chondronectin found
In cartilage
Types of soft connective tissue
Mesenchyme, loose connective tissue, desne regular connective tissue and dense irregular connective tissue
Mesenchyme
Embryonic connective tissue that differentiates into cells that become fibroblasts, chondrocytes, adipocytes and osteocytes
Loose connective tissue
Loosely packed fibres separated by abundant ground substance
Where is loose connective tissue found
Mesentery, adipose tissue, stroma of many organs
What is loose connective tissue also known as
Areolar tissue
Dense regular connective tissue
Densely packed aligned collagen fibres
Dense irregular connective tissue
Densely packed collagen fibres that run in many directions
