8. Loose and dense Connective Tissue Flashcards
What are the 6 main groups of connective tissue?
- Loose connective tissue
- Dense connective tissue
- Adipose tissue
- Blood
- Bone
- Cartilage
What are the 6 functions of connective tissues?
1) binding and supporting
2) protecting
3) insulating
4) storing reserve fuel and cells
5) transporting substances within the body
6) separation of tissues
What is the function of adipose tissue?
padding and shock absorber, insulation and energy reserve
What is the function of dense connective tissue?
helps attach muscles to bones and link bones together at joints.
What is the general function of loose connective tissue?
holds organs in place and attaches epithelial tissue to other underlying tissues.
What is the function of blood?
transport vehicle for cardiovascular system, carrying nutrients, wastes, respiratory gases and many other substances
What is the function of bone
internally supports body structures, very active tissue, heals much more rapidly than cartilage
What is the function of cartilage
dense, flexible tissue similar to bone tissue
What are the 3 components of connective tissue?
- Cells
- Fibres
- Ground substance
What makes up the extracellular matrix?
Ground substance + fibres
Where is loose connective tissue found?
under epithelial cell layers (e.g. lamina propria) and around glands, surrounds capillaries, nerves and sinusoids
What are the main cells found in loose connective tissue?
Fibroblast, macrophages, other white blood cells, mast cells and adipocytes
What are the two main fibres in loose connective tissue?
Collagen and elastic blood vessel
What is the ground substance in loose connective tissue composed of?
Proteoglycans, hyaluronic acid
What are the specific functions of loose connective tissue?
- 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
What are fibroblasts and what is their function?
- Cells that synthesise and secrete the fibres that lie within the ground substance (extracellular matrix).
- cells primarily responsible for the formation of scar tissue
- Myofibroblasts are modified fibroblasts that contain actin and myosin. They are responsible for wound contraction when tissue loss has occurred - pull the wound closed
What are the functions of macrophages?
- phagocytic and can degrade foreign organisms and cell debris
- Macrophages are ‘professional antigen presenting cells’
What are mast cells?
cells filled with basophil granules, found in numbers in connective tissue and releasing histamine and other substances during inflammatory and allergic reactions.
Which granules do mast cells contain?
- Histamine (increases blood vessel wall permeability)
- Heparin (an anticoagulant)
- Cytokines that attract eosinophils and neutrophils
Where are mast cells absent from and why?
Absent from CNS - avoid damaging effects of oedema
What happens to mats cells during an allergic reaction
Mast cells become coated with IgE, molecules which specifically bind allergens When an allergen cross-links these surface-bound IgE molecules, the contents of the granules are all rapidly released from the cell - degranulation
What are adipose cells generated from?
immature fibroblasts or mesenchymal stem cells
What are the two types of adipose tissue?
- Unilocular - white adipose tissue
2. Multilocular - brown adipose tissue
How many lipid droplets are there in white adipose tissue And what is their size?
single enormous lipid droplet
Where is the nucleus and other organelles in white adipocytes?
nucleus, cytoplasm and organelles all squeezed to one side of the cell
What is the mitochondria number in white adipocytes?
• Normal number of mitochondria
What is the function of white adipose tissue?
padding and shock absorber, insulation and energy reserve
Are white adipose tissue found mainly in adults or children? And why
- In adults, found in large numbers so lipid breakdown is slow and heat only generated after shivering reflex
- Found in small number in neonates because they cannot shiver to generate heat so need brown adipose tissue that have fast lipid breakdown to generate heat
How many lipid droplets are there in brown adipose tissue And what is their size?
Multiple small lipid droplets