Week 1 - Connective tissue and Cartilage Flashcards
Definition of tissue?
A group of cells that usually have a common embryonic origin and function together to carry out specialised activities.
What factors are the structure and properties of a specific tissue influenced by?
→ Nature of extracellular matrix
→ Connections between cells that compose the tissues
What form may tissues in the body take?
Hard (bone)
Semisolid (fat)
Liquid (blood)
What are the 4 principal types of tissue in the body?
Epithelial (skin)
Connective
Muscular
Nervous
Role of epithelial tissue?
→ covers body surface
→ lines hollow organs, body cavities, ducts
→ forms glands
→ first line of defence against pathogens
Examples of connective tissue?
skeletal tissue, cartilage, bone, blood, fat etc
Role of muscular tissue?
→ cells specialised for contraction/generating force
→ generating body heat
Role of nervous tissue?
→ detects change in a variety of conditions
→ responds by generating electrical signals - action potentials that activate muscular contractions and glandular secretions
What are the functions of connective tissue?
- binds together, supports + strengthens other body tissues
- protect and insulate internal organs
- major transport system - blood
- store energy reserves - adipose
- main source of immune response - platelets/lymph
What are the 2 basic elements of connective tissue?
Cells
Extracelular matrix
What is the extracellular matrix?
Material located between the widely spaced cells
What does the extracellular matrix consists of?
→ protein fibres
→ ground substance (material between cells and fibres)
How is extracellular matrix formed?
Cells usually secrete ECM components and create environment in which they are living.
The type of connective tissue secreted by cells determines tissue type.
e.g.
Cartilage → ECM - firm but pliable
Bone → hard and inflexible (calcified)
Examples of immature connective tissue cells and role?
blast = bud or sprout
e.g.
fibroblasts → loose and dense connective tissue
chondroblasts → cartilage
osteoblasts → bone
Retain the capacity for cell division and secrete the extracellular matrix
What do resident cells do?
They stay where they are made and never move.
What do fluctuating cells do?
Move around body in order to get to specific areas depending on their function.
Key note about resident and fluctuating cells?
Some cells e.g. macrophages can be resident and fluctuating but cells normally fall into either or category.
When do immature connective tissue cells mature?
Once cells have finished producing the extracellular matrix and have done all the cell division needed.
They begin to differentiate.
What is the mature cell suffix?
Cyte
What is the role of mature cells?
Reduction in capacity for cell division and extracellular matrix.
Mostly involved with maintaining the matrix (look after it rather than create it).
What are the 6 types of connective tissue cell types?
(vary according to type of tissue as cell produces ECM + fibres and that determines tissue type)
- Fibroblasts → connective tissue
- Adipocytes/Lipocytes → fatty tissue
- Macrophages → immunity
- Lymphocytes → immunity
- Mast cells
- Plasma cells
What are the resident connective tissue cell types?
Fibroblasts → present in general connective tissue, most numerous
Adipocytes/Lipocytes
What are the fluctuating connective tissue cell types?
Macrophages
Lymphocytes
Mast cells
Plasma cells
What do fibroblasts do?
Secrete extracellular matrix e.g. collagen, active during wound repair - forms granulation tissue.
What do adipocytes/lipocytes do?
Store and synthesise fats
What do macrophages do?
Engulf and digest bacteria or foreign bodies (Phagocytosis)
May be resident or fluctuating
What do lymphocytes do?
Involved in defence mechanism, migrate to sites of parasitic invasions and allergic responses.
What do mast cells do?
Produce histamine (chemical mediator) through vasodilation.
Involved in defence mechanism.
What do plasma cells do?
Involved in defence mechanisms, secrete antibodies
What ways can the ground substance take form?
→ Fluid
→ Semifluid
→ Gelatinous
→ Calcified