WEEK 2: Connective Tissue Flashcards
What is connective tissue?
An umbrella term that encompasses a wide variety of types including loose and dense, adipose, cartilage, bone and blood.
Function of connective tissue
- Support
- Protection
- Structure
- Store fat for energy
- Transports nutrients and waste (blood)
- Helps repair of damaged tissue.
Where is all connective tissue derived from?
Mesenchyme that produces:
- fibroblasts > fibrocyte
- chondrocytes > chondrocyte
- osteoblasts > osteocyte
- hematopoietic stem cells > blood cells
Continuation of layers:
- connective tissue proper > loose (areolar, adipose, reticular) and dense (regular, irregular, elastic)
- cartilage > hyaline, fibrocartilage, elastic
- osseous (bone) > compact, spongy
- blood
What are the three components of connective tissue?
- ground substance
- fibres
- cells
The ratio of these three components determines the type of tissue i.e., bone has heaps of ground substance, but blood vessels are super flexible.
What is the extracellular matrix?
- Non-cellular environment (ground substance and fibres)
- Provides a biomechanical environment for optimum cellular function.
Function of ground substance in connective tissue
- Gel substance in between fibres and cells
- Composed of water, proteoglycans, and cell adhesion proteins.
- Allows for the exchange of nutrients between cells and capillaries
Function of fibres in connective tissue
Provide strength and support.
3 TYPES:
COLLAGEN = large, strong fibres that provide tensile strength i.e., cartilage, ligaments, tendons (thick fibres)
ELASTIC = thin fibres that provide stretch and recoil i.e., aorta, lungs, and skin. (Wavy fibres)
RETICULAR = delicate fibres that crosslink to form a fine meshwork i.e., liver spleen and lymph nodes (branching, framework fibres)
Function of cells in connective tissue
- Functioning, living portion of tissue.
- Specialised cells tissue that are only found in some i.e., chondrocytes (cartilage), osteocytes (bone), and red blood cells.
- Common connective tissue cells found in more than one type i.e., fibroblast, mast cells, plasma cells, macrophages, adipocytes and leukocytes.
Cell types: fibroblast
- Most common cell
- Produce ground substance and fibres.
- Recognised by abundant rough ER. They need lots of protein to produce the substances.
- Large/ flat/spindle-shaped cells/ processes extend from the body.
- Immature fibrocytes are what produce the fibre and ground substances.
- Mature cells are concerned with the maintenance of the tissue and cellular metabolism.
Cell types: Mast cell
- Immune cells which mediate inflammation and allergic response
- Contain granules of chemical mediators (histamine, heparin, enzymes)
- When a cell comes into contact with an antigen/allergen, degranulation occurs, and the cell spits out the contents of the granule.
- Chemical mediators produce responses characteristic of an allergic reaction: increased permeability of blood vessels, and contraction of smooth muscles (airway).
Cell types: Macrophages
- Specialized phagocytosis
- Engulf and digest substances and cellular debris via phagocytosis.
- Identify the antigens on the substance, surround and engulf it, destroy it.
- Stimulate the action of other immune cells.
Cell types: Adipocyte
- Lipocytes or fat cells
- Store energy as fat, mainly in the form of triglycerides
- This can provide energy for long period of time.
- Typically, don’t make cells, but the cells hypertrophy (a fatter person holds more fat)
Cell type: Leukocyte
- Immune cells
- Defend body from infection and disease by digesting, destroying infectious agents or by antibodies
GRANULOCYTES (have granules in cytoplasm) – neutrophils, eosinophils and basophils.
AGRANULOCYTES (no granules) – monocytes and lymphocytes
What are the two common branches of connective tissue?
Proper = more common type (loose/dense)
Specialised = only found in one thing
