Histology - Connective Tissue Flashcards
What are 3 functions of connective tissue
Space filler and mechanical support; main fat and calcium store; attachment and protection
Name the 2 types of connective tissue
Soft connective tissue; hard connective tissue
What are the 4 types of resident cells of connective tissue
Fibroblasts; adipose cells; osteocytes; chondrocytes
What are fibroblasts
Elongated cells with tapered ends that are widely distributed
What is the function of fibroblasts
They produce and maintain the extracellular matrix
What is the function of adipose cells
With the release of fatty acids into the bloodstream, they provide energy for other cells
What does the extracellular matrix of connective tissue consist of
Fibres; ground substance; tissue fluid
What is the most abundant protein in the human body
Collagen; makes up roughly 25% of total body protein
Describe the structure of collagen type 1
Inelastic and has a tensile strength (on a weight for weight basis) similar to mild steel
What are elastic fibres composed of
The proteins elastin and the microfibril fibrillin
What are reticular fibres made of
These thin fibres are made of type III collagen
What are the 2 types of soft connective tissue
Loose (most common) and dense
Where can loose connective tissue be found
Mesentery; adipose tissue; stroma of many organs
Name the 2 forms of dense connective tissue and give examples of each
Regular = fibres aligned (e.g. tendon); irregular = fibre bundles run in many directions (e.g. dermis of skin)
What are the 2 types of hard connective tissue
Bone and cartilage
Describe what cartilage is
Semi-rigid connective tissue consisting chiefly of scattered cells surrounded by an amorphous appearing ECM
What does the ECM contain in hyaline
75% water; 25% organic material
What is the connective tissue called that surrounds cartilage
Pericondrium
How many layers does the pericondrium have; and name them
2; outer fibrous layer and inner chondrogenic layer
What is the outer fibrous layer of the pericondrium’s main function
Provides support
What does the inner chondrogenic layer of the pericondrium provide
New chondroblasts to the adjacent cartilage
What does hyaline cartilage look like in real life
Blue-white and translucent
Name the 3 types of cartilage
Hyaline; elastic cartilage; fibrocartilage
Describe how elastic cartilage is different to hyaline cartilage
ECM contains a preponderance of elastic fibres, making it very flexible
What is fibrocartilage a mixture of
Dense regular connective tissue and islands of cartilage cells and and cartilage matrix
Is bone permeable
No
Name the 5 main functions of bone
Support; levers for movement; protection; calcium store; haemopoiesis (formation of blood cells, esp. in bone marrow)
What is bone composed of (include %)
Bioapatite (65%); collagen (23%); 10 & (water); non-collagen proteins (2%)
What type of bone forms the outer shell of the shaft
Dense cortical
What type of bone occupies the ends of bone (epiphyses)
Cancellous/trabecular
What arteries provide the interior of bone
Osteonal arteries
Name the 4 bone cells
Osteoblasts; osteocytes; osteoclasts; osteoprogenitor cells
What is the function of osteoblasts; and how big are they
They are bone forming cells; roughly 15-30 micrometres across
What are osteocytes; and how big are they
Bone cells trapped within the bone matrix; roughly 25 micrometres across
What is the function of osteoclasts; and how big are they
Large multinucleated cells responsible for bone reabsorption; 40 micrometres across or more
What is the function of osteoprogenitor cells
Serve as a pool reserve of osteoblasts
What is the periosteum
Dense connective tissue sheath surrounding the bone except at articular surfaces
How many layers does the periosteum have when bone is being made
2; an outer fibrous layer and an inner osteogenic layer of osteoprogenitor cells and osteoblasts
How many layers does the periosteum have when no new bone is being made
Just 1; the inner layer is inconspicuous
