Connective Tissue Flashcards
What are the four types of bone cells derived from mesenchyme?
1) Osteoprogenitor cells
2) Osteoblasts - secrete osteoid and mineralize it
3) Bone-lining cells - periosteum and endosteum
4) Osteocytes - maintain bone matrix
What are osteoclasts?
- Derived from monocyte lineage
- Break down bone and maintain blood calcium levels
What are two classifications of bone tissue?
1) Compact (cortical) bone - at the surface of bone
2) Spongy (cancellous or trabecular) bone - deep to surface, surrounds open spaces
How are bones classified by their shape?
- Long
- Short
- Flat
- Irregular
What are sesamoid bones?
Bone, such as patellae, that develop within tendons due to friction
All bones have a ____ of spongy bone, and a ____ of compact bone.
All bones have a medulla of spongy bone, and a cortex of compact bone.
CT consists of both….
Cells and extracellular matrix
ECM consists of ______ and ______.
Protein fibres and ground substance
Which component of CT determines its characteristics?
The ECM
Ground substance consists of _____ and _____.
Organic molecules and tissue fluid
Ordinary CT consists of cells called _____.
Fibrocytes
What are the two types of protein fibres found in CT?
1) Collagen fibres
2) Elastic fibres
What is collagen?
- Most abundant protein in body
- Flexible, large, inelastic protein with great tensile strength
- Consists of three polypeptide α-chains coiled into a triple helix
- Different types of collagen are formed based on combinations of α-chains
Describe the 5 types of collagen.
Type I: most common, strongest, dominates ordinary CT and bone
Type II: finer, cartilage specific
Type III: very fine, forms reticular fibres that support liver, bone marrow and lymph node tissues
Type IV: non-fibular, forms a meshwork in the BM for anchorage
Type VII: forms anchoring fibrils which bind the BM to type I and type II collagen in the underlying CT
What are elastic fibres in CT?
- Composed of elastin embedded in fibrillin microfibrils
- Fibrillin acts as a scaffold that organizes elastin into a fibrillation form
- Allows ordinary CT to be resilient (bounce back after stretch)
Ground substance resists….
Compression
Tissue fluid is derived from…
Blood
The right lymphatic duct drains lymph…
From the right side of the head and neck, the right arm and the right thorax, into the right subclavian vein
The thoracic duct drains lymph…
From the left side of the body and lower limbs into the left subclavian vein
The two classes of organic molecules found in ground substance are…
1) Proteoglycans
2) Adhesive glycoproteins
What are proteoglycans?
- Organic component of ground substance, along with adhesive glycoproteins
- Consists of glycosaminoglycans (GAGs), which are polysaccharides that link to a core protein
- Negatively charged and intensely hydrophilic
Basement membrane contains…
Collagen type IV and VII, proteoglycans, and glycoproteins
What is the function of mesenchymal cells?
- Fixed cells in CT
- Multipotent stem cells that can differentiate into different cells types
What is loose areolar CT?
- A type of loose CT
- Least specialized and has all cell and fibre types
- Consists of mostly ground substance
- Can be found in superficial fascia, between muscles, BVs, laminate propria underlying digestive epithelium
What is dense irregular CT?
- Largely made of collagen type I fibres arranged in a meshwork sheet
- Relatively little GS, cells, and cell types (mostly fibrocytes)
- Forms periosteum, perichondrium, organ capsules, joint capsules, GI submucosa, reticular layer of dermis
What is dense regular CT?
- Conmposed largely of collagen type I fibres arranged in parallel arrays
- Imparts tensile strength in only one direction
- Relatively little cells, GS and cell types (mostly fibrocytes)
- Found in tendons, aponeuroses, and ligaments
What is reticular CT?
- Dominated by reticular fibres, or collagen type III
- Forms an extensive network called the stroma (scaffolding) which houses parenchyma, or functional cells
- Found in the liver, kidneys, spleen, lymph nodes, smooth muscle, and bone marrow
What is adipose tissue?
- Specialized CT proper
- Composed mostly of adipocytes in a reticular stroma
- Highly vascular
- Store triglycerides
- Acts as an energy depot, thermal insulator and shock absorber
- Abundant deep to skin, behind the eyes, and around kidneys
- Usually found with areolar CT
