13. Fibrous Connective Tissue Flashcards
What are the various functions of connective tissues?
- Structural framework of the body
- Protection—e.g.,dermis,bones
- Supports and interconnects other tissues
- Energy storage– e.g., adipose tissue
- Transports fluids, cells, and dissolved chemicals throughout the body
- Defense against invasion by microorganisms
What are the 6 main cell types of connective tissue?
– Fibroblasts: produce collagens, proteoglycans and glycoproteins
– Mesenchymal cells: connective tissue stem cells
– Adipocytes: store and release fats
– Chondrocytes: produce and maintain cartilage components
– Osteoblasts: produce bone components
– Hematopoietic stem cells: produce red blood cells and immune cells (e.g., macrophages, mast cells, lymphocytes, plasma cells)
What 3 fiber types form the fibrous component of connective tissue?
- Collagens: resists tension (several different types, type-I most common)
- Elastin: stretchable fiber (assembly of tropoelastin, fibulin-1, and fibrillins1/2)
- Reticular fibers: forms supportive meshwork
Name and describe
Type-I collagen fibrils: are aligned and crosslinked to increase tensile strength
- In electron micrographs, banding of collagen fibers is observed due to fibril alignment
Scurvy: due to vitamin C deficiency; co-factor in cross-linking collagen fibers; weakens CT
Ehlers-Danlos Syndrome: abnormal collagen synthesis leading to weak collagen fibers (multiple forms)
What are the 4 types of amorphous ground substance?
Proteoglycans:
- Chondroitin sulfates
- Heparan sulfates
- Keratan sulfates
Hyaluronan:
Glycoproteins:
- Cytokines
- Growth factors (e.g., TGF-ß, EGF)
- Structural proteins (e.g., fibronectin, laminins, tenascins, link proteins)
Extracellular proenzymes:
Name and describe
Embryonic Connective Tissue:
- Rich in ECM
- Rich in mesenchymal stem cells (multipotent)
- Some but not as many collagen or reticular fibers
- In umbilical cord, sometimes referred to as “Warton’s jelly”
What are the general characterisitcs of loose connective tissue?
Loose Connective Tissue
- Areolar: low density tissue with both fixed and wandering cells; widespread
- Adipose: fat containing tissue
- Reticular: rich in reticular fibers; forms an open framework to create a supportive mesh for holding free cells
What are the general characteristics of dense connective tissue?
Dense Connective Tissues
- Dense irregular connective tissue: fibers are deposited in a random pattern (Dermis of the skin)
- Dense regular connective tissue: fibers are deposited in a highly regular pattern (Tendons connecting skeletal muscle to bone)
- Elastic connective tissue: rich in elastin fibers
What are the 2 types of loose areolar connective tissue?
Fixed Cells:
- Fibroblasts
- Adipocytes
- Mesenchymal Cells
Wandering Cells:
- Macrophages
- Mast Cells
- Leukocytes/Lymphocytes
- Plasma Cells
Loose Areolar CT
White Adipose CT
White Adipose CT:
- functions in energy storage, insulation, cushioning vital organs, and hormone secretion
Brown Adipose CT:
- key thermogenic tissue
- abundant in newborns
- greatly reduced in adults
Reticular CT:
- Rich in reticular fibers
- Forms an open framework to create a labyrinth for holding free cells
- Found in liver, bone marrow, lymph nodes and spleen where the meshwork it forms houses blood cells and immune cells outside the blood and lymphatic vessels
Reticular CT
Dense Irregular CT:
- ECM of tightly packed, interwoven collagen fibers running in a random pattern
- Fibroblasts are the principle cell type
Found in:
- dermis of skin
- capsules that surround internal organs
- perichondrium and periosteum
- fascia
Dense Regular Ct:
- ECM of tightly packed, regularly arranged collagen fibers
- Fibroblasts are the principle cell type
- Resists pulling forces
- Poorly vascularized
- When not under tension, has wavy appearance
Found in:
- Tendons
- Ligaments
- Aponeuroses
- Dense fascia, joint capsules
Dense Regular CT
Elastic CT:
- Contains a high proportion of elastic fibers
- Allows recoil of tissue following stretching
- Found in blood vessel walls, bronchiole tubes, and special ligaments (e.g., ligamentum nuchae)
What are the general characteristics of Marfan Syndrome?
- Autosomal dominant disorder where elastin is weak (mutation in fibrillin-I gene—component of elastin fibers)
- Principle targets ocular, skeletal, and cardiovascular systems
- Life threatening cardiovascular anomalies (e.g. dissecting aneurysms, mitral prolapse)
- Patients tend to be tall with long arms/legs (skeletal defects)
- Incidence 2-3/10,000
Fibroblast: function is to produce the collagen, elastin, reticular fibers, proteoglycans, and glycoproteins in the extracellular matrix
Adipocytes:
- Closely packed with their nuclei pushed to the side by large fat droplet
- Removes lipids from blood, stores it, and releases it into the bloodstream when needed
- Provides reserve energy source
Macrophage:
- Differentiate from blood monocyte
- Function is phagocytosis and destruction of bacteria, damaged or sick cells, removal of cell debris, and antigen processing and presentation to lymphocytes
Mast cells: secrete chemicals such as histamine that mediate the allergic response and heparin (an anti-coagulant of blood)
Mast cells: secrete chemicals such as histamine that mediate the allergic response and heparin (an anti-coagulant of blood)
Plasma Cell:
- Differentiate from B-lymphocytes
- Function is to produce antibodies that mediate immunity
What is the tissue type?
A. Dense regular CT
B. Dense irregular CT
C. Loose areolar CT
D. Adipose CT
E. Elastic CT
B. Dense irregular CT
What is the tissue type?
A. Dense regular CT
B. Dense irregular CT
C. Loose areolar CT
D. Adipose CT
E. Elastic CT
C. Loose areolar CT
What is the tissue type?
A. Dense regular CT
B. Dense irregular CT
C. Loose areolar CT
D. Adipose CT
E. Elastic CT
A. Dense regular CT
