Connective Tissue Flashcards
one of the basic tissues which gives structural and metabolic support to organs and other tissues of the body
Connective Tissue
Functions of Connective Tissue:
- Support: Structural & Mechanical
- Packing: Fills spaces, Shape to organs
- Storage: Adipose tissue: energy
- Loose areolar CT: water & electrolytes
- Transport: Medium for nutrients & metabolic wastes
- Repair: Fibroblasts: matrix and fibres
- Defense: Cells: phagocytosis or antibodies
Connective tissues develop from the ______
mesoderm
All connective tissues apart from blood and lymph consists of 3 components:
- Fibers (elastic and collagenous fibers)
- Ground substance
- Cells
Connective tissues can be broadly subdivided into:
- Connective tissue proper
- Loose connective tissue
- Dense connective tissue
- Dense regular
- Dense irregular
- Special connective tissue
- Reticular connective tissue
- Adipose tissue
- Cartilage
- Bone
- Blood
Fixed cells (intrinsic cells):
- Fibroblast & Fibrocytes
- Mesenchymal cells
- Adipocyte
- Fixed macrophages
Free cells (extrinsic cells/wandering cells)
- Free Macrophage
- Mast cell
- Plasma cells
- Leucocytes
Types of fibers:
- Collagenous fiber- bind bones and other tissues to each other
- Alpha polypeptide chains located in tendon, ligament, skin, cornea, cartilage, bone, blood vessels, gut, and intervertebral disc.
- Elastic fibers (also made by smooth muscle)- allow organs like arteries and lungs to recoil
- elastic microfibril and elastin located in the extracellular matrix.
- Reticular fibers- form a scaffolding for other cells
- type III collagen located in the liver, bone marrow, and lymphatic organs
Types of Collagen:
- Type I Collagen: Most abundant (eg., in tendons, ligaments, bone, etc.) - Type 1 - bONE
- Type II Collagen: Cartilage - Type 2 - carTWOlage
- Type III Collagen: Reticular Fibers -
- Type IV Collagen: Basal Laminae - Type four - floor
- Type VII Collagen: Anchoring Fibrils in Skin - Type 7 (fibrils) has 7 letters
Collagen synthesis takes place in
The rough endoplasmic reticulum
A glycoprotein essential for the formation of elastic fibers
Secreted into the extracellular matrix by fibroblasts and becomes incorporated into the insoluble microfibrils to provides a scaffold for the deposition of elastic
fibrillin
Main component of ground substance (substance between cells and fibers)
proteoglycans function to hold water
Influences the timing of puberty and regulates the hypothalamic control of feeding
Leptin
can diminish effects of insulin upon muscle
resistin
Have pale, bean-shaped nuclei, abundant cytoplasm
Ig G receptors
macrophages
arise from blood cells called monocytes that migrate from the bloodstream
Secreted by Macrophages
- can cause apoptosis of tumors
- decreases fat deposition
- can decrease blood pressure and cause migration of leukocytes into organs: SEPTIC SHOCK = “blood poisoning”
TNF
Production & Maintenance of Extracellular Matrix.
Fixed cells
Tissue reaction to injury or invasion of microorganisms.
Free cells
Fiberblast form 3 major types of tissue
- Loose Connective Tissue
- Dense Irregular Connective Tissue
- Dense Regular Connective Tissue
Prolyl and lysyl hydroxylase require ______ as a co-factor; deficiency causes ________
Vitamin C; scurvy
Extracellular cleavage of peptides from procollagen allows assembly of tropocollagen molecules into
collagen fibrils
Scurvy (reduced hydroxylation due to ascorbate/vitamin C deficiency) has what symptoms?
- Petechiae, ecchymoses
- Loose teeth, bleeding gums
- Poor wound healing
- Poor bone development
Cross linking of Elastin Causes
Elasticity
Abnormal fibrillin causes_____. What are the symptoms?
Marfan’s Syndrome
- Symptoms:
- Unusually tall stature
- Poor elasticity of connective tissue
- Ruptures of blood vessels enriched in Elastin and Fibrillin
important for the chain alignment of TE (tropoelastin) mediating the interplay with lysyl oxidase or lysyl oxidase-like enzymes
Fibulin-4
White adipose tissue
- contain large lipid droplet, few mitochondria
- secretes adipose derived hormones, that regulate insulin sensitivity and satiety
- stores excess energy as triglycerides, releases fatty acids during fasting periods
Brown adipose tissue
- contain multiple small lipid droplets, rich in mitochondria
- densely vascularized and innervated by sympathetic nerve endingss
- expression of uncoupling protein I
- dissipates chemical energy (mainly from fatty acids) to generate heat
In adipose cells free fatty acids are transport by ______ and glycerol is imported via ________.
Fatty acid binding protein; “aquaporins” water channels
Leptin Decreases the firing of ______ in the ______ and diminishes ______
NPY+ Neurons; hypothalamus; appetite
fat cell hormone that can improve effects of insulin upon muscle
adiponectin
Function of Brown Fat
- Generation of heat
- (non-shivering thermogenesis)
- Brown fat is located to transfer heat to specific organs, eg., brown fat is near
- Kidneys
- Carotid arteries leading to brain
Allows the Flow of H+ ions in the absence of ATP Synthesis
The Uncoupling Protein
Resilient and smooth elastic tissue
composed of specialized cells called chondrocytes that produce a large amount of collagenous extracellular matrix, abundant ground substance that is rich in proteoglycan and elastin fibers
Classified in three types:
Cartilage
Classified in three types:
- elastic
- hyaline
- fibrous
involved in the creation and mineralization of bone
osteoblasts
involved in the reabsorption of bone tissue
osteocytes and osteoclasts
Structure that constitutes part of the vertebral skeleton, supports and protects the various organs of the body, and is made up of dense connective tissue
bone
The mineralised matrix has an organic component mainly of collagen and an inorganic component of bone mineral made up of various salts
How do Macrophages recognize antigens?
Opsonization of antigen with immunoglobulins
Phagocytosis of novel anigens via “scavenger receptors”
Autoimmune reaction to snRNP’s in nucleus leads to inflammation
Lupus Erythematosus
Molecules Secreted by Mast Cells
- Histamine: binds to vessel histamine receptors, causes a RAPID increase in permeability; role in ANAPHYLACTIC SHOCK
- Proteases: bind to vessel receptors, cause a SLOW AND PROLONGED increase in permeability
- Proteoglycans: stabilize proteases and promote their effects
TNF stimulates _________ - possible role in arthritis and lupus erythematosus
Drug that blocks TNF:
lymphocytes
(Enbrel) can reduce symptoms of arthritis and lupus
Originate in bone marrow and has IgE receptors
Mast Cells
Mast cell proteases activate receptors _______
that regulate _______ Permeability
PAR-2; Tight Junction
Mast cells release tryptase to do this
Function of Fixed and Free Cells
- Fixed Cells: Production & Maintenance of Extracellular Matrix
- Free Cells: Tissue reacton to injury or invasion of microorganisms.
Elastin Synthesis and Export
- TE is synthesized on the rough ER where it binds to the chaperone protein EBP.
- The EBP‐TE complex is transported through the Golgi apparatus and secreted to the cell membrane.
- TE is released from the chaperone and forms globules at the cell surface, while EBP dissociates as a result of interaction with glycosaminoglycans and is recycled back into the cell.
- Fibulin‐4 is important for the chain alignment of TE mediating the interplay with lysyl oxidase or lysyl oxidase‐like enzymes. The oxidation of lysine residues forms covalent intra‐ and intermolecular cross‐links.
- After clusters of TE molecules reach a critical size, they are moved from the plasma membrane through the ECM and aggregate onto the microfibril scaffold to eventually form the elastic fiber.
Ground substance between
cells and fibers
Adipose tissue is metabolically active and is now considered as an _______
organ
Adipocytes Produce Hormones
Leptin
Regulates the hypothalamic control of feeding
Leptin also influences the timing of puberty
Causes of Human Obesity
- Abnormal function of leptin can cause obesity in very rare, inherited cases of human obesity
- Majority of cases of human obesity are of uncertain origin, probably epigenetic
can dimish effects of insulin upon muscle
resistin
possible explanation for linkage between obesity, insulin resistance, and the development of diabetes mellitus
Cold-induced brown adipose tissue activation in adult man
In warmed patients, glucose uptake is mainly into brain and heart; in cold patients, glucose is also taken up by metabolically active brown fat
Have pale, bean-shaped nuclei, abundant cytoplasm
Arise from blood cells called monocytes that migrate from the bloodstream
Macrophages
Macrophages secrete ________
Which can cause:
Decease:
Decease:
TNF
TNF can cause apoptosis of tumors
TNF decrease fat deposition
TNF can decrease blood pressure and cause migration of leukocytes into organs:
SEPTIC SHOCK = “blood poisoning”
Mast Cells have metachromatic staining of granules with ________
toluidine blue
Due to binding of Toluidine Blue by Highly Charged Proteoglycans
Mast Cells often Adhere to
Blood Vessels
Proteases cleave off a portion of a receptor, allowing a remaining portion to fold back and
act as a ligand
