CT Proper & Adipose CT Flashcards
What are the properties of Connective Tissue? x3
- Physically connects tissues of different types
- Fills spaces to form a seamless continuum of functionally integrated tissues
- Forms pathways for vessels and nerves traveling to and from tissues
What are the functions of connective tissue? x5
- Imparts mechanical properties to larger structures
- Provides structural support to larger structures or to the whole body
- Defense and Repair
- Physiological support and metabolite storage
- Signaling medium
What is the general composition of connective tissue?
ECM that contains fibers and ground substance
Cells that are permanent residents or temporary residents
What are defining characteristics of connective tissue?
ECM»_space; cells - depends on type of tissue
Fibers»_space; ground substance - types of fibers depends on type of CT
Usually vascularized
What are three common fibers present in almost all connective tissue? What is their general properties?
- Collagen I Fibers - semi-rigid and resist tensile forces
- Elastic Fibers - elasticity
- Reticular (collagen III) fibers - internal 3D support in tissues, glands, and rogans that are soft and solid
Where are collagen I fibers common?
Bone - impart flexibility
Where are elastic fibers common?
Blood vessels walls
What types of fibers do blood and hyaline and elastic cartilage have?
Blood - Fibrin
Hyaline & Elastic Cartilage - Collagen II
What is ground substance and its function?
Can be fluid or gel like depending on tissue type.
Provides lubrication, resists compression, and provides physical support
What are the 3 classifications of Connective Tissue?
- CT proper
- Embryonic CT
- Specialized CT
What connective tissues are part of CT proper? What is the function of CT proper?
Function is to form physical connections between organs and provide physical support in tissues.
Loose (areolar) CT
Dense collagenous CT (regular and irregular)
Elastic CT
Reticular CT
What tissues are embryonic CT? Where are they found?
Found only in embryos and fetuses.
Includes mucous CT and mesenchyme
What tissues are included in specialized CT? What is their function?
Function is to provide physiological support and/or structural support for the entire body.
Adipose CT - white and brown
Cartilage
Bone
Blood
What are sarcomas?
Malignant cancers that originate in or from CT proper, cartilage, bone, or adipose CT
DO NOT include cancers arising from blood cells or their precursors
What are the functions of resident cells?
Develop, remain, and perform their main functions within connection tissue
Permanent residents
What are examples of resident cells?
Fibroblasts
Adipocytes
Mast Cells
Macrophages
What are transient cells and what do they do?
Free/Wandering Cells. Short lived cells and population changes through time
Originate in bone marrow and circulate in blood for a while
Recruited to CT to perform a specific function - temporarily residents
What are examples of transient cells?
Plasma cells (plasma B lymphocytes)
Other types of leukocytes (WBCs)
Where are most cells that give rise to CT from?
Mesoderm
What is mesenchyme and the function of mesenchymal cells?
Embryonic connective tissue
Cells synthesize ECM of embryonic CT, pluripotent stem cells, and give rise and differentiate into the resident CT cells that synthesize ECM components (fibers and ground substance)
What are examples of CT stem cells?
Mesenchymal cells - chondroblast, fibroblast, osteoblast
Hematopoietic stem cells
What are fibroblasts and their function?
Fiber builders
Synthesize ECM components
Stem cells that can differentiate into adipocytes and several other CT cells
What are characteristics of fiberoblasts?
Abundant
Low turnover
Synthetically active or inactive
What are the functions of active fibroblasts? How do they appear in LM?
Actively synthesize ground substance components for secretion into the ECM
In LM, basophilic cytoplasm when synthesizing fibers, oval euchromatic nucleus, and close association with ECM fibers. “Spindle shaped”
What are inactive fibroblasts and how they appear in LM?
Fibrocytes that are synthetically less active or synthetically inactive.
In LM - nucliei are small, flat, and heterochromatic. Cytoplasm is more acidophilic
What are most adipocytes in CT proper?
Unilocular adipocytes - white fat cells
What are the functions of adipocytes in CT proper? Where do they come from?
Synthesize, store, and release fats
Derived from mesenchymal cells or fibroblasts. Terminally differentiated cells - do not divide
What are the functions of mast cells? What are mast cells derived from and where are mast cells located?
The functions are initiate type I hypersensitivity reactions (main type of allergic reaction) and mediate the subsequent inflammatory response
Derived from hemopoietic stem cells.
Located in CT proper (all over body) and mucous membranes of respiratory and digestive tracts
What the signature feature of mast cells? What is the function of that feature?
Mast cell granules - intensely basophilic, metachromatic
Granules are very large secretory vesicles that contain histamine, heparin, enzymes, and chemicals that recruit white blood cells
What are the characteristics of macrophages and what do they do?
Functions are phagocytosis, present antigens to lymphocytes, and promote wound healing
Have off center nucleus and nucleus is kidney shaped and usually euchromatic
Have pseudopods and phagosomes
What are macrophages derived from?
Monocytes
What are the functions of plasma cells and what do they look like?
Plasma cells are lymphocytes
Synthesize and secrete antibodies - continuous secretion
Often have large Golgi ghost and a clock face nuclues from the heterochromatin
What are the two types of embryonic CT?
Mucuous CT
Mesenchyme
What is mucous CT and what is its function?
Mostly ECM
Only present in umbilical cord - helps resist compression and prevent umbilical vessels from being compressed
What are the functions of mesenchymal cells? What do they look like?
Synthesize ECM of embryonic CT - differentiate into resident CT cells
Mesenchyme condenses over time, but had more ground substance and fewer cells
What is the function of loose CT? What are its characteristics?
Loose, disorganized, amorphous cobwebs - mostly collagen I and elastic fibers
Vascularized
Includes fibroblasts and macrophages
Functions as transition between epithelia and deeper underlying CT
Protects and cushions blood vessels and nerves traveling within it
What is the function of dense regular CT? What are its characteristics?
Has many parallel and closely packed collagen I fibers and fiber bundles
Main CT forming tendons and ligaments - can resist strong tensile forces coming from one directions
Not well vascularized. Fibroblast nuclei between fibers
What is the function of dense irregular CT? What are its characteristics?
Many collagen I fibers and fibers bundles going in many direction
Found in dermis of skin, organ capsules, epineurium, and perichondrium - fibers resists moderate tensile forces coming from many directions
Moderately vascularized. Fibroblast nuclei scattered
What are the functions of elastic CT? What are its characteristics?
Densely packed elastic fibers (long, thin, Y shaped) or broad sheets of elastic called elastic lamellae and elastic laminae
Found in ligamentum flavum - provides elasticity and flexible support to spine
Found in large and medium arteries - enables arteries to accommodate a constantly changing volume of blood
What are the functions of reticular CT? What are its characteristics??
Reticular fibers form internal 3D scaffold that supports the cells of solid organs and glands.
Forms 3D scaffold of bone marrow and adipose CT. Forms endomysium (muscle tissue)
Main cell is fibroblasts
In places like red bone marrows, glands, liver, and adipose CT.
What are characteristics of adipose CT?
Cells dominate and very little ground substance. Mainly contain adipocytes and each adipocyte is surrounded by layer of ECM called an external lamina
Reticular fibers form scaffold. Rich blood and nerve supply
What are the functions and characteristics of white adipose CT?
Functions are insulation, cushioning, and lipid/energy storage. Also mechanical padding (shock absorber), and stem cell reserve.
Cells are unilocular adipocytes. Vascularized and rich nerve supply.
What endocrine function do unilocular adipocytes have?
Synthesize adipokines - hormones that regulate fatty acid metabolism
leptin - reduced appetite
adiponectin - reduced glucose release by liver and facilitates weight loss
Retinol-binding protien 4 - induces insulin resistance, promotes glucose release by liver, and contibute to inflammatory response
What are the characteristics and functions of brown adipose CT?
Heat generation by decoupling oxidative phosphorylation and lipid storage
Cells are multilocular adipocytes = have many mitochondria
More abundant in fetuses and newborns than adults
