Connective Tissue Flashcards
2 broad types of connective tissue
- Connective tissue proper- Dense and loose (areolar)
2. Specialized- Elastic and reticular
Characteristics of Dense CT (also called fibrous)
- Can either be dense REGULAR (parallel orientation of collagen fibers) or dense IRREGULAR (lack of definite orientation)
- Composed of collagen fibers arranged in bundles with elongated fibroblasts in between fibers and at their edges.
- Offers resistance and protection.
- Lack of open space, resulting in less flexibility
What does Dense CT form?
Dermis, Cornea, ligaments (bone to bone) and tendons (muscle to bone)
Loose (areolar) CT composition, functions, and features
- Most common CT in the body
- Composed of collagen, reticular and elastin fibers, fibroblasts, macrophages.
- No specific orientation in terms of the fibers
Functions to fill space between muscle cells and supports the epithelial tissues such as the lamina propria and blood vessels.
Features:
Delicate in consistency, flexible, well-vascularized(will bleed a lot), and not very stress resistant(easy to deform).
Loose CT are usually areas that get swollen, puffy, or have edema.
What does loose CT form?
Eyelids, iris, stroma, choroid, ciliary body
Reticular CT (specialized) composition and locations
- Delicate, loose connective tissue
- Forms a sponge like network allowing blood cells and fluids to travel through.
- Composed of reticular fibers and fibroblasts.
Located in hematopoietic and lymphoid organs such as bone marrow, spleen, thymus, and lymph nodes.
Elastic CT (specialized) composition, function, and locations
-Similar to dense regular CT, but with high proportion of elastic fibers.
Functions to allow recoil of tissues and stretch- arteries with high pressure blood flowing through or lungs/bladder which expands.
Composition: Rich in thick, parallel elastic fibers with collagen fibers and flattened fibroblasts between.
Located in aorta, lungs, bladder.
Most common cells in connective tissue
Fibroblasts
Function of fibroblasts
Produce the components of the extracellular matrix. The components are produced inside the cell and released via exocytosis.
To do this, they contain many mitochondria, abundant rER and golgi
Fibroblasts release which proteins in order to form type 1 collagen fibers and elastin fibers?
Tropocollagen- protein released to form collagen type 1
Proelastin and fibrilin- proteins released to form elastin fibers
Fibrocytes
Dormant version of fibroblasts. Fibroblasts become fibrocytes after producing the CT. If the CT is damaged, they can reactivate and fill the injured space.
Fibrocytes can also become myofibroblasts, which contain actin and myosin filaments. These filaments can help to pull the edges of wounds together and promote healing
Myofibroblasts
A type of fibroblasts that contain actin and myosin filaments. These filaments can help to pull the edges of wounds together and promote healing if CT is damaged.
Macrophage
Phagocytosis, APC, break down of tissues that are no longer needed. Irregular shape
Ex of tissue they break down before birth- hyaloid artery that gives nutrients to the lens of an unborn baby. Before the baby is born, macrophages break down the artery.
If the hyaloid artery is not broken down, it could cause an obstruction to vision if blocking macula and cause a mittendorf spot (where hyaloid artery connects to lens.
Hyaloid artery
Artery that connects to the lens in an unborn baby to supply it with nutrients. Is broken down before birth by macrophages. If not broken down (could be due to genetics), then it could cause an obstruction to vision.
mittendorf spot can be detected during eye exams- (where hyaloid artery connects to lens)
Mittendorf spot
Where hyaloid artery remains connect to lens
Mast cells contain
Many secretory granules including histamine, heparin, and eosinophil chemotactic factor of anaphylaxis (ECF-A)
Releases these during an inflammatory response.
Plasma cells
Are formed after B cells are activated. Production and release of Ab
Adipose cells and types
Scattered within connective tissue. Similar to fibroblast, except that it accumulates fat in the cytoplasm.
Unilocular adipose cell- Single droplet of fat and all the cell contents are pushed to the side.
Multilocular- Multiple fat droplets
Most common collagen type in the body
Type 1. They make up much of the extracellular matrix and many connective tissues.
How are collagen fibers produced
Tropocollagen produced by fibroblasts form into fibrils extracellularly. Many fibers create fibrum and the space between is ground substance. The fibrum and ground substance make up collagen.
Type II collagen
Less organized. Found in cartilage.
Type IV collagen
Assembles in a meshwork that builds basal lamina throughout the body.
Reticular fibers
Specialized type of collage fibers that form into a network instead of bundles.
- Smaller in diameter than type 1 collagen.
- Prevents rupture
- Often found near basal lamina, anchors fibrils of type VII collagen to reticular fibers.
Three types of fibers of connective tissue
Collagen, Reticular fibers, and elastic fibers
Elastic fibers
Composed of elastin and fibrillin proteins.
-Elastin is at the center of the fiber and fibrillin forms microfibrils which surround the core. This stretches easily with tension.
Fibrillin without elastin
Can form oxytalan fibers. Non-elastic form, but creates suspensory ligaments of the lens. Zonules.
What fiber creates the zonules of the lens
Oxytalan, which is fibrillin protein that forms microfibrils. This is non-elastic, which is good for making sure the lend doesn’t bounce around.
Ground substance
- Fills the space between fibers and cells in the connective tissue
- High in water content. Transparent.
- Contains glycoasminoglycans, proteoglycans, and glycoproteins.
What components are in blood
Plasma and formed elements. Formed elements- RBC, WBC, and platelets (thrombocytes)
What is within plasma
water, proteins (albumin, fibrinogen, immunoglobulins, and macromolecules)
Role of albumin in the plasma
Helps maintain osmotic pressure and homeostasis. Since it is such a large protein, wherever it goes, water will follow.
If pt needs to use eye drops frequently and wants to avoid preservatives or is allergic, eye drops can be made from pt’s albumin. It is most similar to pt’s pH and will bend in better with the tear film.
erythrocytes
- No nucleus or organelles
- contains 4 polypeptides of hemoglobin, which helps transport oxygen and carbon dioxide.
- biconcave molecule.
- 4 to 6 million per microliter
Leukocytes- 2 categories
Spherical, travel in blood stream and enter CT by diapedesis.
2 categories- granulocytes or granulocytes.
Granulocytes- contain secretory granules in the cytoplasm and multi-lobed nuclei. Neutrophils, basophils and eosinophils
Agranulocytes- WBC without granules in cytoplasm. Lymphocytes (B and T cells) and monocytes (precursor to macrophages)
Three granulocytes
Neutrophil, basophil, and eosinophils
2 types of agranulocytes
Lymphocytes (B and T cells) and monocytes, which are precursors to macrophages
Neutrophil role
Phagocytic function
Basophil role
Secrete histamine and other Inflammatory factors in response to antigens.
Eosinophil role
Release enzymes and proteins that attach parasites that are too large to be phagocytized.
Inhibit degranulation of mast cells and basophils.
Phagocytize antibody-antigen complexes
Platelets are also called
Thrombocytes
Role of platelets
Form the platelet plug when endothelium is damaged. Help forms blood clots when larger injuries occur.
Two types of supportive connective tissue
Mucous tissue and adipose tissue
Mucous tissue
A type of supportive connective tissue.
Jelly-Like tissue, primarily made of fibroblasts. Found in the umbilical cord and the pulp of young teeth.
Adipose tissue
A type of supportive connective tissue that stores energy as fat and makes up 15-25% of the body weight. (distribution varies per gender)
Thermal insulation for the body.
Composed of adipocytes that are divided into lobules- either unilocular or multilocular.
Difference between unilocular and multilocular
Uni- the fat is in a single dropout and the remainder of the cytoplasm and cell nucleus are pushed to the periphery. Signet ring appearance. Forms common, yellow adipose tissue found in adults.
Multi- Multiple lipid droplets in the cytoplasm. Forms brown adipose tissue that provides fat store and heat for infants. Few found in adult.
