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80 Cards in this Set

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Is connective tissue widely separated or closely separated?
It is widely separated, and has lots of material between them, like fibers and ground substance
What do fibers and ground substance together make up?
They make up the extracellular matrix, found between connective tissue cells
What is adult loose connective tissue?
It is a filling and packing material in the blood vessels and nerves
What do they do functionally?
They prevent nerves and blood vessels from rattling around
What is the mesentery spread?
It is the structure that suspends the GI tract from the dorsal body wall
How is the mesentery different in preparation for microscopy than most cells?
It is thin enough to drag onto slides
Fibroblasts are also known as?
Fibrocytes
Are macrophages / histocytes common in loose connective tissue?
Yes
You may see an indentation on these cells, and what does this come from?
This harks back to where these cells came from: They are derived from one type of white blood cells, monocytes
What is the function of macrophages?
Phagocytosis of damaged or severed tissues, worn out cells, bacteria, and foreign antigens
Are fibroblasts larger or smaller than macrophages?
They are generally larger than macrophages
How are macrophages antigen-presenting cells?
When they ingest an antigen, they break the antigen up into pieces, which are then presented on the surface of the macrophages so that other components of the immunse system can read them.
What is the method to identify macrophages?
You inject an animal with ferritin, which is a foreign protein, and all the macrophages will digest the ferritin in order to get rid of it
So how does this help to identify macrophages?
Macrophages can then be stained blue by tryphan, which stains ferritin, but not macrophages
What does this look like?
If you see a slide showing mesentery spread, you can see the nucleus of the cells and the blue granules of ferritin
If you used this technique all over the body, where could you likely find macrophages?
The lymphatic organs, such as lymphnodes, thymus, and spleen, as well as the liver and lung and bone marrow
Are plasma cells found in loose connective tissue?
Not commonly
What if there was an inflammation or infection in the connective tissue?
Since plasma cells are part of the immunie system, they would increase in number during an inflammation / infection
Where can plasma cells usually be found?
They can be found under the epithelium of the GI and respiratory tracts
Why is this such a great place for plasma cells?
Under the epithelium of the GI and respiratory tracts are partially where foreign antigens get into the body, so they'll be there to stop them.
What do plasma cells contain lots of?
They contain lots of basophilic cytoplasm and must be full of rough ER
How can you easily find plasma cells on slides?
They are easily recognized by the heterochromatin pattern, which is clumped in the nuclear membrane like a clock face: it is called a clock-faced nucleus
What do plasma cells make?
Circulating antibodies
What do mast cell granules contain?
They contain herparin and histamine
What does histamine do?
It is involved in dilation, and it increases the permeability of the cap and venules, allowing fluid to leak out
What causes edema?
Leaking out of fluid, which is one consequence of an allergic reaction
Why can't you see these cells in dissection material, but you can see them in mesentery cells?
Because in preparation the fluid leaks out
How do mast cells work the first time you are exposed to an antigen?
The body will make a certain class of antibody called IgE, and mast cells have a receptor for a portion of the IgE. IgE will coat the mast cell and wait for exposure to the antigen
What happens the second time, now that the IgE coats the mast cell because of the initial exposure?
The mast cells will cross-link the antibodies, kicking off de-granulation.
What is degranluation due to?
It is due to a violent reaction to an antigen
What happens during degranulation?
There is a release of calcium, granules fuse, and granule contents are dumped from the cell via exocytosis
Are myofibroblasts usually found in connective tissue?
They are not normally seen in connective tissue until there is a wound
What are the two ways to heal a wound?
Migration of cells from the periphery until they fill the holes, or by the pulling of the margins of the wound together
Which way is slow?
Migration of cells is waaaay too slow, and this is not actually how a wound heals
How does a wound heal?
Myofibroblasts contain transmembrane proteins, and these are linked proteins which are integral proteins. They are in myofibroblasts and have the capacity to bind to actin fibers inside the cell as well as collagen fibers outside the cell simultaneously.
So what actually happens via myofibroblasts?
They attach to actin fibers inside the cell and collagen fibers outside the cell, and they pull the collagen inward, closing the wound
Where are mesenchymal cells found?
They are common in the embryo
What are mesenchymal cells?
They are undifferentiated cells that are capable of forming different cell types (such as fibroblasts or endothelial cells)
What is one possible location of then in adults?
There may be an association with small blood vessels around capillaries, where they form a pericyte
What do pericytes give rise to?
They may give rise to fibroblasts whent eh basal membrane around a capillary splits, with part continuing around the capillary and part around the mesentery. Part goes under the endothelial cell and part goes around the pericyte
What do mesenchymal cells contribute to?
They contribute to the pool of cells that repopulate a wound
Why do you rarely see the fat contained in an adipose cell?
Because the solvents in slide preparation dissolve the fat
What is the outside edge of the fat cell called?
The signal ring
Where are wandering cells found?
In most connective tissues
What are wandering cells?
These are all the various white blood cells, which leave the vessels and migrate to the tissues to perform their functions
What do collagen fibers look like in mesentery spread
They are the faint long criss-crossing threads in the background
What do fibrils of collagen look like?
They have a cross-banded pattern, looking like X's
What is a collagen fibril made up of?
It is made up of tropocollagen strands that are aligned end-to-end and side-to-side
What does quarter-staggered mean when referring to collagen fibrils
At each side to side allignment of collagen fibrils the row is shifted a quarter of the length, while at the end to end arrangement, there are gaps between the heads and tails
What do you use to stain collagen fibrils for EM?
Osmium
How does it work?
It accumulates in the gaps to produce the visible bands
Each tropocollagen molecule is composed of what?
Three twisted chains of amino acids
What are the chains?
Two are alpha chains, and the third is a similar but not identical alpha 2
What are the common amino acids in collagen?
Praline, hydroxyproline, and glycine
Having hydroxyproline in collagen allows for easy what?
Because hydroxyproline if found in few other materials, measuring the amount of hydroxyproline can be a measure of the amount of collagen
What is type 1 collagen?
It is 90% of all collagen
An example of type collagen in a structure is?
The sclera, or whites of eyes
Where is type 2 collagen found?
It is found in cartilage, hyaline, and elastic cartilage, specifically embryonic and intervertebral discs
Where is type 3 collagen found?
It is found in more delicate fibers
Type 4 is different why?
It is not fibrilar, so there are no fibers
Where is type 4 collagen found?
It is found in kideny glomeruli
What secretes type 4 collagen?
Epithelial cells, which is odd since most collagen is usually secreted by non-epithelial cells
What does [α1(1)]2 mean?
It means there are 2 chains of the first kind of chain
What does α2(1) mean?
It means there is one chain of the second kind
What does [α1(II)]3 mean?
It means there are 3 chains of the second kind of chain
Are reticular fibers small or large?
They are small fibers
Are collagen fibers large or small?
They are large
How do reticular fibers branch being so small?
They branch and form a netlike reticulum
Why do you not see reticular fibers in regular stains (H and E)?
They require silver stain because carbohydrates (major part of reticular fibers), are argylic or silver-loving
What are reticular fibers made of?
They are made of type-3 collagen
When are fibers known as collagen fibers?
They are known as collagen fibers if they are made of Collagen 1
What are elastic fibers?
They anastomose freely, meaning they run together
Can elastic fibers be seen with H&E?
Yes, but they often merge with collagen
Where are elastic fibers found?
They are found in the dermis of the skin, which has lots of elastic fibers
What do elastic fibers allow?
They allow your skin to go back to its original state after being pinched
What makes elastic fibers?
They are made by smooth muscle cells and fibroblasts
Why do people with Marfan Syndrome have blurred vision?
The vision can be a symptom because the lens of the eye is held by delicate fibrillin fibers
In the absense of elastic fibers, the wall of vessels cannot expand and recoil to give diastolic pressure, and because of this the wall can rupture. What is this called, and when does this arise?
It is called an aortic aneurism, and has an increased incidence in Marfan Syndrome sufferers
Do arteries contain elastic sheets with fibrillin?
No, they dont have fibrillin
Why do people with Marfan's Syndrome have defective elastic sheets if the sheet dont have fibrillin?
Fibrillin is used to make the vessels and is gone by adulthood