Glossary of Catos 2nd exam

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Epithelia can come from all 3 germ layers, where would these be?
Ectoderm epithelia is all the outside layers. Endoderm epithelia is lining the GI tract. Mesoderm epithelia is lining the CV system, urogenital system and serous cavities.
What location do you not find epithelia?
Over articular surfaces
Is epithelium vascular or avascular?
AVASCULAR, gets it's nutrition from the vascular underlying CT.
What are the IF's found in epithelia? What are the exceptions?
Endothelium and mesothelium are vimentin
What is the mucocutaneous junction?
When inside epithelium meets outside epithelium like in the rectum-anus junction
What are the 2 examples of mesothelium?
Pericardium, pleura and peritoneum
Locations of simple squamous epithelium? Functions? Defining characteristics?
Alveoli, pleura, pericardium, blood vessels, loop of Henle, lympathics and parietal layer of Bowman's capsule.
Functions: Exchange
Flat nucleus of single layer of cells.
Locations of simple cuboidal epithelium? Functions? Defining characteristics?
Kidney tubules, thyroid follicles, ducts of secretory unit.
Function: secretion and absorption.
Round nucleus of single layer of cells.
Locations of simple non-ciliated columnar epithelium? Defining characteristics?
Small and large intestines, GB and large ducts of glands.
Single layer of cells with a basally located oval nucleus and no cilia on the surface. In addition, covered with striated border microvilli and goblet cells.
Locations of simple ciliated columnar epithelium? Defining characteristics?
Oviduct, uterus, efferent ducts and small bronchi.
Single layer of cells with a basally located oval nucleus and the surface covered with cilia.
TRUE!!! Only simple epithelia have cilia. Pseudostratified epithelia are classed as simple epithelia.
Locations of pseudostratified ciliated epithelium? Defining characteristics?
Trachea and bronchi
All cells touch the BM but not all touch the surface. Have an oval shaped nucleus and goblet cells
Locations of pseudostratified non-ciliated epithelium? Defining characteristics?
DON'T BE CONFUSED, these have stereocilia to increase absorption. There are also NO goblet cells in the non-ciliated version.
What is 1 thing to remember when classifying stratified epithelia?
Locations of stratified squamous keratinized epithelium? Function? Defining characteristics?
Dry surface epithelia like skin.
Protection from abrasion
There are no nuclei in the outer layer which usually looks separated from the surface during fixing.
Locations of stratified squamous non-keratinized epithelium? Function? Defining characteristics?
Wet surfaces of the oral cavity, esophagus and vagina.
Protection from abrasion.
Flat nuclei are found in the outer layer.
What is the predominant cell junction in stratified squamous epithelia?
DESMOSOMES to resist abrasion.
Locations of stratified cuboidal epithelium? Function? Defining characteristics?
Ducts of sweat glands, male urethra and esophageal glands (VERY RARE).
Protection, limited secretion and absorption.
2 layers of cells with round nuclei
Locations of stratified columnar epithelium? Defining characteristics?
Large excretory ducts of some glands, male urethra and conjunctiva of the eye.
2 layers of cells with oval nuclei
Locations of transitional epithelium? Function? Defining characteristics?
Ureters and urinary bladder.
Permit distention
Binucleated surface cells is defining because this will look like stratified squamous non-keratinized. In addition, the surface is puffy like clouds.
Which cells can divide in simple vs. stratified epithelium?
All simple epithelia retain the ability to divide. Only the basal layer of stratified epithelia retain the ability to divide.
What is metaplasia?
When cells of a certain region change into a different but still normal looking type of cells. E.g. stratified squamous in the trachea
What is dysplasia?
Abnormal looking tissue due to damage. This is still reversible.
What is anaplasia?
Non-reversible abnormal looking tissue which is usually cancer.
Why is cancer of the glands called adenocarcinoma and what is cancer of the epithelia called?
Glands are classified as epithelium and cancer of the epithelium is called carcinoma, therefore glandular cancer is adenocarcinoma.
What are the different shapes of the secretory units of glands?
The pancreas is a good example of what type of gland secretion?
Serous secretion which is watery, protein rich substance
Goblet cells are a good example of what type of gland secretion?
Mucus secretion which is rich in glycoproteins. This secretion is merocrine although it looks like holocrine
What is special about mixed mucoserous glands?
They have serous demilunes with intercellular secretory canaliculi.
What type of secretory product do sebaceous glands release?
Sebum which is filled with wax, cholesterol, TGL's and cell debri. Remember this is holocrine secretion.
What is the difference between apocrine sweat glands and eccrine sweat glands?
Apocrine product is similar to eccrine sweat except it is filled with protein and this allows bacteria to thrive. This makes apocrine sweat smelly and these are found in axilla and groin areas.
What product do eccrine sweat glands release?
Sweat which is a hypotonic water solution with very low protein
What product is released from mammary glands?
Milk which contains minerals, electrolytes, carbs, IgA and proteins
What method is milk released by?
Protein portion is released by merocrine but lipid portion is released apocrine.
4 things to know about intercellular secretory canaliculi?
They are modified ECF spaces
They have microvilli
They are closed off by ZO's
The product eventually gets into a true duct.
What are the 2 types of CT found in stroma of glands?
Dense irregular CT with type I collagen is found in capsule, septa and trabeculae.
Loose connective tissue with type III collagen is found surrounding each acinus.
What is the difference in lining between intralobular ducts and interlobular ducts?
Intralobular are lined with simple cuboidal or columnar.
Interlobular are lined with stratified columnar.
What is the difference between an intercalated duct and a striated duct?
Intercalated ducts are lined by simple cuboidal and connect acinus to striated duct.
Striated ducts are simple columnar and have basal infoldings making them striated.
What is the germ layer of origin of myoepithelial cells and why is this weird?
Germ layer of origin is ectoderm so have keratin intermediate filaments BUT THEY ARE SMOOTH MUSCLE CELLS.
True/False Myoepithelial cells have cell junctions?
YES, they have hemidesmosomes, desmosomes and gap junctions. ON THE EXAM!!!
What is the difference in location of channels in epithelia vs. normal cells?
Na/K pump and K channel in basolateral membrane. Na channel in apical membrane for absorption. In normal cells, these channels are randomly distributed.
What is the sequence for electrogenic Na absorption?
1) K channels in basolateral membrane create negative cell interior.
2) With a negative interior, the driving force for Na is an electrical force directed towards the inside of the cell.
3) The Na/K pump is always working and pushes this Na out of the cell.
4) A transluminal potential develops with the lumen negative. This pushes Cl through paracellular pathway into blood.
5) Some Na goes paracellular back to the lumen.
What is the point of electrogenic Na absorption?
To create an osmotic gradient which favors the absorption of water with the help of aquaporins.
What is the sequence for electrogenic Cl secretion?
1) K leak channel creates a negative cell interior.
2) Cl is driven out of cell into lumen by electrical gradient.
3) Na/K/2Cl pump in basal membrane replenishes Cl which leaked out apical surface.
4) Transluminal potential with lumen negative draws Na into lumen and water follows.
What is the point of the Na/K/2Cl pump?
The pump moves 2Cl and 1Na along their concentration gradients into the cell to replenish the Cl lost from the apical surface. The K moves solely to maintain electrical neutrality but is actually moving against conc. gradient.
What do we need in the alveoli to maintain a fluid layer?
Due to cardiovascular hydrostatic pressure, there is always fluid in the alveoli. Our purpose is to reduce this fluid and this is done with electrogenic Na reabsorption.
Which cell is responsible for maintaining the fluid balance in the alveoli?
Type II alveolar cell.
What do we need in the trachea to maintain a fluid layer?
Because the cardiovascular system hydrostatic pressure is insignificant, fluid must be created for the trachea. This is done with electrogenic Cl secretion.
Why does CF affect the trachea?
In order to maintain a fluid layer in the trachea, electrogenic Cl secretion occurs. This Cl channel is the CFTR channel which is deficient in CF. W/o the channel, the mucus is very thick.
Why do patients with CF have salty sweat if Cl secretion is altered?
The Cl channel in the secretory unit of the gland is not a CFTR channel. These patients can still secrete Cl no problem.
The CFTR channel is reversed in the duct and so they can't reabsorb the Cl fast enough.
Why use the CFTR channel for Cl reabsorption in the sweat duct?
The sweat duct still reabsorbs Na through the electrogenic method, however Cl does not move paracellular, this is not quick enough. The CFTR channel is inserted into the membrane to make this absorption quicker.
What is the difference between epithelia and CT extracellular matrix?
Epithelia only have basal lamina whereas CT have extensive ECM.
What are the 4 cells that are not classified as CT normally but still contain VIMENTIN?
Endothelium, mesothelium, mast cells and smooth muscle.
Is connective tissue vascular or avascular?
It is very vascular as it provides blood to the avascular epithelium under which it sits.
What do mesenchymal cells have that is unusual for CT?
Gap junctions. Cell junctions are not very numerous in CT.
What are the 4 types of loose connective tissue?
Areolar, reticular, adipose and lamina propria
Classify? Chief packing material CT around the body
Adipose tissue which the primary cell being an adipocyte.
Classify? CT with a large amount of type III collagen
Reticular CT
Where would one find reticular CT and what cells does it contain?
Bone marrow, spleen and lymph nodes. Reticular CT basically forms the hematopoeitic and lymphoid tissue stroma.
Reticular CT contains reticular cells which make the type III collagen.
Where would one find lamina propria?
As part of the mucosa of respiratory, digestive, reproductive and urinary tracts.
What is specific to areolar CT?
It has all 3 types of fibers: collagen, elastic and reticular. It also has a crapload of resident cells such as macrophages, fibroblasts, mast cells, plasma cells and adipocytes.
What composes the ground substance of areolar CT?
Hyaluronic acid, dermatan, keratan and chondroitin sulfate.
What is the difference btw dense and loose CT?
Dense CT has lots of type I collagen fibers and the key resident cell is the fibroblast.
Where would you find dense regular CT?
Tendons, ligaments, deep fascia and aponeuroses.
Where would you find dense irregular CT?
Reticular layer of dermis, periosteum, perichondrium, organ capsules, septa, trabeculae, perineurium and perimysium.
What causes myxedema?
Lack of thyroxine increases the synthesis of GAGS which increases tissue colloid osmotic pressure thereby drawing water into the ISF.
What are the 8 resident cells of CT?
Fibroblasts, mast cells, plasma cells, adipocytes, macrophages, endothelial cells, pericytes and vascular smooth muscle cells.
What is the function of the fibroblast?
Secrete procollagen, proelastin, GAGS and all components of the ECM.
What 2 things are required for fibroblasts to grow?
Fibroblast growth factor (FGF).
Transforming growth factor.
What special proteoglycan is found in the membrane of a fibroblast?
Syndecan which is chondroitin and heparan sulfate.
Is it high or low thyroid hormone that causes GAGs to accumulate?
Low thyroxine levels.
What are the 3 differences between fibroblasts and fibrocytes?
Fibroblasts - high metabolic activity. Fibrocytes - darker nucleus due to condensed euchromatin.
Fibroblasts - actively secreting, fibrocytes don't secrete.
Fibroblasts - actively dividing, fibrocytes may or may not divide.
What is a myofibroblast?
A fibroblast with actin and myosin found in areas of wound healing. Have an external lamina
What is another name for fixed macrophages? What about lung, liver, bone and CNS macrophages?
Alveolar macrophage
Kupffer cells
4 characteristics of macrophages?
Come from monocytes
Have lots of lysosomes, golgi and RER
High phagocytosis
Have Fc receptors for binding of ab and complement
What are the 3 functions of macrophages in CT?
Turn over the old ECM material.
Act as APC's (antigen presenting cells)
Release IL-1, TNF-a, chemotactic factors and enzymes (lysozymes and collagenase)
What do macrophages release to activate T-helper cells?
What intermediate filaments do endothelial cells contain?
Vimentin and Desmin
Where do you find pericytes?
Around continuous capillaries and post-capillary venules
What is the function of pericytes?
Release vasoactive substances to change capillary diameter. Contain smooth muscle to act like muscular layer of bv.
What replaces pericytes in all other blood vessels other than capillaries and post-capillary venules?
Vascular smooth muscle cells
What is the precursor to the adipocyte?
What is special about white adipose tissue?
The adipocytes are surrounded by a basal lamina which is the only CT cell to have this.
What connects unilocular adipocytes to one another?
Reticular fibers
Can unilocular adipocytes divide?
Not while they have fat in them.
When are the 3 times that adipocytes can divide and form?
Last 3 months of fetal life
5 years postnatal
Pre-puberty due to the estrogen
What do sympathetics do to brown adipose tissue?
Skin sensory receptors sense cold, send impulse to CNS whereby sympathetics to B3 receptors on Brown adipose are activated by Nepi. This activates hormone sensitive lipase which breaks down TGL's so that they can be used for oxidation. The mitochondria do not use these for energy production but rather heat production.
What allows brown adipose tissue to make heat?
Thermogenin (UCP-1) is an uncoupling agent which prevents ATP from being made in the mitochondria.
Where is lipoprotein lipase found?
It is found lining endothelial cells but it is made by adipocytes
What is the effect of insulin on adipocytes?
It inhibits hormone sensitive lipase to prevent TGL breakdown. It also activates the GLUT4 receptor to increase blood glucose uptake. This is because adipose tissue can't use glycerol to synthesize fats.
What do prostaglandins do to adipose tissue?
Inhibit hormone sensitive lipase to prevent TGL breakdown
List 3 activators of hormone sensitive lipase and what is the mechanism.
ACTH, glucagon and Nepi (sympathetics)
They increase levels of cAMP.
Why do obese people have hypertension?
Capillaries in adipose tissue are particularly long which causes increased TPR thereby leading to hypertension.
What is the function of leptin and where is it made?
Hormone made by adipose tissue which goes to the hypothalamus to decrease apetite.
What is the subQ fat that is found all over an infant's body called?
Panniculus adiposus
What are the locations of brown adipose in the adult?
Axilla, neck, mediastinum and kidney hilus
Which is highly vascularized brown or white adipose tissue?
BOTH and both receive sympathetic stimulation
What is the immediate precursor of the mast cell?
What is found in the granules of a mast cell?
Primary mediators: Histamine, eosinophil chemotactic factor and neutrophil chemotactic factor.
What are the secondary mediators of a mast cell and what is their function?
Leukotrienes C4 and D4 - produce vascular and bronchospasm.
Prostaglandin D2 - produce bronchospasm.
What is the origin of the secondary mediators of a mast cell?
The leukotrienes and prostaglandins come from arachidonic acid which came from phospholipase A2 breaking down DAG.
How do you activate mast cells?
First exposure to antigen (bee venom) binds IgE and causes it to move to mast cell PM.
Second exposure - antigen binds to IgE on the mast cell surface and activates adenylate cyclase. This increases cAMP which causes Ca2+ release. The Ca2+ release causes the granules to fuse and be released.
What is compound exocytosis?
It is when the granules of the mast cell fuse together before being released.
How do you cause mast cells to release their secondary mediators?
Phospholipase C converts PIP2 into IP3 and DAG. The DAG is converted into arachidonic acid with phospholipase A2 which can then be converted into leukotrienes C4 and D4 and prostaglandin D2.
Why is the plasma cell cytoplasm basophillic?
Due to RER
What accounts for the perinuclear clear area of the plasma cell?
Large Golgi apparatus
What are the red granules of the eosinophil?
Where is mucosa found?
Reproductive, respiratory, digestive and urinary systems.
What makes us a serosa?
Loose CT with overlying mesothelium
What is special about synovial membranes?
They do not have an epithelium. Contain 2 cell types. Type A - macrophages and Type B - fibroblasts (make synovial fluid)
What is synovial fluid made of?
Hyaluronic acid and lubricin
What are the components of skin?
Stratified squamous keratinized epithelium and dense irregular CT.
What are the components of mucosa?
Simple columnar or pseudostratified epithelium with lamina propria.
What are the components of serosa?
Mesothelium and submesothelial layer (loose CT)
In term of blood vessels, epithelium is to connective tissue as ....
Cartilage is to bone.
What is the composition of cartilage ground substance?
Aggrecan (chondroitin and keratan sulfate), and chondronectin (glycoprotein). There is no mineral component like bone
What is the composition of bone ground substance?
Chondroitin and keratan sulfate, osteocalcin and osteopontin. Finally, hydroxyapatite is the mineralized component of bone.
What types of collagen are found in cartilage? What about bone?
Type I and II collagen
Type I collagen
Which resident cells of cartilage can divide? How about bone?
Chondroblasts and cytes can divide.
Only osteoprogenitor cells can divide. Osteoblasts and cytes cannot divide.
True/False Cartilage has no nerves, blood or lymphatics?
What are the locations of elastic cartilage?
Pinna, auditory tube, vocal cords, epiglottis
Where would I find hyaline cartilage?
Nasal cartilage, thyroid cartilage, tracheal and bronchial cartilage, ARTICULAR CARTILAGE and costal cartilage.
You also find hyaline cartilage in the epiphyseal plates of long bones.
Fibrocartilage is found in 4 locations, what are they?
Intervertebral discs, pubic symphysis, muscle insertions and menisci
Why is it called hyaline cartilage?
Because the type II collagen doesn't form fibers, it forms fibrils which make it look glassy. Hyaline means glassy.
What type of collagen is found in hyaline cartilage?
Type II collagen
Chondronectin has 4 binding sites, what are they?
Type II collagen
Integrins of chondroblasts and cytes
Chondroitin sulfate
Hyaluronic acid
What is the perichondrium?
2 layers surrounding cartilage. It has a fibrous layer and a chondrogenic layer.
What is the fibrous layer of the perichondrium composed of?
It is dense irregular CT with lots of blood vessels, type I collagen and elastic fibers. The resident cell is a fibroblast.
What is the purpose of the chondrogenic layer of the perichondrium?
The chondrogenic layer is where we find chondroblasts which allow for appositional growth of cartilage.
What are 2 things special about articular cartilage?
The cells are lined up in rows instead of nests and the only other place that this occurs is the epiphyseal plate.
What is the type of collagen in mesenchyme?
TYPE III reticular fibers.
Discuss how hyaline cartilage is made?
1) Begins as mesenchyme with these cells making reticular fibers and hyaluronic acid.
2) Precartilage forms when these cells stop making hyaluronic acid and start making aggrecan. The cells cluster into groups called centers of chondrification.
3) Mesenchymal cells are now chondroblasts which secrete matrix and trap themselves in lacunae. Once this occurs, they are chondrocytes.
4) Chondrocytes divide and form territorial matrix.
When chondrocytes divide and form secondary lacunae this is called?
Interstitial growth and only happens in young cartilage.
How does articular cartilage divide?
ONLY BY INTERSTITIAL GROWTH because there is no perichondrium
Which hormones increase cartilage growth rate?
Thyroid, testosterone and GH
Which hormones decrease cartilage growth rate?
Cortisone, hydrocortisone and estradiol
Hypovitaminosis A causes?
Reduced epiphyseal plate width
Hypervitaminosis A causes?
Accelerated epiphyseal plate ossification stunting growth
What does hypovitaminosis C do?
Inhibits matrix formation and deforms the epiphyses
If the chondrocytes can proliferate but the matrix can't calcify, what could be the problem?
Hypovitaminosis D
What is the predominant fiber type in elastic cartilage?
TYPE II COLLAGEN, don't say elastic fibers although these are very prevalent.
Why does elastic cartilage cause thrombosis?
Fibrillin in the elastic cartilage is one of the most thrombogenic substances in the body.
How does fibrocartilage develop?
Fibroblasts of dense regular CT mature into chondrocytes. IT MAY AS WELL BE CALLED DENSE REGULAR CT.
What are the characteristics of fibrocartilage?
No perichondrium
Chondrocytes are in rows
Type I collagen
What is osteoid?
The organic component of bone which has type I collagen and ground substance (chondroitin sulfate and osteocalcin)
What is the composition of ground substance in osteoid?
Chondroitin sulfate and osteocalcin.
What does osteocalcin do for bone?
It binds Ca2+
What makes up the mineral component of bone?
Hydroxyapatite is CaPO3 crystals.
What does the mineral component and osteoid confer to bone?
Mineral confers rigidity and osteoid confers tensile strength.
What are the 4 types of bone cells?
Where would you find osteogenic cells?
In the osteogenic layer of the periosteum and in the endosteum.
What is the precursor to the osteogenic cell?
They are actually mesenchymal cells of the bone.
What enzyme do osteoblasts contain that allows them to form bone?
Alkaline phosphatase
When osteoblasts are found on the resting surface of bone, what are they called?
Bone lining cells and they have flat nuclei.
Which bone cells synthesize osteoid?
How do osteocytes communicate with one another?
Through canaliculi and gap junctions.
What hormone stimulates fast Ca2+ exchange and what is fast Ca2+ exchange?
PTH stimulates osteocytes to suck up Ca2+ from the lacunar fluid and transfer it through canaliculi to osteoblasts which dump the Ca2+ into the blood.
What 3 enzymes do osteoclasts have?
Carbonic anhydrase to generate protons from CO2.
Acid phosphatase.
Cathepsin K.
What does PTH do to osteoclasts?
It stimulates them to perform slow Ca2+ exchange which is break down of bone to yield Ca2+
What are the spaces called that osteoclasts live in?
Howship's lacunae.
Why do osteoclasts have ruffled border?
To increase surface area for bone resorption.
What 2 hormones regulate osteoclast activity?
Vitamin D and PTH
Why can't bone grow by interstitial growth?
Because osteoblasts and osteocytes can't divide.
What is another name for fast Ca2+ exchange?
Osteocytic osteolysis
Describe the basic structural unit of bone?
The haversian system (osteon) is made up of concentric lamellae which are alternating left and right hand helices.
A central blood vessel sits in the haversian canal and these are connected through Volkman's canals.
Canaliculi interconnect osteocytes around the rings.
Who produces the inner and outer circumferential lamellae?
The osteogenic layer of periosteum produces the outer circumferential lamellae and the endosteum produces the inner circumferential lamellae.
What are interstitial lamellae?
Older haversian systems that have been replaced.
Is bone vascular or avascular?
Bone is VERY vascular.
What are Sharpey's fibers?
Pieces of dense irregular CT from the fibrous periosteum which dip down into the outer circumferential lamellae.
Where are the 3 places you don't find periosteum?
Articular cartilage
Where tendons and muscles insert
On sesamoid bones
Where are the 4 places that you find blood vessels in bone?
1) Blood vessels, nerves and lympathics in the fibrous layer of periosteum.
2) Volkman's canals
3) Nutrient artery in bone marrow
4) Haversian/central canal
What are the 3 types of bone surfaces?
Forming, resting and resorbing.
Describe the 2 phases of bone formation?
Matrix formation - Osteoblasts lay down osteoid which contains osteocalcin.
Osteocalcin binds Ca2+ in the area and keeps it there.
Osteoblast secretes alkaline phosphatase which increases [Ca2+] and [PO4] in the area.
Osteoblasts secrete vesicles of Ca2+, PO4 and alkaline phosphatase which crystallizes in the matrix.
Describe intramembranous ossification?
There is no cartilage model. Mesenchymal cells develop directly into osteoblasts which start making osteoid.
The osteoid binds Ca2+ and starts to mineralize, forming the primary ossification center.
Describe endochondral bone formation?
Begin with hyaline cartilage model with perichondrium surrounding except at articulating surfaces.
Perichondrium becomes vascularized and this stimulates osteoblasts to differentiate.
This causes a periosteal collar to form around the bone diaphysis.
Periosteal bud (blood vessel) invades the middle of hyaline cartilage causing chondrocytes to die.
Osteogenic cells come in with blood and differentiate into osteoblasts which form the primary ossification center.
How does one create a marrow cavity in the bone?
Bone is added to the outer sides of the periosteal collar and cartilage is removed from inner side.
When does the secondary ossification center form?
Only after birth is the hyaline cartilage in the epiphysis replaced
During bone formation, what is the only place that hyaline cartilage will remain forever?
At the articular cartilage region.
When do the epiphyseal plates go away?
~25 yrs of age.
What are the 5 zones of the epiphyseal plates?
Zone of resting cartilage - between epiphysis and epiphyseal plate.
Zone of proliferation - chondrocytes mitosing for interstitial growth.
Zone of hypertrophy - chondrocytes get huge, deposit matrix and die.
Zone of calcification - calcification of the matrix occurs.
Zone of ossification - osteoblasts ossify the matrix.
What are the main regions we find red bone marrow?
Pelvic bones, sternum, vertebrae and skull
What is the difference between red and yellow bone marrow?
Yellow marrow is full of fat and is not hematopoietic
Describe blood flow to bone marrow?
Nutrient artery from periosteum splits into central longitudinal arteries which then split into radial arteries. The radial arteries enter Volkman's canals and then central canals.
What supports the venous sinusoids in bone marrow?
Adventitial reticular cells support the thin simple squamous endothelium
What lines the venous sinusoids in the bone marrow?
What type of collagen do you find lining the venous sinusoids?
Reticular fibers.
True/False Adventitial reticular cells in the bone marrow make reticular fibers
How do blood cells leave the venous sinusoids, through or between the endothelial cells?
There are migration pores in the endothelial cells so the blood cells go right through these pores (through the cells).
What are the 4 stromal cells of the bone marrow?
Macrophages, reticular cells, fibroblasts and endothelial cells.
What is the function of the 4 stromal cells in the bone marrow?
Macrophages phagocytose RBC nuclei.
Endothelial cells and fibroblasts make growth factors.
Reticular cells make reticular fibers (NOT ADVENTITIAL RETICULAR CELLS) and store fat in some instances.
What are the relative locations of cells in the bone marrow cords?
RBC's develop in erythroblastic islets close to sinusoids.
Here macrophages can recycle the iron and phagocytose pyknotic nuclei.
Neutrophils develop further away.
Megakaryocytes have to be right next to sinusoid walls to release platelets.
Where does hematopoiesis occur between 2 weeks and 3 months of age?
In the mesoderm of the yolk sac. These are nucleated RBC's and it is the mesoblastic stage.
Where is hematopoiesis from 6 weeks to birth?
In the liver and spleen, these are still nucleated RBC's
When does hematopoiesis begin in the bone marrow?
At 6th week the primary ossification center develops and is in full swing by 5 month.
What are the 3 classes of cells in the bone marrow?
Stem cells
Progenitor cells
Precursor cells
What is PHSC?
Pleuripotential hematopoietic stem cells of bone marrow which can self-renew or give rise to MHSC (multipotential)
What is MHSC?
Multipotential hematopoietic stem cell which are either CFU-S (myeloid line) or CFU-Ly (lymphoid line)
What are examples of progenitor cells?
Progenitor cells are committed to a single cell lineage.
What is a precursor cell?
Cell in each lineage displaying unique characteristics.
Which precursor cell responds to erythropoietin?
CFU-E. Although so can BFU-E during severe anemia which is why it is called burst forming unit.
Why are they called primary and secondary granules?
Because the primary azurophillic granules form before the secondary specific granules.
What are criteria used to ID proerythroblast?
Huge cell
Central nucleus with nucleoli
Basophillic cytoplasm due to ribosomes
Can mitose
What criteria are used to ID basophillic erythroblast?
Very dark blue cytoplasm (RIBOSOMES MAKING HB)
Clumped chromatin and more condensed nucleus.
Can mitose
What are criteria used to ID polychromatophillic erythroblast?
Grey cytoplasm due to accumulation of hemoglobin
What is the last cell in the erythroid line that can divide?
The polychromatophillic erythroblast
What are criteria used to ID orthochromatophillic erythroblast?
Cytoplasm is same as mature erythrocyte (ortho means same).
Nucleus is eccentric dark round circle.
What are criteria used to ID reticulocytes?
No nucleus
Pink cytoplasm
Special stains pick up RNA as black fibers in cell
4 things needed to make an erythrocyte?
Glycolytic enzymes
Plasma membrane
Why is the cytoplasm of a myeloblast slightly basophillic?
Due to RER
At what stage are the azurophillic granules first made during granulocyte maturation?
The promyelocyte stage
When are the secondary granules made during granulocyte maturation?
What is the difference in colors of the secondary granules of granulocytes?
Neutrophil is iliac
Eosinophil is red-orange
Basophil is blue-purple
What is the final cell that can mitose in the granulocyte lineage?
What are the characteristics of the metamyelocyte?
Eccentric, kidney-bean shaped nucleus.
Light blue cytoplasm
How much of the peripheral blood is neutrophils?
What do neutrophil azurophillic granules contain?
Lysozyme, acid phosphatase, myeloperoxidase and defensins (antibacterial proteins)
What do neutrophil secondary granules contain?
Lactoferrin (binds iron away from bacteria)
How much of the peripheral blood is eosinophils?
3% (1-4%)
What is found in eosinophil secondary granules?
Major basic protein (forms holes in parasite PM)
Histaminase (reduce inflammation)
How could you increase the levels of granulocytes in peripheral blood?
Neutrophils - bacterial infection.
Eosinophils - parasite or worm infection.
Basophils - allergic reaction.
How much of the peripheral blood is basophils?
How is a basophil similar to a mast cell?
Both contain IgE receptors on their surface and when this is bound by antigen, both release histamine.
At what stage do the azurophillic granules of monocytes arise?
How much of the peripheral blood is monocytes?
6% (4-10%)
What does a monocyte look like?
Largest cell in the blood with azurophillic granules and large eccentric kidney shaped nucleus.
How do megakaryoblasts divide?
By endomitotic division (64N)
What granules do megakaryocytes have?
α granules - vWF, PGDF, platelet aggregation factors
δ granules - serotonin and other platelet adhesion factors
λ granules - lysosomes for clot dissolution
Why do you need α granules in megakaryocytes?
α granules are responsible for vessel repair, platelet aggregation and coagulation of blood.
Why do you need δ granules in megakaryocytes?
They contain factors that facilitate platelet aggregation, adhesion and stimulate vasoconstriction
Why do you need λ granules in megakaryocytes?
Contain hydrolytic enzymes for clot resorption
What part of the megakaryocyte do the platelets come off of?
The platelet demarcation channels
What are the 2 parts of the platelet called?
The hyalomere which is the outer light part (microtubules) and the granulomere which is the part containing the 3 types of granules.
What is the difference between serum and plasma?
Serum is plasma without the coagulation proteins
Name 3 common anticoagulants?
The latter 2 are Ca2+ chelators
When does DNA recombination occur in the B cell?
Before birth in the germline cells.
What is clonal selection?
When an antigen binds a specific B cell and stimulates it to tweak it's DNA to bind that antigen specifically
Why do we need Vit. K for coagulation protein synthesis?
The enzyme γ-glutamyl carboxylase needs Vit. K as a cofactor in order to γ carboxylate factors II, VII, IX and X.
Why do you need γ-carboxylation of the coagulation factors?
In order for them to interact with Ca2+. Ca2+ binds the negative phospholipids on the endothelial surface (and platelet surface) to the negative γ-carboxyglutamic acid residues on the coagulation factors.
This allows them to interact with each other.
Where in the coagulation protein are the glu residues that we γ-carboxylate?
They are on the N-terminus and the carboxylation process forms γ-carboxyglutamic acid residues (Gla)
How do you start the intrinsic clotting cascade?
HMW kininogen, prekallikrein and factor XII all work together to activate XII to XIIa
What is the embryonic origin of blood?
Mesoderm derived because it is CT without fibers (until clotting occurs)
Where are tPA, Antithrombin III, heparin and thrombomodulin made?
Made and released by the endothelium
Where are protein C and protein S made?
With all the other factors in the liver (except factor III)
Are protein C and protein S anticoagulants or coagulants?
They are anticoagulants because they degrade factor V and factor VIII
How do you activate protein C and protein S?
Once thrombin is formed during coagulation, it stimulates protein C. With the help of thrombomodulin released from the endothelium, protein C is activated 1000 fold. Activated protein C degrades factor V/VIII but also requires protein S as a cofactor to do this.
What is pre-prothrombin?
It is prothrombin before γ-carboxylation by γ-glutamyl carboxylase.
How do warfarin and coumadin work?
They block epoxide reductase which prevents the conversion of Vit. K epoxide back into the active form of Vit. K.
Why do you need epoxide reductase?
γ-glutamyl carboxylase requires Vit. K to carboxylate pre-prothrombin. When this happens, Vit. K is converted into Vit. K epoxide (an inactive form). Epoxide reductase converts Vit. K epoxide back into Vit. K.
What is an inhibitor of plasmin?
α2-antiplasmin is an antagonist of plasmin to ensure that the clot isn't broken up too fast.
What is the difference between the stochastic and deterministic theories?
Stochastic means that progenitor cells randomly decide to form differentiated cells or self renew.
Deterministic means that cytokines and growth factors stimulate the process.

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