8/19 Epithelial Cells Flashcards
Explain the mechanisms underlying epithelial functions of protection, absorption, and secretion. I.E. how is it like an international border?
Protection: Mechanical barrier due to junctions, mucus and cilia in some cases to expel foriegn particles, and defensins (small cationic atibiotic peptides) and antibody transport. in some case as well Absorption/Secretion: Through pumps such as the N,K-ATPase, or through carrier or channels (co-transport, passive etc.) through gap junctions to adjoining cells,
Describe the fundamentals of tissue maintenance by stem cells.
cells turnover, in days to months and progenitor cells (stem cells) divide to replace them, Mitosis occurs on basal layer (touching the basal lamina) so stem cells are there. They recieve signals from cytokines (influence rate of development) etc. Transient amplifying cells or the proliferating progenitors of the stem cells divide rapidlyto move in and fill the epithelial as it is lost.
identify the 9 types of epithelia
- Simple Low – single layer of squished cells 2. Simple Cuboidal – single layer of round cells 3. Simple Columnar – single layer of tall cells 4. Statified Squamous – multi-layer with squished on top 5.Stratified Cuboidal – multi-layer round cells 6. Stratified Columnar – multi-layer tall cells 7. Urothelium – domed at the top with multi-nucleated 8. Pseudostratified Columnar – look multilayer, but tall and not multi-layer 9.Ciliated/non; Karatinized/non; Stereociliated/non; microvilli/non (brush border)
Describe the classification, of connective tissue proper
Loose conective tissue (lots of cells and ground substances and less connective tissue, just below basil lamina); Dense connective tissue (less cell bodies many collagen fibers, and below the loose connective tissue); Adipose tissue (recognizable from the large clear circles of lipids
list and describe the sources and properties of the resident and transient connective tissue cells
Resident: Fibroblasts (make ECM), Macrophages (immune responce and stimulate ECM createion), Mast Cells (immune and allergic response), Adipocytes (energy and hormones/cytokines) Transient: Plasma cells (Activated B Lymphocytes; they have a clockface or wheel and spoke nucleus lots of gogi and ER); Lymphocyte(
describe the components, properties of the extracellular matrix: ground substance and extracellular fibers
Components: Fibers and Ground Substance
Properties:
Fibers: 3 main types: Collagen (collagen I), Reticular (collagen III), Elastic
Collagen: Very abundent, 20 types and 4 catagories: figril forming (I,II,III), gibril associated, and two found in the basal lamina: anchoring fibrils (VII) and network forming (IV).
reticular Small, non-bundling, not as supportive, loose connective tissue!
Elastic Fiber: Straight fibers composed of randomly coiled molecules; elastin surrounded by fibrillin
Ground Substance: Viscous transparent filled with glycoprotiens, proteoglycans, tissue fluid; store electrolytes and water, resist compression, and form viscous barrier, and attachment amd movement of cells in ECM.
made of GAGs and connected togeterh to form a proteoglycan: looks like pipe cleaner, highly necative charge, and very hydrated/viscous
describe the basics of wound healing
Epidermal stem cells at the periphery provide source of new epithelium, and the epitheilial cells express integrins and laminins to coat the fibers in the wound bed and cause migration of cells (Create own road to travel across the wound bed)
Thin wound:
- Inflammation (24 hours): neutrophils in the space, clot forms due to platelets
- Proliferation (3-7 days): myogibroblasts appear (new epithelial cells start to form, granulatied tissue, macrophages, fibroblasts, new blood capillaries)
- Maturation: Fibrous union and normal tissue
Larger wound with scar: also have contraction take place
Describe the nature of granulation tissue
Wound granulation is an important stage in healing, where an injury fills with a matrix of fibrous connective tissue and blood vessels. This creates a framework for other cell types to grow, filling in the wound and restoring function
Describe the consequences of fibrosis rather than normal healing
this is due to persistant tissue damage, like cirrrhosis, chronic inflamatory diseases etc.) This will result in diminished function and permanent change in the composition of the tissue. Can impede blood flow and cell function!
Define Adenocarcinoma
malignant tumor formed from the glanular structures in the epithelial
define apical and basal
The top and bottom layer of the epithelial cell layer
Define barrier epithelia
epithelia that are facing the outside world: skin, trachia, esophagus, intestines etc. characterized by a need to provide a tight physical barrier.
Define basal lamina
the electron microscophy term for the basement membrane
Define basement membrane
the layer just under the epithelium: containing mixture of proteins including laminin and type IV collagen and glycosominoglycans.
Define brush border
the thin cilia lining the simple colomnar cells of the interstinal tract.
Define carcinoma
a cancer arising from the epithelial tissue
Define CFTR
CFTR is an ABC transporter-class ion channel that codes for a protein that conducts chloride[3] and thiocyanate[4] ions across epithelial cell membranes. Mutations of the CFTR gene affecting chloride ion channel function lead to dysregulation of epithelial fluid transport in the lung, pancreas and other organs, resulting in cystic fibrosis.
Define cilia
Long, motile, apical membrane projections (move mucus)(move the ovum)
Define connexons
one of six proteins that form a gap junction
define defensins
Small cationic protiens that have antibiotic properties
Define desmosome/macula adherens
a linkage between epithelial cells: made of keratin filaments into the cell and cadherins linking the cell like velcro.
Define dysplasia
the disease (often cancer realted) related change in the tissue of an adult
define endo / exo / and transcytosis
transport into out of and through out a cell.
define endothelium
Cells lining blood vessels etc. a lining to the inside of the body not the outside.
define focal adhesion complex
This is a linkage to for the epithelia to the basal lamina that is made of intigrins and actin fibers.
define gap junction
an open connection between the cells of an epithelial layer. alows the movement of components and signals.
define goblet cell
a mucus producing cell that looks clear and a bit fuzzy and is embeded in the epithelial layer of the trachia.
define hemidesmosome
a connection between the epithelial basal layer and the basal lamina: these are made of keratin fibers linking to the cell, and integrins linking to the basal lamina.
define integrin
a transmembrane protien that acts as structural support and signal transduction between cells and cells and cells and ECM.
defind junctional complex
The combination of the zonula occludens and zonula adherens that appear as the terminal bar in light microscopes. They encircle the cell like a steal band that links different cells together. Prevents diffusion accross the apical surface of the epithelium
define keratin
a type of intermediate filaments that provide structure.
define metaplasia
the change in the arrangement of tissue in an adult
define microvilli
short projections, increase suface area of epithelial cells esp. the intestinal tract and the brush border. supported by microfilliments.
define mucous
slippery secretion that aid in forming a physical barrier to infection.
define Na,K-ATPase
an ATP dependent pump in the membrane of many cells that pumps 3 sodium out and 2 Pottasium in. (remember: low table salt in the cell, and potasium) hehe the cell isn’t doing salts but it sure is doing pot!
define parenchyma and stroma
the bulk and functional parts of an animal!
stroma is the connective and structural parts i.e. everyting else!
define serous
fluid that is transparent or yellow and aids in the movement of digestion exrection and resperation
define stem cell
any cell the divides to produce a progeniter and another stem cell. characterized by their unique ability to divide to replace lost cells
define terminal bar
the light microscopic appearence of the junctional complex that is composed of the zonula occludens and the zonula adherens.
define terminal web
Actin based microfilament bundles that attach to the zonula adherens
Remember: The tight junction/zonula occludens is above the adherens junctions/zonula adherens that together form the terminal bar!
define zonula adherens
Adherens juntion, just below the tight junction/zonula occludens. form a physical barrier!
define zonula occludens/tight junctions
prevent diffusion between cells. encircles the top of the epithelial cells: creates an apical and basal domain, the membrane differs in the two domains!
define adipose cell - adipocyte
Fat storage cell, also excretes hormones and cytokines
define adipose tissue
connective tissue made of adipose cells
define collagen I
Fibril forming resist stretch, provide tensile strength, found in dermis, organ capsules, bone , tendon, and fibrocartilage.
define collagen II
no fibers, helps associate with collagen i, and III to make fibers etc.
define collagen III
Fibrils and smaller than type 1, no bundles; in the stroma of smooth muscle and hematopoietic organs, loose connective tissue in endocrine glands and liver, endoneurium
define collagen IV
link head to head and found in the basal lamina, forms sheets.
define tropocollagen
the formation of colloagen begins in the cell, then outside of the cell the procollagen has the ends cleaved off to form the tropocollagen. the absence of this step leads to Ehlers Danlos syndrome
define collagen fibers
fibers of tropocollagen that form in triple helix to then form collagen
define dense connective tissue (regular and irregular)
The connective tissue that is relatively absenct of cellular bodies, being made mosely of collogen fibers and elastic fibers and ground substance (ECM). Regular is arranged in symetric pattern.
define elastic fibers
Fibers of elastin core surrounded by fibrillin. found in the larynx, skin, trachea, bronchi, arteries
Define elastin
Elastic fibrous glycoprotien found in connective tissue
Define Fibrillin
elastic glycoprotien that appears to provide a scaffold for elastin to form elastic fibers
Define extracellualr matric (ECM)
composed of cologen, elastic fibers, and ground substance. found outside of the cell esp. in connective tissue.
Define fibroblast
The cell in the connective tissue that is most prominant and produces the collogen and elastic fibers, etc.
define fibrosis
Creation of excess connective tissue due to persistent damage to an organ.
define gylcosominoglycans (GAGs)
linear chains of disaccharides, negatively charged and very hydrophobic, hydrated!
defind granulation tissue
tissue often found in a wound or infection of inflamation that is new tissue that is growing to fill the wound, containing ECM, immune cells, etc.
defien ground substance.
The ECM component that is not fibers, but is made up of GAGs plycoprotiens, proteoglycans etc.
define lamina propria
the layer of loose connective tissue just below the epithelial cells
