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What are the different tissue types in the body
Epithelium, connective tissue, muscle, and nervous tissue
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What are the three different domains of the epithelium
- Apical (lumen)
- Lateral (between ajoining cells)
- Basal (basement membrane side)
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Basal Lamina
The basal lamina is a layer of extracellular matrix on which epithelium sits
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Intestine lining is replaced how often
4 to 6 days
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Epithelium in the skin is replaced every
Twenty eight days
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What tissue is avascular (no vessels)
Epithelium
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Principle functions of the Epithelium
- 1. Barrier (protection)
- 2. Secretion
- 3. Absorption
- 4. Transport
- 5. Detection of sensations
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P.A.S Periodic acid-Schiff (PAS) is
A staining method used to detect glycogen in tissues (shows basement membrane in epithelium). 
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Basal Lamina is present in what cells
- SAME
- Schwann cells
- Adipose cells
- Muscle
- Epithelia
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Functions of Basal Lamina
- 1) Physical support (structural attachment)
- 2) Limits contact – compartmentalization
- 3) Selective barrier
- 4) Cell to cell interaction
- 5) Location and movement during embryogenesis
- 6) Polarity
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Two types of basement membranes are
- Renal corpuscle
- Basement membrane of epithelium
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Basal Lamina has what layers
- Lamina densa, an electron dense layer
- Lamina lucida, an electron lucent layer
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Lamina lucida consists mainly of
- Glycoproteins
- Laminin
- Enactin
- Extentions of integrins and dystroglycans
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Lamina densa is made up of
- Collagen type IV
- Fibronectin
- Perlacan
- Heperan sulfate
- GAG's
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Fibronectin is made by
Fibroblast cells
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Anchoring fibrils attach
Basal lamina to the lamina reticularis
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Anchoring fibrils are made of
Collagen type VII
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Lamina reticularis is made of
Reticular fibers - collagen Type III
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Microfibrils attach
Basal lamina to elastic fibers
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Basal lamina is made by
Epithelial cells, not fibroblasts
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Laminin has binding sites for
- Collagen type IV
- Heparan sulfate
- Integrins of epithelial cells
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Heparan sulfate restricts
Negatively charged molecules
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Basement Membrane is made up of
Basal Lamina + Lamina reticularis
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Dystrophin does what, and lack of it results in
Helps muscle cells bind to laminin and to actin filaments inside the cell.
Duchenne’s muscular dystrophy, a progressive muscular weakness. (Found only in males.)
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Dystrophin is located on which chromosome
X chrom
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Mutation of Collagen VII gene results in what condition
- Dystrophic epidermolysis bullosa
- An inherited blistering skin disease in which the Epithelium is detached below the B.M
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Determining whether Epithelia is a covering or lining is based on what
- Number of cell layers
- Shape of cells
- Surface characteristics – microvilli, cilia, flagella
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Three surface characteristics of epith.
Microvilli, Cilia, Flagella
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Simple Squamous Epithelium are found where
- Location: parietal layer of Bowman’s capsule, lining of blood vessels (called endothelial cells), lining of alveoli
- Function: sites for fluid, metabolite or gas exchange.
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Simple Cuboidal Epith are found where
- Location: kidney tubules, covering of ovary, ducts of glands.
- Function: protection, secretion and absorption
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Simple Columnar Epith are found where
Location: stomach, small intestines, gall bladder Function: protection, secretion, absorption
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Pseudostratified Columnar Epith characteristics and locations they are found
- Not all cells reach the surface
- Nuclei are stratified at 2 or more levels
- Cells are crowded – varying shapes
- All cells touch the basal lamina
- Location : trachea, epididymis, bronchioles
- Function : protective lining, secretion, absorption
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Stratified Squamous Epith have what two subgroups and characteristics
- Mucous (non- keratinized) – esophagus
- Cutaneous (keratinized) - skin
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Stratified Cuboidal Epith are found where
Ducts of sweat glands and large ducts of Exocrine glands
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Stratified Columnar Epith
Ducts of large glands
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Transitional Epith
- Bladder, ureter, urethra (4-6 layers)
- Transitional because it will go through changes.
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Microvilli are
Cytoplasmic extensions of cell
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Microvilli are made up of what
They have a core of actin microfilaments, actin binding filaments are attached to the PM by myosin I.
The core is attached to the actin filaments of the terminal web which contains intermediate filaments and spectrin as well
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What is spectrin
Spectrin anchors the terminal web to the apical plasma membrane.
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What is contained in the terminal web
- Myosin II
- Tropomyosin
- Spectrin
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Stereocilia
Very long microvilli
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Microvilli and stereocilia are used for
Absorption
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How do cilia move
Subunit A contains a pair of dynein arms which has ATPase activity. Radial spokes project from subunit A to the central sheath.
Subunit B has Nexin, an elastic protein, connects adjacent doublets.
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Kartagener’s syndrome
Immotile cilia syndrome, results from hereditary defects of dynein (absence of dynein arms). Mucociliary transport in the respiratory epithelium is not functional. In males, this syndrome results in sterility since sperms are immotile
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Terminal bars have what 3 groups
- 1. Occluding (impermeable) junctions
- 2. Anchoring (adhering) junctions
- 3. Communicating junctions – gap junction
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Tight Junction (Zonula Occludens) do what
- Create an impermeable junction so much so that blood will go into the intercellular space and then through the cell, not between the junctions
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Zonula occludens (tight junctions) use what proteins to bind to each other
The transmembrane proteins are called occludins & claudins
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What type of pathogens can make it through the tight junctions
- Cytomegalovirus
- Cholera toxins
- These act on the junctions resulting in a permeable junction
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Zonula adherens
Form a continuous lateral adhesive band that encircle & hold cells together. It is located beneath zonula occludens
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E- cadherins
- These are calcium dependent
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Macula adherens or desmosome have what function
These help to resist shearing forces.
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Pemphigus vulgaris
Caused by autoantibodies produced against desmosomal proteins (resulting in blistering of skin)
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Gap Junction, nexus or communicating junctions are located in what type of cells
Epithelia, cardiac and smooth muscle cells, and neurons
Composed of connexins
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Gap junctions open or close via what conditions
- Low pH or increase Ca+ concentration closes the channels
- The opposite opens channels.
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Hemidesmosomes
Anchor intermediate filaments of the cytoskeleton to the basement membrane.
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Focal adhesions
- Anchor actin filaments of the cytoskeleton to the basement membrane.
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Hemidesmosome are part of what family
Integrins found on the basal side
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Endocrine glands differ from exocrine in that they
Secrete hormones directly into the vascular system, so they don’t have ducts
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An example of a unicellular and multicellular exocrine systems are
- Goblet cell (Uni)
- Pancrease (Multi)
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Apocrine gland is
Bud their secretions off through the plasma membrane producing membrane bound vesicles in the lumen. One example is the arm pits.
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Merocrine gland is
Excretions via exocytosis from secretory vesicles
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Holocrine gland is
Rupture of the plasma membrane (oily secretions)
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