Histo Exam 1 Flashcards
(140 cards)
1
Q
Histology
A
The study of microscopic anatomy of cells and tissues of plants and animals
2
Q
The four basic types of tissue
A
Epithelial
Connective
Muscle
Nervous
3
Q
Bichat’s contribution to histology
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Introduced the notion of tissues as distinct entities and maintained that diseases attacked tissues and not whole organs and the body
4
Q
Schledien and Schwann created for
Kolliker contribution
A
S&S- the discovery that all living organisms are composed of cells
K- wrote the first textbook in histology and model textbook for embryology
5
Q
Virchow’s contribution
A
Realized early on that the cell theory required all cells to be from existing cells which would give insight into pathological processes
6
Q
The Jansens contribution to science and Hooke
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Jansens- They produced the first operational compound microscope that magnified 30X
Hooke- introduced the term cell
7
Q
Anthony Leeuwenhoek
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Made over 247 simple microscopes that were capable of magnification of 100x
8
Q
How is refractive index calculated?
A
Velocity of light / velocity of light inside the transmitting medium
9
Q
Focal point V. Focal length
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FP- the point thru which all parallel rays of light pass after passing thru each part of the lens
FL- the distance of the center of the lens to the focal point
10
Q
Real image is:
A
- Formed when the object is placed outside the focal point
- Inverted
- Projected onto a screen
- Differs in size from the object
11
Q
Virtual image is:
A
- Formed when the object is placed inside the focal point
- Not inverted
- Can’t be projected
- Can be magnified
12
Q
Resolution (define, formula, improve resolution)
A
D-The ability of a microscope to distinguish two small points as separate points
F- 0.61* wavelength/ n sin a
I- use higher refractive index or shorter wavelengths
13
Q
What is the maximum visual acuity in the human eye?
A
1.5-2 um
14
Q
Components of Light micro
A
Light source
Condenser
Stage
Objective lens
Ocular lens
15
Q
Pros & Cons of light micro
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Ability to magnify
Ability to resolve structural detail
Specimen must be thin
Relatively little contrast in unstained specimen
16
Q
Advantage of a phase contrast microscope
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Can be used to examine unstained cells & tissue
Useful for examination of living cells
17
Q
Basic steps for tissue fixing & embedding
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Fixing
Dehydration
Removal of alcohol
Embedding
18
Q
Purpose for fixing tissues
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Fixing prevents further deterioration of tissue specimen & hardens tissue prior to embedding & sectioning
Ideal fixatives give optical contrast w/ staining w/ least amount of distortion
19
Q
Purpose for dehydration & hydration cycles used to tissue processing
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Tissue sample will eventually be embedded & infiltrated w/ a hydrophobic material, all water needs to be removed
20
Q
Purpose for embedding tissues for sectioning
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Tissue specimen is moved thru several melted paraffin baths. Final bath is placed in a mold to be filled w/ melted paraffin mold rapidly is placed in cold water bath
21
Q
What are the advantages of rotary microtomes over hand-held microtomes
A
Can be used for different tissue types, larger knife, can do serial sectional, thinner cuts
22
Q
Tissue sectioning for TEM
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Sections are cut at 50 to 150 nm
Diamond knives are used
23
Q
Why do tissues need to be stained
A
To bring out detail, since they are typically colorless
24
Q
Steps for embedded speciemens
A
The paraffin must be removed from section and mounted on slide
Accomplished with xylene
Xylene is removed using a graded series of alcohol down to water
Stains are applied and dehydrated again (thru levels of dehydration)
Drop of cement is followed by a cover slip
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Stains such as H&E (hematoxylin & eosin)
Display structural features
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Hematoxylin stain
Nuclear material & some cytoplasmic components
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RER and Eosin stain cytoplasmic components differently
RER- dark Blue to light blue or purple
Eosin- yellowish to pinkish color
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Basic dyes V. Acidic dyes
B- React w/ an ionic groups of tissue components such as phosphate, sulfate, and carboxyl groups
A- bind to tissue components by forming electrostatic linkage w/ cationic groups like amino groups of proteins
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What does metachromasia refer to? Give an example
Refers to phenomenon which changes color after reacting w/ a tissue component
Ex: a toluidine blue used to stain cartilage or mast cells
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What does histochemistry refer to
Used to study the chemistry of cells & tissues
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Example of histochemical techniques
Perls’ Reaction- used to present the iron in tissue esp. w/ patients that have iron storage problems
Insoluble blue ppt. Occurs
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Histochemical stain for lipids
Uses dyes that are soluble in lipids such as Sudan IV, Sudan black, oil red O, & Nile blue
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Tissue classification
Epithelium
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Tissue Class
Connective
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Tissue
Bone
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Tissue Class
Nervous
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Tissue Class
Muscle
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Tissue
Simple Columnar:
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Tissue
Simple Columnar:
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Tissue
Simple cuboidal
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Tissue
Stratified Squamous
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Tissue
Transitional
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Tissue
Dense Bone
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Tissue
Dense Bone
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Tissue
Cancellous
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Tissue
Adipose
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Hyaline Cartilage
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Skeletal Muscle
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Cardiac Muscle
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Smooth Muscle
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Purkinje Cell
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Tissue
Cerebral Cortex
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Tissue
Cerebral Cortex
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Schiff reaction
A reaction depends on formation of aldehyde groups after the exposure to HCL or periodic acid
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Fuelgen Reaction
Mild hydrolysis w/ HCl exposes aldehyde groups on deoxyribose
Schiff reagent reacts w/ this and forms a deep-pink
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PAS (Periodic acid-Schiff Reaction):
Periodic acid used to cleave bonds, btw adjacent carbons of carbon & form aldehyde gps. Schiff reacts with this and forms a deep-pink
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Clinical application of Schiff reagent reaction, PAS
Biopsies of tissues from patient with glycogenoses (glycogen storage disease)
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Best Carmine
Is a dye that may also be used to demonstrate glycogen deposits
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What does Immunocytochemistry refer to
They are techniques that are used to study the presence of specific constituents, AKA antigens, by using monoclonal antibodies
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General characteristics of epithelial tissues
1. Cells typically have a relatively uniform geometric shape when viewed
2. Cells tightly bound together
3. ET- have little intercellular matrix
4. Typically display free surface
5. Lack a free space
6. Line body cavities & cover body surface
7. For secretory & excretory parts of glands
8. May be innervated
61
Describe the structure of the basement membrane
The basal lamina is next to epithelia layer, composed of type IV collagen plus glycoproteins. Absent in lymph vessels & hepatic sinusoids
Reticular lamina is in contact with underlying CT & consist of argyrophilic fibers, reticular fibers & glycoproteins
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Functions of basement membrane
Selective filtration barrier
Scaffold for embryogenesis & regeneration
Stabilzation of tissue shapes
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Criteria used to classify epithelial tissues
Based on number of cell layers
Based on shape of most superficial layer of cells
Surface modifications on the apical domains- cilia, stereocilia, microvilli
Presence or absence of keratin
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Apical Domain of Epithelial cells
Characterized via surface modifications such as cilia or microvilli & apical domains face a lumen or external environment
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Basolateral domains of epithelial cells
Sides & bases of the cells are characterized by intercellular junctions & these cell surfaces in contact with the basement membrane & surrounding cells
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List the specializations of apical surface
Microvilli- brush border
cilia
Stereocillia
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Locations of Simple Squamous epithelium
Lines Lumina of ducts, vessels, & other tubular structures
Forms walls of alveoli, Bowman’s capsules & inner surfaces of membranous labyrinth & tympanic membrane
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Location of simple cuboidal epithelium
Cells may be low or high- almost squamous or columnar
May have brush border- kid tubes
Ovary, pigmented epithelium of retina, kidney tubes, gland, & ducts, terminal bronchioles, choroid plexus, & anterior capsule of lens of eye
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Location of simple columnar epithelium
Ciliated- upper respiratory tract, uterine tubes, uterus, paranasal sinuses, & central canal of spinal cord
Non-ciliated- digestive tract- st at cardia of stomach, gall bladder, & parts of excretory ducts of glands
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Location of stratified squamous epithelium
Heavy Keratin- epidermis w. CT papillae & cornea w/o CT papillae
Light & or Non- esophagus, vagina, lining of the mouth, tongue & part of epiglottis
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Stratified cuboidal epithelium locations
Seldon found but may occur in small areas of anal mucosa, large excretory ducts of some glands, & part of the male urethra
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Stratified columnar epithelium locations
Seldom found.
Occurs in the ducts of adults sweat glands, fornix of the conjunctiva of the eye, parts of the male reproductive/ urinary tract, the pharynx, & the epiglottis
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Pseudostratifed epithelium locations
Ciliated pseudo columnar, in trachea
Pseudo epi w/ stereocilia in epididymis
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Transitional epithelium (Urothelium) locations
In urinary system
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Types of epithelium
Covering & lining
Glandular
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Functions of epithelium
-covering & lining
-protection
-tight barriers
-Leaky barriers
-secretion/ absorption- Simple/ pseudostratifed
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Structure of Microvillus
Finger-like projections of the apical cell membrane supported via cross-linked actin bundles
Non-motile
Form a uniform border across apical membrane (brush border)
-actin filament core
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Function of brush border & locations
Increase surface area of absorption
Found intestinal epithelium & on parts of renal tubules
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Actin filament core of microvilli
Terminal web
Distal end- capped by formin- interacts w/ barbed ends of actin filament
Actin filaments of core R crossed-linked via villain & fimbrin
Core actin filaments connect intermediate filaments of web
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Structure of cilium
9 peripheral doublets & central pair of micro tubes
Each doublet consist of alpha tubule & beta tubule
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Alpha & beta tubule of cilium
A- 13 protofilaments, radial spokes extending to sheath around central pair, pairs of Dunedin arms project to Beta unit of next doublet
B- 10-11 protofilaments
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The basic Unit of the cell membrane
Consist of phospholipid bilateral in which are embedded or attached a wide variety of proteins & glycoproteins
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Phospholipid bilayer
Consist of hydrophilic (head) & hydrophobic (two tails) end
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Glycolipids
Found in outer leaflet w/ carbo portion facing the extra cellular environment
Creates a cell coat involved in cell to cell interactions & convey antigencity
Links via sugar residues
Important in activation of MAP kinases associated w/ signal transmission
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Lipid rafts
Small patches of cholesterol & spingolipids (sphingomyelin & glycolipds)
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Glycocalyx
Carbohydrate coat on extracellular surface of the cell membrane & composed of carbo portions of glycolipds & glycoproteins
Protects cell from ionic & mechanical stress, barrier against micros. Involved in cell to cell interactions
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Peripheral proteins
Found on both the outer & inner leaflets of the cell membrane facing either the extracellular or the in trace lunar fluid
Can be removed more easily than integral proteins by changing ionic Conc. Or pH
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Integral proteins
Embedded w/in the phospholipid bilayer
Extracellular portion typically glycosylated
Associate with non polar core of bilayer directly or indirectly
Includes proteins that span the lipid bilayer one more more times & proteins anchor the lipid bilayer but don’t pass thru
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Transmembrane proteins
Integral proteins pass completely thru both layers of bilayer
Serve as channel & transporter proteins
Single pass or multiple pass
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Diffusion
High to low conc.
No energy or transport required
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Osmosis
Movement of water
No energy or transport required
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Facilitated diffusion
High to low conc
Requires transport of molecule but no energy required
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Active transport
Movement against conc. Gradient
Requires both energy and transport molecules
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Unitransporters
Carries single molecule or ion unidirectionally
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Symporters
Co-transporter
Carries 2 molecules or ions simultaneously or sequentially in same direction
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Antiporters
Co-transporter
carries 2 molecules or ions simultaneously or sequentially in opposite directions
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Antiporters
Co-transporter
carries 2 molecules or ions simultaneously or sequentially in opposite directions
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Components of Basal lamina
-Laminin
-Fibronectin
-Type IV Collagen
-Entactin
-Proteoglycans
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Laminin characteristics
Major components of basal lamina -> consists of three chains a, b, y
Laminin has binding sites for integrins, type IV collagen, entactin & proteoglycans
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Fibronectin Characteristics
- is a protein made up of two polypeptide chains cross-linked by disulfide bonds
-has binding sites for - heparan, integrins, collagen, fibrin
101
The three classes of Cadherins & where they can be found
* cadherins (+ selections) R Ca+ dependent
1. E-cadherins -> in epithelial tissues
2. N-cadherins -> found in nerve cells
3. P-cadherins -> found in placenta
102
Why are selectins classified as lectins & what is there function
-they bind to carbohydrates
Fxn- involved in movement of leukocytes from blood to tissues (extravasation)
103
Describe the major functions of integrins
Integrins are glycoproteins which are mainly involved in cell-extracellular matrix interactions. The Laminin and Fibronectin in basement membrane interact w/ collagen (incl. type IV), heparan sulfate proteoglycans, & entactin (nidogen)
104
What are the three categories of junctional complexes
-Adherens
-Occludens
-Gap Junctions
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Adherens V. Occludens V. Gap Junctions
-anchor cells together & reinforce physical integrity of tissue & the cells that make up the tissues
-establish an impermeable barrier btwn adjacent cells, especially epithelial, that prevent paracellular transport
-composed of molecular pores which enable cells to rapidly exchange ions & small molecules which help coordinate activities among cells that make up tissues
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Zonula V. Macula
-either Adherens or Occludens. Travel all the way around the circumference of the cell and link neighboring cells to the central cell. Associated w/ intracellular actin
-A spot or snap-like junction. Adherens variety and are often referred to as desmosones or hemidesmosomes. Associated w/ intracellular intermediate filaments
107
Describe the strucutre & function of Zonula occuludens
- A zonula occuludens (tight junction) is a belt-like occluding junction. Which provides a barrier against paracellular transport pathway whereby solutes & fluids are transported from one side of epithelial barrier to the opposite side passing between cells
-Claudins & Occludins are transmembrane proteins that are associated w/ junctional complex & r responsible for occlusive properties of tight junctions. They attach intracellular y to Zonula Occludens proteins ZO-2 & ZO-3
108
Describe the structure of a gap junction and distinguish btwn connexons & connexins
-A gap junction consists of connexons-> each connexons consists of 6 connexins-> form a hexagonal strucutre w/ a hollow center
Connexons- facilitate movement of molecules up to 1.2 nm in diameter
connexins- are often clustered into patches
109
List and differentiate the three types of cytoskeleton components
Microfilament (actin)- 7nm thick
Intermediate filaments (8-10 nm thick)
Microtubules (25 nm in diameter)
110
Describe polymerization (inclu treadmilling)
1. Nucleation: a trimmer is formed & additional actin monomers can then be added to either end.
Polymerization is reversible, ATP-actin associates w/ the growing ends & ATP is hydrolyzed to ADP following polymerization
Minus end is slow growing end, very low concentration of G-actin favor disassembly of actin filaments.
Intermediate concentrations favor a dynamic equilibrium btwn minus end & plus end (treadmilling)
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Describe the basic structure & assembly of intermediate filaments
-central rods of two polypeptides form a coiled dimer- rods aligned tail-tail and head-head
-dimers associate in staggered antiparallel fashion to form tetramers->Bc antiparallel association of dimers polymerized filaments dont have distinct ends-> more stable then actin & dont demonstrate dynamic behaviors
-Tetramers assemble end to end to form protofilaments
- Eight protofilaments are wound together to form filaments
112
Describe the structure of a microtubule
25 um in diameter
Composed of tubulin dimers -a & b unit
Protofilaments are longitudinal rows of tubulin dimers
Microtubules consists of 13 protofilaments arranged parallel to form a cylinder w/ a hollow core
Protofilaments have a fast grow end (+ end) and a slow grow end (- end)
113
Describe treadmilling & instability in relation to Microtubules
Grows more rapidly than minus end in presence of low CA ion concentration
At high concentrations of tubulin-GTP, dimers are added more rapidly than GTP is hydrolzed & Microtubules grow. If concentration is dropped tubulin-GTP drops, GTP @ plus end hydrolzyes and dimers lost
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Describe the role of Microtubules & motor molecules in intracellular & axonal transport
1. Anterograde transport of cargos along a Microtubules is mediated by kinesin
2. Retrograde transport of cargos along Microtubule is mediated by cytoplasmic dynein
3. Disassembly of raft protein complex-cargo molecular motor machinery
For axonal transport 1 & 2 are same; goes from minus end to positive end
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Myosin 1, myosin 2, kinesin, cytoplasmic dynein number of heads, tail binds to, heads binds to, direction of head motion
Myosin 1- one, cell membrane, Actin, barbed end (+ end)
Myosin 2- two, myosin 2, actin, barbed end
Kinesin- two, vesicle, microtubule, plus end
Cytoplasmic dynein- two, vescile, microtubule, minus end
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Endocrine V. Exocrine gland
Endo- epithelial down growth may degenerate, leaving secretory tissue isolated from its parent epithelial layer. Include: pituitary, pineal, parathyroids, adrenals, goads, liver, & pancreas
Exo- epithelia down growth may remain connected to epithelial layer form which it originated. Include: salivary glands, mammary gland, sweat glands, sebaceous glands, liver, and pancreas.
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Secretion terminology to differentiate types of glands (Exocrine, endocrine, paracrine, & autocrine)
Exocrine- secretory product is transported via duct system to lumen or organ surface
Endocrine- secretory product (hormone) is released directly into blood in absence of a duct
Paracrine- secretion affects neighboring cells
Autocrine- secretion affects the cell that released the secretory product
118
Classification of glands based on:
-number of cells comprising the gland
-absence or presence of ductal branching
-shape of secretory portion
-unicellular or multicellular
-Simple multicellular (no branching) or compound multicellular (branching)
-Tubular, Alveolar (Acinar), or Tubuloalveolar (-acinar)
119
Types of compound & simple glands based on the structure of excretory
Simple secretory portion: tubular, coiled, tubular branched, or acinar/alveolar
Compound secretory portion: branched tubular, branched alveolar (acinar) or branched tubuloaveolar (-acinar)
120
List and describe categories of glands based on their type of secretion & give example
Serous- watery, enzyme-filled secretion. Ex: parotid salivary gland
Mucous- thick, mucin-containing secretion
Mixed (serous-muucous)- secretion is a combo of serous & mucous, acinus = mostly mucous capped via half-moon shaped group of serous cells forming a serous demilune
Ex- submandibular ( mostly serous) or sublingual (mostly mucous)
121
Categories of glands by secretion w. Examples holocriene, merocrine, apocrine
Merocrine (eccrine)-secretory product is typically stored in membrane bound vessels & cytopla,/CM is retrieved in an exocytosis/endocytois cycle -> includes most glands
-Apocrine- apical cytoplasm released along with secretory product-> axillary sweat glands
-Holocrine- entire cell is released as part of secretory product -> sebaceous gland
122
Hierarchical strucutre of a compound glands
Lobes- a lobe is a subdivision of a compound gland separate via adjacent lobes by septae -> septae separate lobes; & contain Bld vessels & interlobular ducts lined w/ pseduostratided epit
-Lobules- is a subdivision of a lobe via septae (but they’re dont have blood vessels)
123
Describe the hierarchical duct system of a compound gland (for intralobular ducts)
Intralobular ducts are ducts that lie w/in a lobule and have two types:
1. Intercalated ducts- drain secretory acini, lined via simple squamous epithelium transitioning to low cuboidal epithelium, involved in bicarbonate/chloride ion exchange
2. Striated duct- lined by cuboidal epithelium transitioning to columnar epithelium w/ basal striaitons; actively reabsorb sodium ions; passively reabsorb chloride ions; actively secrete potassium ions
124
Interlobular ducts V intralobar V lobar ducts
-formed via confluence of 2 or more striated ducts & R found in the septae btwn adjacent lobules. Lined w/ pseudostratifed columnar epithelium
-joined via confluence of 2 or more interlobular ducts, Lined w/ columnar epithelium transitioning into stratified columnar epithelium
-formed via confluence of 2 or more intralobar ducts; lined w/ stratified columnar epithelium
125
Compare and contrast the three major salivary glands
Parotid- composed of almost entirely of serous acini; apical regions contain zygotes granules, RER predominates in basal regions of secretory cells
Submandibular- are mixed glands w/ both mucous & serous acini (predominant); myopithelia cells surround acini
Sublingual- mixed glands but mucous are predominant (pale in color) ; myoepithelia cells surround acini
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Charcterisitcs of CT
-relatively few cells
-abundant matrix
-CT contains many varies amounts of protein fibers
-classifed via type of matrix, fiber density, & fiber organization
127
Characterize embryonic CT and where its located
Foun in umbilical cord and in pulp of developing teeth -> referred to as Wharton’s Jelly in umbilical cord
Composed of some collagen & elastic fibers mostly an abundance of extracellular matrix
128
Compare brown fat from white fat
White= distributed throughout the body unilocular
Brown= contain numberous smaller lipid droplets: mutlicoular, slightly more cytoplasm, abundant mitochondria (gives more brown color)
129
Collagen synthesis
T1 collagen = synthesized as prepropeptide -> signal sequence is cleaved after translocation of polypeptide into ER lumen of fibroblast, then propeptide molecule is secreted via fibroblast into extracellular matrix
-the procollagen mole is terminal non-helical end prevents polymerization-> they get cleaved (pepidases)->molecule is referred to as tropocollagen
-Tropocollagen monomers assemble into staggered array to form collagen fibrils -> are crossed linked to form collagen fibers (side by side)- mediated via proteoglycans & FACIT
130
Elastic fiber synthesis
Synthesized as preproptide, wh/ secreted as propeptide, -> converted to tropoelastin via extracellular enzyme (also secreted by fibroblast )-> trpoelastin monomers are assembled into amorphous fibers or sheets w/ aid of several types of fibrillins
131
Four groups of glycosaminoglycans
Hyaluronic acid
Heparin & heparan sulfate
Chondroitin sulfate & dermatan sulfate
Keratin sulfate
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Hyaluronic acid
Largest of the GAGs
Cartilage, skin, synovial fluid, & general CT
Only GAG wh/ lacks sulfate gps
Present in nearly all CT & vitreous body of eye, synovial fluid & Wharton’s jelly
Binds readily w/ H2O & serves as a lubricant in synovial fluids
133
Heparin & heparan sulfate
Basement membrane, skin, lung, blood vessels, mast cell granules. Repeating unit in N-acetylglucosoamine & D-glucuronic acid
134
chondroitin sulfate & dermatan sulfate
Cartilage, bone, skin, blood vessels, heart valves, cornea, most abundant sulfated GAGs
135
Keratin sulfate
Type 1 is found only in cornea
Type 2 is found in cartilage & nucleus purposes of intervertebral disks
136
Describe proteoglycans aggregate
Formed by:
1. An axial Hyaluronan molecule
2. Core proteins attached to hyaluronan molecule via linker protein
3. Glycosaminoglycans attached to a core protein
137
Common types of cell residents include (for fibrous CT)
Macrophages
Mast cells
Plasma cells
138
Macrophages
10-30um
Ovoid or indented heterochromatic nucleus
Irregular in shape w/ blunt processes- wandering macrophages R somewhat oval in shape,. Fixed macrophages are more irregular in shape w/ long processes
Capable of ameboid movement
Part of mononuclear phagocytic system (RAS)
139
Mast cell
Irregularly oval in outline
Small spherical/ovoid nuclei often masked by membrane-bound granules
Stain w/ toluidine blue
140
Plasma cell
Activated by B lymphocytes
Large pale nuclei w/ “clock face” distribution of heterochromatin
