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Histology (Lectures 43 and 44) (Lectures 53 and 54) - Coggle Diagram

- - - - Tissue chemically fixed
        
        Most common - 37% formaldehyde
        
        Terminates metabolism
        
        Prevents enzymatic degredation (important for tissues which autolyze after death)
        
        Kills microorganisms
        
        Causes protein crosslinking to harden structures
        
        Gluteraldehyde + immersion in OsO4 (for EM)
        
        Heat
        
        Freezing (preserves lipids) - good for quick during surgery
        
        Soluble small molecules dissolve (tRNA, proteins, lipids, glycogen, ions)
        
        Creates insoluble macromolecular complexes (protein-protein NA-protein, protein-polysaccharide)
        
        Tissue embedded in parafin or plastic resin
        
        Sectioning on microtome/cryostat (steel blade for parafin 1-10um, or diamond plade for plastic <1um)
        
        Mounting
        
        Staining
        
        Contrast
        
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        Cytochemistry
        
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        Immunohistochemistry (IHC)
        
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        Microscopy
        
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        In Situ hybridization
        
        Oligonucleotdie probes (20-1000bps)
        
        Probes labelled with radioactivity or fluoro dyes (FISH)
        
        Autoradiography
        
        Process (see image)
        
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- - - - a) Covering, lining & protecting
      - b) Absorption
      - c) Secretion
      - d) Specialized: sensory
      - a) Tightly packed cells
      - b) Very little ECM
      - c) Avascular (nutrients?)
      - d) Associated with C.T. (BM)
      - e) Highly regenerative
      - f) innervated
      - g) Polarity (next slide)
        
        One side designated for apical surface, one side designated for basement membrane
        
        Apical side can be specialized (microvilli brush border or cilia)
        
        Basement Membrane
        
        Thin felt like sheet of macromolecules
        
        Functions
        
        1) Structural support
        
        2) Attach epithelia to C.T.
        
        3) Filtration
        
        4) Scaffold for regeneration/repair
        
        5) Acts as physical barrier against tumor cell invasion
        
        Parts
        
        Basal Lamina
        
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        Reticular Lamina
        
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      - Covering Epithelia (line all body surfaces)
      - Glandular Epithelia (secretory)
    - - Shape
        
        Squamous
        
        Cuboidal
        
        Columnar
        
        Named for number of layers and shape
        
        Special epithelial tissues
        
        Pseudostratified
        
        Transitional
        
        Can go from aggregated like a "pile of ball bearings" to a flat layer and vise versa. Found in urinary tract. Also called urethelium.
        
        Simple Squamous Epithelium
        
        Passive diffusion and filtration
        
        Serous membranes
        
        Renal corpuscles
        
        Alveoli
        
        Lining of heart
        
        Vessels (blood and lymph)
        
        Serosa
        
        Endothelium
        
        Slick lining of hollow organs
        
        Mesothelium
        
        Lines peritoneal, pleural, and pericardial cavities
        
        Simple Cuboidal Epithelium
        
        Mostly secretive with some absorptive
        
        Kidney tubules, secretory portions of small glands, ovaries, thyroid follicles
        
        Simple Columnar Epithelium
        
        Absorption and secretion of: mucus (goblet), enzymes, and other substances
        
        Ciliated type propels mucus or reproductive cells (small bronchi, uterine tubes and uterus)
        
        Pseudostratified Columnar Epithelium
        
        All cells originate at basement membrane
        
        Only tall cells reach the apical surface
        
        May have goblet cells and/or cilia
        
        Non-ciliated in male reproductive tubes and ducts of large glands
        
        Ciliated in trachea and most of upper-respiratory tract
        
        Stratified Squamous Epithelium
        
        Thickest epithelia tissue (deeper layers appear cuboidal)
        
        Keratinized or non-keratinized
        
        non-keratinized at body openings
        
        Keratinized forms epidermis
        
        Protects underlying tissue from abrasion
        
        Stratified Cuboidal and Columnar Epithelium
        
        :star: Rare
        
        Cuboidal - excretory ducts of salivary and sweat glands
        
        Columnar - conjunctiva, anorectal juncture
        
        Transitional Epithelium (urothelium)
        
        Basal cells usually cuboidal or columnar
        
        Superficial cells are dome-shaped (umbrella)
        
        Stretches and permits distention of urinary bladder
        
        Lines ureters, urinary bladder, parts of urethra
        
        Glandular Epithelium
        
        Exocrine: ducts carry products to epithelial surface
        
        Mucus-secreting, sweat and oil, salivary, enzymes from liver and pancreas, mammary glands
        
        Unicellular
        
        Goblet cells - mucin + water, protects internal body surfaces, digestive and respiratory tracts
        
        Multicellular
        
        Merocrine (Exocytosis)
        
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        Hypocrine (whole cell disintegrates like sebaceous glands)
        
        Apocrine (apical portion is lost like mammary glands)
        
        Endocrine: hormones into tissue fluid
        
        Ductless
        
        Singular or in small groups
      - Number of layers
        
        Simple
        
        Stratified
    - - Tight (occluding) junctions
        
        Prevent paracellular transport
        
        Interaction between transmembrane proteins Claudin and Occludin
        
        C. Perfringens (gas gangrene) enterotoxin targets Claudin
      - Adherens Junctions
        
        Below tight junctions
        
        Anchors: mechanical attachments between cells
        
        Cadherins bind catenins that link to actin
      - Gap junctions
        
        Channel between 2 adjacent cells
        
        Allow small molecules (cAMP) ions to move
        
        Cells connected by hollow cylinders of connexins
      - Desmosome (macula adherens)
        
        Single "spot weld"
        
        Stress and stretch resistance
        
        weakness causes regular blisters and elderly blisters
      - Hemidesmosomes
        
        Like desmosomes but connect cell to basal lamina rather than cell to cell
  - - - Processes are called axons and dendrites
      - Uni, bi, or multi-polar
      - Sensory, motor, and inter-neurons
    - - CNS: astrocytes, oligodendrocytes, microglia, and ependymal cells
      - PNS: Schwann and satellite cells
  - - - Attach to bones or other muscle
      - Long, multinucleated, cylindrical cells
      - Mostly voluntary
      - Striated with a sarcomere
    - - Uni or bi-nucleated branching cells called myocardium
      - Striated with intercalated discs
      - Involuntary and autonomous
    - - Spindle-shaped cells with central nucleii
      - No striations or sarcomeres
      - Involuntary and autonomous
      - Walls of hollow organs and blood vessels
      - Neuromuscular Junctions (NMJ) is distinctive
        
        Varicosities
  - - - Protein fibers: collagen, elastin, reticular
        
        Fibers
        
        Collagen
        
        :green_cross: Key element of ALL connective tissue, BM, external laminae of muscle, and nerve cells
        
        Strong, resistant to normal tearing and shearing forces
        
        Primarily resists PULLING (non-contractile)
        
        28 families of collagen
        
        Fibrillar
        
        Type I (most abundant), Type II, Type III (reticular)
        
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        Sheet-forming
        
        Type IV (epithelial basal laminae)
        
        Elastin
        
        Elastin (thinner than collagen) and fibrillin
        
        Stretching or bending (vocal cords, lungs, arteries)
        
        Don't stain well (hard to tell apart from collagen)
        
        Produced by fibroblasts/vascular smooth muscle cells
        
        :warning:Damaged by sun and smoking
      - Ground substance: proteoglycans, glycosaminoglycans (GAGs), and glycoproteins
        
        Viscous, clear with slippery feel/high H2O
        
        Proteoglycans (aggrecan, syndecan),
        
        Multi-adhesive glycoproteins (Laminin, fibronectin) &
        
        Glycosaminoglycans (dermatan sulfate, chondroitin sulfate)
        
        :star: Different connective tissues secrete different ratios of ground substance molecules
      - ECM functions:
        
        Provide mechanical & structural support
        
        Biochemical barrier
        
        Anchor cells & influence migration
        
        Retain growth factors & influence cell growth
    - - Binding & Support
        
        Skeleton and ligaments
      - Protection
      - Transportation
        
        Skeleton
      - Repair
        
        Fibroblasts
      - Production and maintenance of blood cells
      - Insulation
        
        Fat, sinuses
    - - Embryonic CT
        
        Mesenchyme and Mucous CT
      - CT Proper
        
        Loose CT (areolar)
        
        Thin, sparse fibers w/lots of ground substance
        
        Forms later beneath epithelial lining of organs
        
        Fills spaces between muscle and nerve fibers
        
        Diffusion of gas and nutrients
        
        1st location for many invaders (very permeable)
        
        Dense CT
        
        Regular (parallel fibers)
        
        Tendons, ligaments, aponeuorses (one direction of pulling/contraction)
        
        Irregular (anything other than parallel)
        
        Few fibroblasts and ground substance, poor vasculature, strong!
        
        Dermis, submucosa of intestine (many directions of pull/contraction)
      - Specialized CT
        
        Bone
        
        Support and protect organs, provide attachment sites for muscles, store calcium and minerals, store fat, red marrow for blood cell formation
        
        Bone Cells
        
        Osteocytes
        
        Osteoblasts (build bone)
        
        Osteoclasts (digest bones)
        
        Types
        
        Compact/dense/cortical
        
        Trabecular/spongy/cancellous
        
        Cartilage
        
        Firm, durable, 80% water, type II collagen and elastic fibers, high conc of GACs and proteoglycans, AVASCULAR, chondrocytes in lacunae, covered in perichondrium
        
        Hyaline (most common)
        
        Homogenous and semitransparent
        
        Supports, cushions, resists repetitive stress
        
        Surfaces of moveable joints, walls of large respiratory passages, epiphyseal plates
        
        :warning: Loss causes osteoarthritis
        
        Growth stimulated by somatotropin
        
        Elastic (ears and larynx)
        
        Like hyaline with more elastic fibers
        
        Flexible, maintains shape and structure
        
        external ear, epiglottis, upper respiratory tract
        
        Fibrocartilage (vertebral discs, pubic symphysis, cranial sutures)
        
        hyaline cartilage and dense connective tissue
        
        tensile strength and absorption of compressive shock
        
        Intervertebral discs and pubic symphysis
        
        Adipose
        
        Blood
        
        Transport Co2, O2, metabolites, hormones
        
        Heat distribution (why arteries and veins run together)
        
        Maintenance of acid/base balance and osmotic pressure
        
        Reticular
        
        Hemopoeitic
        
        Lymphatic
    - - Resident
        
        Fibroblast
        
        Principle CT cells
        
        Synthesize all fibers and ground substance
        
        Target of many growth factors
        
        Adults rarely divide and live in G0
        
        Macrophages
        
        Resident monocytes
        
        Phagocytic
        
        APCs
        
        M1
        
        Classically activated, chronic inflammation and tissue injury
        
        M2
        
        Alternatively activated, resolution of inflammation and repair
        
        Adipocytes
        
        fat storage and hormone production
        
        White fat (single large vacuole)
        
        Brown fat (multiple vacuoles)
        
        :warning:Babies have a lot of brown fat because it helps generate heat without shivering! (ever noticed babies don't really shiver when cold?)
        
        Mast cells
        
        Fried egg appearance ("yolk" is histamine granule)
        
        Similar to basophils
        
        Many products including histamine and heparin
        
        :warning: Mast cell tumors are so dangerous because one good hit to the tumor can send the person into major anaphylaxis
        
        Adult stem cells
        
        Differentiate to only ONE lineage
        
        Ex) bone marrow, basal GI cells
        
        Myofibroblasts
        
        Shares properties with fibroblasts and smooth muscle
        
        Wound healing, scar tissue (dense irregular CT)
        
        Contractile
      - Transient
        
        Lymphocytes (including plasma cells)
        
        T cells, B cells, NK cells
        
        Express CD molecules
        
        B cells are plasma cells
        
        PMN cells (AKA granulocytes)
        
        neutrophils, basophils & eosinophils
        
        Monocytes
- - - - Primary tissue types appear
      - Major organs are in place
      - Adulthood
        
        Only a few tissues regenerate
        
        Many tissues still retain stem cell populations
        
        Increasing Age
        
        Epithelia thin
        
        Collagen decreases
        
        Bones, muscles, and nervous tissue atrophy
        
        Poor nutrition and circulation lead to poor tissue health
        
        Increased chance of developing cancer
- - - - epidermis & derivatives, cornea, lens, enamel, internal ear, adenohypophysis, oral and anal mucosa
    - - CNS and PNS