Histology Flashcards
List the 4 fundamental body tissues
epithelium, connective tissue, nervous tissue, muscle
Locations & 3 characteristics of epithelia
List 3 domains of epithelial cells
Covers/Lines surfaces of body and Interfaces with various biological compartments
- Anchored to Basement Membrane (resting on connective tissue)
- AVASCULAR (relies on diffusion from connective tissue)
- Tightly connected to each other laterally via SPECIALIZED JUNCTIONAL COMPLEXES
Apical (lumen facing), Lateral, Basal (interstitium facing)
How are the different types of epithelial tissues named/characterized? (3 ways)
- Number of cell layers (Simple, Pseudostratified, Stratified)
- Cell Shape (Squamous, Cuboidal, Columnar)
- Keratinization (Keratinized, Non-keratinized)
Simple Squamous Epithelium (Characteristics, Example)
- Monolayer, flat cells, tightly connected
- Parietal layer of Bowman’s Capsule, Blood vessel endothelium, Lung Alveolar Wall, Body Cavity Mesothelium (Peritoneum, Pericardium, Pleura)
Simple Cuboidal Epithelium (Characteristics, Example)
- Monolayer, square cells
2. Renal Tubules, Thyroid follicles, Glandular tissue
Simple Columnar Epithelium (Characteristics, Example)
- Monolayer, very elongated cells
2. Small Intestine, Bronchioles
Pseudostratified Epithelium (Characteristics, Example)
- Monolayer because every cell is touching the basement membrane; however, the different positioning of nuclei give appearance of multiple layers
- Trachea, Epididymus (male reproductive)
Stratified Squamous Epithelium (Characteristics, Example)
- Multi-layered, flat cells on top, square cells near basement membrane (where new cells are generated)
- Moist areas (esophagus, oral cavity, vagina, anal canal)
Keratinized Stratified Squamous Epithelium (Characteristics, Example)
- With the multiple extra layers of dead cells (no nuclei) - to act as protective layer
- Skin
Transitional Epithelium
Characteristics, Example
Specially made for its location
TWO STATES
1. Relaxed: 5-6 layers, top layer is large, pillowy, cuboidal cells
2. Stretched: 2-4 layers, top layer is flattened
3. Urinary Tract (ureter and bladder)
3 Specializations of the Apical Domain (examples for each)
- Microvilli - greatly increase surface area of apical side for reabsorption (intestinal lumen and kidney PT)
- Stereocilia - very long, thin, non-motile microvilli in male reproductive system (epididymus + ductus deferens)
- Cilia - actively motile processes (line respiratory tract and female reproductive tract - help move ovum/particles along)
Tight Junction (Name, Family/Location, Function, Proteins)
- Zona Occludens
- At TOP of Apical Junctional Complex in Lateral Domain of Epithelia
- Block Movement b/w cells in ECM, maintain cell polarity, prevent fluid penetration
- Claudins + Occludins
Adherens Junction (Name, Family/Location, Function, Proteins)
- Zonula Adherens
- Just below zona occludens in Apical Junctional Complex in Lateral Domain of Epithelia
- Provide Strength, links nearby cell’s actin cytoskeletons, form continuous band around cells - 6 pack appearance
- Cadherins (binding actin)
Desmosomes (Name, Family/Location, Function, Proteins)
- Macula Adherens
- Deep below zonula adherens in Apical Junctional Complex in Lateral Domain of Epithelia
- binds IF cytoskeletons - abundant in stratified epithelia exposed to stress
- Cadherins (bind IF not actin)
Gap Junction (Name, Family/Location, Function, Proteins)
- Scattered throughout Lateral Domain of Epithelia
- Direct pore between 2 closed membranes - allows passage of small mLc/nutrients b/w adjacent cells
- Helps coordinate epithelial function
- Connexons
2 components of the basal domain
- Basement membrane - thin non-cellular layer between epithelium and connective tissue - structural support for epithelium + selective barrier for material movement
- Hemidesmosomes - like desmosomes but anchor cell to BM (not other cells); attaches to keratin IFs with INTEGRINS (bind type IV collagen in BM)
Definition of histology + Components of the H&E Stain
Histology - the way we observe cells make up our body
H - Hemotoxillin - basic - stains purple - binds DNA/nucleus
E - Eosin - acidic - stains pink (ex. collagen)
Connective Tissue (Function, Location, Developmental Derivation)
- Supportive Framework for all other tissue types in the body
- Found in every organ system and helps align epithelium
- Derived from Mesodermal layer during development (Paraxial Mesoderm - somatic tissues; Lateral Plate Mesoderm - visceral tissues)
2 Roles of Basement Membrane in tissue structure
- Structural: anchors epithelium to connective tissue
2. Protective: acts as barrier between epithelium and connective tissue
6 types of connective tissue cells and their role
- Fibroblast/Myoblast: Make type IV collagen, nucleated, structural support + healing/remodeling - used to make scars
- Macrophage: (AKA: histiocytes in tissue), structural support + healing/remodeling
- Adipocyte: Fat Storage
- Pericyte: Structural support around blood vessel
- Mast Cell: Round cell with granules, defense + healing/remodeling by releasing cytokines to trigger immune system
- Neutrophils (Other WBC): Defense + Healing/Remodeling
Dense Connective Tissue (Features, Function, Example)
- Irregular - non-parallel pink fibers to provide multidirectional impact resistance (ex: skin, joint capsules b/w fascia)
- Regular - parallel pink fibers to provide tensile strength and resistance to lengthening (ex: tendons)
Mainly composed of collagen fibers (elastin fibers somewhat present)
Loose Connective Tissue (Features, Function)
- Vascular, Pink collagen fibers, with more space (space filled with ground substance - GAGs and Hyaluronan)
- Space allows room for material to pass from blood to epithelium
Connective Tissue in Arteries
- Predominantly Elastin fibers in the Tunica Media of arteries to help vessel stretch and expand to increase volume load
- helpful when paired with smooth muscle (can expand AND contract)
* NOT A TYPE OF CONNECTIVE TISSUE *
Reticular Connective Tissue (Features, Function, Example)
- Meshwork in hematopoietic tissues to open up spaces for cells to pass through while providing structure
- Spleen and lymphoid tissues