Tissue Lecture 1 Flashcards
Cell Junctions
Purpose, Components, Types
Purpose: Connect cells to form tissues, regulate tissue homeostasis, provide tissue barrier function, facilitate cell proliferation.
Components: Interlocking transmembrane proteins.
Types: Tight junctions, Adherens junctions, Desmosomes, Hemidesmosomes, Gap junctions.
Tight Junctions
Function, Location
Function: Bind adjacent plasma membranes, prevent passage of water and solutes between cells.
Location: Stomach, intestinal tract, bladder.
Adherens Junctions
Structure, Function, Formation
Structure: Contains plaque made of actin filaments attached to cadherin proteins.
Function: Resist separation during contractile activities.
Formation: Often form extensive adhesion belts encircling cells.
Desmosomes
- Similar to adherens junctions but with specific plaque locations.
- Attach to intermediate filaments containing keratin.
- Found in epidermis and cardiac muscle cells.
Hemidesmosomes
- Anchor cells to basement membrane using integrin transmembrane protein.
- Similar structure to desmosomes but attach to laminin in the basement membrane.
Location: Between epidermis and dermis.
Gap Junctions
Composition, Function
Composition: Tunnel-like connections made of connexins.
Function: Provide intercellular communication by transferring substances like ions, nutrients, and waste products.
Epithelial Tissue
Functions, Structure, Characteristics
Functions: Protection, absorption, secretion, excretion.
Structure: Cells arranged in layers, may be single or multiple layers.
Characteristics: Avascular, ample nerve supply.
Epithelial Cell Surfaces
Apical, Lateral, Basal
Apical Surface: Faces body cavity or lumen, may contain cilia or microvilli.
Lateral Surface: Shared with adjacent cells, location of cell-to-cell junctions.
Basal Surface: Opposite to apical surface, attaches to basement membrane.
Basement Membrane
Purpose, Components
Purpose: Attaches epithelial tissue to underlying connective tissues.
Components: Basal lamina (collagen fibers, laminin, glycoproteins), reticular lamina (fibrous proteins).
Epithelium Classification
Based on, Number of cell layers, shape of cells(4)
Based on: Number of cell layers and shape of individual cells.
Number of Cell Layers: Simple (single layer), Stratified (multiple layers), Pseudostratified (appears layered but is single layer).
Shape of Cells: Squamous (flat), Cuboidal (cube-shaped), Columnar (rectangular), Transitional (able to alter between cuboidal and squamous).
Simple Epithelium
Description, Function, Examples
Description: Single layer of cells.
Function: Fast exchange across the epithelium.
Examples: Capillaries, Alveolar sacs of the lungs.
Stratified Epithelium
Description, Function, Examples
Description: Multiple layers of cells.
Function: Strength, reinforcement, protection.
Examples: Mouth, pharynx, esophagus, Skin (epidermis).
Pseudostratified Epithelium
Description, Types
Description: Appears multilayered but is actually one layer.
Types: Ciliated (respiratory tract), Non-ciliated (male reproductive tract).
Squamous
Description, Examples
Description: Flat, allows high rate of absorption.
Examples: Capillaries, Alveolar sacs of the lungs.
Cuboidal
Description
Description: Cube-shaped, may have microvilli, allows secretion and absorption.
Columnar
Description, Examples
Description:Column or rectangular shaped, may have microvilli, allows secretion and absorption.
Examples: Stomach, small intestinal lining.
Transitional
Description: Superficial layers can alter between cuboidal and squamous, allows distension and stretch.
Examples: Bladder, ureters, parts of urethra.
Simple Squamous Epithelium
Description, Function, Location
Description:Single layer of flat cells, thinnest and most delicate type.
Function: Filtration (e.g., blood filtration), diffusion (e.g., oxygen diffusion into lungs), secretion in serous membranes.
Location:Lines blood vessels (endothelium), heart (endocardium), serous membranes of body cavities (mesothelium), and air sacs of lungs (alveoli).
Simple Cuboidal Epithelium
Description, Function, Locations
Description: Single layer of cube-like cells with centrally located nucleus.
Function: Secretion and absorption.
Locations: Covers ovary surface, anterior surface of lens capsule, pigmented epithelium of retina, kidney tubules, secreting portion of some glands like thyroid gland.
Non-ciliated Simple Columnar Epithelium
Description, Location, Function
Description: Single layer of non-ciliated column-like cells, often with microvilli and goblet cells.
Location:Lines digestive canal.
Function: Secretion and absorption, secretes mucus for lubrication and protection against stomach acid.
Ciliated Simple Columnar Epithelium
Description, Location, Function
Description: Single layer of ciliated column-like cells.
Location: Lines respiratory tract bronchioles, uterine tubes, uterus, brain ventricles.
Function: Cilia beat to move mucus and foreign particles toward throat for removal, aids in moving oocytes from ovaries to uterus.
Non-ciliated Pseudostratified Columnar Epithelium
Description, Function, Location
Description: Appears to have several layers due to nuclei at various levels; lacks cilia and goblet cells.
Function: Absorption and secretion.
Location: Epididymis, parts of male urethras, vas deferens, larger ducts of many glands.
Ciliated Pseudostratified Columnar Epithelium
Description, Location, Function
Description: Appears to have several layers; contains ciliated and goblet cells.
Location: Respiratory mucosa lining much of the respiratory tract.
Function: Secretes mucus to trap foreign particles; cilia sweep away mucus for elimination.
Stratified Squamous Epithelium
Description, Non-keratinized Location, Keratinized Location, Function
Description: Two or more layers; apical layer squamous, deeper layers vary.
Non-keratinized Location: Lines moist surfaces like mouth, esophagus, vagina.
Keratinized Location: Skin (epidermis), hair, nails.
Function: Protection against abrasion, water loss, pathogen invasion.
