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.
Stratified Cuboidal Epithelium
Description, Location, Function
Description: Two or more layers; apical layer cube-shaped.
Location: Ducts of adult sweat glands, esophageal glands.
Function: Protection, limited secretion and absorption.
Stratified Columnar Epithelium:
Description, Location, Function
Description: Basal layers irregularly shaped, apical layer columnar.
Location: Large excretory ducts of some glands, anal mucous membrane, conjunctiva of eye.
Function: Protection and secretion.
Transitional Epithelium (Urothelium)
Description: Variable appearance; stratified cuboidal when relaxed, stratified squamous when stretched.
Location: Lines urinary bladder, ureters, and urethra.
Function: Allows stretch and maintains protective lining while holding variable fluid amounts.
Goblet Cells
Mucous-secreting cells, found in respiratory tract
Ciliated
Describes cells with cilia.
Mesothelium
Simple squamous epithelium of serous membranes
Endothelium
Simple squamous epithelium lining blood vessels.
Endocardium
Simple squamous epithelium lining heart and heart valves.
