Chapter 4 Flashcards
Tissues
Collections of specialized cells and cell products organized to perform a limited number of functions
Histology
Study of cells
Four Tissue Types
- Epithelial
2 Connective - Muscular
- Nervous
Location of Epithelial Tissues
Found in areas of: body coverings, body lining; lines all free surfaces, and glandular tissue
Epithelium Characteristics
- Cells fit closely together; little intracellular space
- Cells show polarity;
Apical surface: free surface (always)
Basal surface: attached to surface - The lower surface is bound by a basement membrane called basal lamina acellular, non-living
- Avascular (no blood supply)
- Regenerates easily
Functions of epithelium
- Physical protection
- Controls permeability
- Provide Sensation
- Produces specialized secretions
Specilization of epethilium
- Movement of materials across the surface (Cilia)
- Movement of fluids through the epithelium; absorption (Microvilli)
- Production of secretions (Mucous)
Epithelial Integrity
Cells attach via Cell Adhesion Molecules (CAMs)
Cell Junctions
Tight Junction
Prevent substances from passing between cells (Apical Region)
Desmosomes
- Like button snaps
- Strong - holds cells together
- Resists stretching
Gap Junctions
- Cylinder with pore
- Communication Junctions
- Allows substances to move from cell to cell
Simple epithelia
One cell layer over basement membrane
Stratified epithelia
Many cell layers between apical surface and basement
Squamous apical cells
Flat cells
Cuboidal apical cells
Cube shaped cells
Columnar apical cells
tall, thin cells
Representative epithelial cells
- Simple squamous
- Simple cuboidal
- Simple columnar
- Pseudostratified columnar
- Stratified squamous
- Transitional
Characteristics of simple squamous epithelia
- Single layer squamous cells
- Covers organs, lines cavities (serous membranes)
- Diffusion, filtration, reduces friction by secreting lubricating fluids
- Lines blood vessels, found in kidneys, lungs and serous membranes
Characteristics of simple cuboidal epithelia
- Single layer of cube shaped cells
- Secretion and absorption
- Found in glands, ducts and kidney tubules
Characteristics of simple columnar epithelia
- Single layer of columnar cells
- Secretion of digestive enzymes, absorption of nutrients
- Lining of GI tract (stomach large intestine)
Characteristics of pseudostratified ciliated columnar epithelia
- Single layer, but some cells are shorter than others
- Often looks like a double cell layer
- Secretion ; (Production of mucus) and may have cilia
- Lining of respiratory tract
Characteristics of stratified squamous
- Many layer of epithelial cells; cells at the free edge are flattened (squamous)
- Protection, withstands abrasion
- Skin, lining of oral cavity, throat and esophagus
Characteristics of transitional epithelium
- Specialized to change in response to increased tension
- Shape of cells depends upon the amount of stretching, may be cuboidal (relaxed) or squamous(distended)
- Allows organ distension
- Urinary bladder, ureters
Characteristics of Connective Tissue
- Cells spread out, much extracellular space
- Different types of cells
Matrix
- Not living
- Ground substance
- May contain fibers, calcium deposits etc.
Two types of connective tissue
- Connective tissue proper - cell diversity, fiber diversity
- Specialized (supporting) - Matrix has more densely packed fibers, little cell diversity (Bone & Cartilage)
Functions of Connective Tissue
- Establishing a structural framework
- Transporting fluids and dissolved materials
- Protecting delicate organs
- Supporting, surrounding and interconnecting tissues
- Storing energy reserves
- Defending the body from microoorganisms
Fibroblasts (Connective Tissue Proper)
Always present in connective tissue proper; produce matrix
Fibrocytes (Connective Tissue Proper)
mature; maintain matrix
Macrophages (Connective Tissue Proper)
Phagocytic white blood cells
Adipocytes (Connective Tissue Proper)
Fat cells
Mesenchymal cells (Connective Tissue Proper)
Stem cells
Melanocytes (Connective Tissue Proper)
produce pigments
Mast cells (Connective Tissue Proper)
Histamine and heparin; produce inflammation
Collagen fiber (Connective Tissue Proper)
Most common; very sturdy, resist pulling forces; won’t tear; straight
Reticular fibers (Connective Tissue Proper)
Smaller and branching; from a network of interwoven fibers; resist forces in all directions
Ground substance (Connective Tissue Proper)
Clear, colorless, viscous; fills space between cells and fibers
Elastic fibers (Connective Tissue Proper)
Stretch and recoil; wavy
Loose connective tissue
- Embryonic mesenchyme, mucous connective tissues
- Areolar tissue
- Adipose tissue
- Reticular tissue
Areolar tissue
- Most common; contains all cells and fibers
- Binds skin to muscle below
- Holds organs and tisues together
- Protection
- The one that looks like a spider web
Dense connective tissue
- Dense regular CT
- Dense irregular CT
Adipose tissue
- Adipocytes; large lipid droplets occupt most of the cell
- Vascular
- Under layers of skin, around organs
- Stores lipids (energy)
- The one that looks like fat blobs
Dense regular connective tissue
- Collagen fibers arrange in one direction with fibroblasts
- Withstands tension
- Little blood flow
- Found in tendons and ligaments
Prefix (tissue cells are found in)
- Chondro - cartilage
- Osteo - bone
Suffix (types of cells)
- Blast - matrix forming cells
- Cyte - maintains matrix
- Clast - breaks down matrix
Cartilage (Supporting connective tissue)
- Provides shock absorption and protection
- matrix is a firm gel
- Avascular
Hyaline cartilage
- Avascular
- Between articulating bones
- Provides flexible support and reduces friction
- Multiple chondrocytes in a lacunae
Elastic Cartliage
- Elastic support
- looks like veins
Fibrocartilage
- Strongest cartilage
- Resist compressive shock
- Only ONE chondrocytes within lacunae
Bone
- Vascular
- Support, protect
Muscle tissue
Specialized to contract
1. Skeletal
2. Smooth
3. Cardiac
Nerve tissue
Specialized to send electrical impulses
Brain, spinal cord, nerves
Membranes
Continuous multicellular sheets composed of two tissue types
1. Epithelial and connective
2. From a barrier; line, cover and protect surfaces; lubricate surfaces
Four types of membranes
- Mucous
- Serous
- Cutaneous
- Synovial
Mucous membranes
- Line cavities that open to the exterior
- Absorption, secretion, protection
- May produce mucous
- Diogestive and respiratory systems
Serous membranes
- Lines cavities that don’t open to the exterior
- Produce serous fluid
- Parietal (lines cavity) Visceral (Covers organs)