Basic Tissues Flashcards
What is the body organised into?
- Cells - fundamental structural and functional unit of the body
- Tissues - A collection of cells that perform a particular function
- Organs - multiple tissues that perform a particular function by working together
- System - group of organs with a collective function
- Organism - whole individual
What are the basic tissues?
- epithelia
- connective tissue
- muscle
- nervous
What’s the location of the epithelia?
- Covers surfaces
- Lines cavities and tubes
- forms glands
What are some important characteristics of epithelia?
- attached to a membrane
- Provide physical protection
- Control Permeability
- Provide sensation (have a large sensory nerve supply)
- Produce specialized secretions (gland cells)
- Avascularity (no blood vessels in the cells)
- Regenerate
- Polarity (apical - faces lumen/surface and basal - attached to basement membrane)
How can you classify epithelia?
Based on number of cell layers and the shape of the cells
In epithelia what are the number of cell layers called?
Simple: one layer
Stratified: two or more layers
What are the different shapes of epithelial cells you can get?
- squamous (flat)
- Cuboidal (cube)
- Columnar (rectangle)
You can see this in the nucleus of the cell
What are the main types of epithelial cells?
- simple squamous
- keratinised stratified squamous
- Non-Keratinised stratified squamous
- Simple cuboidal
- Simple columnar
- Pseudostratified columnar with goblet cells
Give features of Simple Squamous epithelia
- Flat cells - oval shaped nuclei
- One layer of cells
- Main function: exchange of nutrients and gases
- Smooth edge
- Location: blood vessels, lining the heart, alveoli
Give features of Keratinised Stratified Squamous epithelia
- Flat surface cells with oval shaped nuclei
- Many layers
- Keratin
- Major function: protection, barrier (waterproof because of Keratin)
- Location: skin and some areas of oral cavity (gums and hard palette)
- usually located where mechanical stresses are severe
Give features of Non-Keratinised Stratified Squamous epithelia
- Flat surfaces with oval shaped nuclei
- Many layers
- Major function - protection, barrier
- Location - oral cavity, oesophagus
- resists abrasion but will dry out and deteriorate unless kept moist
Give features of Simple Cuboidal Epithelium
- Square cells with round nuclei
- One layer
- Major function: secretion and absorption
- Location: glands, kidney tubules
Give features of Simple Columnar Epithelium
- Tall cells with oval, basally located nuclei
- One layer
- Major function: absorption and secretion
- Location: gastrointestinal tract
- Surface modifications: microvilli
Give features of Pseudostratified Ciliated Columnar Epithelium with Goblet cells
- Tall cells: column
- Appears stratified as some cells don’t reach free surface (lumen/apical membrane)
- All cells touch basement membrane
- Modification with cilia and goblet cells
- Functions: mucociliary escalator
- Location: trachea and large respiratory airways
What are intracellular junctions?
Specialised areas of cell membrane that bind to one another. Found in epithelial cells
What are examples of intracellular junctions?
- Desmosomes
- Hemidesmosomes
- Tight Junctions
- Gap Junctions
Give features of Desmosomes
- Very strong connections between adjacent cells
- Resist stretching and twisting
- made of proteoglycans
Give features of Hemidesmosomes
- Attach cells to the basement membrane
- Stabilise the position and anchor cell to underlying tissue
Give features of Tight junctions
- Interlocking proteins bind tightly together near apical edge
- Prevent passage of water and solutes between cells (e.g. in digestive tract)
Give features of Gap Junctions
- Cells held together by interlocking membrane proteins containing a central pore called connexons
- Allows movement of small molecules and ions between cells: found in cardiac muscle
What are the functions of connective tissue?
- forms a structural framework for the body
- Supports, surrounds and interconnects other tissue types
- Protects delicate organs
- Transports fluids and dissolved minerals
- Stores energy reserves
- Defends body from microorganisms
What do all types of connective tissue consist of?
Cells within an extracellular matrix
What type of cells can be found in connective tissue?
- Fibroblasts; the main type that synthesises the extracellular matrix
- Other cell types; adipocytes, macrophages and mast cells
What does the extracellular matrix in connective tissue consist of?
- Ground substance
- Tissue (extracellular fluid)
- Fibres; collagen, reticular and elastic
How can you classify Connective tissue?
Specialised Connective tissue: - Blood (fluid matrix) - Bone (solid matrix) - Cartilage (mixture of both) Connective tissue proper (packaging between organs)
How is Connective Tissue proper classified?
According to type, arrangement and abundance of fibres, cells and ground substance
What are the three main types of Connective Tissue proper?
- Loose areolar
- Dense irregular
- Dense regular
Give features of Areolar Connective Tissue
- Lots of ground substance
- Forms a layer that separates the skin from deeper structures
- Few fibres (collagen and elastic)
- Variety of cells: Fibroblasts, Adipocytes and Macrophages
- Found under the epithelium that lines the body surfaces
Give features of Dense Irregular Connective Tissue
- Little ground substance
- Many collagen fibre bundles arranged haphazardly
- Few cells (mainly fibroblasts)
- Resists excessive stretching and distention
- Found in the dermis of the skin
Give features of Dense Regular Connective Tissue
- Little ground substance
- Many densely packed bundles of collagen fibres arranged in parallel rows
- Few cells (mainly fibroblasts)
- Found in tendons and ligaments
What does muscle tissue do?
Produces movement and is specialised for contraction