Lecture Topic 4: Basic Tissues

Define a cell

Fundamental structural and functional unit of the body

Define a tissue

A collection of cells that perform a particular function

Define an organ

Multiple tissues that perform a particular function by working together

Define a system

A group of organs with a collective function

What are the 4 basic tissues?

Epithelia / connective / muscle / nervous

What are all the locations of epithelia tissue?

Cover surfaces / line cavities and tubes / form glands

What are all the important characteristics of epithelia tissue?

Attachment / avascularity / regeneration / polarity (apical and basal)

What are epithelia tissues consisting of?

Consist of loosely-packed cells supported by a basement membrane

What does the epithelia tissue do?

Covers exposed surfaces, lines internal passageways and chambers, and forms glands

How are epithelia tissues classified?

Based on number of cell layers and shape of the cells in the most superficial layer

Define the word superficial

Existing or occurring on the surface

What does connective tissues do?

Fills internal spaces, provides structural support for other tissues, transport material within the body and stores E

What does nervous tissues do?

Carries info from one part of the body to another in the form of electrical impulses

What is the study if tissues called?

Histology

What does avascularity mean?

Lack blood vessels

Epithelia tissues are avascular, how do they get nutrients?

Diffusion or absorption across exposed or attached epithelial surface

What are the 2 functional regions that make epithelia cells polar?

Apical surface / baso-lateral surface

What is the apical surface?

Where the cell is exposed to an internal or external environment

What is the base-lateral surface?

Include both the base (basal surface) and the sides (lateral surfaces)

What are all the different shapes of epithelia cells?

Squamous (flat) / cuboidal / columnar (rectangle)

What does stratified mean in terms of number of cell layers?

2 or more layers

What are the main types of squamous epithelia cells? (3)

Simple squamous / Keratinised stratified squamous / non keratinised stratified squamous

What are the main types of columnar epithelial cells

Simple columnar / Pseudo-stratified stratified columnar with goblet cells

What are the main types of cuboidal epithelial cells?

Simple cuboidal

What is the structure of simple squamous?

Oval shaped nuclei, one layer of cells

What is the major function of simple squamous?

Exchange of nutrients and gases

What are the locations of simple squamous?

Blood vessels / alveoli

What is the structure of keratinised stratified squamous?

Flat surface cells with oval shaped nuclei / many layer / keratin

Where are keratinised stratified squamous cells located?

Skin

What is the function of keratinised stratified squamous cells?

Protection, barrier (waterproof)

What is the function of non-keratinised stratified squamous cells?

Protection, barrier

Where are non-keratinised stratified squamous cells located at?

Oral cavity, oesophagus

What is the structure of simple cuboidal epithelium?

Square cells with round nuclei, one layer

What are the major functions of simple cuboidal epithelium?

Secretion and absorption

Where are simple cuboidal epithelium located at?

Glands / kidney tubules

What is the structure of simple columnar epithelium?

Tall cells with oval, nasally located nuclei / one layer

What is the major function of simple columnar epithelium?

Absorption / secretion

Where are simple columnar epithelium located?

Gastrointestinal tract

What surface modifications can simple columnar epithelium have?

Microvilli

What are the major functions of pseudo-stratified ciliated columnar epithelium with goblet cells?

Mucociliary escalator

Where are these pseudo-stratified ciliated columnar epithelium with globlet cells located?

Trachea and large respiratory airways

What is the structure of pseudo-stratified ciliated columnar epithelium?

Tall cells, appears stratified as some cells don’t reach free surface, all cells touch basement membrane

What 3 factors that help maintain the physical integrity of an epithelium?

Intercellular connection / Attachment to the basement membrane / epithelial maintenance and repair

What are intercellular junction??

Specialised areas of cell membrane that bind one cell to another

What are the examples of intercellular junction?

Desmosomes / hemidesmosomes / tight junctions / gap junctions

Structure and function of desmosome

Very strong connections between adjacent cells / resist stretching and twisting

Structure and function of hemidesmosomes

Attach cells to the basement membrane / stabilise the position and anchor cell to the underlying tissue

Structure of tight junctions?

Interlocking proteins tightly bind cells together near apical edge

Function of tight junctions

Prevent passage of water and solutes between cells

Structure of gap junction

Cells held together by an interlocking membrane proteins containing a central pore

Function of gap junction

Allows movement of small molecules and ion between cells - found in cardiac muscle

What are fibroblasts?

The main cell type that synthesises the extracellular matrix

What cells does connective tissue consist of?

Fibroblasts / adipocytes / macrophage / mast cells

What does the extracellular matrix consist of?

Ground substance / tissue (extracellular) fluid / fibres; collagen, reticular and elastic

What are the 2 classification of connective tissue?

Specialised connective tissue / connective tissue proper

State 3 specialised connective tissues.

Blood / bone / cartilage

State 3 connective tissue proper.

Loose areolar / dense irregular / dense regular

Where are loose (areolar) connective tissues located?

Founder under epithelium that covers and lines the body surface

What does loose (areolar) connective tissue contain?

Lots of ground substance / few fibre / variety of cells

What variety of cells are in loose (areolar) connective tissue?

Fibroblasts / adipocytes / macrophages (transient)