Introduction to histology Flashcards
Why is histology important?
- Provides structural basis for gross anatomy (and many of the life sciences)
- Is essential for understanding function and pathological change
What are the 4 categories of tissues recognised in histology?
- Epithelial tissue
- Connective tissue
- Muscular tissue
- Nervous tissue
What are the main specialised functions epithelial tissue perform?
- Barrier internal/external environment
- Mechanical protection
- Absorption/secretion
What can epithelial tissue be subdivided into?
- Surface epithelium
- Glandular epithelium
How can the specialised functions in epithelium be mediated?
- Structural modifications
- Internal modifications
- Special types of junctional complexes between cells
What is the function of occluding (tight) junctions?
prevent diffusion of molecules between adjacent cells - form a variously permeable permeable barrier
What is the function of anchoring (adhering) junctions?
link cells together and provide mechanical strength
What is the function of communicating (gap) junctions?
allow movement of molecules between cells
What are three criteria to classify surface epithelia?
- number of cell layers (simple or stratified)
- Shape of surface cells (squamous, cuboidal or columnar)
- Surface specialisations (keratin, cilia, microvili)
What do epithelial cells rest?
all epithelial cells rest on the basement membrane
What are the three types of simple epithelium?
- simple squamous epithelium
- simple cuboidal epithelium
- simple columnar epithelium
Where is squamous epithelium suited?
functionally suited to surfaces where mechanical protection is not required e.g. lining of blood vessels - low resistance to flow
Where is simple cuboidal epithelium suited?
functionally suited to surfaces with an absorptive/secretory role e.g secretory cells of exocrine glands
Where is simple columnar epithelium suited?
functionally suited to surfaces with an absorptive role e.g small intestine - large surface area - microvili
What are the 3(4?) types of stratified epithelium?
- Stratified squamous
- Keratinised stratified squamous
- Stratified cuboidal/stratified columnal
Where is stratified squamous/keratinised stratified squamous epithelium suited?
Functionally suited to surfaces where there is varying amount of mechanical protection required e.g oesophagus, foot pad
Where are stratified cuboidal/columnar epithelium suited?
Functionally usually associated with ducts (of glandular epithelium)
What are some examples of special types of surface epithelium?
- transitional epithelium or urothelium
pseudostratified - (ciliated) columnar epithelium (with goblet cells)
Where are transitional epithelium or urothelium suited?
Functionally suited to surfaces which are required to stretch e.g urinary bladder
Where are pseudostratified - (cilliated) columnar epithelium (with goblet cells)
Functionally suited to surfaces involved in cleansing cells (cilia) and moistening e.g goblet cells e.g respiratory system
What are two types of glandular epithelial tissue?
- Goblet cells ( single cells that retain connection with surface epithelial cells)
- Secretory cells embedded in the underlying connective tissue
How to describe glandular epithelium with a duct to the surface?
exocrine gland
How to describe glandular epithelium without a duct?
endocrine
How to describe endocrine glands?
ductless, localised and have highly specialised functions
