HISTOLOGY - Overview Flashcards
What is the main type of staining used for histological samples?
Hematoxylin and eosin (H&E)
List the four layers of tissue that are identified in histological samples
Epithelial tissue
Connective tissue
Muscular tissue
Nervous tissue
What are the functions of epithelium?
Forms a barrier between the internal and external environments
Mechanical protection
Absorption and secretion
What is the function of junctional complexes between adjacent epithelial cells?
To determine what can or can’t pass through the adjacent epithelial cells
Describe the function of occluding (tight) junctions
Prevent the diffusion of molecules between the adjacent epithelial cells
Describe the function of anchoring (adhering) junctions
Adhere adjacent epithelial cells together to provide mechanical strength
Give two examples of anchoring (adhering) junctions
Demosomes
Hemi-demosomes
Describe the function of communicating (gap) junctions
Allow direct movement of molecules between adjacent cells
List and describe the different types of epithelial cell layers
Simple: one epithelial cell layer
Stratified: more than one epithelial cell layer
List the different shapes of epithelial cells
Squamous
Cuboidal
Columnar
Which surfaces are squamous epithelial cells functionally suited to?
Squamous epithelial cells are functionally suited to surfaces where mechanical protection isn’t required
Why is simple squamous epithelium functionally suited to lining blood vessels?
Simple squamous epithelium is smooth and thus creates low resistance to blood flow
Which surfaces are cuboidal epithelial cells functionally suited to?
Cuboidal epithelial cells are functionally suited to surfaces with an absorptive/secretory role
Which surfaces are columnar epithelial cells functionally suited to?
Columnar epithelial cells are functionally suited to surfaces with an absorptive role
List the different epithelial surface specialisations
Keratin
Cilia
Microvilli
Which surfaces are stratified squamous and keratinised squamous epithelial cells functionally suited to?
Stratified squamous and keratinised squamous epithelial cells are functionally suited to surfaces that require a high degree of mechanical protection
Which surfaces are stratified cuboidal/columnar epithelial cells functionally suited to?
Stratified cuboidal/columnar epithelial cells are functionally associated with the ducts of exocrine glandular epithelium
Where in the body is transitional epithelium/urothelium located?
The urinary system
Which surfaces are transitional epithelium/urothelium cells functionally suited to?
Transitional epithelium/urothelium cells are functionally suites to surfaces that are required to stretch
Describe pseudostratified epithelium
Stratified epithelial cells with no distinct layer as the cells are still in contact with the epithelial membrane
Give an example of singular secretory cells associated with the surface epithelium
Goblet cells
What are the two types of secretory cell groups embedded in the underlying connective tissue of the epithelium?
Exocrine glands
Endocrine glands
What are the main functional differences between the exocrine and endocrine glands?
- Exocrine glands secrete mucus or serous secretions onto the surface of the epithelium via ducts
- Endocrine glands secrete hormones directly into the bloodstream
What are the histological differences between the exocrine serous and mucus secretions?
Mucus: stains pale
Serous: stains dark
List the three different types of connective tissue
Loose connective tissue
Dense connective tissue (regular or irregular)
Adipose tissue
List the main components of connective tissue
Ground substance
Protein fibres
Resident cells
Transient cells
List the different protein fibres that can be found in connective tissue
Elastin fibres
Collagen fibres
Reticular fibres
List the different resident cell types that can be found in connective tissue
Fibroblasts
Firbocytes
Adipocytes
Macrophages
Mesenchymal stem cells
What is the function of fibroblast cells found in the connective tissue?
The production of protein fibres and ground substance
List the different transient cells types that can be found in the connective tissue
Plasma B-lymphocytes
Eosinophils
Neutrophils
Lymphocytes
What is the main structural difference between loose and dense connective tissue?
- Loose connective tissue has more cells than protein fibres
- Dense connective tissue has more fibres than cells
What is the main structural difference between regular and irregular dense connective tissue?
- The protein fibres of regular dense connective tissue are arranged in an alignment
- The protein fibres of irregular dense connective tissue are arranged randomly
What is the main cell type found in adipose tissue?
Adipocytes
What are the different functions of white fat and brown fat?
White fat: energy storage
Brown fat: heat production
List the different muscle types
Skeletal muscle
Smooth muscle
Cardiac muscle
Describe the appearance of skeletal muscle on a longitudinal histological sample
Striated
Peripheral nuclei
Multinucleated fibres
Long fibres
Very little connective tissue between the fibres
Describe the appearance of skeletal muscle on a transverse histological sample
Peripheral nuclei
Multinucleated fibres
Very little connective tissue between the fibres
Myofibrils present in the cytoplasm
Describe the appearance of cardiac muscle on a longitudinal histological sample
Striated
Central nucleus
Short, branched fibres
Lots of connective tissue between the fibres
Intercalated discs
Describe the appearance of cardiac muscle on a transverse histological sample
Central nucleus
Lots of connective tissue between the fibres
Describe the appearance of smooth muscle on a longitudinal histological sample
Non-striated
Central nucleus
Short spindle shaped fibres
Limited connective tissue between the fibres
Describe the appearance of smooth muscle on a transverse histological sample
Only a few fibres with a central nucleus due to the spindle shape of the fibres
