Histology ๐ฉโ๐ฌ Flashcards
Outline simple columnar epithelia
Taller than wide
Oval nucleus with longer parts adjacent to the longer sides of the cell
Often either have cilia (resp tract) or microvilli (gut erythrocytes)
Outline intestinal epithelium
Enterocytes interspersed with goblet cells
More goblet cells in large intestine than small intestine
Brush border of microvilli
Microvilli- what, why, make up, where
Projections from columnar cells
Canโt see them individually but seen as a brush border
Increased SA for absorption
Glycocalyx on outer surface
Found on most epithelial cells esp. on absorptive ones e.g in gut + kidney
Contain actin and myosin filaments
Ciliated epithelium- where, how many per cell and what does it do
- Lines nose, larynx +bronchial tree w goblet cells
- 300ish cilia per cell, help move mucus to the throat after it has trapped inhaled particles
- Also found in the fallopian tube to transport the ovum
Outline cuboidal epithelium
- Square in profile with a round nucleus
- Rarely over 2 layers of cells
- Occur in the ducts of glands e.g sweat and salivary and the pancreas
- Form much of nephron in the kidney
Outline squamous epithelia
- Single layer
- Surrounds most thor +abd organs (aka serosa)
- Also lines pleural and peritoneal cavities
- Flattened cells
- Kept moist by watery (serous) extrudate -> lubes it so organs can slide over each other
- If destroyed organs can stick together forming adhesions
Outline compound (stratified) epithelia
- Multi layered
- Found in wear and tear situations
- Most common is stratified squamous
- Keratinised form forms epidermal layer of skin
- Cells replaced from stem cells in basal layer of tissue
- Cells discarded when they reach the top layer
Outline the layers of keratinising stratified squamous epithelium
- Lower layers similar to moist stratified
- Upper layers synthesise proteins which interacts with cytoskeleton to produce keratin
- Once filled with keratin the upper layers die off
Outline Pseudo-stratified epithelium
- Appears stratified but is more like simple epithelium
- Appears multi-layered but is actually single layered when stretched
- Lines trachea + bronchi allowing for expansion in inspiration (also in urothelium)
Outline cell junctions
- Cells have to be tightly joined together to act as barriers so macromolecules +/or fluids canโt go past
- 3 typed of cell-cell contact: Desmosomes, tight (adherent) junctions and gap junctions
Outline epithelia
- One or more sheet of cells resting on basement membrane
- For protection, absorption and secretion
- Simple - single layer
- Stratified - 2 or more layers
How does cilia move?
Using tubulin and dynein
What is basement membrane mostly made up of?
Type 4 collagen
What do desmosomes do?
Bind cells to eachother
What do hemidesmosomes do?
Bind cells to the basement membrane
What are the 3 types of cell junctions?
Occluding junctions
Anchoring junctions
Communicating junctions
Outline occluding junctions
- Links cells to form impermeable barrier
- In secretory or absorpatory tissue
Outline the scaffolding of tissues
- Most tissues have scaffolding of extracellular fibres set in a jelly like matrix
- Governs functional organisation of the tissue and dictates the shape of organs
Outline the main fibres of the extracellular scaffolding of tissues
- Main fibres collagen and elastin
Used because of: - High molecular weight
- Strongly hydrophilic and negatively charged polysaccharide polymers
-> Retain water to help with turgor pressure
What are glycosaminoglycans?
Jelly like complexes
What synthesises glycosaminoglycans?
Can be synthesised by many different cells incl. epithelial, muscle, cartilage and bone
But mainly by fibroblasts which can synthesise many different extracellular constituents depending on the environment and mode of stimulation
What can undifferentiated mesenchymal cells become?
Osteoblasts (bone)
Chondroblast (cartilage)
Fibroblast (connective tissue)
Outline soft connective tissue
Flexible and gel-like
Present in most tissues between major tissue elements
Divisible into fibrous or fatty connective tissue
Outline hard connective tissue
Various forms of cartilage and bone