Histology Quiz #1 Flashcards
Simple Epithelium Vs. Stratified epithelium
Simple = one layer of cells
Stratified = Multiple Layers of cells
Where is Simple epithelium found
- Lung Alveoli
- Gland and duct lining
- Germal Epithelium in male and female reproductive organs
- Epidermis of skin
- Taste buds
Function of Simple epithelium
- Passive Diffusion
- Secretion + Absorbption
- Provide protection on sin
- Sensory reception
Simple squamous epithelium
Single layer of thin and flattened cells
- Cells = wide and large irregular shape
Found - heart + blood vessles + Lympatic vessles + Serious memebranes + Air sacs + Bowman’s capsule (Kidney) + Tympanic emebranes
Thin = can allow transfer of material across surface = Function - Diffusion + Filtration + Secretion (Exchange gasses + Nutrients)
Structures in Simple Epethlim
Have specialized structures:
1. Microvilia
2. Cilia
3. Sterocillia
Characteristics of Simple epethlium
- No blood supply (A-vasuclar)
- Attaches to basment membrane
- Have latteral attatchments (Sides of cels are attached)
Apical vs. basal side of Epithelial cells
Apical = Side going towrads the lumen
- Side used for function
Basal = Bottom of cell attached to basement memebrane
Simple Squamous epithelium histology
Things to look for:
1. Nuceo are taller than cell (Becuase cell is thin)
Image -
Left - Endothelium(Simple squamous epithlimum lining Blood vessles, lymphatic vessles, and heart)
Right - Mesothelium (Simple squamous epithelium lining body cavities - secretes lubricating substances)
Simple cuboidal epithelium
Single layer of cube-like cells
- Nucleus = in center
Location - Tubules of kindey + overy + thyroid pancerus + repstory tracts
- Are as tall as they are wide
Function - Protection + absorption + Secretion + Excrete waste
Histology of SImple cuboidal epithelium
Things to notice: Uniform shape + karge spherical nucleus in the center
Simple columnar epithelium
Single layer of tall rectagular epithelial cells (taller than they are wide)
Function - barrier + absorbption + Secretion
Specilization of Simiple columnar epithelium
Specilize in secretion (in reproductive and digestive tracts)
Reproductives - secreted growth hormones and cytokines
Digetsive - Keep out pathogens + facilitate absoption of nutrients
Histology of simple columnar
Things to notice - oval shape nucleus closer to the bottom
ALSO see goblet cells (secrete mucus)
Psudeofied epithelium
Appears to be arranged in layers because nuclei appear at different heights BUT it is only one layer of cells
- IS simple because all cells are attached to the basment memebrane
Location - Respitory tract _ fallopian Tubes
Function - Abroptions or secretion
Psudeofied epithelium histology
Things to look for - Pusdofied epithelial cells = associated with goblet cells
Trachea image = can see the cells are ciliated + have thick basment membrane + near goblet cells
Image 2 - salivary gland
Apical surface of epithlium
Faces environments (face lumen or body cavity)
- Free end of the epithelium
Has 3 specialized sturctures:
1. Microvillia
2. Sterocilli
3. Cilia
Microvilia
Finger-like protrusions supported by actin cytoskelaton
- Found on simple cuboidal + columnar epithelium (because function in nutrient uptake)
Location - small intestoine + Proximal tube in kidney
Function - Increases the surface area of the cell to maximize absorption + secretion + reabsorption
- maximizes function of cell surface
Histology of microvillai
Things to look for: Smaller and narrower than cilia (light pink brush boarder on lumen side)
Small intestine - forms a brush borader
Cilia
Finger-like protrusions that beat in coordinated metachronal waves
- Membrane bound organelle
Location - line respitory tract and follopian tubes
Function -
Trachea = movment of Mucus
Fallopian tubes = movment of ovum
Histology of Trachea
See finger projections lining epithelum
Histology of Steroecillia
Things to look for - can see projections facing into the lumen
Stereocillium
Hairlike protrusion on the surface of sensory cells
- Longer than mcrovilla but similar composition
- Not motile = diffreent from cillia
Location - inner ear + epidermis + vas deferens in male reproductive
Function - Mechanosensors aiding in hearing and balance + increase Surface area to faclitate absprotion in male reproductive
Stratified epithelium
Epithlium with multiple layers (only the bottom is in contact with the basement memebrane)
Function - Extrection + secretion + Absorption
Stratified Squamous epitheliam
2+ layers of flat sheet-like epithliaum
- Has flat nucelus
Function - Protection + prevent wtaer loss + stop pathogen invasion (uses tight junctions)
Non-keratinized and kertinized subtypes
How do you define the shape of stratified epithelium
Defined by the shape of cells on teh apical surfce (NOT close to the basal layer)
- basal layer of squamous could be coiboidal or columnar BUT i is still classified as squamous
Non-keratinized statified squamous
Wet and permeable
Secretions prevent drying out
Mucous + tears
Location - Esophogus + tongue + pharnyx + vagina + Cornea
Keratinized
Cells are filled with keratin and dead - has a lyer of dead cells full of keratin = proetcts against abration on the skin
Dry and impermeable
Protects skin from abrasions
Location - Epidermis + parts of mouth
Histology of Startified squamous
Espophogues (non-keratinized) - cels near the lumen are flat and sheet like BUT in multiple layers
Epidermis (keratiziized) - Thicker layer on top = dead cells filled with keratin
Stratified cuboidal
2 or ore layers of cube like epithelia + has a round nucelus in the middle
Function - Protects and strength walls of glands and ducts (fond in salivary glands and sweat glands)
Histology of stratifed cuboidal
Things to look for - see multiple layers of cube cells with round purple nucelus
Esaphagas - have 2 layers of cube cells with round nuceli
Stratified columnar
Layers of stacked epiltheial cells that appear like columns
- More rare form of stratified epithelial
Function - protective + mucus secretion (Ex. lubricate eye)
Histology of Stratified columnar
Salivary gland - in top area = statified columnar
- At the bottom see psuedostartified columnar at the bottom (less compact)
Transitional Epithelial Cells
Cells that change shape and become flattened when stretched
- Changes shape based on expanding and contracting
Top most cells = umbrella cells (covers the layers of cell beneath them)
Location - Bladder
Function - Allows organs to expad and contract by changing shape
Histology of Transitional Epithelial Cells
Relaxed cells = more circular
Contracted = cells are more elongated (lose distict shape)
Types of Junctions
- Tight junctions
- Anchroing Junctions
- Gap Junctions
Tight Junctions
Joins the plasma membrane of adjacent cells
- Can be selective about what can get through the junction (uses specialized transport proteins to only take what they want
Function - forms a barrier to prevent diffusiion + seals off intracellular space
Proteins at junctions - Claudin and occulin proteins
Location - In tissue where need selective permeability - Between cells in GI + between endothelial cells
Celiac and IBD
Result from tight junctions abnormalitiesn –> because increase permability = things get in
Tight Junction Histology
See web of tight junctions at base see based on microvillia)
Anchoring Junctions
Attaches cells to each other and to ECM
Function - resists mechanical stress + prevents cells from pulling apart
Location - In tissues subject to mechanical stress (Ex. Muscle = epidermis)