Histo-epithelial Tissue Flashcards
Functions of epithelial tissue
- Physical protection, 2. permeability,
- secretion,
- sensation
*diverse tissue group
Characteristics of epithelial tissue
Cellularity (having cells; porous) Polarity (allow specialized functions) Attachment Avascular (lack of blood vessels) Innervation Regeneration
How are epithelial cells classified
Cell shape or number
*lots of glands found through out the epithelial
In epithelial polarity, what are the three designated regions that are associated with different structure and functions
- Basal domain
- rests on basal lamina
- anchors cells to underlying connective tissue - Apical Domain
- exterior surface/lumen of enclosed cavity or tube - Lateral domain
- communicates with adjacent cells
- specialized attachment areas
What are apical specializations? What are the four types ?
-specializations dictate the function or purpose of that tissue
- increase surface area for absorption
- move substances along epithelial
- may be external or lumenal
- Cilia
- Flagella
- Microvilli
- Stereocilia
What are microvili
*type of apical specialization
- has actin core
- increase surface area for absorption (20-30x)
- number and shape relate to absorptive capacity
- 1mm long with 100k present on a single cell
What is stereocilia/ stereovilli?
*type of apical specialization
- unusually long microvilli
- immotile
- actin core (= rigidity)
- increase surface area for absorption
- secretion
- only in epididymis and sensory cells of inner ear (hair cells)
*epididymis = sperm carrying tube from testes to ductus deferens
What is cilia?
*apical specialization
- hair - like
- contains axoneme (microtubule )
- basal body core anchors cilia
- 10 mm long, 300+ on one
3 kinds:
- Motile
- Primary - immotile and function as chemosensors, osmosensors, and mechanosensors
- Nodal - embryonic; role in L/R axis determination (asymmetry of heart, viscera, brain)
What is flagella/
*apical specialization
- modified, motile cilia
- provides sperm movement
- 50-100 mico-meters
What is the proximal and distal centriole on sperm ?
In the neck region (head-tail coupling apparatus)
- proximal centriole = attached to nucleus (implantation fossa)
- distal centriole = generates axoneme (microtubule structure for flagella)
What are the 5 types of intercellular junctions
- Occluding junction
- Anchoring junction
- Gap junctions
- Focal adhesions
- Hemidesmosomes
What is an occluding junction ? (Zonula occludens)
*intercellular junction
- impermeable cell barrier
- cover apical surface
- can be occludins or Claudine
**more junctions = less permeability
What is anchoring junctions
*intercellular junction
- link adjacent cells together (connect adjacent cytoskeletons)
- 3 types
1. Zonula adherents - bind with actin filaments in cell
- Macula adherents (desmosomes)
- bind with intermediate filaments - Cadherins
- Z-A …F-A
*M-I ..H-I
-
What are gap junctions
*intercellular junction
- fluid-filled channel
- connect adjacent cells
- mediate communication
- connexin aggegreates
What is focal adhesion?
*intercellular junction n
- anchor actin filaments to basement membrane
- integrins
What is hemidesomosomes ?
*intercellular junction
- anchor intermediate filaments to basement membrane
- integrins
What are the three shapes of epithelia cells
Squamous, cuboidal, columnar
What are the 2 arrangements of epithelial cells
- One layer (simple )
- endothelium
- mesothelium - More than one layer (stratified)
What are simple squamous cells important for
- line blood and lymphatic vessels (endothelium)
- line serous (cavities) membranes (mesothelium)
- line alveoli in lungs, loop of Henle in kidney, and various ducts
- function- exchange, barrier, lubrication
What are simple cuboidal cells important for
- in kidney tubules, glands, terminal bronchioles, covering of ovaries
- FUNCTION : absorption, barrier, secretion
What are simple columnar cells important for?
- auditory tubes, uterus, oviducts, stomach, SI/LI, gallbladder
- FUNCTION: absorption and secretion
- ciliated simple columnar epithelium is found in oviducts to move egg through the ducts
What are pseudostratified columnar ciliated cells important for ?
Function- absorption and secretion, debris and particulate movement
- lining of nasal cavity, pharynx, trachea, and bronchi
- have goblet cells in it to make it look like it is stratified
What are urothelium cells important for ?
- urinary bladddr, ureters, urethra
- FUNCTION: barrier, distensible property
*dome shaped superficial cell
*
What are nonkeratinized stratified squamous cells important for ?
- oral cavity, portions of pharynx, esophagus, anus vagina urethra, cornea
- FUNCTION: barrier and protection
- have nuclei in apical layers *but apical layer usually loses nuclei
