Epithelial Tissue Flashcards
Functions of connective tissues
Fills internal spaces, binds organs together, transports materials within the body and stores reserve energy
Functions of muscle tissue
Specialised for contraction; generates the physical force needed to make body move
Functions of neural tissue
- Carries information from one part of the body to another in the form of electrical impulses
- Helps maintain homeostasis
Define epithelial tissue
Line the cavities and surfaces of blood vessels and organs throughout the body
Characteristics of epithelial tissue (5)
- Apex always faces an open space
- Cells are closely packed together
- Cells are polarised
- Base always sits on a basement membrane
- Cells are regenerative
Are epithelial tissues vascular or avascular?
Avascular which means they must get rid of their waste at their apical or basal surfaces by diffusion or absorption
Functions of epithelial tissue (9)
- Forms boundaries
- Secrete
- Filter
- Line and surface
- Microvilli
- Cillia
- Protects
- Absorb
- Line
Expand on ‘forms boundaries’ as a function for epithelial tissue (2)
- Permeable (absorption)
- Impermeable (water, bacteria, toxins)
Expand on ‘secrete’ as a function for epithelial tissue
Milk, mucous, perspiration, digestive enzymes, hormones
Expand on ‘filter’ as a function for epithelial tissue
-Regulation of movement of gases, macromolecules, fluid
Expand on ‘line and surface’ as a function for epithelial tissue
Transcellular transport
Expand on ‘microvilli’ as a function for epithelial tissue
Increases surface area of cells
Expand on ‘cillia’ as a function for epithelial tissue
Substances move across the epithelial surface by synchronised beating of cillia
Expand on ‘protects’ as a function for epithelial tissue
Abrasion, dehydration
Expand on ‘absorb’ as a function for epithelial tissue
Surface area, intestine, respiratory epithelia
Expand on ‘line’ as a function for epithelial tissue
Barrier, transport, respiratory epithelium
2 types of secretion
- Endocrine
- Exocrine
How is endocrine secretion secreted?
+ example
Discharge secretions (hormones) directly into the bloodstream Eg. Pituitary gland
How is exocrine secretion secreted?
+ example
Posses ducts for discharging through their secretions onto the body surface
Eg. Sebaceous glands
3 modes of secretions
- Merocrine
- Apocrine
- Holocrine
Merocrine (+ example)
Expelled by exocytosis
Eg. Enzyme secreting gland
Apocrine (+ example)
Secreted by membrane vesicles
Eg. Mammary gland
Holocrine
Secretory product releases as cells breaks open- entire cell is lost
Eg. Sebaceous gland
What do mucin-secreting cells have to help for secretion?
An expanded Golgi system
What do steroid-secreting cells have to help for secretion?
An extensive SER system
What do ion-pumping cells have to help for secretion?
Lots of mitochondria and a large surface area
Rough ER’s job in secretion
To produce proteins that will be secreted from the cell
2 types of structures involved in secretion
- Tubular secretory
- Alveolar secretory
Why are some epithelial cells may be grouped into glands?
To allow focused production of a secreted product- when much more secretion is required
How does keratin help in keratinisation?
An alpha helical fibrous protein that protects epithelial cells from damage or stress
Function of keratinised stratified squamous epithelia
Keratin is waterproof- acts as a mechanical barrier
