Chapter 1: Epithelium Flashcards
What are the 3 general functions of Epithelium
- Absorption
- Secretion
- Provide a barrier
What are the 3 specialized functions of Epithelium
- Transport molecules across Epithelium
- Prevent transport of materials across Epithelium (selective permeability)
- Sensory (taste buds, retina in eye…)
What are some basic characteristics many types of Epithelium share
Cells are adjacent to each other (helps them provide a barrier)
Associated with a complete or partial basement membrane.
Epithelium is avascular (cells obtain nutrition by diffusion)
Associated with vascular connective tissue)
Cells are help together by cell junctions)
What are the 2 parts of a complete basement membrane
Basal lamina (produced by the Epithelial cells) Reticular lamina (produced by fibroblasts in connective tissue that is going to be near by)
What is the 1 part of a partial basement membrane
Basal lamina (produced by the Epithelial cells)
What are the 3 functions of a basement membrane
- Provides a surface for Epithelial cell attachment
- Molecular filter => limited
- Limited stretch => protective funtion
What are the 2 functions of Connective Tissue (CT)
- Provides nutrition
2. Source of defensive cells
What are the 4 types of Cell junctions (these are important)
- Zonula Occuldens (tight junctions)
- Zonula Adherens (adhesion junctions)
- Macula Adherens
- Gap Junctions
What are the functions of Zonula Occuldens
These junctions involve the sharing of intrinsic membrane proteins BETWEEN adjacent cells.
- Provides strong attachment
- Prevents the passage of materials between cells
What are the regions and functions of Zonula Adherens
Regions:
1. Cadherins (linkage proteins) between cells
2. Marginal bands (microfilaments) which attach the cytoskeleton to the cell membrane at these areas
Functions:
1. Strong attachment
2. Provide cell structural stability
What are the functions of Macula Adherens (desomosomes)
Provides strong attachment
What is a gap junction and its functions
Six connexins (proteins) arranged in a cylinder. The size of the openings can be controlled by the cells. A connexon= 1 complete structure.
Functions:
1. Strong attachments
2. Communication and exchange of materials
What is a Junctional Complex and what does it consist of
3 junctions in the following order beginning with the free cell surface:
- Zonula Occuldens
- Zonula Adherens (adhesion belt)
- Macula Adherens
What is the purpose of Hemidesmosomes
Help to connect Epithelial cells to the basal lamina (basement membrane)
What are Focal Point Contacts
Integrin (a transmembrane proteins of the cell membrane) binds to structural CT glycoproteins and also connect to cytoskeleton
What is Bullous Phephigoid
An autoimmune skin disease causing large blistering lesion that burst, but do heal
What is Pemphigus Vulgaris
An autoimmune skin disease causing skin blistering that do not heal easily, excessive bleeding likely and can be fatal
What are the 5 types of Simple Epithelium (epithelium that is a single cell thick)
- Simple Squamous
- Simple Cuboidal
- Simple Columnar
- Ciliated Pseudostratified Columnar Epithelium
- Surface Specializations
What are the details and functions of Simple Squamous cells
Cells should look flat (ex. lung, serosa on the outside of organs) A single later of flattened cells Functions: 1. Provide a barrier 2. Living filter
What are the details and functions of Simple Cuboidal Epithelium
A single layer of cube shaped cells (ex. exocrine ducts, thyroid follicular cells, kidney tubules) Functions: 1. Provides a barrier 2. Secretion 3. Absorption
What are the details and functions of Simple Columnar Epithelium
A single later of cells that have height, more cell cytoplasm than cuboidal, rectangular looking (ex. stomach, small intestines, gallbladder) Functions: 1. Provide barrier 2. Secretion 3. Absorption
What are the details and functions of Ciliated Pseudostratified Columnar Epithelium (respiratory epithelium)
This epithelium have 3 cell types of various heights so it can have the appearance of a stratified epithelium (ex. trachea, respiratory region of nasal cavity, bronchi) 3 cell types: 1. Goblet Cells 2. Ciliated Columnar Cells 3. Basal cells
What is the details and functions of a Goblet cell found in a Ciliated Pseudostratified cell
Modified columnar cell
Function:
To produce mucus
What is the details and functions of a Ciliated Columnar cell found in a Ciliated Pseudostratified cell
Columnar cells that contain CILIA (cilia are anchored in the apex of the cell by basal bodies)
Function:
To move mucus over the surface
What is the details and functions of a Basal cell found in a Ciliated Pseudostratified cell
Short pyramidal shaped cell that does not reach the surface
Function:
To be the stem cell for this type of Epithelium
What are the 4 different Surface Specializations types
- Microvilli
- Stereocilia
- Cilia
- Glycocalyx
What is a microvilli and its functions
Finger-like projections at the apical surface on some epithelial cells (also called brush boarder on a striated boarder)
Functions:
To increase surface area so as to increase absorption (ex. kidney tubule cells, small intestines)