Epithelia Tissue Flashcards
1
Q
- Groups of cells that are similar in structure and perform a common or related function
- Four major types:
- Epithelial (Covering & secretion)
- Connective (Support)
- Muscle (Movement)
- Nervous (Control)
A
Tissue
2
Q
- gets its name from a term that means laid on, or covering.
- most form a sheet of cells that covers a body surface or lines a body cavity.
- Form boundaries between different environments
- control permeability because any substance entering or leaving the body must cross an ____, and therefore is subject to regulation and selection by the plasma membranes of all the cells comprising the ____.
- For example, the epidermis of the skin lies between the inside and the outside of the body
- are characterized by having a large supply of sensory receptors and nerves.
- Examples include absorption of nutrients by the lining the digestive tract, filtration of blood by the kidneys, and exchange of oxygen and carbon dioxide by the lungs.
- Surface ____ provide us with information such as touch, pressure, temperature and pain. Similarly, our internal ____ can also send signals regarding the status of our internal organs
- Two forms: Covering & Lining, & Glandular
- Special characteristics include: Polarity, Attachment, Avascularity, and Regeneration.
- Functions include: (1) Protection, (2) absorption, (3) Filtaration, (4) Excretion, (5) Secretion, (6) Sensory Reception
A
Epithelial Tissue Or Epithelium
3
Q
- Forms the outer layer of the skin; dips into and lines the open cavities of the urogenital, digestive, and respiratory systems
- Covers the walls and organs of the closed ventral body cavity
A
Covering and lining Epithelium
4
Q
- Fashions the glands of the body
- The cells comprising ___ ___produce a variety of secretory products
- Produce a variety of secretory products:
Sweat
Oil
Ear wax
Hormones
Thyroid hormones
Sex hormones
Insulin
Adrenalin
A
Glandular epithelium
5
Q
- means that there are two different and opposite sides of an object
- Apical and Basal (or basolateral) surface
A
Polarity
6
Q
- Upper or free surface exposed to the body exterior or the cavity of an internal organ
- Faces into a body cavity
- Lines the internal lumen (passage way) of an organ
- Although this surface is smooth and thick, most have microvilli (Finger-like extensions of the plasma membrane). Microvilli increase the exposed surface area.
- Some epithelia have motile cilia (tiny hair like projections) that propel substances along their free surface
A
Apical surface
7
Q
- The opposite lower or attached surface of the cell
- This surface is attached to underlying epithelial cells or to a basement membrane
A
Basal surface
8
Q
- Adjacent to the basal surface of an epithelium is a think supporting sheet called _____
- Noncellular, adhesive sheet that consists largely of glycoproteins secrets by the epithelial cells plus some fine collagen fibers.
- Acts a selective filter that determines which colecules diffusing from the undering CT are allowed to enter the epithelium
- Acts as a scaffolding along which epithelial cells can mirgrate to repair a wound
- The epithelial cells secrete the __ __ which functions to help strengthen the sheet of cells as well as aiding specificity by acting as a selective filter.
A
Basal lamina
9
Q
The Apical surface of the cell faces the exterior of the body, lines body cavities, or lines the internal cavity or ___ of hollow organs and blood vessels.
HOLLOW
A
Lumen
10
Q
Specialized contacts between cells
A
Cell juntions
11
Q
- adhesion belt inter
- locks adjacent cells forming a barrier. Intestinal cells.
- are found on the lateral borders of adjacent cells close to the apical surface.
- A good example of an epithelium whose cells are held together by this junction would be of that lining the digestive tract. Nutrients of the correct size and type must enter through transporters on the apical plasma membrane, whereas unwanted materials are prevented from gaining access to the body because adjacent cells are held together so tightly.
- Another role of ___ ____ is to prevent apical membrane proteins such as transporters, receptors, or channels from diffusing into the basal lateral regions of the plasma membrane
A
Tight Junctions
12
Q
- cell adhesion molecules, filaments and cytoskeleton make the tissue able to withstand twisting, stretching, and compression.
- Skin cells.
- are subject to stretching, compression and twisting.
- The space between the lateral plasma membranes of two adjoined cells is filled with cell adhesion molecules which act like mortar between bricks. A tough plaque is found on the cytoplasmic side of the plasma membranes in which are embedded intermediate filaments of the cytoskeleton (seen in purple in b of the diagram). The intermediate filaments traverse the width of the cell and attach to the plasma membrane on the opposite side forming a network of “guy wires” between the cells. The intercellular space filled with adhesion molecules is also reinforced by linker proteins that lock together like the teeth on a zipper (shown in blue in diagram b).
A
Desmosomes
13
Q
- connexons form channels between cells for the rapid and coordinated passage of small molecules and ions.
- Cardiac muscle, smooth muscle.
- Adjacent plasma membranes are very close and are connected by hollow cylinders made up of transmembrane proteins called connexons. The connexons form channels between the two adjacent cells which allow for selective passage of ions, simple sugars, amino acids and other small molecules.
- are not typically found in epithelia, but are present in excitable tissues such as cardiac muscle in the heart, and smooth muscle in the walls of hollow organs where they help to synchronize the flow of ions used for electrical signals.
A
Gap Junctions
14
Q
- Deep to the basal lamina is another non-living, proteinaceous layer called the __ ___.
- also a layer of extracellular material which contains fine interwoven collagen fibers produced by the underlying connective tissue
A
reticular lamina
15
Q
The epithelial cells attach to the basal lamina by junctions called___
A
hemidesmosomes
16
Q
Basal lamina and reticular lamina form the ___ ____, which reinforces the epithelial sheet, helps it resist stretching and tearing, and defines the epithelial boundary,
A
Basement membrane
17
Q
- Meaning it contains no blood vessels
- helps keep potentially dangerous environmental entities from gaining access to the blood stream.
A
avascular
18
Q
Means that it is supplied by nerve fibers
A
innervated
24
Q
- Consists of a single layer of flattened cells. It is a very thin epithelium and therefore is found where diffusion or filtration of materials must occur.
- For example, exchange of oxygen and carbon dioxide between the lungs and blood stream occurs across the ___ ___ epithelium that lines the air sacs or alveoli. In the part of the kidney where blood is filtered, materials pass across a ___ ___ filtration membrane.
- There are two __ ___ epithelia that have special names because of their location in the body.
- Two ___ __ epithelia in the body have special names that reflect their location: endothelium and mesothelium
A
Simple Squamous Epithelium
27
Q
- Single layer of cubelike cells with large, spherical central nuclei
- Secretes and absorbs
- location: Kidney tubules; ducts and secretory portions of small glands; ovary surface
A
simple cuboidal epithelium
28
Q
- Single layer of tall cells with round to oval nucleil some cells bear cillia; layer may contain mucus-secreting unicellula glands (goblet cells)
- Function: absorption; secretion of muscus, enzymes, and other substances; ciliated type propels mucus (or reporductive cells) by ciliary action.
- dense microvilli on the apical surface of absorptive cells
- tubular glands made primarily of cells that secrete muscus-containing intestinal juice
- Location: nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts or some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.
A
simple columnar epithelium
29
Q
- looks like it is layered but it is not.
- ____ means false, so it is falsely stratified.
- As it turns out, the cells that comprise this epithelium vary in height. Not all of the cells are tall enough to reach the free surface. Because of this, their nuclei look layered as well. This gives the epithelium a stratified appearance, however all of the cells attach to the basement membrane. Therefore, ___ epithelia are technically a simple epithelium.
- can have modifications based on their location.
- mucous secreting goblet cells.
- The good news is that this type of epithelium is confined to the respiratory passageways and so it is simply referred to as “respiratory epithelium”. The non-ciliated variety is found in some ducts especially within the male reproductive system.
- propulsion of mucus by ciliary action
A
pseudostratified columnar epithelium
30
Q
- are found in regions of the body that are subject to friction or abrasion.
- Keratinized & non-keratinized
- Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened; in the kerantinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers
A
stratified squamous epithelium
33
Q
- is found lining urinary passageways and the bladder.
- It has the ability to change the shape of the epithelial cells and the apparent number of cell layers depending on whether it is stretched or contracted. Think of the bladder. As the bladder fills with urine it must expand to accommodate the increasing volume. However, the epithelial cells must stay tightly connected to each other or urine would seep into the underlying connective tissue. It turns out, that the apical membrane of the epithelial cells is folded, and can stretch like an accordion. Furthermore, as the cells slide, the epithelium thins from about a dozen layers to about six. So, both the shape of the cells and the number of cell layers change as the bladder fills or empties. Technically, the ___ ___ is stratified.
- resembles both stratified squamous and stratified cudboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch
- Function: stretched readilu, permits stored urine to distend urinary organ.
- Location: Lines the ureters, bladder, and part of the urethra.
A
Transitional epithelium
