Epithelium And Glands Flashcards
1
Q
Epithelium
A
- sheets of cells covering a surface of lining a cavity
- responsible for the major function of most organs
2
Q
Connective Tissue
A
- cells and ECM that support and connect other basic tissue types in organs
- include bone and cartilage and blood
3
Q
Muscle
A
-contractile tissues
4
Q
Nervous Tissue
A
-conductive tissues that distribute signals that control various body functions
5
Q
Characteristics of Epithelial
A
- continuous sheets
- rest on basement membrane
- junctions
- polarized
- Surface modifications
- Avascular - no blood vessels in the actual epithelium
6
Q
Epithelium Functions
A
- barrier
- absorption and secretion
- removal of particulate matter
- gas exchange
- filtration
7
Q
Surface Modifications
A
- apical surface:
1) Microvilli - actin cytoskeleton, increase absorptive surface area, found in GI tract there they promote uptake of nutrients
2) Stereocilia - very long Microvilli, actin cytoskeleton, increase absorptive SA, found I epididymis where they promote concentration of sperm, not motile
3) cilia - microtubule cytoskeleton, motile surface extension that move luminal contents, in respiratory tract move particulate matter out of lungs, in female reproductive tract assist in movement of gametes
8
Q
Microvilli
A
- increase apical surface area for absorption and secretion
- actin core provides support to the plasma membrane
- anchored by terminal web
9
Q
Cilia
A
- motile
- found in locations where movement serves function
- respiratory epithelium - cilia keep airway free of particulate matter
10
Q
Basal Surface Specializations
A
- basal unfolding of the plasma membrane
- associated with mitochondria
- high level of transport activity
- find in proximal convoluted tubule in the kidney and striated ducts of salivary glands
11
Q
Classification of Epithelial
A
- based on shape of cells and number of cellular layers
12
Q
Squamous
A
- thin, flattened appearance
13
Q
Cuboidal
A
-height and width are similar
14
Q
Columnar
A
-height greater than width
15
Q
Simple
A
-single layer
16
Q
Stratified
A
-multiple layers
17
Q
Pseudostratified
A
-appears stratified, but all cells touch basement membrane, some do not reach apical surface
18
Q
Transitional
A
-transitional appearance between stratified columnar and stratified squamous and depends on physiological state
19
Q
Simple Squamous
A
- mesothelium found lining the external surface of internal organs
- secrets fluid that reduces friction between organs
- Endothelium found lining the internal surfaces of the heart and blood vessels
- facilitates transport of fluids, nutrients, metabolites, and gas exchange between flood and surrounding tissues
20
Q
Simple Cuboidal
A
- lining of ducts of glands, kidney tubules, thyroid follicles
- taller cells provide additional support
- cells can be active in transport, synthesis and secretion of substances
- Height can depend on activity of the cell and range from low to almost columnar
21
Q
Simple columnar
A
- found lining the digestive tract and uterine tube
- can have more than one type with different functions
- absorptive
- secretory (mucus)
22
Q
Stratified Epithelium
A
- multiple layers of cells, number of layers varies
- basal layer rests o basement membrane, upper layers rest on cells below not on the basement membrane
- uppermost layer at the free surface
- take their name from the uppermost layer, can be squamous, cuboidal or columnar
- basal layer can be one type and the upper layer a different type
- cells in the basal layer may divide to maintain the integrity of the epithelium as upper layers are lost
23
Q
Stratified squamous
A
- thick and thin skin, non-keratinizing wet skin (mouth)
24
Q
Stratified cuboidal
A
-glandular ducts and large salivary excretory duct
25
Stratified Squamos Epithelium
- 2 types: non-keratinizing, keratinizing
- provides barrier and protection against abrasion
- Non-keratinizing is found in moist areas that are subject to abrasion such as oral cavity, esophagus, vagina and anal canal
- keratinizing is found in skin where upper layers lose their nuclei and contain large amounts of keratin
26
Pseudostratified Epithelium
- may appear stratified
- nuclei are at different heights making epithelium appear stratified
- however all cells touch the basement membrane
- some cells are not as tall as others and the apical surface of the cell may not reach the top of the epithelium
- found in respiratory tract and epididymis
27
Transitional Epithelium
- found exclusively in the bladder and adjacent regions of the urinary system
- changes shape depending on the extension of the bladder
- Relaxed: multiple layers, surface layer has rounded dome cells that are often binucleate
- Extended - multiple layers, but doesn't appear as many as relaxed state
28
Glands
- invaginations of sheets of epithelium that grow downward into the underlying connective tissue
- Exocrine: glands that maintain their connection to the surface, secretory products released into the duct and travel to the surface (sweat glands)
- Endocrine: glands that lose their connection to the surface, surrounded by capillaries where secretory products enter the blood (adrenal, thyroid)
29
Exocrine
- unicellular, single cell type (goblet cells in intestines)
- multicellular (most common), Ductal portion, secretory portion
- Classification:
1) Structure of the duct (simple or compound)
2) shape of secretory units ( tubular or actin acinar/alveolar)
3) Type of secretion (serous, mucous or mixed)
4) Mechanism of secretion (apocrine, merocrine, holocrine)
30
Duct Shape
1) Single duct - simple gland
| 2) Branched duct - compound gland
31
Secretory unit shape
- tubular gland
| - acinar gland is sphere-like in shape
32
Large exocrine gland anatomy: Connective tissue divides gland into lobes and lobules
- Parenchyma - functional component of organ
- Stroma - supportive CT component of organ
- Hillum: Doorway for ducts, nerves, and blood and lymph vessels to go to/from gland. These structures course through the CT of trabeculae (septa) to reach parenchyma
33
Mechanisms of secretion
- Apocrine secretion: loss of cytoplasm and apical cell membrane, occurs in mammary gland
- Merocrine secretion: exocytosis of secretory vesicles, occurs in typical glands (salivary)
- Holocrine secretion: entire cell is shed and cell breaks down releasing its substance stored in vesicles, occurs in sebaceous glands
