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23 Cards in this Set

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  • Back
Tissue
an aggregate of cells and intercellular substances specialized to perform a particular function
Basic Tissues
connective
muscle
nervous
epithelium

organs consist of various arrangements of four basic tissues
Epithelium
a group of closely apposing cells of similar morphology with very little intercellular space having one free(apical) and another attached (basal) surface
-subdivisions:
surface epithelium:sheets of aggregated cells of similar type that cover/line all external and internal surface of the body
glands (epitheloid): secretory cells of endocrine and exocrine glands, proliferation of surface epithelium into underlying connective tissue
epithelial characteristics
-basal and apical surface
-little intercellular substances
-derived from all 3 embryonic tissues
-polar
-contacts basement membrane
-acascular
-mitosis
Table 2.2
Functions
Protection
Absorption
Secretion
Excretion
Selective Permeability/barrier
Basement Membrane
-present wherever any tissue comes in contact with connective tissue
-acts like glue
layers of basement membrane
lamina lucida:
electron micrograph is light layer(low density), hemidesmososmes, anchoring filaments
basal lamina/lamina densa/lamina basalis:
collagen, don't make dark filaments
sub-basal lamina:
reticular fibers (produced by fibroblasts), connects lamina densa to subepithelial connective tissue

first two produced by epithelium
Functions: Ultrafiltration and selective barrier
Classification
based on number of cell layers
- Based on number of cell layers:
- Simple (one layer of cells)
- Stratified (2 or more layers of cells)
- Pseudostratified (appears to have more than one layer)
based on shape of surface cells
- Squamous
- Cuboidal
- Columnar

In real life you will encounter forms in the middle
simple squamous epithelium
- Single layer of thin flat cells with spherical,oval, flattened nucleus
- Scale-like cells with serrated borders (in surface view)
-location:
blood vessels, alveoli, pleura, peritoneum (want it where materials can need to pass through quickly)
fxns:
diffusion
simple cuboidal epithelium
- Single layer of hexagonal cells with equal height and width
- Appears square in cross section
- Low and tall cuboidal epithelia
-location: ducts where secretion takes place, collecting ducts of the kidney
-fxns: where material passes with little processing
Simple columnar epithelium
- Tall & narrow cells
- Oval and basally located nuclei
-location:
intestines, where absorption/secretion occurs, gallbladder, bulbourethral gland
fxns:
perform processing of material
Pseudostratified epithelium
- Single layer of cells but appears multi-layered, nuclei at
different levels, all cells rest on basement membrane
- Cell types:
- Basal cells
- Ciliated cells
- Non-ciliated cells
- Goblet cells
-location:
lining of bronchioles, trachea, uterus, nasal cavity
-fxns:
present where you need rapid turnover of cells
Stratified squamous epithelium
-surface cells are squamous
2 types:
- Stratified Squamous Keratinized Epithelium: surface cells lose nuclei, filled with keratin (a water resistant
protein) so forms protective barrier
- Stratified Squamous Non-keratinized Epithelium: surface cells retain nuclei
-location:
skin
3 layers=non-keratinized
4-5=keratinized
layers BSGLC
Stratum:
Basale
Spinosum
Granulosum
Lucidum
Corneum
basale
deepest layer w/ mitotically dividing cells (cuboidal to columnar)
Spinosum
- Polyhedral cells forming varying number of layers; contain numerous desmosomes; “spiny processes” contain intermediate filaments, for strength
Granulosum
ABSENT in non-keratinized and hard keratin tissues
contain keratohyalin and lamellar granules
Lucidum
ABSENT in hairy skin
translucent appearance due to eleidin protein
Corneum or station superfiale(in non-keratinized)
contain keratinized cells w/ no/pyknotic nuclei or organelles
stratified cuboidal epithelium
- Two or more layers of cells
- Surface layer is typical cuboidal
- Mostly occur as 2-layered epithelium
-location:
excretory ducts of glands
stratified columnar epithelium
- Several layers of cells
- Surface layer is columnar (often prismatic)
- Deeper cells are small & polyhedral
-location:
urethre, mandibular ducts, parotid ducts
transitional epithelium
- Pseudostratified type of epithelium
- Wide variety of appearances
- Basement membrane: thin & folded
-location:
lines hollow organs w/ considerable capacity for distension, urinary system
-shape of cells depends on stretching