Tissues
I. Four Tissue Types
A. Epithelial
B. Connective
C. Muscle
D. Neural
II. Cell Attachments
A. Glycocalyx/ Cell Adhesion Molecules
B. Cell Junctions (primarily proteins)
1. Tight Junctions
2. Gap Junctions
3. Desmosomes
III. Epithelial Tissue
A. Characteristics
1. Tightly bound cells
2. One side faces the world or the interior of a
tube
3. Attached to a basement membrane (basal lamina)
4. High rates of cell replacement and stem cell
division
5. Avascular
B. Functions
C. Specializations
D. Classification- Layering of cells: Shape of cells:
simple vs. stratified vs. pseudostratified; squamous,
cuboidal, columnar
[Extra Figures from other chapters in the book (Martini)
5-9a: sweat glands, stratified cuboidal-the big "empty"
areas are ducts, lined by epithelial cells. At certain
points, you can see the 2 nuclei of the separate cells
stacked upon each other.
18-10c: thyroid follicles, simple cuboidal- these are not
ducts, but big "bubbles" where thyroid hormones are stored.
Thyroid hormones are produced by the epithelial cells
lining the interior of the follicles. You don't need to
know anything about thyroid gland/hormones until chapter
18, but it's a good example of simple cuboidal.
19-2b: capillary with red blood cells, simple squamous- the
labels point out the flattened nuclei of the cells lining
the capillary. The cells, too, are flat, which is
characteristic of squamous cells. Simple squamous line
surfaces where exchange/passage of substances takes place.
For instance, the respiratory surfaces of lungs (alveoli)
are also lined by simple squamous (there are also pictures
in the respiration chapter, but not quite as clear).
23-2b: trachea, psuedostratified columnar (ciliated)- the
tracheal epithelium also includes lots of goblet cells,
which secrete mucous onto the surface. The bulk of goblet
cells is taken up by huge vesicles filled with mucin
(proteoglycan)/mucous (mucin + water). In the trachea,
goblet cells secret mucous onto the surface, and the
ciliated cells sweep the mucous and trapped debris upward
to the pharynx.
24-7b: submandibular salivary gland, stratified columnar- I
think the picture from chapter 4 is better for this (also a
salivary gland). The only area in which shape can be
somewhat made out is lining the duct.
24-17e: small intestine and 24-24: large intestine, simple
columnar- If you compare these with the psuedostratified
and stratified, the nuclei tend to be lined up a little
more, although you can still see nuclei of underlying
cells, and the nuclei of goblet cells tend to be squished
toward the bottom, giving it a somewhat stratified
appearance. Still, if you look at the proportion of "single
file" cells, they are a bit higher in simple columnar.
26-8 a: renal corpuscle (filtering area of kidneys)- you
can see 2 different epithelia here. The parietal and
visceral epithelium are both simple squamous, although you
can't really tell with the visceral epithelium because it's
wrapped around large structures. The parietal epithelial
cells are so thin they're hard to make out. The purple band
behind the parietal epithelium is connective tissue.
The distal and proximal convoluted tubules are both lined
with simple cuboidal epithelium. The proximal convoluted
tubule is also lined with microvilli, which I think you can
make out a bit; the surface looks a bit fuzzier and darker
than the surface of the distal tubule. In any event, you
won't need to be able to identify microvilli on a slide at
this point (cilia, yes.).]
E. Glands- individual cells or groups of cells that
produce and release secretions (mucous, enzymes,
hormones, etc.)
1. Endocrine glands- produce hormones which enter
the bloodstream. No ducts to deliver their
products.
2. Exocrine glands- produce a variety of
substances including lubricant & enzymes. Release
their products through ducts onto epithelium of
nearby tissues/organs.
a. How exocrine glands release products
i) Merocrine
ii) Apocrine
iii) Holocrine
b. Secretion Types
i) Serous
ii) Mucous
ii) Mixed
c. Gland structure- For gland structure, you
will not need to name/identify specific
types of gland structures. Know the "3
characteristics used to describe structure":
tubular vs. alveolar, simple vs. compound,
and unbranched vs. branched.
IV. Connective tissue
A. General Info
1. Specialized cells
2. Matrix: extracellular protein fibers and
ground substance (glycoproteins & proteoglycans
suspended in water)
3. Usually vascular to varying degrees
4. Functions
B. Overview of types
1. Connective tissue proper-loose & dense
2. Fluid- blood & lymph
3. Supportive- cartilage & bone
C. Fibers & Cells of Connective tissue
1. Protein fibers
a. Collagen
b. Elastin
c. Reticular fibers- made of collagen
subunits, arranged differently than collagen
fibers.
2. Cells
a. Specialized cells of the specific
connective tissue- secrete the matrix of
the connective tissue (blood and lymph are
exceptions).
i. Connective tissue proper: fibroblasts
ii. Bone: osteoprogenitors,
osteoblasts, osteocytes
iii. Cartilage: fibroblasts,
chondrocytes
iv. Blood: erythrocytes, leukocytes
v. Lymph: leukocytes (esp. lymphocytes)
b. Cells of the immune system, includes mast
cells, macrophages, leukocytes,
lymphocytes.
c. Other cells, depending on the tissue
type: ex. mesenchymal (stem cells that
replace damaged cells), melanocytes (pigment
cells), adipocytes (these are all found in
connective tissue proper).
3. Ground substance- proteoglycans &
glycoproteins in water. Ratio of ground
substance: cells: proteins varies by tissue type.
D. Connective tissue proper
1. Loose
a. Areolar
b. Adipose
c. Reticular
2. Dense
a. Regular
b. Irregular
E. Fluid Connective tissues
1. Blood
2. Lymph
F. Supporting Connective tissues
1. Cartilage
a. Avascular
b. Surrounded by perichondrium
c. Chondrocytes in lacunae
d. Growth: division of chondrocytes within
cartilage or division of fibroblasts lining
perichondrium.
e. Matrix: collagen, elastin, and lots of
glycosaminoglycans (proteoglycans):
hyaluronic acid and chondroitin sulfates.
Water interacts with molecules of the
matrix, adding to the resilient properties
of cartilage.
f. Types: hyaline, elastic, and
fibrocartilage
2. Bone/osseous tissue
a. very little ground substance
b. lots of collagen laid upon by calcium
salts
c. vascular; osteocytes and blood vessels in
"tunnels" called canaliculi
G. Membranes- coverings and separations that consist
of contributions from both connective and eithelial
tissue.
1. Mucous membranes/mucosae- not named for the
secretion of mucous, although many mucosae do
secrete mucous (but not all). Line tubes that
lead to the outside (digestive, urinary);
epithelia underlain by areolar tissue, which is
called the lamina propria; moist- either by
mucous or fluid in the tube (ex. urine)
2. Serous- line the subdivisions & organs of the
ventral body cavity. Serous membranes are folded,
double membranes. The inner fold lines an
organ/organs ("visceral"), the outer fold
separates the cavity from other cavities
("parietal"). Serous fluid, secreted by
epithelial cells, fills the space between the
folds. The ventral body cavity includes the
following subdivisions:
a. Pleura- lines the lungs
b. Pericardium- lines the heart
c. Peritoneum- lines the abdominopelvic
cavity & its organs
3. Cutaneous- the skin, which we will discuss in
detail in chapter 5.
4. Synovial- lines joints, which we will discuss
in detail in chapter 9.
H. Connective Tissue layers: Fasciae (fash-ee-ee)
(singular= fascia)- sheets of connective tissue;
separate organs & layer of the body; protect & support
organs; allow independent movement of organs, layers
of the body.
1. Superficial/subcutaneous- areolar & adipose
2. Deep- dense connective
3. Subserous- areolar
V. Muscle & Nerve tissue; - Please read these sections of
the chapter for an introduction and to familiarize yourself
with the information here, as you may want to return to it
as we reach the respective chapters. Do know for the exam:
- 3 main muscle types, which are voluntary/involuntary,
which are striated/non-striated, and (generally) where they
are found
- 2 main nerve types
VI. Tissue Repair (Inflammation & Regeneration)