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Anatomy Lecture Notes
Chapter 4
I. tissue components
A. cells that perform related functions and are similar in structure
B. extracellular material - made by cells and secreted into interstitial space
II. tissue types
A. epithelium (e.) = sheet of cells that covers a body surface or lines a body cavity or
forms glands
1. characteristics
a. cellularity - cells directly attached to other cells, very little extracellular
material
b. cell junctions - attach cells to each other
c. polarity - apical surface is free (not attached to other cells) and basal surface
is attached to c.t.
d. supported by c.t. on basal surface (basement membrane)
e. avascular - contains no blood vessels
f. regenerate easily
2. classification
a. number of cell layers
simple - 1 layer
stratified - more than 1 layer
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pseudostratified - 1 layer but looks like more than one
b. shape of cells
squamous - flat, wider than they are tall; nucleus flattened horizontally
cuboidal - as tall as they are wide; nucleus rounded and central
columnar - taller than they are wide; nucleus flattened vertically
3. common types
a. simple squamous
structure:
functions: diffusion, filtration
locations: lungs, kidneys
endothelium = lining of vascular system, walls of capillaries
mesothelium = component of serous membranes
b. simple cuboidal
structure:
functions: secretion, absorption, transport
locations: kidney tubules, ducts and secretory portions of many glands
c. simple columnar
structure:
ciliated: specialized to move materials across apical surface of cells
with microvilli: specialized to increase surface area
functions: absorption, secretion, transport
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locations:
nonciliated - stomach
ciliated - oviduct, small bronchi
with microvilli - small intestine
d. pseudostratified ciliated
structure:
cells vary in height
all cells rest on basement membrane
not all cells reach apical surface of tissue
short cells are precursors for tall cells
nuclei are at several levels
goblet cells are unicellular mucous glands
cilia move mucus
functions: secretion and movement of mucus
locations: trachea and large bronchi
e. stratified squamous
structure:
surface cells are squamous
basal cells are cuboidal or columnar
basal cells undergo mitosis; replace surface cells
keratinized - surface cells dead (no nuclei); contain the protein keratin
non-keratinized - surface cells alive (nuclei) and do not contain keratin
function: protection
location:
nonkeratinized - esophagus, vagina
keratinized - skin
f. transitional
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structure:
stratified
basal cells cuboidal or columnar
surface cells vary in shape depending on amount of stretch
function:
locations:
4. gland = cell or group of cells that secretes a product, usually containing proteins
a. endocrine = no ducts, releases secretory product (hormone) via tissue fluid
into blood
b. exocrine = secretes product onto surface of epithelial membrane; may have
ducts
unicellular = one cell
goblet cells - secrete mucus
multicellular = many cells
ducts: simple vs branched (compound)
secretory units: tubular vs alveolar or acinar
5. epithelial surface features:
a. cell junctions
desmosomes =adhesive spots that hold cells together along their lateral
surfaces
plaques
cadherins/linker proteins
intermediate filaments
tight junctions = belt-like junctions that form tight seals between adjacent
cells
fusion of plasma membrane proteins
no space between cells
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gap junctions = hollow cylinder of proteins (connexons) forms opening
between cytoplasm of two adjacent cells
also found in smooth muscle and neural tissue
b. basal lamina
noncellular material on basal surface consists of proteins secreted by
epithelial cells
acts as filter, guides regenerating epithelium
with reticular fibers from underlying c.t., forms basement membrane
c. microvilli = fingerlike extensions of apical membrane; increase surface area
d. cilia = whip-like extensions of apical membrane; core of microtubules; move
materials
B. connective tissue (c.t.)
connective tissue proper
loose
dense
cartilage
bone
blood
1. characteristics
a. cells separated by extracellular matrix
b. all types originate from mesencyme
2. extracellular matrix secreted by c.t. cells consists of fibers and ground substance
a. there are 3 types of fibers
collagen fibers - proteins that withstand tension
reticular fibers - proteins that act as scaffolding for cells
elastic fibers - proteins that recoil after being stretched
b. ground substance is amorphous
composition varies with specific type of c.t.
in loose c.t. it is made of proteins and glycoproteins and holds tissue fluid
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glycosaminoglycans
proteoglycans
3. mesenchyme = embryonic c.t.
cells are undifferentiated and multipotent
4. common types
a. areolar c.t.
fibroblasts
gel-like ground substance consists of hyaluronic acid; holds fluid
collagen, reticular, and elastic fibers
defense cells:
macrophages (phagocytes)
plasma cells (antibodies)
mast cells (histamine)
adipose cells
located under epithelia, around organs, between muscles, blood vessels,
and nerves
b. adipose c.t.
adipocytes - store fat
matrix sparse
located under skin, around organs
stores energy, insulates, protects
brown fat = non-shivering thermogenesis
c. reticular c.t.
fibroblasts (reticular cells)
loose matrix
network of fine reticular fibers
location - lymphoid organs, bone marrow, spleen
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d. dense irregular c.t.
fibroblasts
collagen fibers running in all directions
located in dermis, organ and joint capsules
withstands tension in several directions
e. dense regular c.t.
fibroblasts
collagen fibers in parallel bundles
located in tendons and ligaments
withstands tension in one direction
f. hyaline cartilage
chondroblasts are immature cells that are secreting matrix
chondrocytes are mature cells that are surrounded by matrix
these cells occupy spaces in the matrix, the spaces are called lacunae
ground substance = chondroitin sulfate
collagen fibers
avascular
located at ends of bones, between ribs and sternum, supports nose and
trachea
support with flexibility
g. fibrocartilage
chondroblasts/chondrocytes in lacunae
ground substance = chondroitin sulfate
collagen fibers
avascular
located in intervertebral discs and other joints
strength and compression
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h. elastic cartilage
chondroblasts/chondrocytes in lacunae
ground substance = chondroitin sulfate
elastin fibers and collagen
avascular
located in external ear and epiglottis
flexibility and support
i. blood
matrix is a liquid called plasma
formed elements include erythrocytes, leukocytes, and thrombocytes
main function is transport
j. bone (Chapter 6)
C. muscle tissue
cells vary in size and shape but all contain the contractile proteins actin and myosin
1. skeletal
cells are multinucleate, cylindrical and very long (run from one end of the
muscle to the other)
striations seen under microscope due to arrangement of contractile proteins
under voluntary nervous control
2. cardiac
cells are cylindrical, but branch and join each other end to end
gap junctions occur where cells join each other at intercalated discs
cells have only one nucleus each and are striated
3. smooth
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cells are spindle shaped and uninucleate
no striations
usually arranged in sheets
in each sheet the cells are usually parallel
D. nervous tissue
consists of neurons and supporting cells (neuroglia)
neurons are characterized by long processes that carry electrical impulses
throughout the body
III. epithelial membranes
A. definition: epithelial sheet + underlying c.t.
B. types
1. cutaneous = skin (Chapter 5)
2. mucous
line organs that open to outside of body: respiratory, digestive, urinary and
reproductive
surface layer moistened by mucus secreted by goblet cells or glands in
underlying c.t.
c.t. layer usually called lamina propria
3. serous
line the closed ventral body cavity
simple squamous e. (mesothelium) on areolar c.t.
fluid produced by filtration from capillaries in c.t.
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IV. tissue repair
regeneration = replacement by same tissue
fibrosis = replacement by fibrous c.t.
repair of skin injury:
 scab formed by drying of fibrin in blood clot
 clot is replaced by granulation tissue (capillaries, fibroblasts, phagocytes)
 epithelium regenerates under scab
 scab falls off
 scar under e. is composed of fibrous c.t.
tissues that regenerate well include epithelia, bone, areolar c.t., dense irregular c.t.
and blood-forming tissue
tissues that do not regenerate well or at all include skeletal and cardiac muscle,
cartilage, nervous tissue
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