Transcript Body Tissues - lewisbiology

BODY TISSUES
O VERVIEW

Human body starts with one cell

Division makes millions of cells

Each specialized for particular functions

Some are so specialized, they can create hazards


Ex. Heart cells
Groups of similar cells that are similar in
structure and function: tissues
T YPES
OF
T ISSUES

Epithelium (covering)
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Connective (support)
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Nervous (control)
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Muscle (movement)
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All interweave to form the fabric of the body
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Tissues organized into organs
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One organ can be composed of several tissue
types
E PITHELIAL T ISSUE
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Also called epithelium
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Lining, covering, and glandular
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Forms glands
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Covers all free body surfaces
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Versatile cells
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Outer skin layer, and lining of body cavities
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Every substance entering or leaving must pass
through these cells
S PECIAL C HARACTERISTICS
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Except for glandular, they fit closely together to
form continuous sheets
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Always have one free surface (apical surface):
exposed to body’s exterior or the cavity of an
internal organ
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Lower surface rests on a basement membrane,
structureless material secreted by cells
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No blood supply of their own (avascular);
depend on diffusion from capillaries
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Regenerate themselves very easily
C LASSIFICATION OF
E PITHELIUM
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Two names
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First name is for number of cells: simple (one) or
stratified (more than one)
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Second name describes shape: squamous
(flattened), cuboidal (cube-shaped), and
columnar (column-shaped)
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Names are combined
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*Stratified epithelia are named for the cells at the
free surface of the membrane, not the those
resting on the basement membrane
S IMPLE E PITHELIA
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Most concerned with absorption, secretion, and
filtration
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Simple Squamous epithelium
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Single layer resting on basement membrane
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Fit closely together
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Usually forms membranes that use diffusion: air
sacs of lungs, walls of capillaries
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Also forms serous membranes or serosae: slick
membranes lining ventral body cavity and cover
organs in ventral cavity
S IMPLE E PITHELIA
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CONTD .
Simple Cuboidal Epi.

One layer resting on basement membrane
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Common in glands and ducts: salivary glands and
pancreas
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Forms walls of the kidney tubules, and covers
surface of the ovaries
S IMPLE E PITHELIA
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
CONTD .
Simple Columnar Epi.
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One layer of tall cells
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Fit close together
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Goblet cells: produce a lubricating mucus, often
seen in this type of epithelium
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Lines entire length of digestive tract from
stomach to anus
*Epithelial membranes that line body cavities
open to the exterior are called mucous
membranes or mucosae
S IMPLE E PITHELIA
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CONTD .
Pseudostratified Columnar Epi.

Rest on basement membrane

Cells are different heights, and nuclei appear at
different heights above basement
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Give false (pseudo) impression of stratified
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Mainly absorption and secretion
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Pseudostratified ciliated columnar epithelium

Ciliated, lines most of respiratory tract

Goblet cells produce mucus to trap dust and
debris
S TRATIFIED E PITHELIA
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Two or more cell layers
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More durable than simple
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Primarily for protection
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Stratified Squamous Epithelium
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Most common stratified
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Usually several layers
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Free edge are squamous, closer to basement are
cuboidal or columnar
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Found in “high friction” areas: esophagus, mouth,
other parts of skin
S TRATIFIED E PITHELIA
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Stratified Cuboidal and Columnar Epithelia
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Usually just two cell layers with (at least) the
surface cells being cuboidal
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Surface cells of stratified columnar are columnar,
but its basal cells vary in size and shape
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Both are fairly rare
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Found mainly in the ducts or large glands
S TRATIFIED E PITHELIA
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Transitional Epithelium
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Highly modified
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Stratified squamous epithelium
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Forms lining of only a few organs: bladder, the
ureters, and part of the urethra
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All part of the urinary system and undergo
considerable stretching
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Basal layer are cuboidal or columnar; those at the
free surface vary in appearance
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Stretching changes shape, cells can flatten and
become squamous-like
G LANDULAR E PITHELIA
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Gland: consists of one more cells that make and
secrete a particular product
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Secretion: typically contains protein molecules in an
aqueous fluid
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Noun and verb: glandular cells obtain needed
materials from the blood and use them to make their
secretion, which they then discharge
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Two types:
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Endocrine glands: no connection to surface
(ductless), secrete hormones through diffusion

Exocrine glands: retain ducts, secretions empty to
surface: sweat and oil glands, liver and pancreas,
internal and external
C ONNECTIVE T ISSUE
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Connects body parts
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Found everywhere in body
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Most abundant and widely distributed
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Protect, support, bind other tissues together
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Most are well vascularized (good blood supply)

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Exceptions: tendons and ligaments have poor and
cartilage has none (tend to heal slower than the
others)
Extracellular matrix: nonliving substance found
outside of these cells
E XTRACELLULAR M ATRIX
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Only found in connective tissue
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Produced by the connective tissue cells then
secreted to their exterior
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Two main elements:

Structureless ground substance: water +
adhesion proteins and large charged
polysaccharide molecules; like the “glue”
between these cells
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Fibers: collagen (white) very strong; elastic
(yellow) stretching; reticular (fine collagen fibers)
make up internal “skeleton” of soft organs such
as spleen
E XTRACELLULAR M ATRIX
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Because of matrix, connective tissue is able to
form a soft packing tissue around other organs,
to bear weight, and to withstand stretching and
other abuses
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Varies depending on tissue type:
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Fat tissue is mostly cells and the matrix is soft
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Bone and cartilage have very few cells and large
amounts of hard matrix which makes them strong
T YPES OF C ONNECTIVE
T ISSUE
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From most rigid to softest:
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Bone
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Cartilage
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Dense Connective tissue
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Loose Connective tissue
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Blood
B ONE
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Called Osseous tissue
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Composed of bone cells sitting in cavities called
lacunae
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Surrounded by layers of a very hard matrix that
contains calcium salts and collagen fibers
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Exceptional ability to protect and support
B ONE P ICTURE
C ARTILAGE
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Less hard and more flexible than bone
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Found only in a few places
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Most widespread is hyaline cartilage: lots of
collagen fibers, glassy, blue-white appearance

Forms larynx, attaches ribs to breastbone, covers
the ends of bones; skeleton of fetus
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Fibrocartilage: highly compressible, forms disks
between the vertebrae of spinal column
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Elastic Cartilage: found where elasticity is
desired; external ear
H YALINE C ARTILAGE P ICTURE
F IBROCARTILAGE P ICTURE
E LASTIC C ARTILAGE P ICTURE
D ENSE C ONNECTIVE T ISSUE
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Also called dense fibrous tissue
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Collagen fibers as its main matrix element
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Between collagen fibers are rows of fibroblasts
(fiber-forming cells)
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Forms strong, rope-like structures such as
tendons (attach skeletal muscles to bones) and
ligaments (connect bones to bones at joints)
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Also makes up lower layers of skin (dermis),
arranged in sheets
D ENSE C ONNECTIVE T ISSUE
P ICTURE
L OOSE C ONNECTIVE T ISSUE
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Softer and have more cells and fewer fibers
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3 types:
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Areolar: most widely distributed of connective;
soft, pliable, “cobwebby”; cushions and protects;
universal packing tissue; holds internal organs
together and in place; lamina propria underlies all
mucous membranes; all types of fibers forming
loose network; provides reservoir of water and
salts for surrounding tissues; inflammation in the
body causes this tissue to soak up excess fluid like a
sponge which causes it become puffy: edema;
phagocytes wander through looking for debris to
destroy
A REOLAR T ISSUE P ICTURE
A DIPOSE T ISSUE
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Commonly called fat
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Areolar with fat cells dominate
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Fat cells = signet ring cells: cells are full of oil – pushes
nucleus to outer rim of cell
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Forms subcutaneous tissue beneath skin
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Insulates and protects from heat and cold
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Protects some organs: kidneys, eyeballs in sockets
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Fat depots in body: hips and breasts where fat is
stored and available for energy if needed
A DIPOSE T ISSUE P ICTURE
R ETICULAR T ISSUE
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Delicate network of interwoven reticular fibers
associated with reticular cells
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Forms the stroma: internal framework, which
can support many free blood cells (mostly
lymphocytes) in lymphoid organs such as lymph
nodes, the spleen, and bone marrow
R ETICULAR T ISSUE P ICTURE
B LOOD
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Vascular tissue
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Consists of blood cells, surrounded by nonliving,
fluid matrix called blood plasma
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“fibers” in blood are soluble proteins that only
become visible during clotting
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Transport vehicle for the cardiovascular system
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Carries nutrients, wastes, respiratory gases, and
many other substances
B LOOD T ISSUE P ICTURE
M USCLE T ISSUE
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Highly specialized to contract or shorten
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Produce movement
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Three types:
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Skeletal muscle
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Cardiac muscle
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Smooth muscle
S KELETAL M USCLE
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Packaged by connective tissue sheets into organs
called skeletal muscles, which are attached to the
skeleton
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Controlled voluntarily (consciously)
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Form the flesh of the body: the muscular system
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When they contract they pull on bones or skin
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Cells are long, cylindrical, multinucleate, and
striations (stripes)
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Often called muscle fibers
S KELETAL M USCLE T ISSUE
S KELETAL M USCLE T ISSUE
C ARDIAC M USCLE
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Found only in heart
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Has striations
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Uninucleate
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Short
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Branching cells that fit tightly together at junctions
called intercalated discs
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Allow for rapid conduction of electrical impulses
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Controlled involuntarily
C ARDIAC M USCLE T ISSUE
C ARDIAC M USCLE T ISSUE
S MOOTH M USCLE
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Also called visceral muscle
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No striations visible
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Single nucleus, and spindle shaped (pointed at ends)
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Walls of hollow organs: stomach, bladder, uterus, and
blood vessels
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Contracts slower than other types
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Peristalsis: wavelike motion that keeps food moving
through small intestine
S MOOTH M USCLE T ISSUE
S MOOTH M USCLE T ISSUE
N ERVOUS T ISSUE
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Cells called neurons
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Receive and conduct electrochemical impulses from one
body part to another
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Irritability and conductivity are major functions
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Unique structure
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Cytoplasm drawn out into long processes (extensions) as
much as 3 ft or more in the leg
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Supporting cells: insulate, support, and protect the
delicate neurons
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Make up nervous system: brain, spinal cord, and nerves
N ERVOUS T ISSUE