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Tissues
“The Building Blocks of Organs”
What is a tissue?
A tissue is a grouping of cells where all the
cells have similar structure and function.
What are the Four Major Tissue Types…
- epithelial
- connective
- neural (=nervous)
- -muscle
“Every Concert Needs Music”
Epithelial Tissue…
What is epithelial tissue?
…a sheet of cells that covers a body
surface or lines a body cavity.
Epithelial Tissue examples
• lines body cavities open to the
exterior
(e.g., digestive and respiratory
tracts)
• moist membranes found in
closed ventral body cavity
Figure 4.9b
In the next set of slides you will
see blue rectangles that cover
up important vocabulary. Try to
figure out the correct vocabulary
term. Then when you hit the
space bar the blue rectangle will
disappear and uncover the
answer.
What is this structure?
A GLAND
Connective Tissue…
What are two distinguishing features of connective tissue?
…cells are spaced apart from each other
and are separated by a “matrix.”
…has an extra-cellular “matrix”
composed of ground substance and
fibers (elastin or collagen).
Functions of Connective Tissue
What are six functions of connective tissue?
•
•
•
•
•
•
Binding (ex: holds skin onto body)
Support (ex: bone, cartilage, ligaments)
Protection (ex: skull, ribs, pelvis)
Cushioning (ex: fat around internal organs)
Thermal insulation (ex: fat below skin)
Transport of materials (ex: blood, lymph)
Fibers
What are two types of fibers found in the
matrix of connective tissue – and what are
their properties?
• Collagen –
– tough, thick fibers; provide high tensile
strength (“ropes”)
• Elastin –
– long, thin fibers; allow for stretch (“rubber
bands”)
How can you tell that this is
connective tissue?
Cells are far apart and there are
fibers and ground substance.
A stretched preparation of loose (areolar) connective tissue. The
pink fibers of different thicknesses are collagenous (or white)
fibers. The dark, thin, more tortuous fibers are elastic (or yellow)
fibers. Most of the nuclei belong to fibroblasts.
Fat cells -- note nucleus and rim of cytoplasm pushed to one side
by the accumulation of fat. In the center of the picture, in the
space bounded by the four large fat cells, there is a small, round
cross-section of a capillary with a dark, shrunken red blood cell
inside. WOW…how cool!
Tendon (dense, regular c.t.), cut longitudinally. The thick collagen
fibers (pink) are lined up parallel to each other. Fibroblasts (cells)
are squeezed between the fibers and therefore also line up in
parallel rows. Note that there are no striations so this is NOT
skeletal muscle even though it resembles it.
Dense regular connective tissue
– tendons and ligaments
Dense irregular conn. tiss. with fibers running in all directions. The
fibers are mainly collagen, but there is a small amount of thinner
elastic fibers (not visible). Found in the joint capsules that enclose
joints.
Connective Tissue: Cartilage
• Hyaline cartilage
– barely visible network of collagen fibers
– has chondrocytes (cartilage cells)
– Supports, reinforces, cushions, and resists
compression
•
•
•
•
ex: costal (rib) cartilage
ex: embryonic skeleton
ex: articular cartilge at ends of long bones
ex: nose, trachea (“windpipe”), and larynx
(“voicebox”)
Hyaline cartilage (greenish matrix), There are some collagen and
elastin fibers in the cartilage matrix, but they are invisible.
Cartilage cells = chondrocytes.
Close-up of two chondrocytes. The matrix appears very smooth,
clear, and glassy (or "hyaline").
Notice the reddish elastin fibers in the
matrix.
Fibrocartilage, with collagen fibers in the matrix. They look
"cotton-y", unlike the sharply defined elastic fibers seen
before.
Connective Tissue: Bone
Describe the properties and functions of bone tissue.
– Hard, calcium phosphate matrix with collagen
fibers
– Osteocytes = bone cells
– Supports, protects, and provides levers for
muscular action
– Stores calcium, minerals, and fat
– Marrow inside bones is the site of blood
production.
Section of bone. In the center of each “spaghetti” is a “canal”
that carries blood vessels and a nerve. Therefore, bone is a well
“vascularized” tissue, meaning that it has a rich blood supply.
(By contrast, cartilage and epithelial tissue are “avascular.”)
Higher magnification of bone. Black smudges are the osteocyters
(bone cells). Notice the canaliculi (red arrows) that radiate outward
from the central canal. This is how oxygen and nutrients get to the
bone cells from the blood vessels inside the central canal.
Even higher magnification of bone.
Nervous Tissue
What are the functions of nervous tissue?
•Functions
•respond to stimuli
•communicate with other cells
•transmit impulses
Muscle Tissue
What are the functions of muscle tissue?
•Functions
•contract
•move bones
•pump blood
•move substances through internal organs
•ex: urinary bladder, uterus, blood vessels,
digestive tract
What type of muscle tissue is this?
Skeletal muscle