Structure and Functions of Yellow Elastic Tissue
Note: This page is
part of the section about the structure and function
of different Tissue
Types, which is related to the
section Histology
and Cells (incl. structure
of animal cells, cell
division, mitosis,
meiosis).
This "Tissue Types" section is included
to cover the knowledge of "Histology - The
Cell" required by some courses in First-Level
Anatomy and Physiology. To read about other tissue
types see the links listed of on the left.
As indicated on the page about classification
of (animal) tissue types, "Yellow
Elastic Tissue" is a form of
mature (rather than embryonic) connective tissue,
and is one of the forms of Dense Connective
Tissue. There are three (3) types of dense
connective tissue.
The 3 forms of Dense Connective Tissue:
|
Dense Regular
Connective Tissue
|
Dense Irregular
Connective Tissue
|
Elastic
Connective Tissue
|
(inelastic) |
(inelastic) |
(elastic)
 also known
as
"Yellow Elastic Tissue"
(due to the yellowish appearance of the
unstained tissue)
|
Definition:
Yellow elastic tissue is connective tissue
in which (yellowish, when unstained)
elastic fibres dominate
the tissue structure resulting in the mass of
tissue having a yellow-ish appearance and considerable
elasticity. That is, the tissue is able to extend
when forces are applied to stretch it, yet return
undamaged to its previous condition when the
(extending) force is realeased.
Structure of Yellow Elastic
Tissue:
The main constituents of yellow elastic tissue
are many freely-branching elastic fibres
(which are responsible for the yellowish colour
of the tissue). Chemically, the elastic fibres
are elastin, which is composed
of the amino
acids glycine,
valine,
alanine,
and proline.
Fibroblast cells (called "fibrocytes")
are also widely present distributed throughout
the structure of yellow elastic tissue (as well
as those of other connective tissues, such as
white
fibrous tissue) and are necessary for production
of the precursors of many constituents of tissues
including those of elastic fibres, and reticular
fibres (which are microscopic, non-elastic branching
fibres).
Functions of Yellow Elastic Tissue:
Yellow elastic tissue enables
organs and parts of organs to stretch
(and contract). This is important when
the function of the organ involves movement
incl. expansion and contraction of membranes
e.g. of lung tissue. |
Locations in the body:
Yellow elastic (connective) tissue is present
in many locations throughout the body, including:
- Lung tissue.
- Walls of elastic arteries.
- Trachea (windpipe).
- Brochial tubes.
- Thyroid ligaments.
Warnings of possible confusion:
Other types of (animal, including human) tissue
include the word "yellow" in their
name and/or description but do not necessarily
have connection or similarity with the connective
tissue described here as "yellow
elastic tissue" - other than
their name, and perhaps to some extent their
colour.
Other "Yellow" tissues:
The following are listed for reference and
completeness.
| Yellow
Spot
(of the eye) |
The macula lutea
is also known as the yellow
spot.
It is the area on the retina
(at the back of the eye)
which surrounds the greatest concentration
of cones
(a type of light-sensing cell located
at the back of the eye and essential for
colour vision). |
| Yellow
Fever
(Tropical Disease) |
Obviously not a "tissue type",
Yellow Fever is an infectious
tropical disease transmitted by mosquitoes.
It is mentioned here both because of its
name, and because one of its symptoms
is jaundice - the term
for yellowing of the skin or whites
of the eyes, indicating excess bilirubin
in the blood: Note that skin/eyes yellowed
due to jaundice are not "yellow
elastic tissue", merely yellowed
in colour as a result of the condition. |
|
