All tissues of the body develop from the three primary germ cell layers that form the embryo:
Mesoderm – develops into epithelial tissue, connective tissue and muscle tissue.
Ectoderm - develops into nervous tissue and epithelial tissue.
Endoderm – develops into epithelial tissue.
Different kinds of tissue have different physical properties. Tissues may be hard (bone), soft (muscle),
or even liquid (blood).
3. Epithelial tissuesEPITHELIAL TISSUES
The epithelial tissues are formed by
cells that cover the organ surfaces
such as the surface of the skin, the
airways, the reproductive tract, and
the inner lining of the digestive tract.
This tissue provides a barrier
between the external environment
and the organ it covers.
Epithelial tissue helps to protect
organisms from microorganisms, injury,
and fluid loss. Epithelial tissues help in
absorption of water and nutrients, and in
elimination of waste product.
4. Connective tissueCONNECTIVE TISSUE
Connective tissue adds
support and structure to
the body. Most types of
connective tissue contain
fibrous strands of the
protein collagen that add
strength to connective
tissue. Some examples of
connective tissue include
the inner layers of skin,
cartilages, bones, blood,
and fat tissue.
5. Muscle tissueMUSCLE TISSUE
Muscle tissue is a specialized tissue that can contract. Muscle tissue
contains the specialized proteins actin and myosin that slide past one
another and allow movement. Examples of muscle tissue are contained
in the muscles throughout your body.
6. Nerve tissueNERVE TISSUE
Nerve tissue contains two
types of cells, neurons and
glial cells, and it makes up
the central nervous system
(CNS) and the peripheral
nervous system (PNS).
Nerve tissue has the ability
to generate and conduct
electrical signals in the
body. These electrical
messages are managed by
nerve tissue in the brain
and transmitted down the
spinal cord to the body.
Organs are the next level of
organization in the body. An
organ is a structure that
contains at least two different
types of tissue functioning
together for a common purpose.
There are many organs in the
body: the liver, kidneys, heart,
even skin is an organ. The heart
is an example of an organ made
up of all four kinds of tissues.
8. Organ systemORGAN SYSTEM
Organ system is a group of
related organs performing a
major function for an organism.
Examples of human organ
systems include the circulatory,
digestive, nervous, reproductive,
respiratory, skeletal, muscular,
excretory, endocrine systems.
The highest level of organization
of life is the multicellular
organisms are composed of the
combination of all its cells,
tissues, organs, and organ