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Animal Levels of Organization
Read sections 2.9, 3.1 and 3.2 in textbook
- Multicellular organisms are made up of difft, cell
types. Each cell type performs a particular function.
- Specialized cells CANNOT survive on their own, they
work as a much larger part of a group that
collectively make up the body of an organism
Levels of Organization
- there are levels of organization within each animal
- these levels form a “hierarchy”- most complex at the
top and least complex at the bottom
Ex: cell tissue organ organ systemorganism
Heart cell heart muscle tissue heart circulatory system man
*The functioning of the whole organism depends on
this hierarchy *
Cells : cells keep us alive-use energy, store
materials, get rid of waste, grow and multiply. They
are the simplest unit of all living things that can
perform the functions of life. There are hundreds of
types ex. brain, liver, skin, muscle. They arise from
stem cells in early life. Stem cells then differentiate
to become specialized.
Tissues: Animals have 4 major types of tissue:
1. Epithelial Tissue: line the surface of the body and
internal organs/body cavities. Ex skin tissue, lining
of digestive system
2. Connective tissue: provides support and
protection ex: blood, fat, bone
3. Muscle tissue: tissues that can contract and enable
the body to move. Ex: skeletal muscle and cardiac
muscle
4. Nerve tissue: conducts electrical signals from one
part of the body to another ex. brain, spinal cord
Organs : a structure composed of different tissues
working together to perform a body function.
Ex. skin-largest organ in human body. It is made up of the
epidermis (epithelial tissue) and dermis (connective
tissue, nervous tissue and muscle tissue)
Heart: muscle tissue and nerve tissue
Stomach: epithelial, connective, nervous, muscle
Organ Systems:
- A system of 1 or more organs that work together to
perform a vital body function.
- There are 11 main organ systems in the human body
- Ex: digestive system, circulatory system,excretory....
** organ systems DO NOT work in “isolation”, they
interact to allow processes for life. Organ systems are
interdependent-the action of one system contributes to
the action of another.
Ex. the heart pumps blood (circulatory system) to the
lungs to pick up oxygen (respiratory system)