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

TISSUES

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)