Hierarchy of Structures in Animals

The Hierarchy of Structure Cells Least complex Tissues Organs Organ Systems Most complex Organism

Organ systems : groups of organs that work together to perform a single function in the organism eg. Digestive system A complex organism such as an animal is made up of various organ systems

Most Organs are composed of several different types of tissue stomach

The Four Types of Animal Tissue Epithelial Connective Muscle Nerve Remember: tissue is made up of multiple cells

Epithelial Tissue-structure Thin sheets of tightly packed cells Covers surfaces and lines internal organs

Epithelial Tissue-function Protects from dehydration Creates low-friction surfaces Ex: skin, lining of digestive system

Connective Tissue-structure Various cells and fibres held together by a matrix of solids and liquids

Connective Tissue-function Provides support and insulation Ex. Bone, tendons, blood, connection between skin and muscle

Muscle Tissue-structure Bundles of long parallel cells Contain specialized proteins that allows fibres to contract or shorten

Muscle Tissue-function Allows movement of tissue and organs Ex. Skeletal muscle (biceps, quads) Cardiac muscle Digestive muscles

Nerve Tissue-structure Long, thin cells Have fine branches at ends to conduct electrical impulses

Nerve Tissue-function Used to sense environment and communicate with the rest of the body Ex. Brain, spinal cord, optical nerves

Stem Cells and Cellular Differentiation

Multicellular organisms develop from a single cell, which is called a zygote.

The zygote divides continuously to form an embryo

Cellular differentiation: occurs when the cells of the embryo divide and begin to differ in shape, size, contents and function.

What do we call plants’ stem cells? Meristems or meristematic cells Located at root tips, terminal and lateral buds of plants

Stem Cells A Stem cell is a cell that can differentiate into many different types of specialized cells.

There are 2 types of stem cells in animals: 1) Embryonic Stem Cells: taken from the embryonic stage can differentiate into any type of cell.

2) Tissue or Adult Stem Cells: found in certain specialized tissue Can differentiate into ONLY certain types of cells. Ex. Bone marrow tissue stem cells can differentiate into white or red blood cells, platelets and many other types of cells.

Stem Cell Applications To study development Aids our understanding of how normal development and abnormal development occurs. May lead to therapies for diseases and birth defects eg Cleft palate

Stem Cell Application To replace damaged cells and treat diseases Treat burns To replace blood in leukemia patients Possible future application: replaced damaged tissues for Parkinson's disease, stroke, heart disease and diabetes.

Stem Cell Application To study disease Stem cells, engineered to contain the diseased gene are used to model & understand the disease process

Stem Cell Application Could provide a resource for testing new medical treatments New medications could be tested for safety on specialized cells generated in large numbers from stem cell lines – reducing the need for animal testing.

What are the ethical issues around stem cell usage? Stem cell research is controversial and involves moral and ethical dilemmas for many people What are the ethical issues around stem cell usage?

Watch: The role of stem cells (12 mins) Go to http://www.learn360.com/ Username: calctor Password: calctor Put in keyword: “Clone the role of stem cells” Click and watch; make sure speakers are on

The End