The Human Body
Cells
basic units of structure and function in the human body, as they are in all living things.
Tissue
A tissue is a group of connected cells that have a similar function.
Connective tissue
made up of cells that form the body’s structure. Examples include bone and cartilage.
Epithelial tissue
made up of cells that line inner and outer body surfaces, such as the skin and the lining of the digestive tract. Epithelial tissue protects the body and its internal organs
Muscle tissue
made up of cells that have the unique ability to contract, or become shorter. Muscles attached to bones enable the body to move.
Nervous tissue
made up of neurons, or nerve cells, that carry electrical messages. Nervous tissue makes up the brain and the nerves that connect the brain to all parts of the body.
Organs
Organ systems
An organ is a structure that consists of two or more types of tissues that work together to do the same job.
Muscular
Supports the body and allows it to move
Circulatory systems
Transports oxgen, nutrients and other substances to cells and carries away wast
Respiratory
Takes in oxygen and releases wast gass
a group of organs that work together to carry out a complex overall function.
Respiratory system: A high concentration of carbon dioxide in the blood triggers faster breathing.
Excretory system: A low level of water in the blood triggers retention of water by the kidneys.
Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas.
specialization they all play the specfic roles
differentiation means blood cells as a catagory
stem cells are a universal cell and they can develop into any cell earlie on