Human Biology Week 1

How does the body get so many individual cells to work together so perfectly? You can begin to answer this question by studying the organization of the human body. The levels of organization in a multicellular organism include cells, tissues, organs, and organ systems. Tissues are groups of similar cells that perform a single function, such as connecting a muscle to a bone. An organ is a group of tissues that work together to perform a complex function, such as sight. An organ system is a group of organs that perform closely related functions. The eleven organ systems of the human body work together to maintain homeostasis.

Cells are the basic unit of structure and function in living things. Tissues are groups of cells that perform a single function. Organs are the group of different types of tissues that work together to perform a single function. Organ systems are a group of organs that perform closely related functions.

4 types of tissues

Homeostasis

Circulatory System

THE HEART The heart muscle contracts on average 72 times a minute, pumping about 70 millimeters with each contract. This means that during one year an average person’s heart pumps enough blood to fill an Olympics size swimming pool. Dividing the left side of the heart from the right side is the septum.

Vein vs. Artery