Organization of Cells

A branch of biology and medicine that considers the structure of living things Human anatomy focuses on the human body

We’ve already learned all about the parts of a cell and the functions of each part…but what about the cell itself? What do cells actually do?? Cells carry on the processes that keep organisms alive. For example, inside cells molecules from digested food undergo chemical reactions that release energy for the body’s activities. Cells also grow, reproduce, and get rid of the waste products that result from these activities.

Cells perform specialized functions in multi- cellular organisms Groups of cells cooperate and form tissues, like muscles. Tissues group together and form larger functional units, called organs. Organs group together to form systems.

Systems come together to form a whole organism. Each type of cell, tissue, organ, and organ system has a distinct structure and functions to serve the organism as a whole. Different body tissues and organs are made up of different kinds of cells. The cells in tissues and organs, that can be found in both animals and human beings, are similar to each other – but they differ from those cells found in plants.

Tissue: a group of similar cells that perform the same function Four types of tissue…found in the human body: Muscle tissue – a body tissue that contracts or shortens, making body parts move Nervous tissue – a body tissue, such as the brain, that carries electrical messages back and forth between the brain and every other part of the body Connective tissue – a body tissue, such as bone, that provides support for the body and connects all of its parts Epithelial tissue – a body tissue, such as skin, that covers the surfaces of the body, inside and out

Organ: A structure that is composed of different kinds of tissue Performs a specific job(s) Example: Heart – contains all four kinds of tissue, each tissue helps the heart to do it’s job of pumping blood The organs all form different organ systems A group of organs that work together to perform a major function

* What happens when all the organs in the body system work together? * Homeostasis occurs * Homeostasis – the body’s tendency to keep an internal balance * Want to prove this? * Take your temperature when you are in a cold room. * Then take it again when in a warm room. * Your body temperature will stay the same in either room because the body can regulate it from the inside.

* What is stress? * Yes it’s what your parents always say about work! * Stress – the reaction of your body to potentially threatening, challenging, or disturbing events. * Example: * What happens to you the night before a test? Especially when you haven’t studied for it? Does your heart race? Do you get really cranky?....Yes?.....Then that is stress.