From Single Cells to Body Systems

The Discovery of Cells Microscopes allow you to see objects that are too small for see with your eyes (magnification) Robert Hooke built and used a microscope to discover cells (tiny rooms) in a piece of cork Cell = the basic unit of structure and function of all living things

Drawing of cork in Hooke’s sketch book Robert Hooke

Kinds of Cells All plants and animals are made up of cells Some organisms have only one cell (bacteria); other organisms have many cells If an organism has many cells, there are usually different kinds of cells which have special jobs or functions The function of a cell determines its size and shape Red blood cells are small and oval Muscle cells are long and thin (contract as they move) Nerve cells are very long Plants have different kinds of cells that do different tasks (take in water, help in the making of food, protect the plant) Cells keep organisms alive in the jobs that they do Release energy from food Get rid of body wastes Make new cells BUT…all cells can perform all these process for itself

Pictures of Kinds of Cells Nerve Cell

Plant and Animal Cells Cells are made up of even smaller structures called organelles, which have functions to keep the cells alive. Cell Membrane = a thin covering around the cell that holds the cell together and separates the cell from its surroundings Nucleus = controls the cells activities is in the center is surrounded by its own membrane is responsible for reproduction because cells only grow to a certain size Chromosomes are threadlike structures that contain the characteristics of an organisms. New cells of the same organism have the same chromosomes. Cytoplasm = jellylike substance containing chemicals to keep the cell functioning Organelles in the cytoplasm Mitochondria – releases food Vacuoles – used for storage (food, water, and waste) Plant cells have… Cell wall – gives it strength Chloroplasts – make food

Plant & Animal Cells Animal Cell Plant Cell

Cell Transport Mitochondria supplies the energy for the cells Need food, oxygen, and water Carbon Dioxide is the waste of the cell Diffusion = movement of materials in and out of the cells…moves from where there are a lot of particles to where there are fewer particles

Diffusion Red blood cells have lots of oxygen so the oxygen diffuses out of the red blood cells into the body cells Carbon dioxide diffuses out of the body cells into the red blood cells Diffusion takes places through the cell membrane like a filter and does not need energy. Energy-free movement is called passive transport. Osmosis = the movement of water and dissolved materials through the cell membrane

Diffusion Osmosis is used in plants getting water. More water in the soil so the water flows to the plant cells and fills up the vacuoles. This pushes against the cytoplasm and causes the plant to stand up straight If the soil is dry, the water leaves the plant cells causing the vacuoles to shrink This causes the cytoplasm to shrink and the plant cannot stand up straight

Cell Transport Not all cells are small enough for diffusion A swimmer’s muscle cells might need more sugar than there is in the blood in order to have the energy he/she needs for a swim meet Active transport uses a carrier to transport materials that are too large to pass through a cell membrane A channel is used in the cell membrane to transport materials To do this a cell needs energy from the cell 1/3 of the energy in the cell is used to transport materials through active transport

Tissues, Organs, and Systems Tissue = cells that work together to perform a specific function Muscle tissue – contraction and relaxation of the muscle to move the skeleton Nervous tissue – brain, spinal cord, sight, hearing, taste, smell touch Connective tissue (bone, cartilage, tendons, and blood) Epithelial tissue (body and organ coverings) Organ = tissues that work together (stomach, heart, etc.). Each organ is made up of several kinds of tissue Skin is an organ that is made up of epithelial tissue, music tissue, nervous tissue & connective tissue Each organ performs a major function to keep the animal alive. System = organs that work together Human body has 10 systems Plant tissues work together to form organs (roots & leaves)

Video – The Living Cell (20 minutes)