1. By Owen Lyke

2. Organ Systems Organ systems are groups of organs that perform specific functions in the body. For example, the respiratory system is made up by the lungs, respiratory muscles, and airways. Although this PowerPoint will mostly cover the human organ systems, most animals and plants have simpler forms of most of these systems. Animals are made up of various systems, called organ systems, which are made up of groups of related organs. Every organ is made up of specialized tissues which are groups of millions of cells that all have their own organelles inside of them.  Respiratory:  Circulatory:  Nervous:  Digestive:  Muscular:  Skeletal:  Urinary/Excretory:

3. Respiratory System  The respiratory system is the body’s way of getting oxygen to it’s cells. Oxygen is vital for cells to live, therefore the respiratory system is vital. The organs that make up the respiratory system include the lungs, respiratory muscles, and airways that get oxygen to the lungs.  When an organism’s brain tells it to take a breath the diaphragm contracts which increases the volume of the chest cavity. This vacuum draws in air to the lungs. In the lungs gas exchange occurs through the alveoli. The alveoli are sacks with a wall thickness of one cell, the process of diffusion carries oxygen into and CO2 out of the capillaries. Exhalation is normally a passive process because the lungs are elastic and naturally deflate until they reach equilibrium with atmospheric pressure.  Most animals use variations this system, but fish have gills, which take oxygen from water, and insects typically breathe through openings called spiracles. In plants, the chemical equation for photosynthesis, which takes in CO2 and releases oxygen, is the opposite of human respiration. Plants take in CO2 through stoma on the underside of leaves.

4. Circulatory System  The circulatory system is the organ system that supplies essential nutrients to the cells of the body. The circulatory system not only includes the cardiovascular system, which transports blood, but also the lymphatic system which distributes lymph. Lymph is the interstitial fluid that surrounds all of the cells in our body. It picks up bacteria and takes it to a lymph node to be destroyed.  The cardiovascular system is a closed system, meaning no blood is lost. (Unless it is opened by a cut or wound.) The cardiovascular system is made up of two parts, the pulmonary circulation, which oxygenates blood with the respiratory system, and the systemic circulation, which pumps oxygenated blood to the rest of the body. Because we have two loops, our heart is made up of two pumps. (Four chambers.)  Other organisms may vary slightly, for example, a fish only has one loop, going to the gills and back, so it only has a one pump heart. Amphibians have tri-chambered hearts.  In plants, the circulatory system is made up of two kinds of tissue, xylem and phloem. Xylem transports H2O and dissolved minerals while phloem transports food produced by the plant.

5. Nervous System  The nervous system of all organisms is the system that the body uses to communicate between itself. It creates and transmits signals to other parts of the body to tell the organism what to do. It also gives the brain feedback such as pain or other signals. The nervous system is made up of two main parts, the central nervous system, and the peripheral nervous system. All of the nervous system is a network made up of nerves, neurons, and pathways that connect them. The central nervous system is comprised of the brain, spinal cord, and the retina. The peripheral nervous system is the network of sensory neurons, neuron clusters, and the pathways connecting them to each other and the brain. The nervous system contains two kinds of cells, neurons and glial cells. The neurons are the cells that actually perform the duties of the nervous system and the glial cells support the life of neurons.  Even in one species, many types of neurons exist and they all perform specific jobs such as sensory input and motor control. Neurons can be classified by the direction that they send information. A neuron has two main structural differences from other body cells. These are the dendrites and the axon. The dendrites receive information from other neurons and the axon sends information electrochemically to more neurons. When an electrical signal reaches the end of a neuron, it releases chemicals which cross a synapse to be picked up by another neuron’s dendrites.

6. Digestive System  The digestive system’s job is to provide energy for the body. When we eat food, it is not in a form that our cells can use. A cell cannot take in a piece of lettuce, it can only use smaller pieces that make up the lettuce. The digestive system is the system that our body uses to break lettuce into the smaller pieces that make it up. (Not just lettuce though.) The circulatory system then distributes these essential fuels to the cells.  The digestive system can be divided into two parts, a series of hollow organs called the digestive tract, and all of the other organs that support the digestion of food like the liver, gallbladder, appendix, and pancreas. The digestive tract starts at the mouth, which is followed by the esophagus and the stomach. After the stomach is the small intestine which is followed by the colon. Lastly are the rectum and anus.  The mouth and teeth break up food in preliminary digestion.  The esophagus transports food to the stomach.  The stomach digests food with acids and enzymes.  Nutrients are transferred to the circulatory system in the little intestine. The tissue of the little intestine is made up of folds called pilacae circulares which are covered in villi, which absorb nutrients through diffusion. These nutrients are then distributed through the body.  Unwanted or indigestible materials are stored in the colon and released through the rectum.  Glands in the stomach lining produce stomach acid and enzymes to break down food. The liver produces bile (which breaks down fat), which is stored in the gallbladder until it is needed for digesting food, when it is injected to the small intestine through the bile ducts.

7. Muscular System

8. Skeletal System

9. Urinary/Excretory System

10. Bibliography