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Shay Dite Sarah Berger Mr. Miller Biology, P2 Systems Cells make up everything. Flowers and trees, fish and fly, human and dog. Cells are what make up everything living. Systems are what make humans function each day. It’s a never-ending cycle of messages and signals to form our health and lifestyles. So what do systems do? What are they? How do cells and systems tie together? The circulatory system is the system that helps control the flow of blood in the body. This is called circulation. The main parts of the system are the heart, arteries, capillaries and veins. When blood circulates, it leaves the heart through the left ventricle and goes into the aorta. The aorta is the largest artery in the body. Blood leaving the aorta is full of oxygen. The oxygen filled blood travels through the body into the arterioles. When blood returns to the heart it travels through the veins. As it reaches the lungs, carbon dioxide is removed from the blood and is replaced with fresh oxygen. Then the cycle starts again. Arteries are tough, elastic tubes that carry blood away from the heart. The farther away from the heart, the smaller the vessels become. The largest arteries can be as big as a thumb while the smallest can be smaller than a hair. The smaller areoles are called arterioles. Veins carry the blood back to the hearts. The smallest veins are called venules. The veins carry back dark that doesn’t have oxygen. Because the returning blood is under less pressure, the veins don’t need to be as strong as the arteries. The air inters the nostrils, passes through the nasopharynx, oral pharynx, through the glottis into the trachea, into the left and right bronchi which branches into the bronchiole that terminates into a cluster of alveoli. This is the complete process of taking a breath of air. In mammals, the diaphragm divides the body cavity into the abdominal cavity, which holds the stomach and intestines, and the thoracic cavity, which holds the heart and lungs. Respiration begins at the nose and filters through the small hairs of the nose and passes through the nasal cavity (above the roof of the mouth). In the nasal cavity, mucous membranes warm and moisten the air which helps prevent damage to the delicate tissues that form the respiratory system. The walls of the nasal cavity are covered with mucus called cilia that trap inhaled particles and are swept into the throat so they are swallowed. The filtered air move into the pharynx, a tube that contains two passages: one for air and one for food/water. The epiglottis is a flap of skin that stays open while breathing and closes when swallowing. The air goes down the trachea. The upper end of the trachea is the larynx. The larynx is the voice box of living organisms. Vocal cords rest here. Depending on how tight the vocal strings are, pitch and volume differ. The trachea branches into two bronchi that lead to the lungs. Bronchioles are small tubes branched off the bronchi that hold air sacs called alveoli. The exchange of gas and air occur in the alveoli. Each lung contains three hundred million alveoli. When oxygen combines with the blood, only a little bit turns into plasma. Oxygen moves into red blood cells to combines with the hemoglobin. Each hemoglobin combines with four iron atoms that bind themselves to the oxygen molecule. When oxygenated blood reaches the cell, the oxygen concentration is higher in the blood than in the cells. When the concentration of carbon dioxide is higher, it diffuses out of the cell and into the blood, instead of releasing it into surrounding cells. Inspiration is taking in a breath. This happens when air is taken in and the diaphragm contracts and the ribcage expands. Expiration is releasing air. The diaphragm relaxes and the ribcages contracts. The immune system is responsible for fighting off pathogens and prevents the growth or spreading of cancer. The organs of the immune system consist of white blood cells and organs scattered around the body. These include bone marrow, thymus, lymph nodes, tonsils, adenoids and the spleen. Each organ has a different job in the immune system. Bone marrow produces white blood cells needed for the body. Some white blood cells travel to the thymus to mature, located in a gland on the upper part of the chest. Lymph nodes filter pathogens from the lymph and expose them to white blood cells, then are transferred to the spleen where it filters the pathogens from the blood. White blood cells are also known as lymphocytes. There are two different types of white blood cells: T cells and B cells. B cells are grown in the bone marrow and stay there to mature, while T cell are grown in the bone marrow but then travel to the thymus to mature. When the body is invaded with pathogens, the body goes into a process called an immune response. This is when lymphocytes attack in invading pathogen. It is the responsibility of the white blood cells to tell the difference between a harmful pathogen and one of their own. Once the immune response occurs, antigens provoke the proper response. An immune response can be different depending on the type of blood cells that are being used. One type of response is called cell mediated immune response uses T cells. Another response is called humeral immune response that uses mostly B cells with some helper T cells. AIDS is when the immune system loses the ability to protect the body from harmful pathogens. HIV, a retrovirus that contains RNA instead of DNA, causes this. HIV cannot reproduce outside the cell, so an infected T cell will let harmful pathogens into the body. Shortly after the infection is when HIV sets to work. The infected body starts to feel the symptoms of flu. Over the course of several years, HIV takes over the immune system as the T cells become infected and cannot control or command the system to do its job. The transmission of HIV is through sex or contaminated needs/syringes. The digestive system needs an element called nutrients to survive. These are called carbohydrates, protein, lipids, vitamins, minerals and water. These are called nutrients, chemical substances necessary for organisms to function properly. All foods of the world have these nutrients, some more than others. With these nutrients, the human body works the digestive system. The gastrointestinal tract (or digestive tract) begins at the mouth and travels through the body to the anus. From the mouth, the nutrients travel through several major organs to make sure the nutrients needed are taken into the body and get rid of other waste. The mouth is the first step of digestion. Teeth break down the food so the other organs can digest it better. Once the food is ground down, it is swallowed and passes through the esophagus to the stomach. The esophagus is about ten inches long and helps moves the food down the tube. The food is passed into the stomach, a sack where the ground food is combined with acids to break the food down even more. From the stomach, the food “pulp” is passed to the small intestine al little bit at a time. The small intestine is the final area for digestion. The small intestine is about 20 feet long all scrunched up. Digestive juices are released to break down the food for the last time. When the stomach growls, it’s the action of the small intestine squeezing the food by, also called peristalsis. Along the small intestine are fingers that are called villa; these absorb important chemicals from the food into the body. This is where food is actually taken in. The food that is not taken in by the villa becomes waste and is passed to the large intestine. The large intestine also holds the colon. The waste forms into feces from water. The water is absorbed back into the body afterwards. It can take up to 20 hours for digestion to be completed. The pancreas is a gland below the stomach that produces enzymes to help digest food. It also produces insulin in the blood to allow sugar and glucose into the bloodstream. People who cannot produce insulin are diabetic. The liver stores glycogen and produces vitamin A. It helps remove old cells, alcohol, bacteria, et cetera from the body. Damage to the liver is serious because it is a vital organ. The gallbladder is a small sack that holds bile that breaks down fat in food for the body. The skeletal system is the frame of the body, the basic structure of almost every organism. It protects vital organs such as the skull protecting the brain and the ribcage protecting the heart. Body movement is carried out by the interaction of muscles and bones. Muscles are connected to bones with tendons while bones connected to other bones are called ligaments. Where bones do meet is called joints. 206 bones create the frame of most organisms. The axial skeleton is the bones that protect the organs of the head, neck and center of the body. These bones are the skull, the sternum, the ribs and the vertebral column. The appendicular skeletons are bones that anchor appendages to the axial skeleton. These bones are the upper extremities, the lower extremities, the shoulder girdle and the pelvic girdle. There are four main types of bones. The first type is long bones. These bones work as lever, such as the femur, metacarpals and tibia. The second type of bones is called short bones. These bones are cubed and short and are found in the wrist and ankles. The third type of bones is called flat bones. Flat bones have a large surface area to protect vital organs and attachment of muscles. Examples of flat bones are ribs, cranial bones and shoulder girdle bones. Irregular bones are bones that don’s fall into the other categories. They vary in shape and placement of the body. The human body is a station of never-ending cycles that tie together. Without the respiratory system, the circulatory system would shut down. Without bones, the immune system would become sick and destroy the body. Without the digestive system, we wouldn’t be able to take in nutrients vital for our body to continue working all the cycles. In the end, humans must dig deep to understand our bodies more as a puzzle to create a whole, rather than a whole made up of many smaller parts. Cells tie into systems because each cell is dependent on the actions of a certain system and systems rely on cells to perform their job correctly. The body is constantly working to keep up with our lifestyle and build our bodies into what they are.