Topic 1.4 How do systems work together in the human body?

1 In 2009, Canadian astronaut Robert Th irsk began a six-month stay on the International Space Station (ISS) orbiting around Earth. Th e astronauts on the ISS place their lives in the hands of the space station s advanced life support system . For the astronauts to survive in space, the temperature and pressure within the ISS must be maintained. An adequate supply of oxygen must be provided, and waste gases, such as carbon dioxide, must be removed. Solid waste must also be removed, but urine is recycled to provide the crew with clean water. All of these functions are achieved with the help of advanced technology the systems on the ISS must work together to support life on board. Th e same is true inside your body. Like the life support system on the ISS, your organ systems must work together to keep you alive. For instance, your body needs systems that enable it to take in oxygen and remove carbon ConceptsTh e respiratory system carries oxygen to and removes carbon dioxide from the e circulatory system transports dissolved gases and nutrients through the e digestive system breaks down food, absorbs nutrients, and eliminates solid systems working together carry out important tasks in the SkillsInquiry Literacy Key Termsgas exchangealveolicapillariesred blood cellsabsorptionHow do systems work together in the human body?

2 Topic MHR UNIT 19/28/09 12:32:21 PM9/28/09 12:32:21 PMStarting Point ActivityImagine that you are on the ISS for a month-long Name at least three jobs that the ISS needs to perform to keep you and the other astronauts Brainstorm to create a list of the organ systems you already know about. How are the life support systems on the ISS similar to the organ systems in your body? Canadian astronauts Julie Payette and Robert Thirsk working together and with other astronauts on the International Space Station during a 2009 how do systems work together in the human BODY? MHR 57 29/28/09 12:32:30 PM9/28/09 12:32:30 PMThe respiratory system carries oxygen to and removes carbon dioxide from the blood. Even when you are at rest, a lot of activities are occurring inside your body. For example, your body is sending messages, transporting nutrients, and creating new cells.

3 Th e cells in your body need a lot of energy to perform these activities. Where does this energy come from? If you answered food, you are only partly right. Cells also need oxygen to release the energy that is stored in food molecules such as glucose. Th ey do this through cellular respiration. Each time you breathe in, the respiratory system takes in the oxygen that your cells require to carry out cellular respiration. Carbon dioxide and water are also produced when cells carry out cellular respiration. Your body gets rid of carbon dioxide every time you breathe out. Th e process of taking in oxygen and releasing carbon dioxide is called gas exchange (see Figure ). Gas exchange occurs in your of the respiratory SystemTh e respiratory system includes many diff erent organs that work together for gas exchange to take place. Figure shows the path that air follows when you inhale.

4 Figure The respiratory system is responsible for the exchange of oxygen (A) and carbon dioxide (B). Figure The path of air through the respiratory system when you inhale1. When air is inhaled, dirt and other particles are trapped by tiny hairs and sticky fl uid in the nose. 2. The air fl ows into the throat and passes through the larynx. The larynx contains vocal cords that vibrate as the air moves through them. This produces the sound of your voice. 3. The air continues through a series of tubes that connect the throat to the The tubes become smaller and smaller as they travel deeper into the lungs. This enables them to carry air to all parts of the MHR UNIT 1 TISSUES, ORGANS, AND 39/28/09 12:32:59 PM9/28/09 12:32:59 PMGas Exchange Takes Place in the AlveoliOnce air reaches the lungs, the actual exchange of gases occurs between the blood and the alveoli.

5 Alveoli are clusters of tiny air sacs in the lungs. Th e wall of each alveolus is a single layer of cells. Alveoli are surrounded by a network of tiny blood vessels called capillaries. Th e wall of each capillary also is a single layer of cells. Th e ultra-thin walls of both the alveoli and the capillaries allow the exchange of gases between the air and the blood, as shown in Figure Once the air enters the capillaries, oxygen from the air is taken up by the red blood cells. Th e red blood cells are responsible for transporting gases in the bloodstream. Oxygen diff uses through the walls of the alveoli, through the capillary walls, and into the red blood e blood also releases carbon dioxide into the lungs. Th e path that carbon dioxide follows is the reverse of the path that oxygen follows. Carbon dioxide diff uses from the blood through the capillary walls, through the walls of the alveoli, and into the alveoli.

6 Once in the lungs, the carbon dioxide is exhaled with the next : the smallest blood vesselred blood cells: blood cells that carry oxygen and carbon dioxide in the blood Figure Gas exchange occurs between the air in the alveoli and the blood in the LINKA ctivity , on page Why do you breathe?2. Where does gas exchange occur?3. Draw a fl owchart showing how air travels through the respiratory system when you breathe Figure shows that capillary walls are very thin. What would happen to a person with a disease that thickened the capillary walls?alveolicapillariesalveolusairred bloodcellscapillaryCO2CO2CO2CO2CO2O2O2O2 O2O2alveoli: air sacs in the lungs where gas exchange occurs (singular is alveolus)gas exchange: the process of taking in oxygen and releasing carbon dioxideTOPIC how do systems work together in the human BODY? MHR 59 49/28/09 12:33:03 PM9/28/09 12:33:03 PMto body cellsfrom body cellsfrom the lungsfrom the lungsfrom body cellsto body cellsto the lungsThe circulatory system transports dissolved gases and nutrients through the body.

7 The respiratory system carries oxygen to and removes carbon dioxide from the blood. Th e system that transports these gases between the lungs and the cells is the circulatory system . How the Circulatory system WorksTh e cells in the body require a constant supply of oxygen and nutrients. Th ey also require the removal of carbon dioxide and other wastes. Th e circulatory system ensures that both delivery and clean-up occur by transporting blood through the body. Th e blood carries oxygen and nutrients to the cells. It also carries carbon dioxide and other wastes away from the cells. Blood is pumped through the circulatory system by the heart and travels to and from the cells in the blood Heart: The Pump of the Circulatory SystemTh e heart is the muscular organ that drives the circulatory system . It pumps blood to the cells and then back to the heart. Th e arrows and numbers in Figures show the path that the blood takes as it moves through the body, heart, and The upper-right chamber (right atrium) receives carbon dioxide-rich blood from the The carbon-dioxide-rich blood moves into the lower-right chamber (right ventricle), which pumps it to the lungs.

8 Inside the lungs, the blood gets rid of the carbon dioxide and picks up oxygen The upper-left chamber (left atrium) receives the oxygen-rich blood from the The oxygen-rich blood moves into the lower-left chamber (left ventricle), which pumps it to the body Figure Blood fl ow through the human heart. The arrows show the direction of blood fl MHR UNIT 1 TISSUES, ORGANS, AND 59/28/09 12:33:08 PM9/28/09 12:33:08 PMBlood Vessels: The Branches of the Circulatory SystemTh ere are many diff erent blood vessels in the human body. Th e main blood vessels are arteries and veins. Th ese blood vessels branch out from the heart as shown in Figure As they move toward the cells, they branch out and grow smaller and smaller. Th is allows them to bring blood to all the cells in the body. As they move away from the cells, they combine and grow larger again.

9 Th e changes in the size of the blood vessels are shown in Figure Figure The arteries and veins in the circulatory system branch out from the heart. Oxygen-rich blood is shown in red. Carbon dioxide-rich blood is shown in blue. Figure Arteries carry oxygen-rich blood from the heart to the capillaries, where gas exchange takes place. From the capillaries, carbon dioxide-rich blood moves through the veins back to the List two functions of the circulatory Refer to Figure Agree or disagree with this statement and give your reasons: Th e heart, arteries, and veins exist to get the blood to the capillaries and from the capillaries. 3. Why do you think that the muscle around the left ventricle is larger than the one around the right ventricle? (Hint: How far does each ventricle have to pump blood?) artery veinvalvecapillaryCapillaries: The capillaries are the smallest blood vessels.

10 All the work of the circulatory system related to gas exchange takes place in the capillaries. They are one-cell thick. Oxygen and nutrients, plus carbon dioxide and other wastes, diffuse easily through the thin capillary : Arteries are thick-walled, elastic blood vessels that carry blood away from the heart. The arteries get narrower the farther they are from the : Veins are thin-walled, inelastic blood vessels. They have valves that keep blood from backing up as it is carried toward the LINKI nvestigation 1C, on page how do systems work together in the human BODY? MHR 61 69/28/09 12:33:14 PM9/28/09 12:33:14 PMThe digestive system breaks down food, absorbs nutrients, and eliminates solid digestive system is a 10 m long coil of churning muscle. Here are a few facts about the digestive system that you may fi nd surprising: Th e stomach contains chemicals that are as powerful as battery acid.