CHAPTER 24 2 The Urinary System SECTION The Digestive and Urinary Systems BEFORE YOU READ After you read this section, you should be able to answer these questions: What is the function of the urinary system? How do the kidneys filter the blood? What are common problems with the urinary system? National Science Education Standards LS 1a, 1c, 1d, 1e, 1f, 3a, 3b What Does the Urinary System Do? As your cells break down food for energy, they produce waste. Your body must get rid of this waste or it could poison you! As blood moves through the body and drops off oxygen, it picks up the waste from cells. The urinary system is made of organs that take wastes from the blood and send them out of the body. The chart below describes the main organs of the urinary system. STUDY TIP Underline As you read, underline any unfamiliar words. Use the glossary or a dictionary to find out what these words mean. Write the definitions in the margins of the text. Organ What it looks like Function Kidneys a pair of organs to clean the blood and produce urine Ureters pair of thin tubes leading from the to carry urine from the kidneys to the bladder kidneys to the bladder Urinary bladder a sac to store urine Urethra tube leading from the bladder to outside your body to carry urine out of the body 1. Identify Which organs clean the blood? The Urinary System Kidney Urinary bladder 2. Identify Use the chart above to help you label the organs of the urinary system. Interactive Textbook 389 The Digestive and Urinary Systems
SECTION 2 The Urinary System continued Math Focus 3. Calculate Your kidneys filter about 2,000 L of blood each day. Your body has about 5.6 L of blood. About how many times does your blood cycle through your kidneys each day? How Do the Kidneys Clean the Blood? The kidneys are a pair of organs that clean the blood. Each kidney is made of many small filters called nephrons. Nephrons remove waste from the blood. One of the most important substances that nephrons remove is urea. Urea is formed when your cells use protein for energy. The figure below shows how kidneys clean the blood. How the Kidneys Filter Blood 1 Blood enters the kidney through an artery and moves into nephrons. 2 Water, sugar, salts, urea, and other waste products move out of the blood and into the nephron. 3 The nephron returns most of the water and nutrients to the blood. The wastes are left in the nephron. 4 The cleaned blood leaves the kidney and goes back to the body. 5 The waste left in the nephron is a yellow fluid called urine. Urine leaves the kidneys through tubes called ureters. 6 The urine is stored in the bladder. Urine leaves the body through the urethra. Nephron Artery Unfiltered blood 4. Explain What happens to blood after it is cleaned in the kidneys? Filtered blood Vein Ureter 5. Identify What structures carry urine from the kidneys? Urine Interactive Textbook 390 The Digestive and Urinary Systems
SECTION 2 The Urinary System continued How Does the Urinary System Control Water? You lose water every day in sweat and urine, and you replace water when you drink. You need to get rid of as much water as you drink. If you don t, your body will swell up. Chemical messengers called hormones help control this balance. One of these hormones is called antidiuretic hormone (ADH). ADH keeps your body from losing too much water. When there is not much water in your blood, ADH tells the nephrons to put water back in the blood. The body then makes less urine. If there is too much water in your blood, your body releases less ADH. Critical Thinking 6. Infer What do you think happens when your body releases less ADH? Drinking water when you exercise helps replace the water you lose when you sweat. Some drinks contain caffeine, which is a diuretic. Diuretics cause kidneys to make more urine. This means that a drink with caffeine can actually cause you to lose water. What Problems Can Happen in the Urinary System? The chart below shows some common problems of the urinary system. Problem Description Treatment Bacterial infections Kidney stones Bacteria can infect the urinary system and cause pain or permanent damage. Wastes can be trapped in the kidney and form small stones. They can stop urine flow and cause pain. Damage to the nephrons can stop the kidneys from working. Antibiotics Most can pass out of the body on their own. Some may need to be removed by a doctor. 7. Explain What problems do kidney stones cause? Kidney disease A kidney machine can be used to filter the blood. Interactive Textbook 391 The Digestive and Urinary Systems
Section 2 NSES LS 1a, 1c, 1d, 1e, 1f, 3a, 3b SECTION VOCABULARY kidney one of the pair of organs that filter water and wastes from the blood and that excrete products as urine nephron the unit in the kidney that filters blood urinary system the organs that make, store, and eliminate urine. 1. List What are the main organs that make up the urinary system? 2. Summarize Complete the process chart to show how blood is filtered. a. Water is put back in the blood. b. Blood goes into the kidney. c. Water and waste go into the nephron. d. Nephrons separate water and waste. 3. Apply Concepts Which of the following has more water: the blood going into the kidney, or the blood leaving it? Explain your answer. 4. Explain How does the urinary system control the amount of water in the body? 5. Infer Is it a good idea to drink beverages with caffeine when you are exercising? Explain your answer. Interactive Textbook 392 The Digestive and Urinary Systems
Life Science Answer Key continued 3. blood plasma, dead cells, pathogens 4. Lymph tissue must be spread out to collect fluid from all areas of the body. SECTION 4 THE RESPIRATORY SYSTEM 1. the way your body gains and uses oxygen and gets rid of carbon dioxide 2. nose, pharynx, larynx, trachea, lung, bronchus, diaphragm 3. It is the main passageway into and out of the respiratory system. 4. the main passageway to the lungs 5. alveoli 6. The person would be unable to inhale. 7. Oxygen moves into the alveoli in the lungs. Then it moves into the blood in the capillaries. It moves from the blood into the other cells in your body. 1. asthma, emphysema, SARS 2. Cellular respiration is the process in which cells use oxygen to break down glucose. The process produces carbon dioxide. 3. Breathing involves only inhaling and exhaling. Respiration involves everything that allows your body to take in oxygen, use it for energy production, and get rid of carbon dioxide. 4. Air can also enter and leave through the mouth. 5. The vocal cords stretch across the larynx. When air moves over them, they vibrate and produce sound. 6. A respiratory disorder can prevent a person from getting enough oxygen. It can also prevent the person from getting rid of enough carbon dioxide. Chapter 24 The Digestive and Urinary Systems SECTION 1 THE DIGESTIVE SYSTEM 1. digestive tract 2. The mouth, pharynx, esophagus, stomach, small intestine, and large intestine should be shaded. 3. The digestive system breaks down food into molecules that are absorbed by the blood in the circulatory system. 4. Chewing helps break your food into smaller pieces and helps mix the food with saliva. 5. 5:8 6. mechanical and chemical 7. to chemically digest chyme 8. to break down fat into small droplets 9. stomach and small intestine 10. A large surface area lets the small intestine absorb as many nutrients from food as possible. 11. They are absorbed by villi and passed into the bloodstream. 1. liver, gallbladder, salivary glands, pancreas 2. Saliva has enzymes that start the breakdown of starches into simple sugars. 3. In mechanical digestion, food is broken, crushed, or mashed. In chemical digestion, large food molecules are broken down into nutrients. 4. mouth, stomach, small intestine 5. The small intestine is long, with folds and cells that absorb nutrients. These give the small intestine a large surface area so more nutrients can be taken into the blood. 6. If the liver did not make bile, fats would not be digested well. There would also be nothing to store in the gallbladder. SECTION 2 THE URINARY SYSTEM 1. the kidneys 2. From top to bottom: ureter, urinary bladder 3. about 350 times 4. The blood flows back to the body. 5. ureters 6. The nephrons do not put as much water back into the blood. You make more urine. 7. They can block the flow of urine and cause pain. 1. kidneys, ureters, urinary bladder, urethra 2. b. Blood goes into the kidney. c. Water and waste go into the nephron. d. Nephrons separate water and waste. a. Water is put back in the blood. 3. The blood leaving the kidney has less water. The nephrons have to take some water from the blood to produce urine. Interactive Textbook Answer Key 27 Life Science
Life Science Answer Key continued 4. ADH tells the nephrons to put more water back in the blood so that you do not lose too much water as urine. When your body has too much water, less ADH is produced. 5. No, caffeine makes you lose water. As you sweat, you also lose water. When you exercise, you need to drink beverages that will help you replace water. Chapter 25 Communication and Control SECTION 1 THE NERVOUS SYSTEM 1. central and peripheral nervous system 2. Part of the nervous system Central nervous system (CNS) Peripheral (PNS) What it includes the brain and the spinal cord all parts of the except the brain and spinal cord What it does takes in and responds to messages from the PNS connects the body to the CNS, carries information to and from the CNS 3. 0.1 seconds 4. Arrow should point toward cell body. 5. You wouldn t be able to move or to feel anything. 6. somatic and autonomic 7. Lifting the pizza to your mouth and chewing are voluntary. Digesting the pizza is involuntary. 8. sympathetic and parasympathetic 9. voluntary movements 10. The left hemisphere, because it mainly controls activities such as reading and writing. 11. to keep track of your body s position, to help you keep your balance 12. medulla 13. cerebrum 14. The vertebrae of the skeletal system protect the spinal cord of the. 15. by using proper safety equipment 1. The CNS receives and interprets messages from the PNS. It also sends signals back to the PNS to tell the body what to do. The PNS carries information between the CNS and the body. 2. First row blanks: central, peripheral Second row blanks: autonomic Bottom row blanks: parasympathetic 3. Dendrites bring information to the cell body. Axons carry information away from the cell body. 4. An injury to the spinal cord can block messages to and from the brain. A person with a spinal cord injury may not be able to move parts of his or her body or feel pain, touch, or temperature. SECTION 2 RESPONDING TO THE ENVIRONMENT 1. pressure, pain, heat 2. brain 3. They reflect red light. 4. rods and cones 5. to control how much light enters your eye 6. to focus light on the retina 7. Ear canal should be blue; ear drum and ear bones should be green; cochlea and cochlear nerve should be red. 8. vibrations 9. Your brain uses taste buds and your nose to detect flavor. When you have a cold, your brain doesn t get as much information from your nose. 1. touch, sight, hearing, taste, smell 2. The integumentary system includes your skin. Your skin has sensory receptors that send messages through your. 3. Reflexes are reactions you can t control. They are not controlled by the brain. Reflexes let your body respond quickly to protect it from getting hurt. 4. Rods let you see in black and white, and cones let you see in color. Rods help you see at night, and cones help you see fine details. Interactive Textbook Answer Key 28 Life Science