Human Body Challenge Practice
| # | Answer |
|---|---|
| 1 | The main function of the circulatory system is to transport oxygen, nutrients, hormones, and wastes throughout the body. |
| 2 | The heart. |
| 3 | Red blood cells carry oxygen from the lungs to body cells. |
| 4 | The respiratory system. |
| 5 | The neuron. |
| 6 | Homeostasis is the process of maintaining stable internal conditions in the body. |
| 7 | The kidneys. |
| 8 | The digestive system breaks down food, absorbs nutrients, and removes solid waste. |
| 9 | In the small intestine. |
| 10 | Alveoli are tiny air sacs where oxygen and carbon dioxide are exchanged with the blood. |
| 11 | Arteries carry blood away from the heart, while veins carry blood back to the heart. |
| 12 | Capillaries allow exchange of oxygen, nutrients, and wastes between blood and body tissues. |
| 13 | It protects organs, helps movement, stores minerals, and produces blood cells. |
| 14 | The cerebellum. |
| 15 | White blood cells help protect the body from infection and disease. |
| 16 | Breathing is the movement of air into and out of the lungs, while cellular respiration is the process cells use to release energy from glucose. |
| 17 | The diaphragm contracts to help air enter the lungs and relaxes to help air leave the lungs. |
| 18 | The skin is considered an organ because it is made of different tissues working together to protect the body and help regulate temperature. |
| 19 | The pancreas produces digestive enzymes that help break down food in the small intestine. |
| 20 | Hormones travel through the bloodstream and usually act more slowly, while nerve signals travel along neurons and act very quickly. |
| 21 | The nervous system sends signals to muscles, causing them to contract and produce movement. |
| 22 | The large intestine absorbs water and forms solid waste. |
| 23 | The heart muscle needs oxygen and nutrients to function, so it is supplied by coronary blood vessels. |
| 24 | Voluntary muscles are controlled consciously, while involuntary muscles work automatically without conscious control. |
| 25 | The immune system helps maintain homeostasis by defending the body against pathogens that could disrupt normal body functions. |
| 26 | The hypothalamus helps regulate body temperature, hunger, thirst, and other homeostatic processes. |
| 27 | Oxygen is needed for cellular respiration, which allows cells to produce usable energy in the form of ATP. |
| 28 | Breathing rate increases during exercise to bring in more oxygen and remove extra carbon dioxide. |
| 29 | Alveoli have thin walls, a large surface area, and many surrounding capillaries, which makes gas exchange efficient. |
| 30 | Red blood cells are shaped to increase surface area and have no nucleus, which gives them more room for hemoglobin. |
| 31 | The respiratory system brings oxygen into the lungs and removes carbon dioxide, while the circulatory system transports these gases between the lungs and body cells. |
| 32 | The nervous system provides fast responses, while the endocrine system provides slower, longer-lasting regulation. |
| 33 | Its long length and inner folds increase surface area for efficient nutrient absorption. |
| 34 | Wastes and extra water would build up in the body, disrupting homeostasis and potentially causing serious illness. |
| 35 | Enzymes speed up chemical reactions that break large food molecules into smaller molecules the body can absorb. |
| 36 | This statement is incomplete because digestion also occurs in the mouth, small intestine, and with help from enzymes made by organs such as the pancreas. |
| 37 | The body cools itself by sweating and by widening blood vessels near the skin to release heat. |
| 38 | Blood leaves the right side of the heart, goes to the lungs through the pulmonary arteries, picks up oxygen, and returns to the left side of the heart through the pulmonary veins. |
| 39 | The left side pumps blood to the entire body, so it needs a thicker muscular wall to generate greater pressure. |
| 40 | A neuron has long extensions called axons that carry signals over distances, and many are insulated by myelin to speed transmission. |
| 41 | The pancreas releases hormones such as glucagon, which signals the liver to release glucose into the blood and restore normal levels. |
| 42 | Feedback control helps the body detect changes and adjust internal conditions to keep them within a safe range. |
| 43 | The endocrine system can release hormones that reduce water loss, and the urinary system can conserve water by making urine more concentrated. |
| 44 | Muscles contract and pull on bones across joints, which creates movement. |
| 45 | Exercise increases muscle activity, so cells need more ATP, which requires more glucose and oxygen for cellular respiration. |
| 46 | Mechanical digestion physically breaks food into smaller pieces, and chemical digestion breaks molecules into smaller nutrients that cells can use. |
| 47 | The immune system recognizes molecules and signals that are normally part of body cells and responds to foreign or unusual markers on pathogens. |
| 48 | They might have difficulty with balance, posture, and coordinated movement. |
| 49 | Cells need stable conditions such as temperature, pH, and water balance so enzymes and metabolic processes can work efficiently. |
| 50 | These changes increase oxygen delivery, remove carbon dioxide, and help control body temperature so muscles can keep producing energy efficiently during exercise. |