How is air conducted through the human respiratory system?

1. A quiz for Chapter 33 How is air conducted through the human respiratory system? (Listing the structures through which air flows and the structure in which gas exchange occurs.)

2. 34 Nutrition and Digestion 0

3. 34.1 What Nutrients Do Animals Need? 34.2 How Does Digestion Occur? 34.3 How Do Humans Digest Food? Chapter 34 At a Glance

4. Nutrients are substances obtained from the environment that organisms need for their growth and survival Nutrients fall into six major categories 1. Carbohydrates 2. Lipids 3. Proteins 4. Minerals 5. Vitamins 6. Water 34.1 What Nutrients Do Animals Need?

5. Most energy is provided by carbohydrates and lipids Cells rely on a supply of energy to maintain their complexity and wide range of activities; without this energy, cells die within minutes Nutrients that supply energy are lipids, carbohydrates, and proteins These molecules are broken down by digestion to their subunits, which are used during cellular respiration Energy from these subunits is released and is captured in ATP 34.1 What Nutrients Do Animals Need?

6. Most energy is provided by carbohydrates and lipids (continued) Energy from nutrients is measured in calories A calorie is the amount of energy required to raise 1 gram of water 1C Food calorie content is measured in units of 1,000 calories (kilocalories), also known as Calories (capital “C”) About 60% of the caloric energy in food is released as heat; the remaining 40% is captured in ATP 34.1 What Nutrients Do Animals Need?

7. Most energy is provided by carbohydrates and lipids (continued) Energy from nutrients is measured in calories (continued) The average human burns 70 Calories per hour at rest, but this value is influenced by several factors People differ in metabolic rate, the speed at which cellular reactions occur Exercise significantly boosts Caloric requirements; well- trained athletes can burn nearly 20 Calories per minute 34.1 What Nutrients Do Animals Need?

8. Table 34-1

9. Most energy is provided by carbohydrates and lipids (continued) Carbohydrates are a source of quick energy Carbohydrates include sugars such as glucose葡萄糖, from which cells derive most of their energy; sucrose蔗糖(table sugar); and polysaccharides多糖, long chains of sugar molecules Cellulose纤维素, starch淀粉, and glycogen糖元are all polysaccharides composed of chains of glucose 34.1 What Nutrients Do Animals Need?

10. Most energy is provided by carbohydrates and lipids (continued) Carbohydrates are a source of quick energy (continued) Cellulose, the major structural component of plant cell walls, is the most abundant carbohydrate on the planet Only a few animals are able to digest cellulose Starch is the principle energy-storage material of plants, and a major source of energy for humans and many other animals 34.1 What Nutrients Do Animals Need?

11. Most energy is provided by carbohydrates and lipids (continued) Carbohydrates are a source of quick energy (continued) Glycogen is used by animals for short-term energy storage Animals, including humans, store glycogen in the liver and muscles Although humans can accumulate hundreds of pounds of fat, most can store less than a pound of glycogen 34.1 What Nutrients Do Animals Need?

12. Most energy is provided by carbohydrates and lipids (continued) Fats and oils are the most concentrated energy source Fats and oils contain over twice as many Calories per unit weight as do carbohydrates or proteins When an animal’s diet provides more energy than it expends, most of the excess carbohydrates and fats are stored as body fat Fat is hydrophobic, and so neither attracts nor dissolves in water, as carbohydrates and proteins do 34.1 What Nutrients Do Animals Need?

13. Most energy is provided by carbohydrates and lipids (continued) Fats and oils are the most concentrated energy source (continued) When an animal’s diet provides more energy than it expends, most of the excess carbohydrates and fats are stored as body fat (continued) Because of this, stored fat does not accumulate water, and so more energy can be stored per unit of weight from fats than from other molecules Fat deposits also provide insulation for animals living in cold environments, such as seals海豹, whales鲸鱼, and walruses海象 34.1 What Nutrients Do Animals Need?

14. Figure 34-1 Fat provides insulation

15. Most energy is provided by carbohydrates and lipids (continued) An evolutionary tendency to store fat can lead to obesity肥胖症when food is abundant Our natural tendency to overeat can become a liability, and some of us need to exert considerable willpower to avoid storing excessive amounts of fat and becoming overweight The body mass index (BMI)体质指数is based on weight and height BMI =Kg/m2 34.1 What Nutrients Do Animals Need?

16. Most energy is provided by carbohydrates and lipids (continued) An evolutionary tendency to store fat can lead to obesity when food is abundant (continued) For people with average amounts of muscle, a BMI between 18.5 and 24.9 is considered healthy In the United States, about 33% of all adults are overweight and an additional 33% are obese 34.1 What Nutrients Do Animals Need?

17. Essential nutrients provide the raw materials原材料for health Our cells can synthesize most of the molecules our bodies require, but they cannot synthesize certain raw materials, called essential nutrients必需营养素, which must be supplied in the diet Essential nutrients for humans include certain fatty acids and amino acids, a variety of minerals and vitamins, and water 34.1 What Nutrients Do Animals Need?

18. Essential nutrients provide the raw materials for health (continued) Certain fatty acids are essential in the human diet Fats and oils provide a source of energy, but also provide essential fatty acids Essential fatty acids serve as raw materials used to synthesize molecules in a wide range of physiological activities 34.1 What Nutrients Do Animals Need?

19. Essential nutrients provide the raw materials for health (continued) Certain fatty acids are essential in the human diet (continued) They help us to absorb fat-soluble vitamins, and are important in cell division, fetal development, and the immune response Sources of essential fatty acids are fish oils, canola oil菜籽油, soybean oil, flaxseed亚麻籽油, and walnuts 34.1 What Nutrients Do Animals Need?

20. Essential nutrients provide the raw materials for health (continued) Amino acids form the building blocks of protein Proteins form muscle, connective tissue, nails, and hair They act as enzymes, receptors on cell membranes, and antibodies The human body cannot synthesize 9 (adults) or 10 (infants， histone) of the 20 different amino acids used in the proteins 34.1 What Nutrients Do Animals Need?

21. Essential nutrients provide the raw materials for health (continued) Amino acids form the building blocks of protein (continued) These essential amino acids must be obtained from protein-rich foods such as meat, milk, eggs, corn, beans, and soybeans Protein deficiency can result in a number of debilitating虚弱conditions, including kwashiorkor夸休可尔症，恶性营养不良, which occurs most frequently in poverty-stricken非常贫穷的countries 34.1 What Nutrients Do Animals Need?

22. Figure 34-2 Kwashiorkor is caused by protein deficiency

23. Essential nutrients provide the raw materials for health (continued) Minerals are elements required by the body Minerals are elements that play many crucial roles in animal nutrition and can only be obtained in the diet or dissolved in drinking water Calcium钙, magnesium镁, and phosphorus磷are major constituents of bone and teeth Sodium钠, calcium钙, and potassium钾are needed for muscle contraction and the conduction of nerve impulses 34.1 What Nutrients Do Animals Need?

24. Essential nutrients provide the raw materials for health (continued) Minerals are elements required by the body (continued) Iron 铁is a central component of hemoglobin in the blood, and iodine碘 is found in hormones produced by the thyroid gland 甲状腺 Animals also require trace amounts of zinc锌, magnesium锰, copper铜, and chromium铬 34.1 What Nutrients Do Animals Need?

25. Table 34-2

26. Essential nutrients provide the raw materials for health (continued) Vitamins play many roles in metabolism Vitamins are organic molecules that animals require in small amounts for normal cell function, growth, and development Human vitamins are grouped into two categories: water soluble or fat soluble 34.1 What Nutrients Do Animals Need?

27. Table 34-3, 1 of 2

28. Table 34-3, 2 of 2

29. Vitamins play many roles in metabolism (continued) Water-soluble vitamins Water-soluble vitamins include vitamin C and the nine compounds that make up the B-vitamin complex Because these substances dissolve in the watery blood plasma and are filtered out by the kidneys, they are not stored in appreciable amounts Most water-soluble vitamins act as coenzymes辅酶 They work in conjunction with enzymes to promote chemical reactions that supply energy 34.1 What Nutrients Do Animals Need?

30. Vitamins play many roles in metabolism (continued) Water-soluble vitamins (continued) Because each vitamin participates in several metabolic processes, a deficiency of a single vitamin can have wide-ranging effects Deficiency of the B vitamin niacin烟酸， B3causes the swollen tongue and skin lesions of pellagra陪拉格病，糙皮病, as well as some nervous disorders Folic acid叶酸, another B vitamin, is required to synthesize thymine, a component of DNA 34.1 What Nutrients Do Animals Need?

31. Vitamins play many roles in metabolism (continued) Water-soluble vitamins (continued) Folic acid deficiency impairs cell division throughout the body It is particularly important for pregnant women to get enough folic acid to supply a rapidly growing fetus Folic acid deficiency can lead to a reduction in red blood cells, leading to anemia 34.1 What Nutrients Do Animals Need?

32. Figure 34-3 Pellagra is caused by niacin deficiency

33. Vitamins play many roles in metabolism (continued) Fat-soluble vitamins Fat-soluble vitamins can be stored in body fat and may accumulate in the body over time The fat-soluble vitamins A, D, E, and K have a variety of functions Vitamin A is used to synthesize the light-capturing molecule in the retina of the eye Vitamin D is required for bone formation; its deficiency can lead to bone deformities such as rickets佝偻病 34.1 What Nutrients Do Animals Need?

34. Figure 34-4 Rickets is caused by vitamin D deficiency

35. Vitamins play many roles in metabolism (continued) Fat-soluble vitamins (continued) The fat-soluble vitamins A, D, E, and K have a variety of functions (continued) Vitamin E is an antioxidant, neutralizing free radicals 自由基that form in the body Vitamin K helps to regulate blood clotting 34.1 What Nutrients Do Animals Need?

36. The human body is about 60% water A person can survive far longer without food than without water All metabolic reactions occur in a watery solution, and water participates directly in hydrolysis reactions that break down proteins, carbohydrates, and fats Water is the principal component of saliva, blood, lymph, interstitial fluid, and cytosol within each cell 34.1 What Nutrients Do Animals Need?

37. The human body is about 60% water (continued) A person can survive far longer without food than without water (continued) By sweating, people use the evaporation of water to keep from overheating Urine, which is mostly water, is necessary to eliminate cellular waste products from the body 34.1 What Nutrients Do Animals Need?

38. Digestion is the process that physically grinds up food and then chemically breaks it down The animal digestive system consists of a series of compartments in which food is processed, as well as organs that produce secretions that aid in digestion The digestive system takes food, breaks down complex food molecules into simpler molecules, absorbs nutrients, and then expels leftover wastes from the body 34.2 How Does Digestion Occur?

39. Animals eat the bodies of other organisms, but some body parts are difficult to digest Each plant cell, for example, is supported by a wall of indigestible cellulose Animal bodies may be covered with chitin, fur, scales, or feathers In addition, the complex lipids, proteins, and carbohydrates in food do not occur in a form that can be used directly 34.2 How Does Digestion Occur?

40. All digestive systems perform five tasks 1. Ingestion采食: Food is brought into the digestive tract through an opening, usually called a mouth 2. Mechanical digestion: The food is physically broken down into smaller pieces that have a greater surface area than do larger particles, allowing digestive enzymes to attack them more efficiently 3. Chemical digestion: Digestive chemicals and enzymes break down large food molecules into smaller subunits 34.2 How Does Digestion Occur?

41. All digestive systems perform five tasks (continued) 4. Absorption: The small subunits are transported out of the digestive tract through cells lining the digestive tract to the blood for use by body cells 5. Elimination: Indigestible materials are expelled from body 34.2 How Does Digestion Occur?

42. In sponges, digestion occurs within single cells Sponges are sedentary filter-feeders that lack a digestive system and rely exclusively on intracellular digestion, in which digestion occurs within individual cells This limits their food to microscopic particles 34.2 How Does Digestion Occur?

43. In sponges, digestion occurs within single cells (continued) Sponges are permanently attached to rocks, circulating seawater with food particles through pores in their bodies Specialized collar cells领细胞 engulf microscopic food particles in the water and ingest them using phagocytosis吞噬作用, forming a food vacuole液泡 34.2 How Does Digestion Occur?

44. In sponges, digestion occurs within single cells (continued) The food vacuole fuses with alysozome溶酶体, a membrane-enclosed packet of digestive enzymes within the cell that breaks down the food into smaller molecules The smaller food molecules are absorbed into the cell cytoplasm Indigestible material is expelled from the cell and sponge through a large opening in the body wall 34.2 How Does Digestion Occur?

45. Figure 34-6 Intracellular digestion in a sponge Water, uneaten food, and wastes are expelled through the large opening at one end of the sponge Waste products are expelled by exocytosis H2O H2O Tube sponges The food vacuole merges with a lysosome where digestion occurs collar cell H2O carrying food particles enters the pores collar H2O H2O Food particles are filtered from the water by the collar lysosome with digestive enzymes food vacuole Food enters the collar cell by phagocytosis, forming a food vacuole A simple sponge Collar cell

46. The simplest digestive system is a chamber with one opening All animals except sponges have evolved a chamber within the body in which chunks of food are broken down by enzymes outside the cells, a process called extracellular digestion A sac with one opening is the simplest digestive system, and is found in the cnidarians such as sea anemones海葵, Hydra水螅, and sea jellies 34.2 How Does Digestion Occur?

47. The simplest digestive system is a chamber with one opening (continued) The cnidarians, such as anemones, have a gastrovascular cavity胃循环腔;腔肠, which has a single opening through which food is ingested and wastes are ejected The animal’s stinging刺一样的tentacles触须capture smaller animals and push this prey through the mouth into the gastrovascular cavity Gland cells lining the cavity secrete enzymes that begin digesting the prey 34.2 How Does Digestion Occur?

48. The simplest digestive system is a chamber with one opening (continued) The cnidarians, such as anemones, have a gastrovascular cavity, which has a single opening through which food is ingested and wastes are ejected (continued) Nutritive cells营养细胞lining the cavity then absorb the nutrients and also engulf partly digested food particles by phagocytosis Further digestion is intracellular, within food vacuoles in the nutritive cells 34.2 How Does Digestion Occur?

49. Figure 34-7 Digestion in a sac prey Hydra with prey Tentacles with stinging cells capture the prey and carry it into the mouth mouth Gland cells secrete digestive enzymes into the gastrovascular cavity; extracellular digestion begins prey Nutritive cells engulf food particles and complete digestion within food vacuoles gastrovascular cavity Food processing in Hydra

50. Most animals have tubular digestive systems with specialized compartments Most animals, including all vertebrates and invertebrates such as mollusks软体动物, arthropods节肢动物, echinoderms棘皮类动物, and earthworms, have digestive systems that are one-way tubes that begin with a mouth and end with an anus 34.2 How Does Digestion Occur?