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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell.

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1 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 40 Basic Principles of Animal Form and Function

2 Overview: Diverse Forms, Common Challenges Anatomy is the study of the biological form of an organism Physiology is the study of the biological functions an organism performs The comparative study of animals reveals that form and function are closely correlated Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3 Fig. 40-1

4 Concept 40.1: Animal form and function are correlated at all levels of organization Size and shape affect the way an animal interacts with its environment Many different animal body plans have evolved and are determined by the genome Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

5 Physical Constraints on Animal Size and Shape The ability to perform certain actions depends on an animals shape, size, and environment Evolutionary convergence reflects different species adaptations to a similar environmental challenge Physical laws impose constraints on animal size and shape Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Video: Galápagos Sea Lion Video: Galápagos Sea Lion Video: Shark Eating Seal Video: Shark Eating Seal

6 Fig (a) Tuna (b) Penguin (c) Seal

7 Exchange with the Environment An animals size and shape directly affect how it exchanges energy and materials with its surroundings Exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells plasma membranes A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Video: Hydra Eating Daphnia Video: Hydra Eating Daphnia

8 Fig Exchange 0.15 mm (a) Single cell 1.5 mm (b) Two layers of cells Exchange Mouth Gastrovascular cavity

9 Multicellular organisms with a sac body plan have body walls that are only two cells thick, facilitating diffusion of materials Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

10 More complex organisms have highly folded internal surfaces for exchanging materials Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

11 Fig cm Nutrients Digestive system Lining of small intestine Mouth Food External environment Animal body CO 2 O2O2 Circulatory system Heart Respiratory system Cells Interstitial fluid Excretory system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Kidney tubules 10 µm 50 µm Lung tissue

12 In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells A complex body plan helps an animal in a variable environment to maintain a relatively stable internal environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

13 Most animals are composed of specialized cells organized into tissues that have different functions Tissues make up organs, which together make up organ systems Hierarchical Organization of Body Plans Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

14 Table 40-1

15 Different tissues have different structures that are suited to their functions Tissues are classified into four main categories: epithelial, connective, muscle, and nervous Tissue Structure and Function Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

16 Epithelial Tissue Epithelial tissue covers the outside of the body and lines the organs and cavities within the body It contains cells that are closely joined The shape of epithelial cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

17 The arrangement of epithelial cells may be simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

18 Fig. 40-5a Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium

19 Fig. 40-5b Apical surface Basal surface Basal lamina 40 µm

20 Connective Tissue Connective tissue mainly binds and supports other tissues It contains sparsely packed cells scattered throughout an extracellular matrix The matrix consists of fibers in a liquid, jellylike, or solid foundation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

21 Fig. 40-5c Connective Tissue Collagenous fiber Loose connective tissue Elastic fiber 120 µm Cartilage Chondrocytes 100 µm Chondroitin sulfate Adipose tissue Fat droplets 150 µm White blood cells 55 µm Plasma Red blood cells Blood Nuclei Fibrous connective tissue 30 µm Osteon Bone Central canal 700 µm

22 Muscle Tissue Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals It is divided in the vertebrate body into three types: – Skeletal muscle, or striated muscle, is responsible for voluntary movement – Smooth muscle is responsible for involuntary body activities – Cardiac muscle is responsible for contraction of the heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

23 Fig. 40-5j Muscle Tissue 50 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth muscle Cardiac muscle Nucleus Muscle fibers 25 µm Nucleus Intercalated disk

24 Nervous Tissue Nervous tissue senses stimuli and transmits signals throughout the animal Nervous tissue contains: – Neurons, or nerve cells, that transmit nerve impulses – Glial cells, or glia, that help nourish, insulate, and replenish neurons Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

25 Fig. 40-5n Glial cells Nervous Tissue 15 µm Dendrites Cell body Axon Neuron Axons Blood vessel 40 µm

26 Coordination and Control Control and coordination within a body depend on the endocrine system and the nervous system The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood A hormone may affect one or more regions throughout the body Hormones are relatively slow acting, but can have long-lasting effects Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

27 Fig Stimulus Hormone Endocrine cell Signal travels everywhere via the bloodstream. Blood vessel Response (a) Signaling by hormones Stimulus Neuron Axon Signal Signal travels along axon to a specific location. Signal Axons Response (b) Signaling by neurons

28 Concept 40.2: Feedback control loops maintain the internal environment in many animals Animals manage their internal environment by regulating or conforming to the external environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

29 A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation A conformer allows its internal condition to vary with certain external changes Regulating and Conforming Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

30 Fig River otter (temperature regulator) Largemouth bass (temperature conformer) Body temperature (°C) Ambient (environmental) temperature (ºC)

31 Homeostasis Organisms use homeostasis to maintain a steady state or internal balance regardless of external environment In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

32 Fig Response: Heater turned off Stimulus: Control center (thermostat) reads too hot Room temperature decreases Set point: 20ºC Room temperature increases Stimulus: Control center (thermostat) reads too cold Response: Heater turned on

33 Feedback Loops in Homeostasis The dynamic equilibrium of homeostasis is maintained by negative feedback, which helps to return a variable to either a normal range or a set point Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off Positive feedback loops occur in animals, but do not usually contribute to homeostasis Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

34 Concept 40.3: Homeostatic processes for thermoregulation involve form, function, and behavior Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

35 Endothermic animals generate heat by metabolism; birds and mammals are endotherms Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and non- avian reptiles Endothermy and Ectothermy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

36 In general, ectotherms tolerate greater variation in internal temperature, while endotherms are active at a greater range of external temperatures Endothermy is more energetically expensive than ectothermy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

37 Fig (a) A walrus, an endotherm (b) A lizard, an ectotherm

38 Variation in Body Temperature The body temperature of a poikilotherm varies with its environment, while that of a homeotherm is relatively constant Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

39 Balancing Heat Loss and Gain Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

40 Fig RadiationEvaporation ConvectionConduction

41 Heat regulation in mammals often involves the integumentary system: skin, hair, and nails Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

42 Fig Epidermis Dermis Hypodermis Adipose tissue Blood vessels Hair Sweat pore Muscle Nerve Sweat gland Oil gland Hair follicle

43 Five general adaptations help animals thermoregulate: – Insulation – Circulatory adaptations – Cooling by evaporative heat loss – Behavioral responses – Adjusting metabolic heat production Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

44 Insulation Insulation is a major thermoregulatory adaptation in mammals and birds Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

45 Regulation of blood flow near the body surface significantly affects thermoregulation Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin In vasodilation, blood flow in the skin increases, facilitating heat loss In vasoconstriction, blood flow in the skin decreases, lowering heat loss Circulatory Adaptations Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

46 The arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange Countercurrent heat exchangers transfer heat between fluids flowing in opposite directions Countercurrent heat exchangers are an important mechanism for reducing heat loss Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

47 Fig Canada gooseBottlenose dolphin Artery Vein Blood flow 33º35ºC 27º 30º 18º 20º 10º9º

48 Some bony fishes and sharks also use countercurrent heat exchanges Many endothermic insects have countercurrent heat exchangers that help maintain a high temperature in the thorax Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

49 Cooling by Evaporative Heat Loss Many types of animals lose heat through evaporation of water in sweat Panting increases the cooling effect in birds and many mammals Sweating or bathing moistens the skin, helping to cool an animal down Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

50 Both endotherms and ectotherms use behavioral responses to control body temperature Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat Behavioral Responses Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

51 Fig

52 Adjusting Metabolic Heat Production Some animals can regulate body temperature by adjusting their rate of metabolic heat production Heat production is increased by muscle activity such as moving or shivering Some ectotherms can also shiver to increase body temperature Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

53 Fig RESULTS Contractions per minute O 2 consumption (mL O 2 /hr) per kg

54 Fig PREFLIGHT WARM-UP FLIGHT Thorax Abdomen Time from onset of warm-up (min) Temperature (ºC)

55 Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes When temperatures are subzero, some ectotherms produce antifreeze compounds to prevent ice formation in their cells Acclimatization in Thermoregulation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

56 Physiological Thermostats and Fever Thermoregulation is controlled by a region of the brain called the hypothalamus The hypothalamus triggers heat loss or heat generating mechanisms Fever is the result of a change to the set point for a biological thermostat Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

57 Fig Sweat glands secrete sweat, which evaporates, cooling the body. Thermostat in hypothalamus activates cooling mechanisms. Blood vessels in skin dilate: capillaries fill; heat radiates from skin. Increased body temperature Decreased body temperature Thermostat in hypothalamus activates warming mechanisms. Blood vessels in skin constrict, reducing heat loss. Skeletal muscles contract; shivering generates heat. Body temperature increases; thermostat shuts off warming mechanisms. Homeostasis: Internal temperature of 36–38°C Body temperature decreases; thermostat shuts off cooling mechanisms.

58 Concept 40.4: Energy requirements are related to animal size, activity, and environment Bioenergetics is the overall flow and transformation of energy in an animal It determines how much food an animal needs and relates to an animals size, activity, and environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

59 Energy Allocation and Use Animals harvest chemical energy from food Energy-containing molecules from food are usually used to make ATP, which powers cellular work After the needs of staying alive are met, remaining food molecules can be used in biosynthesis Biosynthesis includes body growth and repair, synthesis of storage material such as fat, and production of gametes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

60 Fig Organic molecules in food External environment Animal body Digestion and absorption Nutrient molecules in body cells Carbon skeletons Cellular respiration ATP Heat Energy lost in feces Energy lost in nitrogenous waste Heat Biosynthesis Heat Cellular work

61 Metabolic rate is the amount of energy an animal uses in a unit of time One way to measure it is to determine the amount of oxygen consumed or carbon dioxide produced Quantifying Energy Use Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

62 Fig

63 Minimum Metabolic Rate and Thermoregulation Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a comfortable temperature Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature Both rates assume a nongrowing, fasting, and nonstressed animal Ectotherms have much lower metabolic rates than endotherms of a comparable size Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

64 Size and Metabolic Rate Metabolic rate per gram is inversely related to body size among similar animals Researchers continue to search for the causes of this relationship The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

65 Fig Elephant Horse Human Sheep Dog Cat Rat Ground squirrel Mouse Harvest mouse Shrew Body mass (kg) (log scale) BMR (L O 2 /hr) (Iog scale) 10 –3 10 –2 10 – (a) Relationship of BMR to body size Shrew Mouse Harvest mouse Sheep Rat Cat Dog Human Horse Elephant BMR (L O 2 /hr) (per kg) Ground squirrel Body mass (kg) (log scale) 10 –3 10 –2 10 – (b) Relationship of BMR per kilogram of body mass to body size

66 Activity greatly affects metabolic rate for endotherms and ectotherms In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity Activity and Metabolic Rate Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

67 Different species use energy and materials in food in different ways, depending on their environment Use of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, and reproduction Energy Budgets Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

68 Fig Annual energy expenditure (kcal/hr) 60-kg female human from temperate climate 800,000 Basal (standard) metabolism Reproduction Thermoregulation Growth Activity 340,000 4-kg male Adélie penguin from Antarctica (brooding) 4, kg female deer mouse from temperate North America 8,000 4-kg female eastern indigo snake EndothermsEctotherm

69 Torpor and Energy Conservation Torpor is a physiological state in which activity is low and metabolism decreases Torpor enables animals to save energy while avoiding difficult and dangerous conditions Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

70 Fig Additional metabolism that would be necessary to stay active in winter Actual metabolism Arousals Body temperature Outside temperature Burrow temperature Metabolic rate (kcal per day) Temperature (°C) JuneAugustOctoberDecemberFebruaryApril –15 –10 –

71 Estivation, or summer torpor, enables animals to survive long periods of high temperatures and scarce water supplies Daily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

72 PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 41 Animal Nutrition

73 Fig Omnivore, Herbivore, or Carnivore?

74 Concept 41.1: An animals diet must supply chemical energy, organic molecules, and essential nutrients An animals diet provides chemical energy, which is converted into ATP and powers processes in the body Animals need a source of organic carbon and organic nitrogen in order to construct organic molecules Essential nutrients are required by cells and must be obtained from dietary sources

75 Essential Nutrients There are four classes of essential nutrients: – Essential amino acids – Essential fatty acids – Vitamins – Minerals

76 Essential Amino Acids Animals require 20 amino acids and can synthesize about half from molecules in their diet The remaining amino acids, the essential amino acids, must be obtained from food in preassembled form A diet that provides insufficient essential amino acids causes malnutrition called protein deficiency

77 Meat, eggs, and cheese provide all the essential amino acids and are thus complete proteins Most plant proteins are incomplete in amino acid makeup Individuals who eat only plant proteins need to eat specific plant combinations to get all essential amino acids

78 Fig Beans and other legumes Corn (maize) and other grains Lysine Essential amino acids for adults Tryptophan Isoleucine Leucine Phenylalanine Threonine Valine Methionine

79 Essential Fatty Acids Animals can synthesize most of the fatty acids they need The essential fatty acids are certain unsaturated fatty acids that must be obtained from the diet Deficiencies in fatty acids are rare

80 Table 41-1

81 Table 41-2

82 Dietary Deficiencies Undernourishment is the result of a diet that consistently supplies less chemical energy than the body requires Malnourishment is the long-term absence from the diet of one or more essential nutrients

83 Fig. 41-5

84 Concept 41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination Ingestion is the act of eating

85 Fig. 41-6a Humpback whale, a suspension feeder Baleen

86 Fig. 41-6b Leaf miner caterpillar, a substrate feeder Caterpillar Feces

87 Fig. 41-6c Mosquito, a fluid feeder

88 Fig. 41-6d Rock python, a bulk feeder

89 Digestion is the process of breaking food down into molecules small enough to absorb – In chemical digestion, the process of enzymatic hydrolysis splits bonds in molecules with the addition of water Absorption is uptake of nutrients by body cells Elimination is the passage of undigested material out of the digestive compartment

90 Fig IngestionDigestion Absorption Elimination Undigested material Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Small molecules Mechanical digestion Food Pieces of food

91 Fig Gastrovascular cavity Food Epidermis Mouth Tentacles Gastrodermis Animals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of nutrients

92 More complex animals have a digestive tube with two openings, a mouth and an anus This digestive tube is called a complete digestive tract or an alimentary canal It can have specialized regions that carry out digestion and absorption in a stepwise fashion

93 Fig Esophagus Mouth Pharynx CropGizzard Typhlosole Intestine Lumen of intestine Anus (b) Grasshopper Foregut (c) Bird (a) Earthworm MidgutHindgut EsophagusRectum Anus Mouth Crop Gastric cecae Esophagus Mouth Crop Anus Stomach Gizzard Intestine

94 Concept 41.3: Organs specialized for sequential stages of food processing form the mammalian digestive system The mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices through ducts Mammalian accessory glands are the salivary glands, the pancreas, the liver, and the gallbladder

95 Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal Valves called sphincters regulate the movement of material between compartments

96 Fig Cecum Anus Ascending portion of large intestine Gall- bladder Small intestine Large intestine Small intestine Rectum Pancreas Liver Salivary glands Tongue Oral cavity Pharynx Esophagus Sphincter Stomach Sphincter Duodenum of small intestine Appendix Liver Pancreas Small intestine Large intestine Rectum Stomach Gall- bladder A schematic diagram of the human digestive system Esophagus Salivary glands Mouth

97 Fig a Cecum Anus Ascending portion of large intestine Gall- bladder Small intestine Large intestine Small intestine Rectum Pancreas Liver Salivary glands Tongue Oral cavity Pharynx Esophagus Sphincter Stomach Sphincter Duodenum of small intestine Appendix

98 Fig b Anus Liver Pancreas Small intestine Large intestine Rectum Stomach Gall- bladder A schematic diagram of the human digestive system Esophagus Salivary glands Mouth

99 The Oral Cavity, Pharynx, and Esophagus The first stage of digestion is mechanical and takes place in the oral cavity Salivary glands deliver saliva to lubricate food Teeth chew food into smaller particles that are exposed to salivary amylase, initiating breakdown of glucose polymers

100 The tongue shapes food into a bolus and provides help with swallowing The region we call our throat is the pharynx, a junction that opens to both the esophagus and the trachea (windpipe) The trachea leads to the lungs

101 The esophagus conducts food from the pharynx down to the stomach by peristalsis Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipe

102 Fig Larynx Trachea Epiglottis up Pharynx Tongue Glottis Esophagus Esophageal sphincter contracted Food To stomach To lungs Epiglottis down Esophageal sphincter relaxed Glottis up and closed Epiglottis up Esophageal sphincter contracted Sphincter relaxed Relaxed muscles Contracted muscles Relaxed muscles Stomach Glottis down and open

103 Digestion in the Stomach The stomach stores food and secretes gastric juice, which converts a meal to acid chyme

104 Chemical Digestion in the Stomach Gastric juice is made up of hydrochloric acid and the enzyme pepsin Parietal cells secrete hydrogen and chloride ions separately Chief cells secrete inactive pepsinogen, which is activated to pepsin when mixed with hydrochloric acid in the stomach Mucus protects the stomach lining from gastric juice

105 Fig Interior surface of stomach Esophagus Chief cells Small intestine Epithelium Stomach Sphincter Parietal cell Pepsinogen and HCl are secreted. HCl converts pepsinogen to pepsin. Pepsin activates more pepsinogen. Chief cell Folds of epithelial tissue Pepsin Sphincter Pepsinogen HCl H+H+ Cl – Parietal cells Mucus cells Gastric gland µm

106 Gastric ulcers, lesions in the lining, are caused mainly by the bacterium Helicobacter pylori

107 Digestion in the Small Intestine The small intestine is the longest section of the alimentary canal It is the major organ of digestion and absorption

108 Fig Oral cavity, pharynx, esophagus Stomach Lumen of small intes- tine Epithelium of small intestine (brush border) Carbohydrate digestion Polysaccharides Smaller polysaccharides, maltose Polysaccharides Maltose and other disaccharides Disaccharides Protein digestionNucleic acid digestionFat digestion Proteins Small polypeptides Pepsin Pancreatic amylases Salivary amylase Disaccharidases Monosaccharides Small peptides Amino acids Polypeptides Smaller polypeptides Pancreatic trypsin and chymotrypsin Pancreatic carboxypeptidase Dipeptidases, carboxypeptidase, and aminopeptidase DNA, RNA Pancreatic nucleases Fat globules Nucleotides Fat droplets Nucleosides Nitrogenous bases, sugars, phosphates Nucleotidases Nucleosidases and phosphatases Glycerol, fatty acids, monoglycerides Bile salts Pancreatic lipase (starch, glycogen)(sucrose, lactose)

109 The first portion of the small intestine is the duodenum, where acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself

110 Fig Secretin and CCK Stomach Gallbladder Liver + Duodenum of small intestine Bile Gastrin Secretin Pancreas CCK Key Stimulation Inhibition + – –

111 Pancreatic Secretions The pancreas produces proteases trypsin and chymotrypsin, protein-digesting enzymes that are activated after entering the duodenum Its solution is alkaline and neutralizes the acidic chyme

112 Bile Production by the Liver In the small intestine, bile aids in digestion and absorption of fats Bile is made in the liver and stored in the gallbladder

113 Secretions of the Small Intestine The epithelial lining of the duodenum, called the brush border, produces several digestive enzymes Enzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestine Most digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and water

114 Absorption in the Small Intestine The small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumen The enormous microvillar surface greatly increases the rate of nutrient absorption

115 Fig Muscle layers Microvilli (brush border) at apical (lumenal) surface Vein carrying blood to hepatic portal vein Villi Intestinal wall Key Nutrient absorption Large circular folds Blood capillaries Epithelial cells Villi Lymph vessel Basal surface Lacteal Epithelial cells Lumen

116 Each villus contains a network of blood vessels and a small lymphatic vessel called a lacteal After glycerol and fatty acids are absorbed by epithelial cells, they are recombined into fats within these cells These fats are mixed with cholesterol and coated with protein, forming molecules called chylomicrons, which are transported into lacteals

117 Fig Lumen of small intestine Lacteal Chylomicron Phospholipids, cholesterol, and proteins Triglycerides Monoglycerides Triglycerides Fatty acids Epithelial cell

118 Amino acids and sugars pass through the epithelium of the small intestine and enter the bloodstream Capillaries and veins from the lacteals converge in the hepatic portal vein and deliver blood to the liver and then on to the heart

119 Absorption in the Large Intestine The colon of the large intestine is connected to the small intestine The cecum aids in the fermentation of plant material and connects where the small and large intestines meet The human cecum has an extension called the appendix, which plays a very minor role in immunity

120 Fig

121 A major function of the colon is to recover water that has entered the alimentary canal Wastes of the digestive tract, the feces, become more solid as they move through the colon Feces pass through the rectum and exit via the anus

122 The colon houses strains of the bacterium Escherichia coli, some of which produce vitamins Feces are stored in the rectum until they can be eliminated Two sphincters between the rectum and anus control bowel movements

123 Concept 41.4: Evolutionary adaptations of vertebrate digestive systems correlate with diet Digestive systems of vertebrates are variations on a common plan However, there are intriguing adaptations, often related to diet

124 Some Dental Adaptations Dentition, an animals assortment of teeth, is one example of structural variation reflecting diet Mammals have varying dentition that is adapted to their usual diet The teeth of poisonous snakes are modified as fangs for injecting venom All snakes can unhinge their jaws to swallow prey whole

125 Fig Incisors (c) Omnivore Molars (b) Herbivore (a) Carnivore Canines Premolars

126 Stomach and Intestinal Adaptations Herbivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation

127 Fig Cecum Small intestine HerbivoreCarnivore Colon (large intestine) Stomach Small intestine

128 Mutualistic Adaptations Many herbivores have fermentation chambers, where symbiotic microorganisms digest cellulose The most elaborate adaptations for an herbivorous diet have evolved in the animals called ruminants

129 Fig Esophagus Omasum Abomasum Intestine Rumen Reticulum

130 Concept 41.5: Homeostatic mechanisms contribute to an animals energy balance Food energy balances the energy from metabolism, activity, and storage

131 Energy Sources and Stores Nearly all of an animals ATP generation is based on oxidation of energy-rich molecules: carbohydrates, proteins, and fats Animals store excess calories primarily as glycogen in the liver and muscles Energy is secondarily stored as adipose, or fat, cells When fewer calories are taken in than are expended, fuel is taken from storage and oxidized

132 Fig Homeostasis: 90 mg glucose/ 100 mL blood Stimulus: Blood glucose level rises after eating. Stimulus: Blood glucose level drops below set point.


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