Download presentation
Presentation is loading. Please wait.
1
Chapter 41 Animal Nutrition
2
Overview: The Need to Feed
Herbivores eat mainly autotrophs (plants and algae) Carnivores eat other animals Omnivores regularly consume animals as well as plants or algal matter
3
There are four classes of essential nutrients:
Essential amino acids Essential fatty acids Vitamins Minerals
4
Animals require 20 amino acids and can synthesize about half
Essential Amino Acids Animals require 20 amino acids and can synthesize about half Essential amino acids- must be obtained from food in preassembled form “Complete” proteins- provides all the essential amino acids (meat, eggs, and cheese) Most plant proteins are incomplete in amino acid makeup
5
Essential amino acids for adults
Methionine Beans and other legumes Valine Threonine Phenylalanine Leucine Corn (maize) and other grains Isoleucine Tryptophan Lysine
6
Animals can synthesize most of the fatty acids they need
Essential Fatty Acids Animals can synthesize most of the fatty acids they need The essential fatty acids are certain unsaturated fatty acids
7
Vitamins are organic molecules required in the diet in small amounts
13 essential vitamins Two categories: fat-soluble and water-soluble
10
Minerals Minerals are simple inorganic nutrients, usually required in small amounts
12
Dietary Deficiencies Undernourishment- diet with less chemical energy than the body requires Malnourishment- absence from the diet of one or more essential nutrients
13
An undernourished individual will
Undernourishment An undernourished individual will Use up stored fat and carbohydrates Break down its own proteins Lose muscle mass Suffer protein deficiency of the brain Die or suffer irreversible damage
14
Malnourishment Malnourishment can cause deformities, disease, and death
15
The main stages of food processing are ingestion, digestion, absorption, and elimination
Ingestion is the act of eating
16
Suspension Feeders Many aquatic animals are suspension feeders, which sift small food particles from the water
17
Substrate Feeders Leaf miner caterpillar, a substrate feeder Substrate feeders are animals that live in or on their food source Caterpillar Feces
18
Fluid feeders suck nutrient-rich fluid from a living host
Mosquito, a fluid feeder
19
Bulk feeders eat relatively large pieces of food
Rock python, a bulk feeder
20
Absorption is uptake of nutrients by body cells
Digestion is the process of breaking food down into molecules small enough to absorb 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
21
Nutrient molecules enter body cells Mechanical digestion
Small molecules Pieces of food Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Mechanical digestion Food Undigested material 1 Ingestion 2 Digestion 3 Absorption 4 Elimination
22
Digestive Compartments
Intracellular Digestion- food is engulfed by endocytosis and digested within food vacuoles Extracellular Digestion- food particles are broken down outside of cells
23
Tentacles Food Gastrovascular cavity Mouth Epidermis Gastrodermis
24
Crop Gizzard Esophagus Intestine Pharynx Gastrovascular cavity- functions in both digestion and distribution of nutrients Complete digestive tract (alimentary canal)- digestive tube with two openings, a mouth and an anus Anus Mouth Typhlosole Lumen of intestine (a) Earthworm Foregut Midgut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper Stomach Gizzard Intestine Mouth Esophagus Crop Anus (c) Bird
25
Crop Gizzard Esophagus Intestine Pharynx Anus Mouth Typhlosole Lumen of intestine (a) Earthworm
26
Foregut Midgut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper
27
Stomach Gizzard Intestine Mouth Esophagus Crop Anus (c) Bird
28
Organs of the mammalian digestive system
Peristalsis- rhythmic contractions of muscles to push along food Sphincters regulate the movement of material between compartments
29
Salivary glands Mouth Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
30
Duodenum of small intestine
Tongue Sphincter Oral cavity Salivary glands Pharynx Esophagus Sphincter Liver Stomach Ascending portion of large intestine Gall- bladder Duodenum of small intestine Pancreas Small intestine Small intestine Large intestine Rectum Anus Appendix Cecum
31
The Oral Cavity, Pharynx, and Esophagus
Salivary glands Mouth Oral cavity- mechanical digestion takes place Salivary glands deliver saliva to lubricate food Amylase- initiates breakdown of glucose polymers Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
32
The Oral Cavity, Pharynx, and Esophagus
Salivary glands Mouth The tongue shapes food into a bolus and provides help with swallowing Pharynx (throat)- opens to both the esophagus and the trachea (windpipe) Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
33
The Oral Cavity, Pharynx, and Esophagus
Salivary glands Mouth Esophagus conducts food from the pharynx down to the stomach by peristalsis Swallowing causes the epiglottis to block entry to the trachea Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
34
Food Epiglottis up Tongue Epiglottis up Pharynx Esophageal sphincter contracted Epiglottis down Glottis Glottis down and open Esophageal sphincter contracted Larynx Trachea Esophagus Esophageal sphincter relaxed Glottis up and closed Relaxed muscles To lungs To stomach Contracted muscles Relaxed muscles Sphincter relaxed Stomach
35
Digestion in the Stomach- 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, it is activated to pepsin when mixed with HCl Mucus protects the stomach lining from gastric juice
36
Esophagus Sphincter Stomach Sphincter 5 µm Small intestine Folds of epithelial tissue Interior surface of stomach
37
Interior surface of stomach Epithelium
3 1 Pepsinogen Pepsin Pepsinogen and HCl are secreted. 2 HCl Gastric gland 2 HCl converts pepsinogen to pepsin. 1 3 Pepsin activates more pepsinogen. Mucus cells H+ Cl– Chief cells Chief cell Parietal cells Parietal cell
38
Stomach Dynamics Coordinated contraction and relaxation of stomach muscle churn the stomach’s contents Sphincters prevent chyme from entering the esophagus and regulate its entry into the small intestine Esophagus Sphincter Stomach Sphincter 5 µm Small intestine Folds of epithelial tissue Interior surface of stomach
39
Carbohydrate digestion Protein digestion Nucleic acid digestion
Fat digestion Oral cavity, pharynx, esophagus Polysaccharides Disaccharides (starch, glycogen) (sucrose, lactose) Salivary amylase Smaller polysaccharides, maltose Stomach Proteins Pepsin Small polypeptides Lumen of small intes- tine Polysaccharides Polypeptides DNA, RNA Fat globules Pancreatic amylases Pancreatic trypsin and chymotrypsin Pancreatic nucleases Bile salts Maltose and other disaccharides Fat droplets Nucleotides Smaller polypeptides Pancreatic lipase Pancreatic carboxypeptidase Glycerol, fatty acids, monoglycerides Amino acids Epithelium of small intestine (brush border) Small peptides Nucleotidases Nucleosides Disaccharidases Dipeptidases, carboxypeptidase, and aminopeptidase Nucleosidases and phosphatases Monosaccharides Amino acids Nitrogenous bases, sugars, phosphates
40
Digestion in the Small Intestine
Salivary glands Mouth Major organ of digestion and absorption Duodenum (first part of small intestine)- acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
41
Liver Gallbladder Bile Stomach Secretin and CCK – Gastrin + CCK + Pancreas Duodenum of small intestine Secretin + Key CCK + Stimulation Inhibition + –
42
Pancreatic Secretions
Salivary glands Mouth The pancreas produces proteases trypsin and chymotrypsin, protein-digesting enzymes that are activated after entering the duodenum Its solution neutralizes the acidic chyme Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
43
Bile Production by the Liver
Salivary glands Mouth Aids in digestion and absorption of fats Bile is made in the liver and stored in the gallbladder Esophagus Gall- bladder Stomach Small intestine Liver Pancreas Large intestine Rectum Anus A schematic diagram of the human digestive system
44
Secretions of the Small Intestine
The epithelial lining of the duodenum produces several digestive enzymes Most digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and water
45
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
46
Vein carrying blood to hepatic portal vein
Muscle layers Large circular folds Villi Key Nutrient absorption Intestinal wall
47
Microvilli (brush border) at apical (lumenal) surface
Blood capillaries Epithelial cells Basal surface Epithelial cells Lacteal Lymph vessel Villi Key Nutrient absorption
48
Absorption in the Large Intestine
Colon of the large intestine is connected to the small intestine Cecum aids in the fermentation of plant material and connects where the small and large intestines meet Appendix- an extension off the cecum, which plays a very minor role in immunity The colon recover waters that has entered the alimentary canal and houses E. coli strains, some of which produce vitamins
49
Small intestine Large intestine Anus
Ascending portion of large intestine Small intestine Small intestine Large intestine Rectum Anus Appendix Cecum
50
All snakes can unhinge their jaws to swallow prey whole
Dental Adaptations Incisors The teeth of poisonous snakes are modified as fangs for injecting venom All snakes can unhinge their jaws to swallow prey whole Molars Canines Premolars (a) Carnivore (b) Herbivore (c) Omnivore
51
Stomach and Intestinal Adaptations
Herbivores have longer alimentary canals than carnivores, they need more time to digest vegetation Small intestine Stomach Small intestine Cecum Colon (large intestine) Carnivore Herbivore
52
Mutualistic Adaptations
Many herbivores have fermentation chambers, where symbiotic microorganisms digest cellulose (ruminants)
53
1 Rumen 2 Reticulum Intestine Esophagus 4 Abomasum 3 Omasum
54
Energy Sources and Stores
Animals store excess calories primarily as glycogen in the liver and muscles Energy is secondarily stored as adipose, or fat, cells
55
Overnourishment and Obesity
Overnourishment causes obesity, which results from excessive intake of food energy with the excess stored as fat Obesity contributes to diabetes (type 2), cancer of the colon and breasts, heart attacks, and strokes The problem of maintaining weight partly stems from our evolutionary past, when fat hoarding was a means of survival
56
Ghrelin Insulin Leptin PYY
57
Obese mouse with mutant ob gene (left) next to wild- type mouse.
Similar presentations
