The Digestive System And Nutrition 6.2 The Digestive System And Nutrition Sonia Osuna, Emily Brenchley, Alex Gupton, and Lauren Anderson

Nutrition Herbivores- Eat plants and or algae Animals fall into one of three categories of how they get nutrition Herbivores- Eat plants and or algae Carnivores- Eat other animals Omnivores- Eat animals and plants/algae

Specialized Teeth Animal’s Dentition, or their assortment of teeth, are structure variations that determine an animal’s specialized diet. Mammals have highly specialized teeth, which makes them successful Nonmammalian vertebrates also Have specialized teeth, but to a lesser extent.

Carnivore Herbivore Omnivore Incisors Canines Premolars Molars

These are required by all cells and come from an animal’s diet Essential Nutrients Four classes: Amino Acids Fatty Acids Vitamins Minerals These are required by all cells and come from an animal’s diet

Amino Acids Animals require 20 Amino Acids, but can only synthesize half from from molecules The ones that can’t be synthesized are known as the Essential Amino Acids and have to be obtained fully built from food Foods that can provide these essential building blocks are things like eggs, meat, and cheese

Fatty Acids These are used for different cellular components such as phospholipid membranes, storage fats, and signaling molecules in animals Plants can synthesize essential fatty acids

Vitamins Vitamins are organic molecule that the body only requires small amounts of. Humans require 13 different Vitamins Two Groups: Fat-soluble Water-soluble

Minerals Inorganic nutrients Only required in small amounts Ingesting too many leads to homeostatic imbalances.

Nutritional Needs Malnutrition occurs when the body doesn’t get enough of the essential nutrients Deficiencies in essential nutrients can cause deformities, disease, and death Epidemiology- the study of human health and disease in populations

Types Of Feeders Filter- They feed by straining food particles and water through a specialized structure. Sponges are among this group. Substrate- These types of feeders live in or on what they eat. Termites are an example of this. Fluid- Feed on a host. This could be something like mosquitos or leeches Bulk- Feeding on animals or plants is bulk feeding. Humans do this and many other animals.

Parts of Digestion Digestion-is the process of breaking food down into molecules small enough to absorb. There are 2 stages of digestion, mechanical and chemical. Absorption- The uptake of nutrients by the bodies cells. Elimination- The removal of undigested materials from the body.

Intracellular Vs. Extracellular Digestion Intracellular Digestion Extracellular Digestion -Food Particles are engulfed by phagocytosis - food vacuoles fuse with lysosomes containing hydrolytic enzymes. -Extracellular digestion takes place outside of cells. -Completed in compartments, some have stomachs and things like that, others have a gastrovascular activity. The gastrovascular cavity does digestion and distributing nutrients to the cells of the body.

Mammal Digestive System alimentary canals- specialized regions that carry out digestion and absorption accessory glands secrete digestive juices through digestive ducts. -Accessory glands include: Salivary glands, the pancreas, the liver and the gallbladder. -Peristalsis: Muscle contractions move food through the system -sphincters regulate movement of material between compartments.

Mechanical Digestion Takes place in the oral cavity Teeth break down the food into smaller pieces so it may mix with saliva The Salivary Glands release saliva, a mucous made of water, salts, glycoproteins, and salivary amylase-- which begins to break down glucose polymers and starches.

Swallowing The tongue shapes food into a bolus and provides help with swallowing The throat, or pharynx, is the junction that opens to both the esophagus and the trachea The esophagus, which is connected to the stomach, will rhythmically contract to push the bolus down.

1) Ingestion 2) Digestion 3)Absorption 4) Elimination Nutrient molecules enter body cells Mechanical Digestion Chemical Digestion (enzymatic hydrolysis) Undigested materials 1) Ingestion 2) Digestion 3)Absorption 4) Elimination

The Stomach and Chemical Digestion Gastric juices in the stomach mix with food to create Chyme, which has an oatmeal consistency Gastric juice is made up of hydrochloric acid (HCl) and pepsin Pepsin is a protease, or protein-digesting enzyme, that cleaves proteins into smaller peptides The pH of gastric juice is 2, acidic enough to kill bacteria and denature proteins

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 Stomach contents typically pass into the small intestine 2–6 hours after a meal

Stomach Lining Due to the high pH of stomach acid, the interior of a stomach contains a lining to protect itself and the body. A layer of mucous covers the lining to protect it A new epithelial layer is made every 3 days to replace the damaged one

Small Intestine The small intestine is the major organ of digestion and absorption It’s the longest section of the alimentary cavity First section of the intestine is know as the duodenum Chyme mixes with digestive juices from the pancreas, liver, gallbladder, and intestinal walls.

The inner lining of the duodenum also produces digestive enzymes Digestion is finished as the chyme is moved along the small intestine through peristalsis. After digestion is finished in the duodenum, absorption takes place in the jejunum and ileum of the small intestine. The villi and microvilli protections within the intestine increase surface area and therefore speed up absorption.

Liver/Gallbladder Roles The liver produces Bile to be used in the digestion and absorption of fats Bile will also destroy non functional red blood cells. This Bile is stored in the gallbladder

Liver The hepatic portal vein carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules

Pancreas The pancreas produces trypsin and chymotrypsin which are alkaline substances that neutralize the very acidic Chyme.

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

Absorption in the large intestine The colon functions to absorb leftover water that has entered the alimentary cavity Water is absorbed from the undigested material and bacteria, now called Feces It is also home to Escherichia coli, a bacteria that lived on organic material and produce vitamins for the body

Rectum and Feces Feces are stored in the rectum until they can be eliminated through the anus Two sphincters between the rectum and anus control bowel movements

Mutualism Many herbivores have fermentation chambers in their alimentary canals, where mutualistic microorganisms digest cellulose Rabbits and some rodents harbor mutualistic bacteria in their large intestines and ceca The most elaborate adaptations for an herbivorous diet have evolved in the animals called ruminants, including deer, sheep, and cattle. They can ferment plant based nutrients to later absorb them

Rumen Reticulum Intestine Omasum Abomasum

Adaptations And Feedback Many carnivores have large, expandable stomachs Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation

Regulation Each step in the digestive system is activated as needed The enteric division of the nervous system helps to regulate the digestive process The endocrine system also regulates digestion through the release and transport of hormones

Metabolism Bioenergetics-- The flow and transformation of energy in an animal *how fast it is determines nutritional needs* An animal’s energy use per unit of time is called its metabolic rate Metabolic rate can be determined by monitoring an animal’s rate of heat loss, the amount of O2 consumed, or the amount of CO2 produced

Animals must maintain a minimum metabolic rate for basic cell functions Basal metabolic rate, BMR, is the minimum metabolic rate of a non growing endotherm that is at rest, has an empty stomach, and is not experiencing stress standard metabolic rate, SMR, is the metabolic rate of a fasting, non stressed ectotherm at a particular temperature

Energy Storage In humans, the liver and muscle cells are used first; energy is stored as glycogen When glycogen deposits are full, additional excess energy is stored as fat in adipose cells When fewer calories are taken in than expended, the body expends liver glycogen, muscle glycogen, and then fat.

Glucose Homeostasis Insulin and glucagon maintain glucose levels Insulin levels rise after a carbohydrate-rich meal, and glucose entering the liver through the hepatic portal vein is used to synthesize glycogen When glucose concentration is low in the hepatic portal vein, glucagon stimulates the liver to break down glycogen and release glucose into the blood Insulin and glucagon are produced in the pancreas

Diabetes Mellitus Diabetes Mellitus is a disease caused by insulin deficiency, or a decreased response to insulin. Cells are not able to take up glucose to maintain metabolism There are several types and caused to this

Types of Diabetes Type 1 diabetes (juvenile diabetes) is an autoimmune disorder in which the immune system destroys the pancreatic beta cells so no insulin is released Type 2 diabetes (adult onset) is characterized by a failure of target cells to respond normally to insulin Heredity is a factor in type 2 diabetes Excess body weight and lack of exercise increase the risk

Obesity Overnourishment causes Obesity, as the excessive energy is stored as fat This contributes to type 2 diabetes, cancer, heart attacks, and strokes

Appetite Regulation Hormones Ghrelin- Triggers feelings of hunger; secreted by the stomach Insulin- Suppress appetite PYY- Suppress appetite; secreted by the small intestine after a meal Leptin- Suppresses appetite and regulates body fat levels; produced by adipose tissue

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