Term | Definition |
Nutrient | any organic or inorganic substance that is taken in by an organism and is required for survival, growth, development, tissue repair or reproduction |
Nutrition | process of consuming and using food and nutrients |
Organic nutrients are | carbohydrates, proteins, lipids, nucleic acids and vitamins |
Inorganic nutrients are | water and minerals |
Herbivores eat | plants only |
Herbivore's digestive system has | microorganisms that help break down cellulose |
Carnivores eat | meat |
Omnivores eat | plants and meat |
4 phases of digestion are | Ingestion, digestion, absorption and egestion |
Ingestion | food is consumed |
Digestion | nutrients are broken down into smaller molecules in the digestive canal |
Absorption | ions, water and small molecules diffuse or or transported out of the digestive canal into the bodily fluids |
Egestion | undigested waste products are excreted |
Function of carbohydrates | supply energy-wielding glucose and the carbon required for building organic molecules |
Function of proteins | supply amino acids that build new proteins and provide energy |
Function of nucleic acids | components required for DNA, RNA and ATP synthesis |
Function of vitamins | coenzymes in reactions |
Essential nutrients | needed but not made by the body. Must be obtained from outside sources in their entire form |
4 types of essential nutrients | amino acids, fatty acids, vitamins and minerals |
Number of essential amino acids | 9. |
Essential amino acids | builds protein. Made by some herbivores |
Essential fatty acids help with | pain, blood clotting and smooth muscle contraction |
Essential vitamins | coenzymes for metabolic and biosynthetic reactions |
2 categories of essential vitamins | water soluble and fat soluble |
Water soluble vitamins | can't be stored. must be regularly ingested |
Fat soluble vitamins | stored in adipose tissue |
Essential minerals | inorganic ions required by animals for normal functioning. Bone, muscle, nervous tissue, cofactors etc. |
Factors that affect mineral usage | species, age, weight, health status, and food eaten |
Opportunistic animals | have a strong preference for one type of food but can adjust their diet if the need arises |
Ways to obtain food | suspension, bulk and fluid |
Suspension feeders | sieve water, filtering out the organic material and expelling the rest. Water |
Bulk feeders | eat food in large quantities. Humans. Most mammals |
Fluid-feeders | lick/suck fluid from plants or animals. Mosquitos |
Intracellular digestion | phagocytosis to bring food particles directly into a cell where food is put into vacuoles. Hydrolytic enzymes digest food into monomers, then used directly by the cell |
Extracellular digestion | protects cells from hydrolytic enzymes. Food enters digestive cavity, stored, slowly digested, and absorbed gradually over long periods of time. Humans |
Gastrovascular cavity | Part of simplest form of digestion. Digestion occurs in it and fluid movements also serve as a circulatory system to distribute digested nutrients throughout the body. |
Alimentary canal | single, elongated tube. Opening at both ends which food passes from. Smooth muscle and epithelial. |
Lumen | digestive enzyme |
Small hydrophobic molecules... | diffuse down concentration gradients across epithelium |
Ions/other molecules... | transported by facilitated diffusion or active transport. ATP needed |
Alimentary canal aka | gastrointestinal tract |
Human GI consists of | oral cavity, pharynx, esophagus, stomach, small and large intestines and anus |
Accessory structures of GI | tongue, teeth, salivary glands, liver, gallbladder and pancreas |
3 sections of alimentary canal | anterior, middle and posterior |
Anterior | Ingestion. Oral cavity, salivary glands, pharynx and esophagus |
Middle | Storage. Crop/gizzard/stomach, upper part of small intestine, pancreas, liver and gallbladder |
Posterior | final digestion, absorption and elimination. Lower part of small intestine, large intestine and anus |
Saliva produced from glands in | cheeks, tongue and throat. |
Functions of saliva | moisten/lubricate, dissolve food particles, kill bacteria, initiate digestion of sugars |
Amylase | enzyme that breaks down sugar |
In pharynx swallowing is | voluntary |
In esophagus swallowing is | involuntary |
peristalsis | rhythmic, spontaneous waves of muscle contraction that begin near the mouth and end at the stomach |
Crop | storage organ found in most birds. Food is stored and softened. |
Birds that eat more seed have | larger crops |
stomach | saclike organ that evolved as a means of storing food |
True stomach produces | hydrochloric acid |
HCl | helps digest food and kill bacteria |
Inactive pepsinogen is converted by HCl into active | pepsin |
Pepsin | digests protein |
Carbohydrates and lipids are NOT digested in | the stomach |
Chyme | food in its digested form. Contains water, salts, molecular fragments of proteins, nucleic acids, polysaccharides, droplets of fat and other small molecules |
Small intestine | tube that leads from stomach to large intestine. Almost all digestion of food and absorption of nutrients and water |
Digested nutrients are absorbed across _______ _______ and into the blood. | epithelial cells |
Duodenum | first portion of intestine |
Pancreas | secretes digestive enzymes and bicarbonate |
Liver | site of bile production. |
Bile contains | bicarbonate, cholesterol, phospholipids, organic wastes and bile salts |
Bicarbonate ______ stomach acid | neutralizes |
Bile salts break up ______ _____ and increases its accessibility to digestive enzymes | dietary fat |
Gallbladder | releases bile. Precisely times with consumption of fats |
Cecum | first part of large intestine. Small pouch that extends appendix |
Herbivores have a _______ cecum | large |
Colon | second part of large intestine |
Rectum | third part of large intestine. Ends with anus |
Large intestine | stores and concentrates fecal material before defecation absorbs some of remaining salts and water not absorbed by small intestine |
Matter broken down in small intestine | starch, lipids and carbohydrates |
Matter broken down in stomach | protein and carbohydrates |
Vitamins, minerals and water stay in their whole form and are | not digested |
Regulation of digestion is by | nervous and endocrine systems |
Local control of digestion is by | neurons within the alimentary canal |
Long distance control of digestion is by | brain |
Gastrin | hormone that stimulates smooth muscle control in the stomach and moves chyme into small intestine. Stimulates acid production by stomach |
Heartburn | excess stomach acid in esophagus. Happens when sphincter doesn't close entirely or is forced open. Acid irritates nerve endings |
Ulcer | erosion of alimentary canal. Most occur in the stomach. Due to a bacteria |
Diaarhea | loose, watery stool occurring at least 3 times a day. Result from bacteria, virus, stress or reaction to food/medication |