Chapter 15 - BIO 110
Function of gastrointestinal tract | Tract into which several accessory glands release their secretions |
Structure of gastrointestinal tract | Begins at the mouth and includes the pharynx, esophagus, stomach, small intestine, and large intestine |
Mechanical digestion of GI tract | Physical breaking of food into smaller pieces |
Chemical digestion of GI tract | Breaking of chemical bonds so that complex molecules are broken into smaller subunits |
Hard palate | Toward the front, reinforced with bone |
Soft palate | Toward the back, muscle only, prevent food from entering nasal cavities during swallowing |
Function of the mouth | Begins mechanical and chemical digestion, monitors food quality, prepares (moistens and manipulates) food for swallowing |
Function of the teeth | Mechanical digestion breaks food into smaller pieces Incisors – clip and slice Canines – puncture and tear Molars and premolars - crush |
Structure of the teeth | Crown – above the gum Root – below the gum |
Layers of the teeth | Pulp – innermost, with blood vessels and nerves Dentin – hard bonelike Enamel – nonliving, covers crown |
Three parts of the salivary glands | Sublingual (below tongue, submandibular (below jaw), parotid (in front of ears) |
How is saliva released into the mouth? | Water moistens food, mucus binds food, salivary amylase begins chemical digestion of starch |
Tongue | Large skeletal muscle Movement important in speech and food manipulation |
Pharynx | Passageway shared by respiratory and digestive systems |
Esophagus | Muscular tube that transports food from pharynx to stomach |
Structure of the stomach | J shaped expandable sac Band of circular muscle guards opening at each end Wall had three layers of smooth muscle |
Functions of the stomach | Stores food and regulates its release to the small intestine Liquefies food Begins chemical digestion of proteins |
Gastric glands | Some secret hydrochloric acid and some secrete intrinsic factor |
How does the stomach protect itself from gastric juice? | Mucus, pepsin produced in an inactive form, neural and hormonal mechanism that time release of gastric juice to coincide with food entering stomach, stomach lining replaced rapidly |
Structure of the small intestines | Duodenum, jejunum, ileum |
Functions of the small intestines | Chemical digestion and absorption |
Chemical digestion of small intestines | Carbohydrates, proteins, fats, and nucleic acids are broken down into their simplest forms with aids in digestion and absorption of fats |
How does the surface area of the small intestines increase? | Pleated lining, villi, microvilli |
Pancreatic juice | Contains many digestive enzymes and bicarbonate ions Drains from pancreas into pancreatic duct which fuses with the common bile duct before entering small intestine |
Liver | Largest internal organ Produces bile, regulates blood glucose levels, packages lipids with proteins to form lipoproteins, which aid transport in the blood |
Structure and Function of Gallbladder | Structure – muscular pear-shaped sac Function – stores, modifies, and concentrates bile produced by the liver |
Structure and Function of Large Intestines | Structure – cecum, colon, rectum, anal canal Functions – absorbs most of the water remaining in the indigestible food residue, stores and eliminates feces |
Regions of large intestine | cecum, colon, rectum, anal canal |
Structure and Function of Colon | Structure - Pouch at junction of small and large intestines Function – absorbs water and ions, contains beneficial bacteria that produce vitamins |
How does nerves and hormones aid in digestion? | Processes that are quick or anticipatory are controlled by the nervous system Processes that can take more time are controlled by hormones |
Nutrients | Substances in food that provides energy, becomes part of a structure, or performs a function in growth, maintenance or repair |
Lipids | Provide nine calories per gram Include fats, oils, and cholesterol |
Carbohydrates | Provide four calories per gram |
Proteins | Provide four calories per gram Chains of amino acids |
Vitamins | Needed in very small amounts, serve as enzyme or coenzyme |
Minerals | Inorganic substances needed for a variety of life processes |
Food label | Can help you choose foods that will help you increase nutrients that are important to consume and limit those that could be harmful |
Energy balance | Basal metabolic rate: the minimal energy needed to keep an awake, resting person alive |
Obesity | Weighing more than height-weight charts recommend because of too much body fat |