Nutrition Exam 2 Study Guide Chapter 3 The Human Body 1 Why we want to eat a Hunger i The physiological drive for food ii Non specific iii Can be satisfied by a variety of foods b Appetite i The psychological desire to consume specific foods ii Aroused by environmental cues 1 Example seeing chocolate cake then wanting chocolate i Have the physiological need for food but no appetite present c Anorexia cake 2 Hunger a Hypothalamus i Region of brain where visceral sensations are regulated ii Triggers feelings of hunger or satiation fullness and thirst iii Located about pituitary gland 1 Produces hormones to relay signals of hunger b Hormones ii Examples i Chemical messengers secreted into the bloodstream by endocrine glands to help regulate body functions Insulin and glucagon help maintain blood glucose levels 1 2 Feeling full satiated results from signals in stomach and a rise in blood glucose levels a Foods have differing effects on our feelings of hunger b Proteins have the highest satiety value i You will feel full for longer c High fat diets have a higher satiety value than high carbohydrate dies i High fat diets tend to keep you full for longer d Bulky meals are high in fiber and water i They distend the stomach and promote a sense of satiety with less amount of food present e Solid foods are more filling than semisolid foods and liquids 3 Food 4 Why we eat a Food stimulates are senses 5 What happens to the food we eat consume certain foods i Sight smell taste texture how it feels in out mouth and hearing ii Social cultural cues and learned experiences drive our desire to a Digestion b Absorption c Elimination i Large food molecules are broken down into smaller molecules 1 Mechanically and chemically i Process of taking products through the intestinal wall for one s body to be able to absorb specific nutrients i Undigested portions of food waste products are removed from 6 Gastrointestinal Tract the body a Series of organs in long tubes that work together to process foods b Sphincters i Muscles that control the passage of food material from one gastrointestinal organ to the next 7 First Part of Digestion OVERVIEW a Cephalic phase i First thought of food stimulates the release of digestive juices ii Prepares the gastrointestinal tract to digest food b Chewing c Saliva i Moistens food ii Mechanically breaks it down into smaller pieces i Contains digestive juices secreted by salivary gland in mouth ii Binds food particles together and begins the digestion of carbohydrates d Salivary glands i Group of glands found under and behind tongue beneath the jaw ii Releases saliva continuously in response to the thought sight i Small chemicals that act on other chemicals to speed up bodily smell and presence of food e Enzymes processes ii Typically proteins 1 Example salivary amylase f Taste receptors umami savory taste g Olfactory receptors i Detect distinct tastes including bitter sweet salty sour and i Detect the aromas smells of food ii Odorants dissolved in music bind to chemoreceptors in nasal cavity to transmit data about the food to the brain 8 Second Part of Digestion OVERVIEW a Bolus i A mass of food that has been chewed moistened in the mouth ii After swallowed propelled to stomach through the esophagus b Swallowing i Complex process involving voluntary and involuntary motion ii Epiglottis 1 Acts as a trapdoor covering the entrance to the trachea windpipe during swallowing 2 Brain signals the epiglottis to close during swallowing so food and liquid can t enter the trachea a Wouldn t be able to breath without this function b Example can t talk and eat at the same time iii Upper esophageal sphincter opens to allow the passage of food iv Food then travels through esophagus to the stomach 9 Propelling Food a Peristalsis 10 pH scale i The rhythmic waves of squeezing pushing food through body ii Muscular contractions b Gravity helps transport food through the esophagus a Potential of hydrogen b Measures the potential of a substance to release or take up hydrogen ions within a solution i Measure of a compound s acidity or alkalinity c Tissues in the stomach are protected from the effects of this acidity 11 Digestion in Stomach a Gastrin i Hormone secreted by stomach lining cells ii Stimulate the gastric glands to produce gastric juice b Gastric juice c Gastric glands i Acidic liquid secreted within the stomach ii Contains hydrochloric acid pepsin and other compounds i Lined with parietal cells and chief cells 1 They secrete various components of gastric juice d Parietal cells i Hydrochloric acid 1 Keeps stomach interior very acidic 2 Acidic environment kills any bacteria germs that may have entered body through consuming food 3 Helps denature proteins a Breaks bonds ii Intrinsic factor 1 Protein critical for absorption of vitamin B12 e Chief cells i Pepsinogen Inactive enzyme 1 2 Hydrochloric acid helps convert into the active form known as pepsin ii Gastric lipase 1 Enzyme responsible for partial lipid digestion in stomach 12 Mechanical Digestion a Occurs as stomach mixes churns food with gastric juices i Peristaltic waves mix all the contents ii Once mixed creates chyme b Chyme i Liquid product of mechanical chemical digestion ii Enzymes can access liquid chime more easily than solid forms of food which makes this conversion essential 13 Why Stomach Isn t Eroded a Mucus neck cells i Locate din gastric glands b Mucus surface cells i Located in stomach lining ii Secrete a protective layer of mucus c Mucus i Layer that protects stomach lining from the acid in gastric juices ii Without layer ulcer can occur i Type of base that neutralizes acid within the stomach d Bicarbonate 14 Small Intestine a Longest portion of the gastrointestinal tract b Most digestion absorption takes place here i Where most food is broken down into the smallest components 1 Connected via the pyloric sphincter to the stomach c Composed of 3 sections i Duodenum ii Jejunum iii Ileum 1 Middle portion ileocecal valve 1 Connects large intestine to another sphincter called the 15 Large Intestine a Also referred to as the colon b Connects to the ileum of the small intestine c Final digestion i Bacteria assists with digesting some nutrients that have remained ii Help synthesize certain vitamins and stimulate immune system in food residue d Probiotic i Health promoting beneficial bacteria ii Presence in foods support healthy body functioning 16 Chemical Digestion a Enzymes 17 Hormones 1 Reactions that break down
View Full Document
Unlocking...