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202 Ch 17 Digestive
| Question | Answer |
|---|---|
| digestion | mechanical and chemical breakdown of foods into forms that cell membranes can absorb |
| 6 main functions of digestive system | mechanical and chemical breakdown, ingestion, propulsion, absorption, defecation |
| alimentary canal | extends from mouth to anus and includes several accessory organs which release secretions into the canal |
| The alimentary canal is about ___ meters long and passes through the body's ___ and ___ cavities | 8, thoracic, abdominopelvic |
| The wall of the cavity consists of 4 layers: | mucosa, submucosa, muscularis externa, and serosa |
| mucosa | epithelial surface with underlying connective tissue and some smooth muscle; folded with tiny projections that extend into passageway |
| lumen | passageway (in mucosa) |
| The mucosa has glands into which the lining cells secrete ___ and ___ | mucus, digestive enzymes |
| Functions of mucosa | protects tissues beneath it, secretes into lumen, absorbs substances from the diet |
| submucosa | consists of loose connective tissue as well as glands, blood vessels, lymphatic vessels, and nerves |
| Function of submucosa | vessels nourish surrounding tissues and carry away absorbed materials |
| muscularis | provides movements of the tube, consists of two layers of smooth muscle tissue |
| inner layer of muscularis | encircles tube, diameter of tube decreases |
| outer layer of muscularis | cells run lengthwise, when contracts it shortens tube |
| Coordinated contractions of layers of muscularis cause | movements associated with digestion and absorption of food |
| serosa | outer covering of tube, protects underlying tissues and secretes serous fluid, which moistens and lubricates tube's outer surface; enables organs in abdominal cavity to slide freely against one another |
| visceral peritoneum | composes serosa |
| Two motor functions of alimentary canal | mixing movements and propelling movements |
| Occurs when smooth muscle in small segments of the tube contracts rhythmically such as when stomach is full and waves of contractions mix food with digestive juices | Mixing |
| type of movement that aids mixing by alternately contracting and relaxing the smooth muscle in segments of the organ, back and forth motion | segmentation |
| movement in a wavelike motion (peristalsis) in which a ring of contraction occurs in the wall of the tube and moves progressively along its lengths | propelling |
| when the muscular wall just ahead of the ring of contraction relaxes; in peristalsis | receptive relaxation |
| begins when food expands in the tube; causes sounds that can be heard through a stethoscope | peristalsis |
| important in controlling secretions by the gastrointestinal tract | submucosal plexus |
| more extensive; controls gastrointestinal motility | myenteric plexus |
| begins mechanical digestion by breaking solid parts and mixing with saliva (mastication) | mouth |
| chamber between the palate and tongue | oral cavity |
| narrow space between teeth, cheeks, and lips | oral vestibule |
| form lateral walls of mouth, consist of outer layers of skin, pads of subcutaneous fat, muscles, and stratified squamous epithelium | cheeks |
| highly mobile structures, contain skeletal muscles and sensory receptors used for judging temperature and texture; highly vascularized (giving color); mark boundaries between skin of face and mucus membrane of alimentary canal | lips |
| lingual frenulum | connects midline of the tongue to the floor of the mouth |
| papillae | contain taste buds, help move food, detect flavors |
| lingual tonsils | posterior region (root) of tongue which is anchored to hyoid bone, covered in rounded masses of lymphatic tissue called this |
| palate | forms roof of oral cavity and consists of hard anterior part and soft posterior part |
| hard palate | formed by palatine processes of maxillae in front and horizontal portions of palatine bones in back |
| soft palate | forms muscular arch, which extends posteriorly and downward |
| uvula | cone-shaped projection extending down from soft palate |
| palatine tonsils | in back of mouth, on either side of tongue, masses of lymphatc tissue, beneath epithelium lining of mouth, helps protect against infections |
| pharyngeal tonsils | also called adenoids, on posterior wall of pharynx, above border of soft palate, enlarge and block passage between nasal cavity and pharynx, often surgically removed |
| teeth | hardest structures of body, not part of skeletal system, develop in sockets in alveolar processes of mandible and maxillae |
| primary teeth | deciduous teeth, grow in at 6 months to 2 or 4 years; ten primary teeth anchored in each jaw |
| secondary teeth | permanent teeth, push primary teeth out of sockets, set of 32 |
| functions of chewing | increases surface area of food particles, enabling enzymes to interact more effectively with nutrient molecules |
| dentin | bulk of tooth beneath enamel is composed of this living cellular tissue |
| pulp cavity | central cavity of tooth, mass of tissue including blood vessels, nerves, and connective tissue |
| root canal | blood vessels and nerves reach central cavity through this tubular part |
| salivary glands | moistens food particles, helps bind them, begins chemical digestion of carbohydrates |
| saliva | solvent, dissolves foods so they can be tasted, helps cleanse mouth and teeth |
| Bicarbonate ions (HCO3-) | buffers acid in mouth |
| serous cells | one of two types of secretory cells in salivary glands, produces watery fluid that contains digestive enzyme, salivary amylase |
| salivary amylase | splits starch and glycogen molecules into disaccharides, starting chemical digestion of carbohydrates |
| mucous cells | one of two types of secretory cells in salivary glands, secrete a thick liquid, which binds food particles and acts as a lubricant during swallowing |
| parasympathetic impulses | activated reflexly when a person sees, smells, tastes, or thinks about pleasant foods |
| parasympathetic impulses inhibited | occurs when food looks, smells, or tastes unpleasant resulting in less saliva production and difficulty swallowing |
| parotid glands | largest of major salivary glands, lies anterior and inferior to each ear, between skin of cheek and masseter muscle, secrete clear, watery fluid rich in salivary amylase, primarily serous glands |
| submandibular glands | in floor of mouth on inside surface of mandible, about equally serous and mucous glands |
| sublingual glands | smallest of major salivary glands, in floor of mouth inferior to tongue, primarily of mucous type, therefore secretions are thick and stringy |
| Rivinus's ducts | secretions of sublingual glands enter mouth through many separate ducts called |
| pharynx | connects nasal and oral cavities with larynx and esophagus, divided into three parts |
| nasopharynx | one of three parts of pharynx, superior to soft palate, communicates with nasal cavity and provides passageway for breathing |
| oropharynx | one of three parts of pharynx, posterior to oral cavity, upper border of epiglottis, passageway for food moving downward from mouth and air moving to and from nasal cavity |
| laryngopharynx | one of three parts of pharynx, extends from upper border of epiglottis downward to lower border of cricoid cartilage, |
| bolus | tongue rolled mass of food mixture |
| first stage of swallowing | food is chewed and mixed with saliva, forming bolus |
| second stage of swallowing | begins as food reaches oropharynx and stimulates sensory receptors around pharyngeal opening, triggering swallowing reflex |
| third stage of swallowing | peristalsis transports the food in the esophagus to the stomach |
| esophagus | provides passageway for food, propels food from pharynx to stomach, penetrates diaphragm through opening |
| esophageal hiatus | opening through which esophagus penetrates diaphragm |
| lower esophageal sphinctor | some cells in circular smooth muscle layer of esophagus has increased sympathetic muscle tone and forms this |
Created by:
annalawson