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Digestive System
Question | Answer |
---|---|
What does the Digestive System include? | Digestive Tract and Accessory Organs |
What other names is the Digestive Tract called? | Alimentary Canal or Gastrointestinal Tract |
What does the Digestive system include? | mouth, pharnyx, esophagus, stomach, small & large intestines. |
What are Accessories to System? | teeth, tongue, salivary glands, liver, gallbladder & pancreas |
List 3 functions of digestive system | digestion, absorption & metabolism |
What is ingestion? | to take in food |
What is mechanical digestion? | food broken down into smaller particles (chewing) and Churning & mixing actions in stomach |
What is chemical digestion? | complex molecules of carbs, proteins & fats are transformed by chemical digestion into smaller molecules that can be absorbed and used by cells. |
What is hydrolysis? | when chemical digestion uses water to break down the complex molecules |
What do digestive enzymes do? | speed up the hydrolysis process |
What pathway does the food go through? | after ingestion & mastication, the food particles move from the mouth into the pharynx and then into esophagus. |
Another name for swallowing? | deglutition |
What are mixing movements? | occur in the stomach as a result of smooth muscle contraction. These repetitve contractions mix the food particles with enzymes & other fluids |
Peristalsis | the movements that propel the food particles through the digestive tract. (rhythmic waves of contractions that move food particles through the various regions in which mechanical & chemical digestion take place. |
What is Absorption? | food molecules pass through lining of the small intestine into blood |
What is Elimination? | Elimination of food molecules that cannot be digested |
How long is the digestive tract? | 9m (30 ft) in length. Extends from mouth to anus |
List 4 layers of the Wall of the Digestive Tract | Mucosa, Submucosa, Muscular layer (muscularis), Serous Layer or Serosa |
What layer is Mucosa | the innermost tunic |
What is function of Mucosa | lines lumen of digestive tract. In certain regions it develops folds. Increases surface area for absorption. |
What does Mucosa consist of? | epithelium, loose connective tissue, smooth muscle |
What does Mucosa secrete? | Mucus, digestive enzymes, hormones |
What is Submucosa? | Thick layer of loose connective tissue |
What is Submucosa made up of? | Blood & lymphatic vessels. Also contains nerves that form a network called Submucosal Plexus |
What is Submucosa's function? | carries away absorbed nutrients |
What is the function of Submucosal Plexus? | Provides autonomic nerve impulses to the muscle layers of digestive tract |
List two Muscle Layers (muscularis) | Inner Circular Layer and Outer Longitudinal Layer |
What is function of Inner Circular Layer? | Contraction causes decrease in diameter of the tube |
What is function of Outer Longitudinal Layer? | contraction causes shortening of the tube |
What is Myentric Plexus? | Network of automoic nerve fibers between muscle layers |
What is function of Myentric Plexus? | controls movements and secretions of digestive tract (along with submucosal plexus) |
What layer is Serosa or Adventitia | Outermost Layer |
Where is the Adventitia located? | Above the diaphgragm |
What is Adventitia composed of? | connective tissue |
Where is Serosa located? | below the diaphgragm |
What is Serosa composed of? | layer of epithelium covering the connective tissue (visceral peritoneum) |
What does serosa secrete? | Serous fluid for lubrication which allows abdominal organs to move smoothly against each other |
What is function of Mouth? | 1. Receives food by ingestion 2. Breaks food into small particles 3. Mixes food with saliva |
What is the function of Cheeks? | Helps hold food in mouth, keeps food in place for chewing & formation of words for speech. Also provides protection against abrasion from food particles |
What are Lips? | Folds of skeletal muscle. Covered with a thin transparent epithelium |
What is function of lips? | They have numerous sensory receptors to determine temperature and texture of foods |
Why are lips red? | blood vessels underlying the epithelium |
What are cheeks made of? | Covered by skin & subcutaneous tissue. Lined with mucus membrane (SSE) |
What is the Tongue made of? | Skeletal muscle |
What is the major attachment for tongue? | Root. It is anchored by hyoid bone |
Where is Frenulum Linguae located? | connects tongue to floor of mouth |
Where are Papillae located? | tiny projections on dorsal surface of tongue |
What are functions of Papillae? | Provides friction for manipulating food in mouth and contains the taste buds |
What is function of lingual tonsils? | provides defense against bacteria that enters the mouth |
What is function of tongue muscles? | manipulates food in mouth for mastication and moves food around |
Why does tongue muscle move food around? | to mix it with saliva, shape it into a ball-like mass (bolus) and to direct it toward the pharynx for swallowing |
How many Primary (deciduous) teeth do you have? | 10 teeth in each jaw. So a total of 20 |
How many Secondary (permanent) teeth do you have? | 16 in each jaw. So a total of 32 |
Describe Incisors | chisel-shaped and have sharp edges. Used for biting food |
Describe Cuspids (canines) | cone-shaped and have points. Used for grasping and tearing food |
Describe Bicuspids (premolars) and molars | flat surfaces with rounded projections. Used for crushing and grinding food |
List 3 parts of a tooth | Crown, Root & Neck |
What is the Crown? | visible portion of the tooth covered by enamel |
What is the Root of a tooth? | portion embedded in the sockets (alveolar processes) of the mandible and maxilla |
What is the Neck of a tooth? | Small region in which the crown and root meet. Adjacent to the gingival (or gum) |
What is the Pulp Cavity? | Central core of tooth |
What is Pulp? | Consists of connective tissue, blood vessels, nerves |
Where is Pulp located? | in pulp cavity |
Root Canal | term used to describe the pulp cavity located in the root of the tooth |
Apical Foramen | Opening in the root of the tooth for nerves and blood vessels |
Dentin | surrounds pulp cavity and forms bulk of tooth |
What is Cementum? | thin layer of calcified connective tissue |
What are functions of Cementum? | 1. Surrounds dentin in the root of the tooth and 2. Attaches the root to the periodontal ligaments |
Periodontal Ligaments | firmly anchor root in the alveolar process |
Enamel | surrounds the dentin in the crown of the tooth |
What is the hardest substance in the body? | Enamel |
What is the largest Salivary glands? | Parotid Glands |
Where are Parotid Glands located? | each side of head: just in front of ear |
Where are Submandibular Glands located? | in floor of mouth |
Where are Sublingual Glands located? | Also located in floor of mouth. Anterior to the submandibular glands and under the tongue |
What makes up Saliva? | water, mucus and amylase (enzyme) |
What are functions of Saliva? | cleansing action on teeth, moistens and lubes food during mastication and swallowing. Dissolves certain molecules so food can be tasted. Begins chemical digestion of starches |
What does Pharynx connect? | Connects nasal and oral cavities to larynx and esophagus |
Where are the Palatine Tonsils located? | Masses of lymphoid tissue located near the Fauces |
Where does the Laryngopharynx open into? | Both the esophagus & larynx |
What is pathway for food through pharynx? | 1. Food forced into pharynx by tongue 2. When food reaches Fauces the sensory receptors intiate swallowing reflex. Then Peristaltic movements propel food from pharynx into esophagus |
When eating food what does the Uvula do? | Elevates and prevents food from entering nasopharynx |
When eating food what does the Epiglottis do? | Drops downward and prevents food from entering the larynx. It directs food into esophagus |
What is the Esophagus | Collapsible muscular tube |
What is function of the Esophagus? | Passageway for food between pharynx & stomach |
Where is Esophagus located? | behind the trachea and in front of vertebral column |
What is the function of the Esophageal Spincter (cardiac sphincter) | controls movement of food between esophagus & stomach |
Where is stomach located? | Upper Left Quadrant of Abdomen |
Where does stomach receive food from? | Esophagus |
What is the average capacity of the stomach? | 1.5 liters |
What is the Cardiac Region? | Small region around stomach opening from esophagus |
What is the Fundus? | Most superior Region of stomach |
What is function of the Fundus? | Balloons above cardiac region to form a temporary storage area |
What is the Body of the Stomach? | Main portion of the stomach |
Stomach curves to the right creating two curvatures. What are they? | Lesser Curvature: Concave Greater Curvature: Convex |
What is Pyloric Region? | narrow region as body approaches the exit from the stomach |
What is the function of the Pyloric Spincter? | Acts as a valve between the stomach & small intestines |
What is the function of the muscular layer in wall of stomach? | mixes food with enzymes and other fluids |
Where is Rugae located? | Longitudinal folds in the wall of the stomach |
What is function of Rugae? | Allows the stomach to expand |
What are Exocrine Gastric Glands composed of? | mucous cells, parietal cells and chief cells |
What do Exocrine Glands Secrete? | Gastric Juices. 2-3 Liters produced daily |
What do Mucous Cells secrete? | 1. thick and alkaline mucus that forms protective coating for stomach lining and 2. Thin & watery mucus that mixes with food and creates a fluid medium for chemical reactions |
What do Parietal Cells secrete? | Hydrochloric Acid |
What does Hydrochloric Acid do in stomach? | Kills bacteria and provides an acidic environment for the action of enzymes in the stomach |
What do Chief Cells secrete? What is function of Chief Cells? | Pepsinogen. Begins digestion of proteins into polypeptides |
What is Pepsinogen? | inactive form of the enzyme pepsin |
What does Hydrochloric Acid to to Pepsin? | Converts inactive pepsinogen into the active enzyme pepsin. This begins chemical digestion of proteins |
What do Endocrine Cells secrete? | Gastrin. Which regulates gastric activity |
What does Churning action of stomach wall muscles do? | Breaks food into smaller sizes and mixes them with gastric juice. This produces Chyme |
How does Chyme leave the stomach? | through the pyloric sphincter and enters the small intestine |
List 3 Regulations of Gastric Secretions | 1. Cephalic Phase, 2. Gastric Phase and 3. Intestinal Phase |
What does Cephalic Phase do? | anticipates food and prepares stomach to receive it |
What triggers Cephalic Phase? | thinking about food and seeing, smelling or tasting |
What happens when impulses are sent through vagus nerve to stomach? | causes an increase in the secretion of gastric juice and increases sections of the hormone gastrin |
What is pathway of Gastrin? | enters blood and circulates back to stomach |
When does Gastric Phase begin? | when food reaches the stomach. It stimulates reflexes that result in gastrin secretion |
What does Gastrin consist of? | hydrochloric acid and pepsinogen |
What does Hydrochloric Acid do in the Regulation of Gastric Secretions? | acidifies stomach contents and activates pepsinogen into pepsin |
What does the Intestinal Phase do? | regulates entry of chyme into small intestine |
What is Intestinal Phase triggered by? | passage of cyme through pyloric sphincter into duodenum |
What stimulates secretion of intestinal hormones? | distention and the presence of acid chyme in duodenum |
What happens when Chyme is neutralized and moves away from duodenum? | inhibitory responses stop and gastric secretion is again stimulated |
As Chyme accumulates what does the pyloric sphincter do? | relaxes |
how long do fatty foods stay in stomach? | 4 to 6 hours |
What is function of Small Intestine? | finishes process of digestion, absorbs nutrients and passes residue to large intestine |
Where is the Small Intestine located? | extends from pyloric sphincter to ileocecal valve |
What are the plicae circulares? | circular folds in the wall of the intestines. They increase surface area for absorption |
What are Villi? | finger like extensions of the mucosa. They project from the circular folds and further increases the surface area for absorption |
Function of each Villus? | Surrounds a blood capillary network and a lymph capillary (lacteal) and absorbs nutrients |
Where are the intestinal glands located? | between the adjacent Villi |
List the 3 regions of the small intestine | Duodenum, Jejunum and Ileum |
What is the Duodenum? | begins at pyloric sphincter and ends at jejunum. It receives chyme from stomach and receives secretions from liver & pancreas |
Jejunum | Middle portion of small intestine |
Ileum | Last portion of small intestine |
What is Mesentery | extension of peritoneum. Suspends intestines from the abdominal wall |
What is Enterokinase | enzye that activates a protein-splitting enzyme (trypsinogen) from pancreas |
Where does the Large Intestine begin? | at ileocecal junction and ends at anus |
What are Epiploic Appendages? | pieces of fat-filled connective tissue that is attached to outer surface of colon |
Where is the Vermiform Appendix attached? | to Cecum. It has no function in digestion |
What are the functions of the Large Intestine? | Absorption of fluid & electrolytes and to eliminate waste |
What is the largest gland in body? | Liver |
Where is the liver located? | Right hypochondrian and epigrastric regions of abdomen. Just beneath the diaphragm |
How many lobes is the Liver divided into? | Two Major Lobes and Two Minor Lobes |
Where is the Falciform Ligament located? | attaches liver to abdominal wall. It separates right lobe from left lobe (major lobes) |
Name the two Minor Lobes of Liver | Caudate Lobe and Quadrate Lobe |
What is the function of Bile Canaliculi | carries bile |
What are Sinusoids? | venous channels that separate the plates of hepatocytes. |
Function of Sinusoids? | carry blood from periphery of lobule toward the central vein |
What does the portal triads consist of? | 1. Branch of hepatic portal vein, 2. branch of hepatic artery and 3. branch of hepatic duct |
What does the liver secrete? | produces and secretes bile |
What does the liver store? | Iron, glycogen, Vitams A, B12, D, E & K |
What does liver exrete? | hormones, drugs, cholesterol, bile pigments |
What is Lipid Metabolism? | Breakdown of fatty acids. Synthesis of cholesterol. Converts excess carbs and proteins into fat |
What is carb metabolism? | removes excess glucose from blood and converts it to glycogen for storage. Then breaks down the glycogen into glucose |
What is protein metabolism? | converts amino acids into different amino acids (as needed for protein synthesis) |
What are the functions of Kupffer Cells? | removes bacteria, damaged red blood cells and other particles from blood |
How much bile is produced in one day | 1 liter |
What is function of Bile Salts? | breaks down large fat globules into tiny fat droplets. Increases surface area of the fat. Allows for more efficient enzyme action in fat digestion |
Where are bile pigments produced from? | breakdown of hemoglobin from damaged red blood cells |
How is gallbladder attached to liver? | by the cystic duct |
What forms the common bile duct? | the cystic duct joins the hepatic duct |
What happens to bile when it is ejected from gallbladder? | goes into the cystic duct |
What is the function of the gallbladder? | to store and concentrate bile |
What stimulates the gallbladder? | Cholecystokinin |
What is the shape of the Pancreas? | elongated and flattened organ |
Where is the pancreas located? | along posterior abdominal wall |
Where is head of pancrease located? | Right side of pancreas |
What do Islets of Langerhans secrete? | insulin and glucagon into blood |
What do Exocrine portion of pancrease consist of? | pancreatic acinar cells |
What does Pancreatic Amylas act on? | acts on starch and other complex carbs |
What does Trypsin break down? | protein |
What activates Trypsin? | enterokinase |
What is function of pancreatic lipase? | breaks fat into fatty acids |
what is function of secretin? | stimulates pancrease to produce a fluid with bicarbonate ions. Which neutralizes the acids in the duodenum |
What speeds up hydrolysis? | digestive enzymes |
What breaks down starches & complex carbs? | salivary amylase and pancreatic amylase |
List Dissaccharides | sucrose, maltose and lactose |
What are disaccharides broken down into? | monosaccharides (simple sugars) |
What secretes Pepsin | gastric glands |
What activates pepsin | hydrochloric acid |
What is Trypsin secreted by? | Secreted by Pancreas as Trypsinogen (inactive). Activated by enterokinase to Trypsin (active) |
What do pepsin & trypsin break down? | Into shorter chains of amino acids: peptides |
What is function of Peptidase enzymes | produces amino acids and is absorbable end product of protein digestion |
Where is the only place Lipid Fat Digestion occurs? | Small Intestine |
What happens to Fat when it enters the Duodenum? | it is emuslfified by bile |
What is function of Pancreatic Lipases? | break down fat into monoglycerides and fatty acids |
How many liters of food enter the digestive tract daily? | 10 liters |
How many liters of food enters the large intestine? | less than 1 liter |
how many liters of food are absorbed in small intestine? | 9 liters |
Where does absorption take place? | entire length of small intestine. Mostly in jejunum |
What is left of Chyme when it reaches the large intestine? | some water, indigestible materials and bacteria |