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89 Cards in this Set
- Front
- Back
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Digestion |
- The mechanical and chemical breakdown of foods into forms that cell membranes can absorb |
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Mechanical Digestion |
- Breaks down large particles into smaller ones, but does not change chemical composition |
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Chemical Digestion |
- Breaks down food particles by changing them into simpler chemicals |
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Digestive System |
- Organs of the digestive system carry out mechanical and chemical digestion, as well as ingestion, propulsion, absorption, and defecation |
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Alimentary Canal |
- Consists of organs that extend from the mouth to the anus; the food passageway |
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Accessory Organs |
- Consists of organs that empty secretions into the alimentary canal; food does not pass through them |
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Alimentary Canal |
- A muscular tube about 8 m long - Passes through the thoracic and abdominopelvic cavities - Composed of 4 layers |
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Mucosa |
- Innermost layer, mucous membrane
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Submucosa |
- Nourishes cells, transports absorbed food molecules |
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Muscularis |
- Muscles tissue, moves tube and food materials |
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Serosa |
- Outermost layer; serous fluid eliminates friction |
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Mixing Movements |
- Muscle in small sections contracts rhythmically - Does not move materials in one direction - Example: Segmentation |
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Propelling Movements |
- Moves materials in one direction - Example: Peristalsis |
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Peristalsis |
- Ring of contraction progresses down tube; propels food particles down the tract |
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Submucosal Plexus |
- Controls secretions |
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Myenteric Plexus |
- Controls gastrointestinal motility |
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Parasympathetic Impulses |
- Increase activities of digestive system (secretion and motility) |
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Sympathetic Impulses |
- Inhibit digestive actions (secretion and motility) |
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Mouth |
- First part of alimentary canal - Ingests food - Functions as an organ of speech and sensory reception - Surrounded by lips, cheeks, tongue, palate - Includes oral cavity and vestibule |
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Mastication |
- Mechanical breakdown of solid particles, mixes them with saliva |
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Cheeks |
- Form the lateral walls of the mouth
- Contain muscles for facial expression and chewing - Have an inner lining of stratified squamous epithelium (moist) |
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Lips |
- Highly mobile structures that surround the mouth opening - Sensory receptors judge temperature and texture of food |
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Tongue |
- Thick, muscular organ that occupies the floor of the mouth, and nearly fills the oral cavity when the mouth is closed |
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Lingual Frenulum |
- Connects tongue to floor of mouth |
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Papillae |
- Projections that move food, contain taste buds |
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Lingual Tonsils |
- Lymphatic tissue masses on root of tongue |
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Palate |
- Forms the roof of the oral cavity - Consists of a hard (bony) anterior part and a soft (muscular) posterior part - The uvula extends from the soft palate |
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Palatine Tonsils |
- Lymphatic masses on sides of tongue |
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Pharyngeal Tonsils |
- Adenoids - Masses of lymphatic tissue in posterior wall of pharynx |
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Teeth |
- Hardest structures in the body - 20 primary (deciduous) - 32 secondary (permanent) |
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Dental Caries |
- Cavities within enamel of a tooth - Formed when sticky foods lodge between teeth or in crevices of molars - Bacteria on teeth metabolize sugars - Acidic by- products destroy enamel and dentin |
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Prevention of Dental Caries |
- Brush and floss - Dental exams and cleanings - Fluoride treatments - Sealants |
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Salivary Glands |
- Secrete saliva - Moistens food particles and binds them together - Dissolves food so it can be tasted |
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Saliva |
- Contains enzymes (begin chemical digestions of carbohydrates) and bicarbonate ions (keep pH favorable for enzyme activity and protect teeth from acidic foods) |
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Salivary Secretions |
- The different pairs of salivary glands have varying proportions of 2 types of secretory cells (serous cells and mucous cells) |
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Serous Cells |
- Produce a watery fluid containing a digestive system called salivary amylase |
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Salivary Amylase |
- Splits starch and glycogen into disaccharides |
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Mucous Cells |
- Secrete mucus |
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Mucus |
- Binds food particles and lubricates food while swallowing |
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Pharynx |
- Cavity posterior to the mouth - Extends from nasal cavity to esophagus - As well as the esophagus, it does not help in food digestion - this cavity and the esophagus have muscular walls, which function in swallowing |
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Esophagus |
- Tubular organ that extends from the pharynx to the stomach - A muscular food passageway from the pharynx to the stomach - Penetrates the diaphragm through the esophageal hiatus - Contains mucous glands in submucosa - As well as the pharynx, it does not help in food digestion |
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Lower esophageal (cardiac) sphincter |
- Regulates food passage into the stomach |
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Stomach |
- J- shaped, pouch- like organ, about 25-30 cm long - Inferior to the diaphragm, in the upper- left portion of the abdominal cavity - Rugae are folds of mucosa and submucosa that allow for distention - Receives food from the esophagus - Mixes food with gastric juice - Initiates protein digestion - Has limited absorption - Moves food into small intestine - Has an inner circular layer - An outer longitudinal layer - Some portions have third (innermost) layer of oblique fibers |
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Gastric Juice |
- Gastric glands contain 3 types of secretory cells, which produce this mixture - Produced continuously |
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Neural Regulation |
- Sympathetic impulses -> Decrease gastric activity - Parasympathetic impulses -> Increase gastric activity; promote release of histamine, which stimulates gastric secretion |
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Hormonal Regulation |
- Somatostatin -> Inhibits Hydrochloric acid secretion - Gastrin -> Increases gastric juice secretion - Cholecystokinin (CCK) -> Released by small intestine cells when proteins and fat enter the small intestine; decreases gastric motility |
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Gastric Absorption |
- Gastric enzyme pepsin beings breaking down proteins - Wall of stomach is not well- adapted to absorb digestive products - The stomach does absorb: Some water, Certain salts, Certain lipid- soluble drugs, Some alcohol |
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Pancreas |
- An endocrine gland, secreting insulin & glucagon to regulate blood glucose - Also an exocrine gland of the digestive system - In its exocrine function, it secretes digestive fluid called Pancreatic Juice - Has a large head, that fits into the curvature of the duodenum - The tail lies against the spleen |
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Pancreatic Duct |
- Along with the common bile duct from the live and gall bladder, empties into the duodenum of the small intestine |
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Hepatopancreatic Ampulla |
- Pancreatic duct and common bile duct join at this dilated tube |
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Hepatopancreatic Sphincter |
- Surrounds ampulla; controls movement of bile and pancreatic juice into duodenum |
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Pancreatic Juice |
- Contains enzymes that digest carbohydrates, fats, proteins and nucleic acids |
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Components of Pancreatic Juice |
- Pancreatic amylase - Pancreatic lipase - Trypsin - Chymotrypsin - Carboxypeptidase - Nucleases - Bicarbonate Ions |
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Pancreatic Amylase |
- Splits starch and glycogen into disaccharides |
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Pancreatic Lipase |
- Breaks down triglycerides |
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Trypsin |
- Digests protein - Released as inactive trypsinogen, which is activated by enterokinase in small intestine |
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Chymotrypsin |
- Digest proteins - Released as inactive, activated by trypsin |
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Carboxypeptidase |
- Digest proteins - Released as inactive, activated by trypsin (form of proteins) |
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Nucleases |
- Digest nucleic acids |
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Bicarbonate Ions |
- Make pancreatic juice alkaline - Buffer stomach acid |
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Secretin |
- Stimulates pancreas to release pancreatic juice high in bicarbonate ions |
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CCK |
- Stimulates pancreas to release pancreatic juice high in enzymes |
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Liver |
- Largest internal organ - Located in the upper- right abdominal quadrant, just beneath the diaphragm - Reddish- brown organ - Well- supplied with blood vessels |
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Liver Structure |
- Has 4 lobes: 1. Right lobe: Largest 2: Left lobe: Small than right lobe 3. Quadrate lobe: Minor lobe, near gallbladder 4. Caudate lobe: Minor lobe, near inferior vena cava |
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Hepatic Lobules |
- Functional units of the liver - Consist of plates of hepatic cells radiating out from a central vein - Hepatic sinusoids run between plates of cells |
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Hepatic Portal Vein |
- Oxygen- poor blood from the digestive tract is transported to the liver through this vein - It mixes with oxygen- rich blood from the hepatic artery - This blood filters through the hepatic sinusoids |
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Hepatocytes |
- Adjust nutrient concentrations, as the nutrients from the digestive tract flow by - Bile produced by hepatocytes leaves the liver through bile ducts |
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Bile |
- A yellowish- green liquid that hepatic cells continuously secrete - Components are: Water, bile salts, bile pigments, cholesterol and electrolytes |
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Hepatitis |
- Inflammation of the liver - Many types: chronic or acute - Some common cause is one of several types of viruses - Some people have symptoms, and some do not (They can still be carriers) - Some forms are blood- borne - Transmitted by contact with food, body fluids or objects contaminated with feces that contain the virus - Antibiotics are not effective against the virus - C accounts for about half of all known cases |
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Gallbladder |
- A pear- shaped sac on inferior surface of liver - It stores and concentrates bile - Cystic duct from this organ joins with the common hepatic duct from liver to form common bile duct |
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Gallstone |
- Gallbladder normally concentrates bile salts, bile pigments, cholesterol - Sometimes cholesterol precipitates and forms solid crystals - Crystals can enlarge - Causes: excess bile concentration, too much cholesterol secretion by liver, or inflammation of the gallbladder |
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Hormone CCK (Cholecystokinin) |
- Causes the gallbladder to contract, in response to fats entering the duodenum. - The bile is then released into the duodenum |
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Small Intestine |
- Tubular organ that extends from the pyloric sphincter to the beginning of the large intestine - Fills most of the abdominal cavity - Receives chyme from stomach, and liver and pancreatic secretions - Completes digestion of the nutrients in chyme - Absorbs products of digestion - Transports the remaining residue to the large intestine |
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Parts of the small intestine |
- This organ consists of 3 parts: 1. Duodenum: shortest and most fixed portion of small intestine 2. Jejunum: Middle portion, thicker and more active than ileum 3. Ileum: Distal portion; contain's Peyer's patches (Lymph nodules) |
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Peptidases |
- Break down peptides into amino acids |
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Sucrase, maltase, lactase |
- Break brown disaccharides into monosaccharides |
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Lipase |
- Breaks down fats into fatty acids and glycerol |
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Peristalsis |
- Wave-like pushing movements that propel chyme in proper direction down the small intestine |
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Segmentation |
- Ring- like contractions that move chyme back and forth (mixing movement) |
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Parasympathetic Impulses |
- Stimulate both mixing and peristaltic movements, and sympathetic impulses inhibit them |
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Large Intestine |
- Named because diameter is greater than that of small intestine - 1.5 m long - At distal, end, opens to outside of body through the anus - Consists of cecum, colon, rectum, and anal canal - Has little or no digestive function - Contains tubular glands containing goblet cells; secrete mucus, the only significant secretion - Absorbs water and electrolytes - Forms feces and carries out defecation |
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Cecum |
- Pouch, forms beginning of large intestine - Appendix is attached; contains lymphatic tissue |
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Colon |
- Ascending, transverse, descending and sigmoid portions |
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Rectum |
- Extends from sigmoid colon to anal canal |
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Anal Canal |
- Last 2.5- 4 cm of large intestine; opens to outside as anus - Internal and external anal sphincters guard anus |
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Feces |
-Composed of materials not digested or absorbed, and also contain: 1. Water 2. Electrolytes 3. Mucus 4. Bacteria 5. Bile pigments, which provide the color after bacterial alteration - The pungent color is produced by bacterial compounds, including: 1. Phenol 2. Hydrogen Sulfide 3. Indole 4. Skatole 4. Ammonia |
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Diverticulosis |
- Weakening of intestinal wall leads to protrusion membrane; forms outpouchings that can become inflamed and infected |
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Inflammatory Bowel Disease |
- Group of disorders, including: 1. Ulcerative Colitis: Affects mucosa & submucosa of large intestine; causes blood diarrhea, cramps 2. Chron's Disease: More serious; affects all layers, and occurs in both small and large intestines; causes diarrhea and pain |
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Colorectal Cancer |
- Cancer of the large intestine or rectum - Fourth most common cancer in US - Screening tests include fecal occult blood test and colonoscopy |
