Digestive System Flashcards
The digestive system is also called what? (2)
- Alimentary canal
- Gastrointestinal (GI) tract
Consist of a long continuous tube that extends from the mouth to the anus. What is this?
What does this include?
Digestive System
- mouth
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
What are the accessory organs of the digestive system?
- Tongue and teeth
- salivary glands
- liver
- gallbladder
- pancreas
What is the function of the salivary glands, liver, gallbladder, and pancreas?
Secretes fluid into the digestive tract
Food undergoes three types of process in the body which are:
- Digestion
- Absorption
- Metabolism
Digestion and absorption occur in the digestive tract. After nutrients are absorbed, they are available to all cells in the body used by the cells in metabolism
Taking in of food. Preparation of food for use by the body’s cells.
Ingestion
Food broken into smaller particles. Preparation of food for use by the body’s cells. What is this?
What are the 2 forms of this digestion?
Mechanical digestion
- chewing (mastication)
- Churning and mixing actions in stomach
Form of digestion in preparing food for use by body’s cells.
Carbohydrates, proteins, and fats are transformed into smaller molecules– can be absorbed and used by the cells. What is this?
What other thing apart of this form of digestion is involved in the break down of complex molecules in food?
Chemical digestion
- hydrolysis
Water is used to break down the complex molecules in food.
Hydrolysis
known as swallowing
Deglutition
Occur in stomach (smooth muscle contractions)–mix food particles with enzymes
Mixing movements
Rhythmic waves of contractions–propels food particles through digestive tract
Peristalsis
Food molecules pass through lining of the small intestine into blood
Absorption
Food molecules that cannot be digested are eliminated from body.
Elimination
Removal of indigestible wastes (feces) through the anus
Defecation
Long continuous tube, 30 feet long. Opens to outside at both ends (mouth and anus). This is the structure of the digestive tract.
What are the four layers of tunics?
- Mucosa
- Submucosa
- Muscle layer
- Serosa or adventitia
Innermost tunic. Lines lumen of digestive tract. Consists of epithelium, loose connective tissue, smooth muscle. In certain regions, this develops folds. Increase surface area for absorption. Cells here secrete mucus, digestive enzymes, and hormones.
Mucosa
Thick layer of loose connective tissue. Contains blood and lymphatic vessels which carries away absorbed nutrients. Contains nerves that form a network (submucosal plexus).
Submucosa
Contains nerves that form a network. Provides autonomic nerve impulses to the muscle layers of the digestive tract.
Submucosal plexus
Also known as muscularis.
Muscle layer
Contraction causes decrease in diameter of the tube. In muscle layer.
Inner circular layer
Contraction causes shortening of the tube. In middle layer.
Outer longitudinal layer
Network of autonomic nerve fibers between muscle layers. In muscle layer.
Myenteric plexus
Outermost layer of digestive tract tunic.
Serosa or adventitia
Above the diaphragm and is composed of connective tissue.
Adventitia
Below the diaphragm. Layer of epithelium covering the connective tissue (visceral peritoneum.
Serosa
Secretes serous fluid for lubrication and allows abdominal organs to move smoothly against each other.
Visceral peritoneum
Connects nasal and oral cavities to larynx and esophagus
Pharynx
Posterior to nasal cavity. Contains the pharyngeal tonsils (adenoids). Passageway for air. No digestive system function.
Nasopharynx
Posterior to oral cavity. Region where food enters when it is swallowed.
Oropharynx
Opening from oral cavity into oropharynx
Fauces
Masses of lymphoid tissue located near the fauces
palatine tonsils
Lower region of pharynx. Opens into both the esophagus and larynx.
Laryngopharynx
Pathway of food through pharynx:
Food is forced into pharynx by what?
When food reaches the fauces: Sensory receptors iniates a swallowing reflex including what two things?
What then propels food from the pharynx into the esophagus?
- Tongue
- Uvula elevates and epiglottis drops downward
- Peristalsis
Collapsible muscular tube. Passageway for food between pharynx and stomach. Located behind trachea and in front of vertebral column.
Esophagus
What has glands that secrete mucus, keeps lining of esophagus moist and well lubricated, and eases passage of food through the esophagus?
Mucosa
Also called cardiac sphincter. Controls movement of food between esophagus and stomach.
Esophageal sphincter
Receives food from esophagus. Located in the upper left quadrant of abdomen. What is this?
What is the average capacity it can hold?
Stomach
- 1.5 liters
Small region around stomach opening from esophagus
Cardiac region
Most superior region of stomach
Fundus
Main portion of stomach
Body
The Body curves to the right creating 2 curvatures.
What curvature is concave?
What curvature in convex?
- Lesser curvature
- Greater curvature
Narrow region as body approaches the exit from the stomach.
Pyloric region
Acts as a valve between the stomach and small intestine
Pyloric sphincter
In wall of stomach. Mixes food with enzyme and other fluids.
Muscular layer
Longitudinal folds in the wall of the stomach, allow the stomach to expand
Rugae
Composed of mucous cells, parietal cells, and chief cells. Secrete gastric juice. What is this?
How much gastric juice is produced each day?
Exocrine gastric glands
- 2-3 liters
Mucous cells of exocrine gastric gland secretes what form of mucus that forms protective coating for stomach lining? What about mucus that mixes with the food and creates a fluid medium for chemical reactions?
- Thick and alkaline mucus
- Thin and watery mucus
What do parietal cells of exocrine gastric glands secrete? (2)
What one of these two aids in the absorption of vitamin B12?
- hydrochloric acid
- Intrinsic factor (vitamin B12)
What does chief cells secrete that is an inactive form of the enzyme pepsin?
Pepsinogen
Secrete the hormone gastrin
Endocrine cells
Churning action of stomach wall muscles breaks food down into smaller sizes, mixes them with gastric juice and produces a semifluid mixture called what?
Chyme
Chyme leaves the stomach through the pyloric sphincter enters what organ?
Small intestine
Regulation of gastric secretions is accomplished through neural and hormonal mechanisms.
Gastric juice is produced all the time. Regulation of gastric secretions is divided into what 3 phases?
-cephalic, gastric, and intestinal phases
Anticipates food and prepares stomach to receive it. Triggered by:
- Thinking about food
- Seeing, smelling or tasting food.
What is this?
Sensory input stimulates centers in what part of the brain?
Gastric enters blood and circulates back to what organ that increases activity of gastric glands?
- Cephalic phase
- Medulla oblongata
- Stomach
Begins when food reaches the stomach. Presence of food in the stomach stimulates reflexes that result in gastrin secretion.
What is this?
What stimulates secretion of gastric juice (contains hydrochloric acid and pepsinogen)?
Gastric phase
- Gastrin
Acidifies stomach contents. Activates pepsinogen into pepsin, breaks down proteins.
Hydrochloric acid
Regulates entry of chyme into small intestine. Triggered by passage of chyme through pyloric sphincter into duodenum. Distention and the presence of acid chyme in duodenum. Stimulates secretion of intestinal hormones.
What phase is this?
What is neutralized and moves away from duodenum causing inhibitory responses stop and gastric secretion is again stimulated?
Intestinal phase
- Chyme
Within how many hours after a meal, stomach is empty?
Liquids pass through stomach quickly. Solids stay until mixed with gastric juices. Carbohydrates move through rather quickly. Proteins take a little longer. Fatty foods may stay as long as how many hours?
- 4 hours
- 4-6 hours
Extends from pyloric sphincter to ileocecal. Finishes process of digestion, absorbs nutrients, and passes residue to large intestine.
Small intestine
Circular folds in the wall of the intestines. Increase surface area for absorption.
Plicae circulares
Fingerlike extensions of the mucosa. Project from the circular folds. Further increase the surface area for absorption. Each of this surrounds a blood capillary network and a lymph capillary (lacteal) and function is absorption of nutrients.
Villi
Between adjacent villi
Intestinal glands
Surface epithelium on the villi contains tiny hairlike extensions known as this. Form a brush border. Increase surface area for absorption.
Microvilli
First portion of small intestine. Begins at pyloric sphincter and ends at jejunum. receives chyme from the stomach. Receives secretions from liver and pancreas.
Duodenum
Middle potion of small intestine.
Jejunum
Last portion of small intestine
Ileum
Extensions of peritoneum. Suspend intestines from the abdominal wall
Mesentery
Large amounts of watery fluid are secreted by what glands? Keeps chyme in a liquid form. Appropriate environment for chemical reactions. Fluid medium for absorption of nutrients.
Intestinal glands
Protects intestinal wall from acid chyme and digestive enzymes
Mucus
Digestive enzymes are located in microvilli.
What ones act on proteins?
What 3 act on disaccharides?
What acts on fats?
- Peptidase
- Maltase, sucrase, and lactase
- Intestinal lipase
Enzyme that activates a protein-splitting enzyme (trypsinogen) from the pancreas
Enterokinase
Begins at ileocecal junction and ends at the anus.
Large intestine
Where ileum enters the large intestine. Is named for the ileum. There is a circular band of smooth muscle fibers here.
Ileocecal junction and ileocecal valve
What is the last part of the small intestine?
What is the first part of the large intestine?
- ileum
- cecum
Have large number of goblet cells and have no villi.
Mucosa
What is limited to three distinct bands?
What are the three distinct bands that run the entire length of colon?
What contraction creates a series of pouches?
Longitudinal muscle
- Teniae coli
- Haustra
Pieces of fat-filled connective tissue. Attached to outer surface of colon
Epiploic appendages
What is a blind pouch that extends from ileocecal junction?
What is attached to cecum?
- Cecum
- Vermiform appendix
Longest portion of large intestine. What is this?
What are the 4 parts of the ascending colon?
What colon is S-shaped curve of the colon?
Colon
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon (S-shaped)
Mucosa is folded to form longitudinal anal columns
Rectum
Opens to the outside.
What is the sphincter than is under involuntary control? voluntary control?
Anal canal (anus)
- Internal anal sphincter
- External anal sphincter
Absorption of fluid and electrolytes. Elimination of waste products. Chyme that enter here contains materials that were not digested or absorbed in small intestine. Residue that remain becomes feces.
Large intestine
Sluggish mixing and peristaltic movements are more likely to occur after a meal. Results of reflexes are initiated in what organ?
As rectum fills with feces what reflex is triggered?
What is the only secretory product in large intestine that protects intestine wall against abrasion and irritation from chyme and helps hold particles of fecal mater together?
- Small intestine
- Defecation reflex
- Mucus
What is the largest gland in the body that is located in right hypochondriac and epigastric regions of abdomen and just beneath diaphragm? Dives into two major lobes and two minor lobes.
Liver
What attaches liver to abdominal wall and separates right lobe from left lobe (major lobes of the liver)?
Falciform ligament
What are the two minor lobes of the liver?
Where does the hepatic artery and hepatic portal vein enter the liver and hepatic ducts exit liver?
- Caudate and quadrate lobes
- Porta
Functional units of the liver. Consists of hepatocytes. What is this? Hepatocytes radiate outward from central vein and are also known as what cells?
Central veins of adjacent lobules unite to form hepatic veins and drain into what?
What are tiny channels interwoven with the liver cells, carry bile (produced by hepatocytes) toward periphery f the lobule and merge to form right and left hepatic ducts?
- Liver cells
- inferior vena cava
- Bile canaliculi
Functional units of the liver.
Liver lobules
Venous channels that separate the plates of hepatocytes. Carry blood from periphery of lobule toward the central vein. Lined with special phagocytic cells (Kupffer cells)
Sinusoids
Special phagocytic cells that remove foreign particles from the blood
Kupffer cells
Located around the periphery of lobule. Branch f hepatic portal vein, branch of hepatic artery, and branch of a hepatic duct.
Portal triads
Liver receives blood from two sources.
What is brought o liver by common hepatic artery?
Blood rich in nutrients from digestive tract is carried to what organ by hepatic portal vein?
Central veins of liver lobules merge to form larger hepatic veins that drain into where?
- Freshly oxygenated blood
- Liver
- inferior vena cava
What produces and secretes bile?
What facilitate fat digestion and the absorption of fats and fat-soluble vitamins?
What synthesizes albumin fibrinogen, globulins, and clotting factors?
- Secretion
- Bile salts
- Plasma proteins
What does the liver store?
- Glucose in the form of glycogen
- Iron
- Vitamins A, B12, D, E, and K
In liver. Alters chemical composition of toxic compounds makes them less harmful. Changes configuration of certain drugs (e.g. penicillin) - excretes them in the bile for removal from body.
Detoxification
In liver. Hormones, drugs, cholesterol bile pigments. Excreted in the bile
Excretion
In liver. Removes excess glucose from the blood and converts it to glycogen for storage. Breaks down glycogen into glucose when more is necessary
Carbohydrate metabolism
In liver. Breakdown of fatty acids. Synthesis of cholesterol. Conversion of excess carbohydrates and proteins into fat.
Lipid metabolism
In liver. Converts amino acids into different amino acids (as needed for protein synthesis)
Protein metabolism
In liver. What filters and remove bacteria, damaged red blood cells, and other particles from blood?
Kupffer cells
Yellowish-green fluid. Composed of water, bile salts, bile pigments, and cholesterol. What is this?
How much is produced by liver cells each day?
Bile
- 1 liter
Act as emulsifying agents. Facilitate absorption of fat-soluble vitamins. What is this?
What in bile salts break large fat globules into tiny fat droplets, increase surface area of the fa, and allow for more efficient enzyme action in fat digestion?
- Bile salts
- Emulsifying agents
Produced in the breakdown of hemoglobin from damaged red blood cells. Responsible for the color of the urine and feces. What is this?
What is the principle bile pigment?
- bile pigments
- Bilirubin
What is a product of lipid digestion?
Cholesterol
Pear-shaped sac. Attached to liver by cystic duct. Store and concentrate bile.
What is this?
What joins the hepatic duct from liver and forms the common bile duct, empties into duodenum? When gallbladder contracts, bile is ejected from gallbladder into this.
- Gallbladder
- Cystic duct
In Gallbladder. Chyme with fatty contents enter duodenum. What stimulates gallbladder to contract and permits bile to flow from gallbladder into duodenum through cystic duct and common bile duct?
Cholecystokinin
Elongated and flattened organ. Located along posterior abdominal wall. What is this?
What is the right side of the organ called?
What is the left side of the organ called?
Pancreas
- Head
- Tail
What is an endocrine function of the pancreas that secrete insulin and glucagon into the blood?
Exocrine portion consists of what secrete digestive enzymes into tiny ducts between the pancreatic cells and have ducts merge to form pancreatic duct that extends the full length of the pancreas and empties digestive enzymes from the pancreas into duodenum?
- Islets of Langerhans
- pancreatic acinar cells
In pancreas.
Acts on starch and other complex carbohydrates. What is this?
What breaks down protein and is secreted in an inactive form, known as trypsinogen, which activates by enterokinase when it reaches duodenum?
What breaks fats into fatty acids?
- Pancreatic amylase
- Trypsin
- Pancreatic lipase
When acid chyme enters the duodenum:
What produces secretin (hormone)?
What stimulates pancreas to produce a fluid with bicarbonate ions?
What neutralizes acids in the duodenum?
Proteins and fats in chyme stimulate intestinal mucosa to secrete what that also stimulates pancreas to produce a pancreatic juice that contains digestive enzymes that enter duodenum form pancreatic duct?
- Intestinal mucosa
- Secretin
- Bicarbonate ions
- Cholecystokinin
Relies on hydrolysis: Water is used to split molecules. Reactions proceed at a slow rate.
What speeds up hydrolysis reactions? Do not alter the reactions, just make them occur more rapidly.
Digestive enzymes
- All of this is apart of Chemical Digestion
Starches and other complex carbohydrates. Broken down into disaccharides by salivary amylase and pancreatic amylase. Include these (ex. sucrose, maltose, and lactose). Broken down into monosaccharides (simple sugars). By enzymes from the small intestines: sucrase, maltase, and lactase.
What is this??
What are end products of complex carbohydrate digestion? (3)
- Disaccharides
- glucose, fructose and galactose
*All of this is apart of Carbohydrate Digestion
What two things break down proteins into shorter changes of amino acids called peptides?
Peptidase enzymes from the small intestine and pancreas break peptide bonds to produce what which are absorbable end products of protein digestion?
- Pepsin and trypsin
- Amino acids
Where is the only place where lipid (fat) digestion occurs?
When fat enters the duodenum, it is emulsified by what?
What break down fat into monoglycerides and fatty acids?
- Small intestine
- Bile
- Pancreatic lipases
Each day, approximately 10 liters of food, beverage, and secretions enter digestive tract. Less than how many liters enters large intestine? How many are absorbed in small intestine?
What takes place along entire length of small intestine and mostly occurs in jejunum?
When chyme reaches large intestine, all that remains is some water, indigestible materials, and bacteria.
- 1 liter
- 9 liters or more
- Absorption
Due to aging there may be occasional episode of GI tract inflammation due to:
- Excessively spicy food
- Eating food that is contaminated by bacteria or toxins
What is common in teenagers, and decreases with age?
What is common in middle age during high stress time of life?
- Appendicitis
- Ulcers and gallbladder problems
Teeth may become loose with age resulting in what disease which can make chewing uncomfortable?
Salivary glands decrease saliva production and reduces salivary cleansing action leading to what also known as dry mouth and cause taste sensations to diminish?
- periodontal disease
- xerostomia
What involving the mucosa leads to deficiency in hydrochloric acid and gastric juice for digestion in stomach.?
What lack intrinsic factor from gastric mucosa?
Atrophy of what organ lead to fewer enzymes and shorter villi?
- Atrophy
- Pernicious anemia
- Small intestine
Does aging impair digestion and absorption?
In what organ do walls become thinner and weaker and susceptible to diverticulitis?
What is the common complaint with aging that has no basis for it and is likely due to lifestyle habits?
- No
- Large intestine
- Constipation
