STRUCTURAL AND FUNCTIONAL ORGANIZATION OF THE DIGESTIVE SYSTEM Flashcards
What are the two groups of organs that make up the digestive system?
- Gastrointestinal Tract/Alimentary canal
2. Accessory Digestive Organs
What is a continuous tube that extends from the mouth to the anus?
Gastrointestinal Tract / Alimentary canal
What includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine?
Gastrointestinal tract / alimentary canal
What are organs that aid in digestion?
Accessory digestive organs
What are the teeth, tongue, salivary glands, liver, gallbladder, and pancreas?
Accessory digestive organs
How many regions is the abdomen divided into?
three regions
What are the three regions of the abdomen?
- Intrathoracic
- True abdomen
- Retroperitoneal
What region of the abdomen is enclosed by the lower ribs and immediately distal to the diaphragm?
Intrathoracic
Abdominal Regions
These organs are included in what region?
- Liver (solid)
- Gallbladder (solid but contained)
- Spleen (solid)
- Stomach (hollow)
- Transverse colon (hollow)
Intrathoracic
What abdominal region contains the large and small intestines, a portion of the liver, and the bladder?
True abdomen
True or False
In females, the uterus, fallopian tubes, and ovaries are considered part of the pelvic portion of the true abdomen
True
Abdominal Regions
These organs are included in what region?
- Small intestines
- Large intestines
- Liver, lower portions
- Bladder
- FEMALES: uterus, fallopian tubes, ovaries
True abdomen
What abdominal region lies behind the thoracic and true abdominal portions?
Retroperitoneal Abdomen
What abdominal region is separated by the retroperitoneal membrane from the other regions?
Retroperitoneal Abdomen
Abdominal Regions
These organs are included in what region?
- Kidneys
- Ureters
- Pancreas
- Posterior Duodenum
- Ascending and Descending Colon
- Inferior Vena Cava
Retroperitoneal Abdomen
How many basic functions of digestion are there?
Six
What basic function of digestion is this?
Taking in food and liquid through the mouth
Ingestion
What basic function of digestion is this?
Cells lining the GI tract produces water, acid, buffers and enzymes to aid digestion
Secretion
What basic function of digestion is this?
Continuous contraction and relaxation moving food along the GI tract
Mixing and Propulsion
What basic function of digestion is this?
Mechanical and chemical process that breaks down the food we ingest
Digestion
What basic function of digestion is this?
Small molecules produced in digestion moved into spaces to be used by cells
Absorption
What basic function of digestion is this?
Elimination of materials not absorbed by our bodies in digestion
Defecation
Throughout the GI tract, from the esophagus to the anus, the linings of the walls are made up of how many distinct layers of tissue?
Four
What are the four distinct layers of tissues within the GI tract?
- Mucosa
- Submucosa
- Muscularis
- Serosa
What layer of GI tract tissue is this?
Innermost lining of the GI tract in direct contact with the substances passing through
Mucosa
What layer of GI tract tissue is this?
Made up of areolar connective tissues that bind the mucosa to the muscularis. Contains blood and lymphatic vessels which absorb food molecules as they are broken down.
Submucosa
What layer of GI tract tissue is this?
Contains skeletal (voluntary) muscles and smooth (involuntary) muscles
Muscularis
What layer of GI tract tissue is this?
Made up of two sub layers
Serosa
What two sub layers is the Serosa made up of?
- Visceral Peritoneum
2. Parietal Peritoneum
What is the outermost layer around the organs of the GI tract?
Visceral peritoneum
What lines the walls of the abdominal cavity?
Parietal peritoneum
What is known as the “fatty apron” that drapes over the transverse colon and small intestine?
G (greater omentum)
What binds the small intestines to the posterior abdominal wall?
M (mesentery)
How many pairs of salivary glands are there?
Three
What salivary gland is located inferior and anterior to the ears between the skin and the masseter muscle?
Parotid
What salivary gland is located medial and partly inferior to the mandible in the floor of the mouth?
Submandibular
What salivary gland is beneath the tongue and superior to the submandibular glands?
Sublingual
Salivary glands function to produce a watery fluid called what?
Saliva
What helps dissolve foods and begins digestion?
Saliva
What is made up of 99.5% water and 0.5% solutes ?
Saliva
What contains lysozomes that kill bacteria protecting the mouth from infection and tooth decay?
Saliva
What begins digestion of starches in the mouth?
Salivary Amylase
True or False
Mucous produced by the salivary glands lubricate food to assist with the swallowing of food
True
What is an accessory digestive organ, made up of skeletal muscle and forms the floor of the oral cavity?
Tongue
What is highly muscular, maneuvers food for chewing, and forces food to the back of the mouth to be swallowed?
Tongue
What is the fold of mucus membrane in the midline underneath the tongue that limits the movement of the tongue posteriorly?
Frenulum
What are accessory organs of the GI tract, located in the bony sockets of the mandible and maxilla?
Teeth
What performs mechanical digestion by chewing and breaking down food into smaller pieces?
Teeth
What is a funnel shaped tube, located at the posterior end of the oral cavity, lined with mucus membrane and is comprised of skeletal muscle?
Pharynx
How many branches is the pharynx divided into and what are they?
Three
- Nasopharynx
- Oropharynx
- Laryngopharynx
What branch of the pharynx is involved in respiration?
Nasopharynx
What branch of the pharynx is located at the back of the mouth between the naso and laryngopharynx?
Oropharynx
What helps propel food into the esophagus via muscular contractions?
Laryngopharynx
What is a muscular tube, lined with stratified squamous epithelium and lies posterior to the trachea?
Esophagus
What begins at the end of the pharynx and connects to the superior aspect of the stomach?
Esophagus
The muscularis forms what two sphincters composed of smooth muscle at each end of the esophagus?
- Upper Esophageal Sphincter
2. Lower Esophageal Sphincter
What functions to transport food along its path while mixing it with mucous ?
Esophagus
What are the different phases of swallowing?
- Voluntary
- Pharyngeal
- Esophageal
What phase of swallowing is this?
Bolus forced into the oropharynx by the movement of the tongue upward and backward against the palate
Voluntary
What phase of swallowing is this?
Begins when the bolus is in the oropharynx. Breathing is temporarily interrupted. The soft palate and uvula move upward to close off the nasopharynx. The epiglottis seals off the larynx. The upper esophageal sphincter relaxes and the bolus moves into the esophagus.
Pharyngeal
What phase of swallowing is this?
Begins when the bolus moves into the esophagus. Food is pushed through the esophagus via peristalsis. When the bolus reaches the bottom of the esophagus the lower esophageal sphincter relaxes and the bolus moves into the stomach
Esophageal
What is a J-shaped organ of the GI tract, serves as a reservoir and mixing chamber for food, and aids in digestion?
Stomach
What is the pH level of the environment of the stomach?
2
What organ extends from the end of the esophagus to the tip of the duodenum?
The stomach
What is the most elastic part of the GI tract?
Stomach
How many liters of food can the stomach stretch to accommodate?
6.4 liters of food
How many regions of the stomach are there and what are they?
- Cardia
- Fundus
- Body
- Pylorus
True or False
Gastric gland cells are exocrine cells that secrete 3 types of contents that combine to create gastric juices
True
What do mucous neck cells secrete?
Mucous
What do Chief cells secrete?
Pepsinogen
What cells secretes these?
- Hydrochloric Acid (HCL) which helps convert pepsinogen into pepsin (active digestive enzyme)
- Intrinsic Factor (IF), necessary for the absorption of Vitamin B12 in the small intestines
Parietal Cells
What cell secretes Gastrin into the bloodstream in the pyloric antrum of the stomach?
G Cell
What is the major hormonal regulator of HCL secretions?
Gastrin
What is a thick liquid with the consistency of pea soup in the stomach that is made up of gastric juices and macerated food particles?
Chyme
True or False
The pancreas has endocrine and exocrine functions
True
What are some specialized areas within the pancreas?
Islets of Langerhans
The Islets of Langerhans are made up of different type of cells that make what?
Hormones
What are the common most hormones that come from cells in the pancreas?
Beta Cells
What do Beta Cells produce?
Insulin
What is a hormone that is produced by the alpha cells, found in the Islets of Langerhans ?
Glucagon
What is glucagon’s role in the body?
to prevent blood glucose levels from dropping to low
What is one of the most important accessory organs within the gastrointestinal tract?
Pancreas
What organ plays a vital role in chemical digestion, is a retroperitoneal organ that lies behind the stomach?
Pancreas
True or False
Secretions are passed through the pancreatic duct, which joins with the Common Bile duct to form the Hepatopancreatic duct. From the Hepatoprancreatic duct, secretions pass through the Sphincter of Oddi into the duodenum.
True
What is a clear, colorless liquid made up of three enzymes that consist mostly of water, some salts, and sodium bicarbonate?
Pancreatic juice
What is the pH of Pancreatic Juice?
7.1-8.2
What enzymes in pancreatic juice is responsible for protein digestion?
Trypsin and chymotrypsin
When broken down by Trypsin and Chymotrypsin protein is broken down to what?
Amino acids, dipeptides and tripeptides
What inside pancreatic juice is responsible for starch (carbohydrate) digesting?
Pancreatic Amylase
After carbohydrates are broken down by pancreatic amylase what is it absorbed as?
Monosaccharides
What within pancreatic juice is responsible for triglyceride (fat) digesting?
Pancreatic Lipase
After triglycerides are broken down by enzymes, what are they absorbed as?
Monoglycerides and fatty acids
What is nucleic acid digesting?
Ribonuclease
What is the second largest organ in the body located just below the diaphragm and most is located on the right side of the body?
Liver
What organ is responsible for these?
- Carbohydrate metabolism
- Lipid metabolism
- Protein Metabolism
- Processing drugs and hormones
- Excretion of bilirubin
- Storage of vitamins and minerals
- Activation of vitamin D
Liver
What is a bile pigment, one end-product of heme catabolism, and is the chemical responsible for the brown color of human feces?
Stercobilin
What is the major functional cells of the liver that perform metabolic, secretory, and endocrine functions?
Hepatocytes
What is a pear shaped sac that hangs from the inferior margin of the liver?
Gallbladder
What stores bile to be released into the small intestine and aids in chemical digestion, especially digestion of fats?
Gallbladder
Secretions of bile and waste travel through what to the duodenum?
the duct system of the liver and gallbladder
Bile and waste created in the liver are passed into what?
Left and Right Hepatic Duct
Bile produced in the gallbladder is secreted through what?
Cystic duct
The left and right hepatic duct form with the cystic duct to create what?
Common Bile Duct
The common bile duct forms with the pancreatic duct to form the what?
Hepatopancreatic duct
What is the muscular valve that controls the passage of contents from the hepatopancreatic duct into the duodenum?
Sphincter of Oddi
What segment in the GI system comes after the stomach?
Small intestine
Approximately how long is the small intestine in a living person? What about a cadaver?
Living: 3m (10ft)
Cadaver: 6.5m (21ft)
Intestinal glands contain how many types of endocrine cells that secrete hormones into the blood stream?
3 types
What are the 3 types of endocrine cells that intestinal glands contain?
- S cells
- CCK cells
- K cells
What endocrine cells secrete the hormone Secretin, which stimulates the secretion of pancreatic juice?
S cells
What endocrine cells secrete Cholecystokinin, which regulates gastric emptying, stimulates bile and pancreatic juice secretion, causes relaxation of the Sphincter of Oddi, and the feeling of satiety (feeling full to satisfaction)?
CCK cells
What endocrine cells secrete glucose-dependent insulinotropic peptide (GIP), which stimulates the release of insulin?
K cells
What are the three different segments of the small intestine?
- Duodenum
- Jejunum
- Ileum
What segment of the small intestine attaches to the pyloric sphincter of the stomach?
Duodenum
What is a significant landmark of the duodenum, connects at the duodenal-jejunal flexure and serves to secure those segments to the posterior wall?
Ligament of Trietz
True or False
The Ligament of Trietz is the line of the demarcation that denotes upper GI bleeds (above the ligament) and lower GI bleeds (below the ligament)
True
What is the middle section of the small intestine?
Jejunum
What is the predominant function of the jejunum?
Absorption of sugars, amino acids, and fatty acids
What segment of the small intestine attaches to the large intestine at the ileocecal sphincter/valve?
Ileum
True or False
The ileum absorbs remaining nutrients, B12, and bile salts. Bile salts are recycled into the liver and gallbladder for reuse.
True
Most of the digestion and absorption events occur where?
Small intestine
Digestion in the small intestines is mechanical via what?
Segmentation and peristalsis
Digestion in the small intestine is chemical via what?
pancreatic enzymes, bile, and intestinal juice
Nutrients in the small intestine are broken down into their simplest form which can then be absorbed by the what?
Microvilli and villi of the small intestine
After being absorbed by the microvilli and villi of the small intestines, the nutrients then diffuse from the villi to the bloodstream, and finally to the what for use by the body?
Liver
What are the simplest (broken down) forms of food and nutrients that are absorbed?
- Monosaccharides
- Amino acids, dipeptides and tripeptides
- Monoglycerides and fatty acids
- Ions and water
- Vitamins A, D, E, K
What is the last part of the GI tract?
Large intestine
What are the four regions of the large intestine?
- Cecum
- Colon
- Rectum
- Anal Canal
What is the first segment of the large intestine that the appendix attaches to?
Cecum
What part of the large intestine is broken down into the ascending, transverse, descending, and sigmoid portions?
Colon
What connect the sigmoid colon to the anus?
Rectum
What is the last 2-3cm of the rectum consisting of internal (involuntary) and external (voluntary) sphincters?
Anal canal
These are all functions of what?
- Complete absorption - absorbs water, electrolytes, and vitamins
- Absorbs certain vitamins produced by healthy gut bacteria - vitamins B and K. These are needed for normal metabolism
- Forms feces (unabsorbed digested material) to be expelled from the body
Large intestine
How many phases of digestion are there?
Three
What are the three phases of digestion?
- Cephalic
- Gastric
- Intestinal
What phase of digestion is this?
The smell, sight, sound or thought of food activates neural centers in the brain stimulating the salivary glands to secrete saliva and the gastric glands to secrete gastric juice.
Cephalic
What phase of digestion is this?
Starts when food enters the stomach. Gastrin is released promoting the release of gastric juice which increases the mobility of the stomach, relaxes the pyloric sphincter and promotes gastric emptying.
Gastric
What phase of digestion is this?
Starts when food enters the small intestine. Inhibitory effects slow gastric emptying and excitatory effects stimulate the secretion of pancreatic juices to aid in absorption and digestion.
Intestinal
