FINALS DIGESTIVE SYSTEM Flashcards
What are the major organs of the digestive system
Oral Cavity, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine
Small Intestine
Enzymatic digestive and absorption of water, organic substrates, vitamins, and ions
Large Intestine
Dehydration and compaction of indigestible material in preparation for elimination
Oral Cavity (Mouth)
Ingestion, Mechanical digestion
Pharynx
Muscular movement of material into esophogus
Esophagus
Transport material to the stomach
Stomach
Chemical digestion of materials by acid and enzymes
What are the accessory organs of the digestive system?
Teeth, Tongue, Salivary Glands, Liver, Gallbladder, Pancreas
Salivary Glands
Secretion of lubricating fluid containing enzyme that break down carbohydrates
Liver
Secretion of bile, storage of nutrients, many other vital functions
Gallbladder
Storage and concentration of bile
Pancreas
Exocrine cells secrete buffers and digestive enzymes; endocrine cells secrete hormones
Teeth
Mechanical digestion by chewing
Tongue
Assists mechanical digestion with teeth
What are the layers of the digestive tract?
- Inner lining (mucosa)
- Submucosa
- Muscular
- Serosa
Inner lining (muscosa)
- Mucosal Epithelium (mucous membrane)
- Lamina Propria
- Muscularis Muscosae
What does Lamina Propria contain?
Lamina propria is a layer of areolar tissue that contains blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells, and lymphatic tissue.
What is Muscularis Muscosae?
(deep to the lamina propria) is a narrow sheet of smooth muscle and elastic fibers.
What is Submucosa?
Submucosa is a layer of dense irregular connective tissue that binds the mucosa to the muscular layer.
What does Submucosa contain?
Submucosal neural plexus
What is Submucosal neural plexus?
Submucosal neural plexus is a network of intrinsic nerve fibers and scattered neurons.
Where is Submucosa nerual plexus located?
The submucosal plexus lies along the inner border of the muscularis externa (muscularis).
What does the Muscular layer of the Digestive tract contain?
Myenteric plexus
What is Serosa?
Serosa covers the muscularis externa along most portions of the digestive tract inside the peritoneal cavity
How are digestive functions controlled? (3x)
- Local Factors
- Neural Control Mechanism
- Hormonal Control Mechanism
What are the local factors that control digestive functions?
pH, volume or chemical composition
What are the neural control mechanisms that control digestive functions?
Sensory receptors in the wall, motor neuron control smooth muscle contraction.
What are the hormonal control mechanisms that control digestive functions?
Digestive hormones (produced by enteroendocrine cells) can enhance or diminish the sensitivity of the smooth muscle cells to neural commands
What are the 3 major pairs of salivary glands?
- Parotid glands
- Sublingual glands
- Submandibular glands
What is Parotid glands?
The parotid glands produce a serous secretion containing large amounts of salivary amylase. This enzyme breaks down starches
What are Sublingual glands?
These glands produce mucus that acts as a buffer and lubricant.
What are Submandibular glands?
Submandibular glands secrete a mixture of buffers, glycoproteins called mucins, and salivary amylase.
What is the swallowing process (i.e., how food is passed along the digestive tract)?
- Buccal phase
- Pharyngeal phase
- Esophageal phase
- Bolus enters stomach
What is the buccal phase?
The buccal phase is a primary and voluntary phase.
Pushes the food towards the back of the mouth
What is the Pharyngeal phase?
Breathing stops during the pharyngeal phase
The uluva pushing back and prevents the food from entering the nasopharynx
What is the esophageal phase?
The esophageal phase pushes the bolus toward the stomach
The food is forced into the esophogus
What are the structure/components of the stomach?
- Cardia
- Fundus
- Body
- Rugae
- Pyloric Part
- Pyloric antrum
- Pyloric canal
- Pylorus
- Pyloric orifice
What is Fundus?
Fundus, region of the stomach that is superior to the junction between the stomach and the esophagus.
What is Cardia?
Cardia, region of the stomach that connects to the esophagus.
What is Rugae?
Rugae, The prominent ridges in the lining of the empty stomach
What is Body in relation to the stomach?
Body, The part of the stomach that functions as a mixing chamber for food and secretions
What is Pyoric part?
Pyloric part, The region of the stomach that empties into the duodenum.
What is pyloric antrum?
Pyloric antrum is connected to the body
What is Pyloric canal?
Pyloric canal empties into the duodenum
What is pylorus?
Pylorus is the muscular tissue surrounding the pyloric orifice
What are the 3 sections of the large intestine?
- Pouchlike cecum
- Colon
- Rectum
What are the major hormones secreted by the small intestine?
- Gastrin
- Secretin
- GIP
- CCK
- VIP
- Enterocrinin
- Enteropeptidase
Gastrin
G cells in the stomach and duodenum secrete gastrin. Gastrin promotes stomach motility and gastric acid production.
Secretin
Chyme stimulates the duodenum and promotes secretin production. Secretin increases the pancreatic enzyme and buffer, also bile secretion.
GIP
An intestinal hormone that stimulates the release of insulin from the pancreatic islet cells.
CCK
CCK causes gallbladder to contract
VIP
VIP stimulates the secretion of intestinal glands and inhibits acid production in the stomach
Enterocrinin
Intestinal hormone that stimulates mucin production by the submucosal duodenal glands
What are the three sections of the small intestine?
- Duodenum
- Jejunum
- Ileum
Enteropeptidase
activates the key pancreatic proenzyme, trypsinogen.
What are the major functions of bile salt?
Bile salts break the lipid by emulsification →lipid absorption
Where is bile salt secreted into?
into duodenum
Where are Bile salts are reabsorbed from?
small intestine and back to liver
What is the process of “enterohepatic circulation”?
- The liver secretes bile
- Bile travels to the gallbladder and is stored there
- The release of CCK by the duodenum triggers the bile to be released from the gallbladder to the duodenum
- Within the lumen of the digestive tract, bile salt break the lipid droplets
- The Bile is reabsorbed by the small intestine and back to the liver
Where is bile synthesized?
Bile is synthesized in the hepatocyte (liver cells)
What are the structures in the liver? (4x)
- left & right lobes
- gallbladder
- bile duct
What are the two functional portions of the pancreas?
Exocrine portion and Endocrine portion
What are the structural and functional features of the Exocrine portion?
Pancreatic acini (structure)
Exocrine cells secrete pancreatic juice containing an alkaline mixture of digestive enzymes, water, and ions.
What are the structural and functional features of the Endocrine portion?
Pancreatic islets (endocrine structure)
Func: secrete insulin and glucagon (blood sugar control)
What are pancreatic enzymes?
- Pancreatic alpha-amylase
- Pancreatic lipase
- Nucleases
- Proteolytic enzymes
Pancreatic alpha-amylase
a carbohydrase n enzyme that breaks down certain starches.
Pancreatic lipase
which breaks down certain complex lipids, releasing products (such as fatty acids) that can be easily absorbed.
Nucleases
which breaks down RNA or DNA.
Proteolytic enzymes
which break apart proteins.
What are the important cell types in the stomach?
- Parietal cells
- Chief cells
- G cells
- D cells
- Ghrelin
- Rennin
Parietal cells
Intrinsic factor (help absorb Vitamin B12)
Hydrochloric acid (HCl) (indirectly)
Chief cells
Pepsinogen (Acid promote to converted to pepsin, active protelytic)
G cells
Gastrin (stimulates gastric secretion)
D cells
Somatostatin (a hormone that inhibits the release of gastrin)
Ghrelin
This hormone stimulate hunger
Rennin
Stomachs of newborn infants produce rennin, also called chymosin, and gastric lipase (digestion of milk).
What are the three muscle layers in the stomach?
- Longitudinal muscle layer
- Circular muscle layer
- Oblique muscle layer
uvula
a soft gangling process that prevents food from entering the nasopharynx
epiglottis
a flap of elastic cartilage that prevents food from entering the larynx and subsequence trachea (the airway).
How are gastric activities regulated?
(1) Cephalic phase;
(2) Gastric phase;
(3) intestinal phase.
Cephalic phase
CNS sensory or cognitive activation increases neural stimulation of the stomach.
This phase prepares the stomach for the arrival of food (production of gastric juice speeds up).
The vagus nerve stimulates the submucosal plexus in the stomach for gastric juice.
Gastric phase
This phase of gastric secretion is triggered by the entry of food into the stomach.
1. Distension of the stomach
2. Increased pH
3. Undigested materials (meal)
→stimulation of submucosal and myenteric plexus
→gastric juice secretion.
Gastrin promotes gastric juice secretion and mixing wave.
Intestinal phase
Production of intestinal hormones, CCK, GIP and Secretin
CCK, GIP and Secretin inhibit chief cells and Parietal cells, and peristalsis
These begin when chyme enters the small intestine (duodenum).
Myenteric plexus
is a network of parasympathetic ganglia, sensory neurons, interneurons, and sympathetic postganglionic fibers.
