Digestive System Flashcards
What are the functions of the digestive system (6x)
- Ingestion
- Mechanical digestion and propulsion
- Chemical digestion
- Secretion (water, acid, enzyme, hormones, buffer and salts)
- Absorption
- Defecation
What does the digestive system consist of?
the digestive tract (gastrointestinal (GI) tract) and various accessory organs.
What are the accessory organs of the digestive system? (6x)
Teeth, Tongue, Salivary Glands, Liver, Gallbladder, Pancreas
What are the major organs of the digestive tract? (6x)
Oral Cavity, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine
What is the peritoneum?
Peritoneum is membrane that lines our abdominal wall and cover most of the organs
What is mesentery?
The mesentery is a fold of membrane that attaches the intestine to the abdominal wall.
What does mesentery proper support?
The mesentery proper supports all but first 25 cm of the small intestine and provides stability and limited movement.
What does the greater omentum contain?
Greater omentum contains adipose tissue and provides padding for the anterior and lateral portions of the abdomen
What is lesser omentum?
Lesser omentum stabilizes the position of the stomach and provides an access route for blood vessels and other structures entering or leaving the liver.
What is mesocolon?
Mesocolon a mesentery associated with a portion of the large intestine.
What increases the surface area of the mucosa of the small intestine
Circular fold and intestinal villi increase the surface area of the mucosa of the small intestine.
What is Lamina Propria (in relation to the digestive system)?
Lamina propria is layer of areolar tissue that contains blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells and lymphatic tissue.
What is Muscularis mucosae?
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 is submucosal neural plexus?
Submucosal neural plexus is a network of intrinsic nerve fibers and scattered neurons. The submucosal plexus lies along the inner border of the muscularis externa (muscularis).
What is the myenteric plexus?
Myenteric plexus is a network of parasympathetic ganglia, sensory neurons, interneurons, and sympathetic postganglionic fibers.
What is Serosa in relation to the digestive tract?
Serosa covers the muscularis externa along most portions of the digestive tract inside the peritoneal cavity
What does segmentation mean in relation to the digestive system?
Most areas of the small intestine and some portions of the large intestine undergo cycles of contraction that churn and fragment the bolus, mixing the contents with intestinal secretions.
What does Peristalsis contain?
Peristalsis consists of waves of muscular contractions that move a bolus, or soft rounded ball of digestive contents, along the length of the digestive tract
What is Peristalsis?
Peristalsis is the waves of muscular contraction that propel the contents of the digestive tract.
How does the digestive system move material? (4 steps)
- Initial Stage
- Contraction of circular muscles behind bolus
- Contraction of longitudinal muscles ahead of bolus
- A wave of contraction in circular muscle layer forces bolus forward
What controls digestive function? (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 functions of the oral cavity? (4x)
(1) sensory analysis of food before swallowing;
(2) mechanical digestion through the actions of the teeth, tongue, and palatal surfaces;
(3) lubrication by mixing with mucus and saliva;
(4) limited chemical digestion of carbohydrates and lipids.
What is Gingiva?
The ridge of oral mucosa that surrounds the base of a tooth
What is vestibule in relation to the oral cavity?
Vestibule, The space between the cheeks or lips and the teeth
What is the oral cavity lined with?
oral mucosa.
What is the oral mucosa?
(stratified squamous epithelium).
Where is Uvula located?
located at the posterior margin of the soft palate.
How is the dangling process of the Ulva helpful?
The dangling process that aids in keeping food out of the nasopharynx
What does the Palatoglossal arch do?
This extends from the soft palate to the pharyngeal wall.
What is the function of the tongue? (4x)
(1) mechanical digestion by compression, abrasion, and distortion;
(2) manipulation to assist in chewing and to prepare food for swallowing;
(3) sensory analysis by touch, temperature, and taste receptors
(4) secretion of mucins and the enzyme lingual lipase.
How does the pulp cavity receive blood vessels and nerves?
The pulp cavity receives blood vessels and nerves through the root canal.
What is pulp cavity?
The part of a tooth that contains blood vessels and nerves
What is Enamel?
cover the crown of a tooth
What is Dentin?
The bulk of each tooth consists of a mineralized matrix similar to that of bone.
What is Gingival sulcus?
A shallow groove called the gingival sulcus surrounds the neck of each tooth
What does the Periodontal ligament do?
Each tooth is held in the alveolar socket by this ligament
What are the 4 types of Teeth?
- Incisor
- Canine
- Premolar
- Molar
What are Incisor teeth and its function?
Blade-shaped teeth that function in cutting or clipping
What are Canine and its function?
or cuspids, are conical with a single, pointed cusp. the canines are used for tearing or slashing.
What are Premolar teeth and its function?
or bicuspids, have flattened crowns with two prominent rounded cusps. They crush, mash, and grind.
What are Molar teeth and its function?
Teeth with flattened crowns and prominent ridges that are adapted for crushing and grinding.
What are the 2 type of teeth that form during development?
Two such dentitions (teeth) form during development: deciduous and permanent.
What are other names used for deciduous teeth?
(primary teeth, milk teeth, baby teeth)
What are the first to appear in terms of teeth?
deciduous teeth
Most children have how many deciduous teeth?
20 deciduous teeth
On each side of the upper/lower jaw, the deciduous teeth consists of what?
On each side of the upper or lower jaw, the deciduous teeth consist of two incisors, one canine, and a pair of deciduous molars for a total of 20 teeth.
How are deciduous teeth replaced by permanent teeth?
The deciduous teeth either fall out or are pushed aside by the eruption, or emergence, of the permanent teeth
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.
Saliva is mostly produced by?
submandibular glands
What is the second most contributor to saliva?
parotid glands
What produces the least amount of saliva?
sublingual glands
What does saliva contain?
99.4 % water, 0.6% electrolytes, buffers, glycoproteins, antibodies, enzymes, and wastes.
What are the 4 steps of swallowing?
- buccal phase
- pharyngeal phase
- esophageal phase
- Bolus enters stomach
What is the buccal phase?
The buccal phase is a primary and voluntary phase.
What is the Pharyngeal phase?
Breathing stops during the pharyngeal phase
What is the esophageal phase?
The esophageal phase pushes the bolus toward the stomach
What is the major functions of the stomach? (3x)
(1) temporarily store ingested food received from the esophagus,
(2) mechanically digest food through muscular contractions, and
(3) chemically digest food through the action of acid and enzymes.
What is chyme?
Ingested substances combine with the secretions of the stomach glands, producing a viscous, acidic, soupy mixture of partially digested food called chyme
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 Body in relation to the stomach?
Body, The part of the stomach that functions as a mixing chamber for food and secretions
What is Rugae?
Rugae, The prominent ridges in the lining of the empty stomach
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 is Gastric pits?
Gastric pits are openings into gastric glands.
Each gastric pits communicates with what?
Each gastric pit communicates with several gastric glands
What are the cells of the gastric glands?
Mostly, parietal cells and chief cells
What do parietal cells do?
secrete intrinsic factor (help absorb Vitamin B12), indirectly secrete hydrochloric acid (HCl)
What do Chief cells do?
secrete pepsinogen (this is converted to pepsin by acid)
What do the stomachs of newborns produce?
produce rennin, also called chymosin, and gastric lipase (digestion of milk).
What are the 3 phases of the stomach?
- Cephalic phase
- Gastric phase
- Intestinal phase
What is the 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).
What is the gastric phase?
This phase is triggered by the entry of food into the stomach.
Then, stomach secretes juice and mixes food into chyme.
What is the intestinal phase?
functions to control the rate of gastric emptying.
involves both neural and endocrine reflexes.
helps ensure that the functions of the small intestine proceed with relative efficiency.
begins when chyme enters the small 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
Teeth and Tongue aid in what digestive function
Mechanic digestion
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
Uvula
The dangling process that aids in keeping food out of the nasopharynx.
Epiglottis
The epiglottis is a flap of elastic cartilage and attached to the root of the tongue. The flap-like structure prevents food from entering the larynx. The epiglottis guards the entrance of the glottis, the opening between the vocal folds.
A structure that helps prevent food from entering the pharynx prematurely is the
uvula
The elastic cartilage that covers the opening to the larynx during swallowing is the
epiglottis
The flap-like structure that prevents food from entering the larynx is called the
epiglottis
What are the 3 muscular layer of stomach?
- Longitudinal muscle layer
- Circular muscle layer
- Oblique muscle layer.
What do the extra layers of the stomach help with?
The extra layers of smooth muscle strengthen the stomach wall and assist in the mixing and churning essential to the formation of chyme.
What are the other gastric hormones?
G and D Cells
What do G cells secrete?
Gastrin (stimulates gastric secretion)
What do D cells secrete?
Somatostatin (a hormone that inhibits the release of gastrin)
What does Ghrelin do?
This hormone stimulate hunger
What does the vagus nerve stimulate?
The vagus nerve stimulate the submucosal plexus in stomach for gastric juice.
What occurs when gastric secretion is triggered by the entry of food
- Distension of the stomach
- Increased pH
- Undigested materials (meal)
What does gastrin promote?
Gastrin promote gastric juice secretion and mixing wave.
What triggers the gasteric secretion?
by the entry of food into the stomach.
What does the gastric phase do?
- Distension of the stomach
- Increased pH
- Undigested materials (meal)
→stimulation of submucosal and myenteric plexus
→gastric juice secretion.
What does the Intestinal phase produce?
Production of intestinal hormones, CCK, GIP and Secretin
What do CCK, GIP and Secretin inhibit?
CCK, GIP and Secretin inhibit chief cells and Parietal cells, and peristalsis
What starts the Intestinal phase?
begin when chyme enters the small intestine (duodenum)
What do the Pancreas contain? (3x)
- Pancreatic duct
- Pancreatic islets
- pancreatic juice
What does the Pancreatic ducts do?
Pancreatic duct delivers the secretions of the pancreas to the duodenum.
What is the exocrine portion of the pancreas is composed of?
pancreatic acini
What does Pancreatic islets (endocrine) secrete?
(endocrine) secrete insulin and glucagon (blood sugar control)
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