Flashcards in Digestive System Deck (128):
What is another name for the GI tract?
List the main organs in the digestive system
mouth, pharynx, esophagus, stomach, small intestine, and large intestine
List the accessory digestive organs
teeth, tongue, gallbladder, salivary glands, liver, and pancreas
In order, what are the main stages in the digestive process?
2. Mechanical breakdown
Which step in the digestive process are swallowing and peristalsis apart?
alting waves of contraction and relaxation
Which 3 components constituent mechanical breakdown?
chewing, churning, and segmentation
What is segmentation?
rhythmic local constrictions of small intestine
Passage of digested end products from GI tract lumen into blood or lymph
Elimination of indigestible substances
What controls GI tract motility and secretion?
Enteric nervous system
What provokes digestive activity?
mechanical and chemical stimuli
When stimulated, receptors in GI tract walls initiate reflexes that...?
1. activate/inhibit digestive glands
2. stimulate smooth muscle
T or F. Controls of digestive activity are both intrinsic and extrinsic
What are the 2 neural mechanisms?
1. Short reflexes- GI tract
2. Long reflexes- CNS center and ANS fibers
Describe hormonal mechanisms.
involve hormone-producing cells in stomach and small intestine
What covers the abdomen?
What type of peritoneum covers the organs?
What comes between visceral and parietal peritoneum?
What type of peritoneum lines the abdominopelvic cavity?
What is the double layer of peritoneum that extends to digestive organs from body wall?
What are the 4 layers of the alimentary canal?
muscosa, submucosa, muscularis externa, and serosa
Which layer of the alimentary canal consist of epithelium, lamina propria, and muscularis externa?
Dense connective tissue; contains blood vessels, lymphatics, and nerve fibers
Inner circular layer; outer longitudinal layer
Bounded by lips, cheeks, palate, and tongue; lines by stratified squamous epithelium
Mouth (oral cavity)
Bone in the oral cavity
What projects from free edges in the mouth?
Positions food during chewing, mixes food with saliva to form a bolus, initiates swallowing
What are the 3 salivary glands?
parotid gland, submandibular gland, and sublingual glands
What are the functions of the saliva?
cleanses mouth, dissolves food chemicals, moistens food, and begins chemical breakdown of starch
Between which 2 ages do teeth begin to erupt?
How many permanent teeth can one have?
What are the 4 classes of teeth? Amount upper L or R?
incisors (2), canines (1), premolars (2), and molars (3)
What are the 3 main parts of the teeth?
crown, neck, and root
Nasopharynx, Oropharynx, and laryngopharynx
Which organ is lined by the stratified squamous epithelium?
Which digestive processes occur in the mouth?
ingestion, mechanical breakdown, propulsion, and digestion
Which digestive process occur in the pharynx and esophagus?
How does mastication occur?
Cheeks and lips hold food between teeth, teeth cut and grind, and tongue from a bolus
How does deglutition occur?
tongue presses against hard palate and bolus is forced into oropharynx
Wha are the 2 phases in delglutition? voluntary?
Buccal phase- voluntary
Paryngeal-Esophageal Phase- Involuntary
What moves food through esophagus?
What are the functions of the stomach?
temporary food storage (50mL/4L), begins chemical breakdown of proteins, and converts bolus to chyme
What controls food entry into the duodenum?
What is the extra layer in the stomach?
In the stomach, where are gastric pits located?
How are gastric juices produces?
gastric pits lead into gastric glands
What are the 4 major cells types in the gastric gland?
mucous neck cells, parietal cells, chief cells, and enteroendocrine cells
Required for absorption of vitamin B12
mucous neck cells
Secretes HCl and intrinsic factor, activate pepsin
Protects stomach mucosa, created by thick layer of bicarbonate-rich mucus
In mechanical breakdown, bolus is converted into..?
In Digestion, what is the purpose of HCl and pepsin?
HCl- denatures proteins
Pepsin- begins digestion of proteins
In propulsion, where is chyme delivered?
In L, how much gastric juices is secreted per day?
What regulates secretion?
long and short reflexes and hormones
What are the 3 phases of the gastric secretion?
cephalic, gastric, and intestinal
When does the cephalic phase occur?
Before food enters the stomach
What triggers the cephalic phase?
triggered by smell, taste, sight or thought
Which nerve stimulates the enteric neurons?
vagus causing secretion
When does the gastric phase occur?
once food reaches the stomach
How much gastric juice is the in the stomach?
What provoked the gastric phase?
distension of short and long reflexes, peptides and rising pH stimulate gastrin
When does the intestinal phase occur?
Once food enters the duodenum
How is the intestinal phase inhibited?
enterogastric reflex and release of intestinal hormones
What provokes the intestinal phase?
distension of duodenum, presence of fats, and acidic chyme
What is inhibited to promote gastric secretion?
Enteric neurons and vagus nerves
Which 2 hormones are secreted by intestinal hormones?
cholecystokinin and secretin
In gastric contractile activity what happen to chyme?
3 ml into dudoenum and 27mL forced back into stomach
Where does the small intestine begin or end?
begins at pyloric sphincter and ends at ileocecal valve
From proximal to distal what are the parts of the small intestine?
duodenum, jejunum, and ileum
Where are the bile duct and main pancreatic duct located?
Bile duct: from liver
Main pancreatic duct: pancreas unite in wall of duodenum
What controls entry of bile and pancreatic juice?
What are the 3 structural modifications in the small intestine?
circular folds, villi, microvilli
What is the function of the 3 structural modifications in the small intestine?
increase surface area for absorption
What forms the circular folds? Purpose
Formed by mucosa and submucosa.
Forces chyme ti slowly spiral through lumen
Fingerlike projections of mucosa and contain capillary beds and lacteals
Form brush border and brush border enzymes
What do the pits of the villi lead?
lymphoid nodules in mucosa of ilium
submucosa of duodenum, secrete alkaline in mucus
stores and concentrates bile
common hepatic duct
What is formed by union of common hepatic and cystic ducts?
What are the 3 parts of the portal triad?
Hepatic artery, hepatic portal vein, and bile duct
Carries blood from digestive organs to liver for processing
hepatic portal vein
Oxygen-rich arterial blood in the liver
Nutrient-rich venous blood in the liver
hepatic portal vein
Runs between hepatocyte platesq
What is the flow of blood in the liver?
hepatic artery and hepatic portal vein -> liver sinuoids-> central vein
Remove bacteria worn-out RBCs, and other debris from blood as flows past
Kupffer cells/ Stellate macrophages
Produce bile, process bloodbome nutrients, store fat-soluble vitamins and plays important role in detoxification
Secreted bile flows through what toward bile ducts?
Yellow-green alkaline solution
cholesterol derivatives that function to emulsify fats
chief bile pigment
Where in the pancreas do the exocrine functions occur?
How does the pancreatic juice enter the dudoenum
What are the 3 components pancreatic juice?
water, digestive enzymes, and bicarbonate ions
What causes the gallbladder to contract, stimulate secretion of enzyme-rich pancreatic juice and relaxes hepatopancreatic juice
stimulates secretion of bicarbonate-rich pancreatic rich
What digestive processes occur in the small intestine?
Mechanical breakdown and propulsion: segmentation and peristalsis
Digestion: enzymes from pancreas; brush border enzymes of microvilli
Absorption: Most water and virtually all nutrients absorbed
List what optimal digestive activity depends on:
1. bile from liver and gallbladder
2. Digestive enzymes from pancreas
3. Bicarbonate ions from the pancreas
4. Slow, measured delivery of chyme from stomach
Most common motion of small intestine, mixes chyme with bile, pancreatic juice, and intestinal juice, moves ileocecal valvve
Begins late in intestinal phase
migrating motor complex
Which 2 mechanisms increase motility of ileum and cause ileocecal sphincter to relax?
Gastroileal reflex and gastrin released by stomach
Three bands of smooth muscle
Pocket-like sacs in wall of large intestine
From small intestine to the anal canal where does the food go?
cecum, ascending colon, transverse colon, descending colon, sigmoid colon
List the subdivisions of the large intestine
cecum, appendix, colon, rectum, and ana canal
What are the 3 sphincters in the anus? Type of muscle?
Internal anal sphincter (smooth muscle) and external anal sphincter (skeletal muscle)
What type of epithelium is the large intestine? Anal Canal?
Large intestine: simple columnar epithelium
Anal canal: stratified squamous
What type of cells do large intestines contains that secrete mucus?
What are the functions of the Bacterial flora in the large intestine?
colonize colo, ferment cellulose and other plant polysaccarides, synthesize B complex vitamins and vitamin K
What are the digestive process in the large intestine?
absorption- absorbs remaining water
Propulsion- propels feces toward rectum
Defacation- eliminates feces toward body
Long, slow-moving, powerful contractile waves, force contents toward rectum
Parasympathetic reflex that is initiated by stretching rectal wall.
What is the result of the defecation reflex
sigmoid colon and rectum contract and internal anal sphincter relaxes