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110 terms

CHapter 24 - Exam 3 Digestive System

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chemical digestion
a series of reactions that break down large carbohydrates, lipids, and protein molecules into smaller molecules that can be absorbed and used by body cells
mechanical digestion
consists of various movements that increases surface area of the food to allow a thorough mixing with the digestive enzymes
absorption
the movement of the end products of digestion through the gastrointestinal tract wall into the blood or lymph for circulation to cells
defecation
the elimination of indigestible and undigested materials from the gastrointestinal tract
what are the 2 main groups that the organs of digestion are divided into
gastrointestinal tract and accessory digestive organs
what are the organs of the digestive tract
mouth, pharynx, esophagus, stomach, small and large intestine
what are the accessory digestive organs
teeth, tongue, salivary glands, liver, gallbladder, and pancreas
peritoneum
the largest of the serous membrane of the body
parietal peritoneum
lines the wall of the abdominal cavity
visceral peritoneum
covers some of the organs
mesentery
a double layer of peritoneum that attaches to the back wall of the abdominal cavity and supports the small intestines
greater omentum
part of the peritoneum attached to the stomach and to the colon and covering the intestines
what makes up the mouth (oral cavity)
cheeks, hard and soft palates and tongue
tongue
forms the floor of the oral cavity and is composed of skeletal muscle covered with mucous membrane
salivary glands
these lie outside the mouth and secrete the major portion of saliva through ducts, which enter into the oral cavity
what are the 3 pairs of salivary glands
Parotid, submandibular, and sublingual glands
what are the 3 parts of the tooth
crown, root and neck
dentin
what are the teeth composed of?
cementum
bone-like substance that attaches the root of the tooth to the periodontal ligament
salivary amylase
Enzyme in saliva that breaks down starch
esophagus
muscular tube that lies posterior to the trachea. it connects the pharynx to the stomach
deglutition
the act of swallowing
peristalsis
the process of wave-like muscle contractions of the alimentary tract that moves food along
bolus
A term used to describe food after it has been chewed and mixed with saliva
stomach
j shaped enlargement of the GI tract which begins at the bottom of the esophagus and ends at the duodenum (first part of small intestine)
rugae
mucosal folds in the lining of the stomach that expands surface area
gastric glands
glands of the mucosa of the stomach that secrete HCl and hydrolytic enzymes (primarily pepsinogen, the inactive form of pepsin, a protein-digesting enzyme), which begins the enzymatic, or chemical breakdown of protein foods.
what are the 4 types of secreting cells that make up the gastric glands
chief cells, parietal cells, mucous cells and G cells
chief cells
cells that release an inactive enzyme, pepsinogen
pepsinogen
The inactive form of pepsin that is first secreted by specialized (chief) cells located in gastric pits of the stomach.
parietal cells
cells that secrete HCl, which aids in the conversion of pepsinogen to active pepsin
intrinsic factor
a substance produced by the mucosa of the stomach and intestines that is essential for the absorption of vitamin B12
mucous cells
cells that secret mucous
G cells
cells that secret stomach gastrin
gastrin
polypeptide hormone secreted by the mucous lining of the stomach. it allows for the secretion of HCl and pepsinogen, relaxes the pyloric sphincter and increases motility
mixing waves
Gentle, ripping, peristalic movements that pass over the stomach every 15 to 25 seconds; softens and mixes food with gastric secretions to form chyme
mechanical digestion
consists of peristalic movements called mixing waves
chemical digestion
consists of the conversion of protein into peptides by the action of the enzyme pepsin
chyme
a semiliquid mass of partially digested food that passes from the stomach through the pyloric sphincter into the duodenum
secretin
peptic hormone produced by the mucous lining of the small intestine. decrease gastric secretion and motility
CCK (cholecystokinin)
...
pancreas
accessory organ which functions as both and endocrine and exocrine organ
pancreatic juice
contains enzymes that digest starch, proteins, fats, and nucleotides
bicarbonate ions
converts the stomach acid contents to a slightly alkaline pH. also inhibits stomach pepsin activity and promotes the activity of the pancreatic enzymes
nervous and hormonal mechanisms
how are pancreatic secretions regulated
left and right lobes
how is the liver divided
what are the lobes of the liver made up of
hepatocytes, sinusoids, kupffer cells and a central vein
hepatic artery and hepactic portal vein
the liver receives a dual blood supply from what 2 things
hepatocytes
cells that secrete bile that is transported by a duct system to the gallbladder for concentration and temporary storage
bile
a substance produced by the liver that breaks up fat particles
gallbladder
sac that hangs from the lower front margin of the liver. it functions to store and concentrate the bile produced by the liver
what is the small intestine divided into
duodenum, jejunum, ileum
maltase
an enzyme that acts upon maltose and converts it into glucose
sucrase
breaks down sucrose
lactase
enzyme that breaks down lactose
peptidases
Enzymes that break down proteins into amino acids
nucleases
pancreatic juice enzymes that digest nucleic acids into nucleotides
name the subdivisions of the large intestine
cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal
how long does chyme remain in the large intestine
3 to 10 hours
name the 6 functions of the digestive system
1. ingestion
2. mechanical processing
3. digestion
4. secretion
5. absorption
6. excretion
mesentery
double sheets of peritoneal membrane that suspend portions of digestive tract within peritoneal cavity by sheets of serous membrane
lesser omentum
stabilizes position of stomach
falciform ligament
helps stabilize positions of liver
dorsal mesentery
enlarges to form an enormous pouch, called the greater omentum
mesocolon
a mesentery associated with a portion of the large intestine
mucosa
inner lining of the digestive tract
enteroendocrine cells
cells that secrete hormones that coordinate activities of the digestive trace and accessory organs
muscularis mucosae
a narrow band of smooth muscle and elastic fibers on the outer portion of the mucosa, contraction of this move the mucosal folds and villi
mucosa
The layer of epithelial tissue that lines body cavities in contact with the outside environment (respiratory, digestive, urinary, and reproductive tracts).
submucosa
layer of dense, irregular connective tissue that surrounds the muscularis mucosae
submucosal plexus (plexus of meissner)
innervates the mucosa and submucosa
muscularis externa
consists of smooth muscle; responsible for segmentation and peristalsis
serosa
a thin membrane lining the closed cavities of the body except in oral cavity, pharynx, esophagus and rectum
vestibule
space between the cheeks or lips and the teeth
gingivae
ridges of oral mucosa
salivary glands
three pairs of exocrine glands in the mouth that secrete saliva; the parotid, submandibular (submaxillary), and sublingual glands
parotid salivary glands
produce a serous secretion containing large amounts of salivary amylase
sublingual salivary glands
on the floor of the mouth; secrete mucus
submandibular salivary gland
located along the floor of the mouth in the mandibular grooves;
secrete a mixture of buffers, mucins and salivary amylase
pulp cavity
part of the tooth that receives blood vessels and nerves through the root canal
deciduous teeth
primary teeth
deglutition
Swallowing
name the 3 phases of swallowing
buccal, pharyngeal, esophageal
regions of the stomach (4)
cardia, fundus, body, pylorus
where are the gastric glands located
fundus and body of stomach
parietal cells
cells that secrete intrinsic factor and HCl
chief cells
cells that secrete HCl and pepsinogen
pyloric glands
Glands located in the walls of the stomach, secreting the hormone gastrin in response to certain substances in food.
where does nutrient absorption occur?
small intestine
duodenum
the segment of the small intestine closest to the stomach
duodenum
part of the small intestine that receives chyme from the stomach and neutralizes acids
jejunum
middle section of the small intestine
jejunum
what part of the small intestine is the location of chemical digestion and nutrient absorption
ileum
the final segment of the small intestine
plicae curculares
transverse folds in the intestinal lining. Permanent features, do not disappear when intestine fills.
brush border enzymes
small intestine enzymes that include disaccharidases and dipeptidases
enteropeptidase
brush border enzyme that does not participate directly in digestion, but does activate trypsinogen
enteroendocrine cells
produce intestinal hormones such as gastrin, CCK, and secretin
duodenal glands
those in the submucosa of duodenum that secrete alkaline mucus to help neutralize acidic chyme
pancreatic alpha amylase
What pancreatic enzyme breaks down carbohydrates or starches?
pancreatic lipase
Enzyme in pancreatic juice that breaks down triglycerides (fats and oils), creating fatty acids and monoglycerides
what are the 3 structures of the portal area
branch of hepatic portal vein, branch of hepatic artery proper, small branch of bile duct
which organ secrete bile
liver
3 functions of the liver
metabolic regulation, hematological regulation, bile production
gallbladder
which organ stores and concentrates bile prior to excretion
name the 3 areas of the colon
cecum, colon, rectum
ascending colon
the part of the large intestine that ascends from the cecum to the transverse colon
transverse colon
the part of the large intestine that extends across the abdominal cavity and joins the ascending to the descending colon
descending colon
the part of the large intestine that descends from the transverse colon to the sigmoid colon
sigmoid colon
the s-shaped curve between the descending colon and the rectum