A&PII Lab 11: The Digestive System - Anatomy Flashcards
Digestive System
system that converts food into a form that the body can use for energy, growth, and repair
Gastrointestinal (GI) tract
sequence of organs forming a single, continuous tube extending from the mouth to the anus; AKA alimentary canal
Accessory organs
organs that support digestion by the secretion of enzymes and other substances into the GI tract
Mucosa
deepest layer of the GI tract; composed of a lining epithelium kept moist by the secretion of mucus, a connective layer (lamina propia), and a thin layer of smooth muscle (muscularis mucosae)
Submucosa
external to the mucosa; composed of loose connective tissue
Muscularis
layer external to the submucosa; composed of 2 layers in all GI tract organs except the stomach; inner layer = circular arrangement of smooth muscle; outer layer = longitudinal arrangement of smooth muscle; stomach has 3rd layer (innermost layer of smooth muscle fibers extending in an oblique direction)
Serosa (visceral peritoneum)
external to the muscularis is this serous membrane; contains a layer of epithelium and a layer of connective tissue
Peritoneum
most extensive serous membrane of the body; combination of simple squamous epithelium with underlying connective tissue; associated with most digestive organs that reside within the abdominopelvic cavity, including the stomach, small intestine, large intestine, and liver
Parietal peritoneum
outer layer; lines the inner wall of the abdominopelvic cavity
Visceral peritoneum
inner layer; attached to the outer wall of most organs within the abdominopelvic cavity to form the serosa
Peritoneal cavity
space between the parietal and visceral peritoneum
Mesentery
fold that attaches the coils of the small intestine to the posterior abdominal wall
Mesocolon
fold that attaches the large intestine
Falciform ligament
fold that attaches the liver to the anterior abdominal wall; can be observed between the right and left lobes of the liver
Ligamentum teres
vestigial structure which served as the umbilical vein that brought maternal blood from the placenta to the liver of the fetus
Greater omentum
largest peritoneal fold; begins from the greater curvature of the stomach and folds back to attach to the large intestine; in most people, it hangs like an apron over most of the anterior abdomen, and is filled with fat and lymph nodes
Lesser omentum
extends between the lesser curvature of the stomach and the liver
Mouth
point of entry of food into the GI tract
Oral cavity
AKA buccal cavity
Lips
opening of the mouth is marked by these fleshy structures
Fauces
opening into the oropharynx; throat
Cheeks
lateral borders of the mouth
Tongue
at the floor of the mouth
Hard palate
bony structure forming the anterior part of the roof of the mouth
Soft palate
posterior part of the roof of the mouth
Gingivae
gums; anchor the teeth
Vestibule
narrow space between the teeth and gingivae
Labial frenulum
bridge of mucous membrane connecting the superior lip and gingivae across the vestibule
Palatoglossal arch, palatopharnygeal arch
bordering the fauces are these 2 arches
Palatine tonsil
between the arches on each side is a slight depression housing this tonsil
Uvula
visible at the back of the mouth; extends from the soft palate to hang downward
Pharynx
when you swallow, movements of the soft palate and tongue push food into this next organ of the GI ; muscular chamber lined with mucous membrane, divided into 3 segments
Nasopharynx
superior segment of the pharynx that receives air from the internal nares, & includes the single pharyngeal tonsil and openings into the auditory tubes
Oropharynx
middle segment of the pharynx; posterior to the fauces of the mouth; common chamber for food, water, and air (due to its location)
Laryngopharynx
inferior to the oropharynx; extends to the glottis of the larynx
Esophagus
when it’s not transporting food, this “gullet” is a flattened tube with muscular walls and a slippery mucosa that stretches open to accommodate swallowed food
Peristalsis
the esophagus propels food by this action, in which the circular and longitudinal muscles in its walls contract sequentially to form a wavelike pattern
Esophageal hiatus
at its distal end, the esophagus passes from the thoracic cavity into the abdominal cavity through this opening in the diaphragm
Lower esophageal sphincter (LES)
near its union with the stomach, the esophageal muscles thicken to form this structure, which opens to allow food into the stomach
Stomach
J-shaped organ immediately inferior to the diaphragm on the left side of the abdominal cavity
Cardia
part that receives the esophagus (in the superior part of the stomach)
Fundus
dome-shaped holding area for food that forms the superior part of the stomach
Body
large, central portion of the stomach
Pylorus
small area to the left of the body of the stomach; the “gatekeeper”
Pyloric valve (pyloric sphincter)
the pylorus unites with the small intestine at this thickening of the stomach wall; opens to allow stomach contents into the small intestine
Pyloric antrum
part of the pylorus adjacent to the body of the stomach
Pyloric canal
part of the pylorus near the pyloric valve
Lesser curvature
medial border of the stomach forms this concave curve
Greater curvature
lateral border of the stomach forms this convex curve
Rugae
ridges of the mucosa on the internal surface of the stomach; provide an additional surface area that permits stretching of the stomach wall to accommodate a large volume of food
Gastric juice
within the stomach, food is mixed and churned with these secretions of the stomach wall
Pepsin
enzyme within gastric juice; performs the chemical digestion of protein molecules
Small intestine
long tube-shaped organ that extends from its union with the stomach to the large intestine, dominating the abdominopelvic cavity; 10 feet long, 1 inch in diameter in an average healthy adult; composed of 3 segments
Duodenum
proximal segment of the small intestine; name derived from its length of “12 finger-widths” (~10 inches); wall of this segment contains glands that secrete mucus, which protect its lining from the acidic material arriving from the stomach; receives enzymes from the pancreas, bile from the liver & gallbladder, and produces its own digestive enzymes
Jejunum
middle segment of the small intestine; measures about 3 feet long; derives its name from early human dissections, during which it was usually found “empty” of any contents
Ileum
distal segment of the small intestine; longest portion at about 6 feet in length; named after peristaltic waves were observed to “roll” through it
Ileocecal valve
the ileum terminates at this valve, where it unites with the large intestine
Plicae circulares
absorption is aided by the presence of these internal circular folds, along with villi and microvilli
Villi
fingerlike projections of the mucosa; aids absorption along with plicae circulares and microvilli
Microvilli
cellular processes that aids absorption along with plicae circulares and villi
Large intestine
5 feet, 3 inches wide; consists of 3 main segments (cecum, colon, rectum)
Cecum
blind pouch arising from the ileocecal valve and extending 2-3 inches before it ends
Appendix
slender appendage that extends from the medial wall of the cecum about 2 inches
Colon
at the level of the ileocecal valve, this portion of the large intestine begins its ascent toward the liver on the right side of the abdominopelvic cavity
Ascending colon
begins its ascent toward the liver on the right side of the abdominopelvic cavity to form this
Right Colic Flexure
colon takes this 90 degree turn just beneath the liver
Transverse colon
part of the colon that extends transversely to the left side of the abdominopelvic cavity
Left Colic Flexure
near the spleen, the colon turns 90 degrees inferiorly
Descending Colon
part of the colon continuing downward along the left side until it turns to form an S-shaped segment (sigmoid colon)
Sigmoid Colon
S-shaped segment of the colon at the level of the iliac crest
Taenia coli
all 4 portions of the colon contain these 3 longitudinal bands of smooth muscle
Haustra
contractions of taenia coli gather the colon into these pouches, which can be observed externally
Epiploic appendages
numerous fat-filled pouches of visceral peritoneum; hang from the taenia coli
Rectum
final segment of the large intestine; about 6 inches long; lacks the taenia coli, haustra, and epiploic appendages of the colon
Anal canal
terminal 2 inches of the rectum
Anal columns
anal canal contains these folds along the inner wall
Anus
rectum opens to the exterior at this structure
Internal & external sphincters
anus is bordered by these smooth muscles and skeletal muscles
Teeth
provide mechanical digestion by breaking up food particles in the mouth
Crown
visible area of teeth above the gum line
Root
submerged area of teeth below the gum line; embedded into an alveolar socket of the mandible or maxilla
Periodontal ligament
root of teeth anchored in place by this ligament which lines the socket
Dentin
most of a tooth is composed of this calcified connective tissue
Enamel
harder than dentin; = compact bone; forms a covering over the crown of a tooth
Cementum
in the root of a tooth, this adhesive connective tissue adheres the dentin to the periodontal ligament
Pulp cavity
the center of the crown of the tooth is this small chamber; filled with pulp, which contains blood vessels, nerves, and lymphatics
Root canal
the pulp cavity and pulp continues into the root as this slender channel
Incisors
teeth with narrow edges for cutting during a bite
Canines (cuspids)
teeth with a pointed edge for tearing food
Premolars
teeth with 2 flat surfaces (cusps) for grinding
Molars
teeth with broad/rounded cusps for additional food grinding
Deciduous teeth
in a child, teeth begin forming several months after birth to eventually form these teeth; AKA primary or milk teeth; temporary with very small roots, lost between the ages of 6-12 years; 20 teeth = 2 incisors, 1 canine, 0 premolars, 2 molars on upper and lower (x 2)
Permanent teeth
32 teeth = 2 incisors, 1 canine, 2 premolars, 3 molars on upper and lower (x 2)
Salivary glands
exocrine glands that secrete saliva
Saliva
watery substance secreted by exocrine glands that lubricates food in the mouth to assist in swallowing; its enzymes begin the process of carbohydrate digestion in the mouth
Parotid glands
largest of the salivary glands are these paired glands; located anterior and inferior to the ear, between the masseter muscles of the jaw and the skin
Parotid ducts
parotid glands secrete saliva into these chambers, which carry it into the mouth near the 2nd molar of the upper jaw
Submandibular glands
paired glands that may be found in the posterior floor of the mouth medial to the mandible
Submandibular ducts
submandibular glands secrete saliva into these ducts, which open into the mouth near the lingual frenulum beneath the tongue
Sublingual glands
paired salivary glands located beneath the tongue in a location medial and superior to the submandibular glands
Lesser sublingual ducts
sublingual glands secrete saliva into these ducts, which open into the floor of the mouth beneath the tongue
Tongue
when relaxed, it lies flat on the floor of the mouth
Lingual frenulum
ventral surface of the tongue contains an extension of mucous membrane called this, which anchors the tongue to the actual floor of the mouth
Papillae
the tongue is covered with a thick mucous membrane and these that are distributed along its dorsal and lateral surfaces
Extrinsic muscles
muscles that attach the tongue to the hyoid bone
Intrinsic muscles
tongue muscles not attached to bone; skeletal muscle fibers that move the tongue during chewing, speech, and swallowing
Pancreas
organ located within the abdominal cavity posterior to the body and pylorus of the stomach and the proximal end of the duodenum; soft glandular organ in 3 parts
Head
expanded portion of the pancreas located posterior to the duodenum
Body
central part of the pancreas behind the pylorus of the stomach
Tail
narrow part of the pancreas located behind the body of the stomach
Pancreatic acinar cells
internally, the pancreas consists of these enzyme-secreteing cells, which dominate its landscape; produce pancreatic juice
Pancreatic juice
produced by pancreatic acinar cells; empties into the duodenum
Pancreatic islets
portion of the pancreas secreting hormones
Pancreatic duct
most acinar cells deliver their secretions into this central duct; extends from the tail to the head of the pancreas
Hepatopancreatic ampulla
within the head, the pancreatic duct joins the bile duct to form this structure, which opens at the duodenum
Accessory pancreatic duct
some acinar cells empty their secretions into this duct, which is a division of the pancreatic duct; also opens into the duodenum
Liver
large, soft organ in the right side of the abdominal cavity that presses against the diaphragm; suspended from the diaphragm and the anterior abdominal wall by the falciform ligament; consists of 4 lobes
Right lobe
largest lobe of the liver
Left lobe
separated from the right lobe by the falciform ligament
Caudate lobe
visible from the posterior view only; superior lobe of the liver; posterior to the right lobe
Quadrate lobe
visible from the posterior view only; inferior lobe of the liver; posterior to the right lobe
Right and left hepatic ducts
bile produced by liver cells is transported by small ducts that eventually unite to form these ducts
Common Hepatic Duct
soon after emerging from the liver tissue, the right and left hepatic ducts converge to form this duct; bile may flow through this to the duodenum where it can be used for lipid digestion or it may flow through the cystic duct to be temporarily stored in the gallbladder
Cystic duct
bile may flow through the common hepatic duct to the duodenum where it can be used for lipid digestion, or it may flow through this duct to be temporarily stored in the gallbladder
Gallbladder
hollow organ with smooth muscle walls; visible as a green-colored sac on the posterior side of the liver, located between the right lobe and the quadrate lobe; receives bile from the liver by way of the cystic duct, and stores it until a meal is consumed
Gastric glands and gastric pits
part of the mucosa of the stomach
Chief (zymogenic) cells
blue-stained cells lining the gastric pit; secrete pepsinogen (acidic environment is necessary to activate pepsinogen into its protein-cleaving form, pepsin)
Parietal cells
red-stained cells within the gastric pit; secrete HCl
Brush border
faint pink line along the surface of the simple columnar cells of the small intestine; indicates presence of microvilli
Goblet cells
cells in the lining epithelium of the small intestine; secrete mucus
Intestinal glands
crypts of Lieberkuhn; produce hormones that participate in digestion
Duodenal glands
Brunner’s glands; embedded in the submucosa of the small intestine; produce mucus to protect the intestinal lining from acid arriving from the stomach
Peyer’s Patches
round clusters of dark-staining cells (lymphocytes and macrophages)
Lobules
microscopic sections of the liver
Hepatocytes
each lobule of the liver is a cylindrical arrangement of these cells that radiate from a central vein
Portal triad
the sectioned lobule contains 6 corners, each of which includes this that is formed by a branch of the hepatic artery, a branch of the hepatic portal vein, and a bile duct
Sinusoids
between the rows of hepatocytes are these blood-filled channels which carry blood through the liver as hepatocytes
Kupffer cells
remove unwanted substances
Bile canaliculi
running parallel to the sinusoids are these, which carry newly formed bile toward the bile duct
