Ch. 25 (Digestive system) SG Flashcards
Organs in Digestive tract
mouth, pharynx, esophagus, stomach, both intestines
Accessory organs
teeth, tongue, salivary glands, liver, and pancreas
Functions of digestive system
ingestion of food, mechanical processing (chewing, swirling), digestion (breakdown of things), secretion, absorption (movement of molecules across epithelium layer into interstitial fluid), excretion (waste products, liver), and compaction (prior to elimination of body, compacted material = feces)
Summary of digestive system process
Mechanically and chemically process food, the foods are broken down so they can be absorbed by epithelial lining for transfer to the circulation blood
4 layers of GI tract
mucosa, submucosa, muscularis externa, and serosa
Mucosa layer
Mucous membrane with a mucosal epithelium, has underlying layer of areolar tissue
Submucosa layer
dense irregular connective tissue, home of large blood vessels and lymphatics
Muscularis externa
dominated by smooth muscle fibers
Serosa
covered muscularis externa by using its serous membrane known as serosa
Peritoneal organs
Lie within peritoneal cavity (stomach, liver, and ileum)
Retroperitoneal organs
Kidneys, ureters, and abdominal aorta; these organs are only covered in this lining on the anterior side (the word means posterior to the peritoneum)
Peritoneum
Covers the abdominal cavity organs; the serosa is aka visveral peritoneum; the peritoneal lining helps lubricate their surfaces
Functions of oral cavity
analyzes material before swallowing, mechanical processing thru teeth, lubricates by salivary secretions, and limited digestion of carbs by enzymes
Oral cavity structures
tongue, salivary glands, teeth, mouth,
Location of salivary glands
floor of the mouth and around the zygomatic arch
Type of epithelium for the oral cavity
lined by an oral mucosa which has nonkeratineized stratified squamous epithelium
Permanent vs. Deciduous teeth
Deciduous are the first to appear which are also called your primary and baby teeth. They are temporary till you get your adult teeth which is about 12 more.
Anatomy of teeth
the part we see is the enamel, right under it is the dentine, followed by pulp cavity which extends down into the root canal, teeth roots are connected to alveolus bone
Tongue
Helps manipulate materials inside mouth and helps mechanically process food and does sensory analysis; contains two muscle groups (intrinsic and extrinsic tongue muscles) - both activated by hypoglossal nerve; its a skeletal muscle
Why cant you swallow your tongue?
You can’t swallow it becuz its connected to the floor of your mouth (by lingual frenulum)
Esophagus
transports food and liquids to stomach; has all the Digestive tract layers except the serosa
3 steps in swallowing process
Buccal phase (compression of the bolus against the hard palata, voluntary action), pharyngeal phase (bolus is propelled into the esophagus), esophageal phase (the sphincter opens and the bolus continues its path down into the stomach)
Bolus
the compaction of debris by the tongue into a small oval mass that makes it ready to be swallowed
Stomach
storage of food, mechanical breakdown of food, and chemical digestion of food; Intraperitoneal; located in the left hypochondriac epigastric of the left lumbar/umbilical region; J shaped; with 2 curvatures (greater is connected to greater omentum and lesser is connected to lesser omentum near liver)
Rugae pits
prominent longitudinal folds where mucosa is thrown into for the stomach when its relaxed; allow for expansion of the gastric lumen
Gastric pits
shallow depressions that open into the gastric surface
Gastric glands
simple branched tubular glands dominated by four types of secretory cells (chief, parietal, mucous neck, and enteroendocrine cells)
Small intestine function
primary role in digestion and absorption (90%) of nutrients
3 parts of small intestine
duodenum (connected to pylorus of the stomach; shortest - serves as a mixing bowl that receives chyme), jejunum (place of chemical digestion), and the ileum (last/longest segment of S.I., which transmits material to L.I. via the cecum)
Intestinal glands
aka intestinal crypts; have enteroendocrine cells responsible for production of several intestinal hormones; secrete digestive enzymes into the lumen
3 structures that increase S.A. of S.I.
intestinal villi, mucosal folds, and microvilli
Peyers patches
Aggregated lymphoid nodules which are lymphoid centers and can reach the size of cherries
Functions of large intestine
reabsorptions of water and electrolytes, absorption of important vitamins, and the storing of fecal material before defication
Segments of L.I.
Cecum (connected to ileum of S.I. - collects and stores arriving materials), colon (larger diameter and thinner wall than S.I. - has four parts = ascending, tranverse, descending and sigmoid), and lastly three is the rectum (sigmoid colon discharges fecal wastes into rectum - temporary storage of fecal matter; once material gets to rectum there is a need to defecate)
Teniae coli
3 separate longitudinal ribbons of the smooth muscle are visible on the outer surfaces of the colon just beneath the serosa
Haustra
a series of pouches that permit considerable distension and elongation
Sphincters in digestive tract
esophegeal, pyloric, external and internal anal sphincter, sphincter of oddi,
Liver
largest visceral organ (intraperitoneal) and it lies in the right hypochondriac and epigastric region; helps with metabolic regulation, hematological regulation, synthesis and secretion of bile
Gross anatomy of liver
has a right and left lobe; and a lateral, medial, anterior, and posterior segment (posterior is on same side as right lobe); round ligament in the middle with hepatic vein and gallbladder attached to it
Round ligament
thickening in the middle margin of the liver; the coronary ligament and the falciform ligament help support it
Bile
synthesized by liver cells, stored in gallbladder, and excreted into the lumen; consists mostly of water, with some iron, lipids, a pigment of hemoglobin; helps with dilution and buffering of acids in chyme
Hepatocytes
liver cells
Portal area of liver
there are six in the liver, and they contain the hepatic portal vein, hepatic artery proper, and small branch of bile duct
Kupffer cells
found in the sinusoidal lining; they are phagocytic cells that engulf pathogens, debris, and damaged blood cells; also engulf heavy metals
Bile caniculi
small passageways where bile is secreted into a network of narrow channels
Gallbladder
pear shaped organ; it stores and concentrates bile before its excretion into the S.I.; intraperitoneal; has 3 regions (fundus, body, and neck)
Common bile duct
Formed by the hepatic duct and the cystic duct; cystic duct from the gallbladder leads to this area; the hepatic ducts (right and left) collect bile from the liver and form to make the common hepatic duct
Bile drains into what?
empties into the duodenum
Ampulla of vater
hepatopancreatic ampulla; formed by the pancreatic duct and common bile duct; marks the anatomical transition between the mid and foregut
Sphincter of oddi
hepatopancreatic sphincter; surrounds the lumen for the duodenum; helps close off the passagewy when contracted to prevent bile transfer into the duodenum
Pancreas
Primarily an exocrine organ that produces digestive enyzmes and buffers them; endocrine cells produce hormones
Pancreatic acini
blind pockets; where islets of langerhans are found; secrete a mix of water, ions, and enzymes into the duodenum; the secretion is called pancreatic juice and do the digestion work in S.I.
Islets of langerhans
region of the pancreas that contain aggregates of endocrine cells
