Chpt 25 Digestive Anatomy And Psyciology Flashcards
List the digestive organs
Gastrointestinal tract (alimentary canal)
Accessory organs
What are the accessory organs
Teeth, tongue, salivary glands, liver, gallbladder, pancreas
Aid in chemical and mechanical digestion
What are the organs in the gastrointestinal tract
Mouth, most of pharynx, esophagus, stomach, small intestine, large intestine
Pathway for food
6 functions of digestive system
Ingestion
Secretion (of water acids, buffers and enzymes into lumen)
Mixing and propulsion
Digestion (chemical digestion-hydrolysis) (mechanical Digestion churns food)
Absorption (passing into blood or lymph)
Defecation (elimination of feces)
4 layers that make up the walls of the organs in the Gi tract
Mucosa
Submucosa
Muscularis
Serosa
Mucosa
inner lining
Epithelium protection, secretion, absorption
Lamina propria – connective tissue with blood and
lymphatic vessels and mucosa-associated lymphatic
tissue (MALT)
Muscularis mucosae – thin layer of smooth muscle
making folds to increase surface area
Submucosa
Connective tissue binding mucosa to muscularis
Contains many blood and lymphatic vessels
Submucosal plexus
Muscularis (externa)
Voluntary skeletal muscle found in mouth, pharynx, upper
2/3 of esophagus, and anal sphincter
Involuntary smooth muscle elsewhere
-Arranged in inner circular fibers and outer longitudinal fibers
-Myenteric plexus between muscle layers
Serosa
Outermost covering of organs suspended in
abdominopelvic cavity
Also called visceral peritoneum
Adventitia- Pharynx, esophagus, rectum lacks serosa
Enteric nervous system (ENS)
branch of PNS
Enteric nervous system (ENS) is Intrinsic set of nerves
- “brain of gut”
Neurons extending from esophagus to anus
2 plexuses of PNS
Myenteric plexus – GI tract motility
Submucosal plexus – controlling secretions
Autonomic nervous system
Extrinsic set of nerves
Parasympathetic stimulation
increases secretion and
activity by stimulating ENS
Sympathetic stimulation
decreases secretions and
activity by inhibiting ENS
peritoneum
Largest serous membrane of the body
peritoneum divided into
Parietal peritoneum – lines wall of cavity
Visceral peritoneum – covers some organs
Also called serosa
space between is called
peritoneal cavity
5 major peritoneal folds
Greater omentum, falciform ligament, lesser omentum, mesentery, and mesocolon
Weave between viscera binding organs together
Lesser omentum
attaches stomach to liver
greater omentum
covers small intestines like an apron
Mesentery of small intestines holds
many blood vessels
Mesocolon anchors
colon to posterior
body wall
the mouth is
the oral or buccal cavity
Oral or buccal cavity
is Formed by
cheeks, hard and sot palates, and
tongue
Oral cavity proper is a
space that extends from
gums and teeth to fauces (opening between oral
cavity and oropharynx
Salivary glands release
saliva
Ordinarily just enough saliva is secreted to keep mouth and pharynx
moist and clean
When food enters mouth,
secretion increases to lubricate,
dissolve and begin chemical digestion
3 pairs of major salivary glands secrete
most of the saliva
Parotid, submandibular, and sublingual
Smaller intrinsic glands also in oral tissues
Salivary amylase1
breaks down carbohydrates
saliva is mostly
water 99.5
0.5% solutes- – ions, dissolved gases, urea, uric acid,
mucus, immunoglobulin A (IgA), lysozyme, and
Salivary amylase1
Salivation is Controlled by
autonomic nervous system
Parasympathetic stimulation promotes
secretion of moderate
amount of saliva
Sympathetic stimulation
decreases salivation
the tongue
is an accessory organ
the tongue does what
Maneuvers food for chewing, shapes mass, forces food
back for swallowing
Lingual glands secrete
lingual lipase2
the tongue has papillae,
which is held by the lingual frenulum
teeth are an
Accessory digestive
organ - mechanical
3 major regions of teeth
crown root an neck
Mechanical digestion in the mouth
Chewing or mastication
Food manipulated by tongue, ground by teeth, and mixed with saliva
Forms bolus
Chemical digestion in the mouth
Salivary amylase1 secreted by salivary glands
Lingual lipase2 secreted by
lingual glands of tongue acts on triglycerides
Nasopharynx
Functions only in respiration
Oropharynx
Digestive and respiratory functions
Laryngopharynx
Digestive and respiratory functions
Esophagus
mucous, transports food – no enzymes no absorpton
2 sphincters are
upper esophageal sphincter (UES) regulates
movement into esophagus,
lower esophageal sphincter (LES)
regulates movement into stomach
deglutition
Act of swallowing, swallowing center-medulla oblongata
Facilitated by secretions of saliva and mucus
deglutition involves
mouth, pharynx, and esophagus
3 stages of deglutition
Oral / Voluntary – bolus passed to oropharynx
Pharyngeal – involuntary passage through pharynx into esophagus
Esophageal – involuntary passage through esophagus to
stomach
Peristalsis pushes bolus forward
the stomach serves as
mixing chamber (mechanical) and holding
reservoir
4 main regions of stomach
Cardia, fundus, body, pylorus
3 types of exocrine gland cells produce
gastric juice
-mucous neck cells
-parietal cells (intrinsic factor and HCl)
-chief cells (pepsinogen3 and gastric lipase4)
-G cell – endocrine cell – secretes gastrin
Mechanical digestion in stomach
Mixing waves – gentle, rippling peristaltic movements – creates
chyme
Chemical digestion in stomach
Digestion by salivary amylase continues until inactivated by
acidic gastric juice
Pancreatic juice secreted
into pancreatic duct and
accessory duct and to small intestine
99% of cells are
acini (exocrine)
1% of cells are
pancreatic islets (endocrine)
pancreatic juice produces
200-1500ml daily
the liver is
heaviest gland on body
Hepatocytes secrete
500-1000mL of bile daily
small intestine parts
3 regions – duodenum, jejunum, and ileum
large intestine function
complete absorption, produce
certain vitamins, and form and expel feces
4 main regions of large intestine
Cecum
colon (ascending, transverse, descending, sigmoid
Rectum with anal canal
function of liver
to make and secrete bile and to process and purify the blood containing newly absorbed nutrients that are coming from the small intestine
