Digestive Anatomy and Processes Pt 1 Flashcards
sequence for the movement of food through the gastrointestinal tract
- take in food
- break food down into its component parts (nutrient molecules)
- absorb the nutrient molecules into the bloodstream
- rid the body of any indigestible remains
Accessory organs
teeth, tongue, gallbladder, digestive glans
Digestive glands
salivary glands, liver, pancreas
ingestion
eating
propulsion
moving food through the GI tract
peristalsis
rhythmic waves of smooth muscle contraction - propels food through the GI tract
mechanical breakdown
chewing, mixing food with saliva, churning food, segmentation
segmentation
local constrictions of the SI to mix food with digestive juices
digestion
series of catabolic steps in which enzymes break complex food molecules down into their chemical building blocking
absorption
passage of digested fragments from the lumen of the GI tract into blood/lymph
peritoneum
robust serous membranes of the abdominopelvic cavity
visceral peritoneum
membrane on the external surface of most digestive organs
parietal peritoneum
membrane on the wall of the abdominal cavity
peritoneal cavity
- fluid filled space between the two peritoneum
- fluid lubricates the mobile organs
mesentery
a double-layer of peritoneum – extends to the digestive organs from the abdominal walls
- provides routes for blood vessels, lymphatics, and nerves
- holds organs in place and stores fat
peritoneal organs
organs located within the peritoneal cavity
retroperitoneal organs
organs located outside - posterior to - the peritoneum
4 tunics of the GI tract
- Mucosa
- Submucosa
- Muscularis Externa
- Serosa
Mucosa
tunica layer that lines the lumen, a moist epithelial membrane
3 sublayers of mucosa
- epithelium
- lamina propria
- muscularis mucosae
epithelium
simple, columnar epithelium rich in mucus-secreting cells
- the mouth, esophagus, anus are stratified, squamous
- protects digestive organs from enzymes, eases food passage
- may create and secrete its own enzymes and hormones
lamina propria
loose, areolar connective tissue
- rich supply of capillaries for nourishment and absorption
- may create lymphoid follicles to defend against microbes
muscularis mucosae
very thin layer of smooth muscle
functions of mucosa
- secretes mucus, digestive enzymes, hormones
- absorbs the end products of digestion
- protects against infectious disease
Submucosa
- areolar connective tissue
- contains blood and lymphatic vessels, lymphoids follicles, and a nerve plexus
- abundant number of elastic fibers to help organs regain their shape after storing a large meal
muscularis Externa
- muscle layer responsible for segmentation and peristalsis
- contains an inner, circular muscle layer and an outer, longitudinal muscle layer
- the circular layer occasionally thickens to form sphincters
Sphincters
act as valves to prevent backflow and control the passage of food
serosa
- outermost, superficial layer
- same as visceral peritoneum
- formed from areolar connective tissue covered with mesothelium
- replaced by fibrous adventitia in the esophagus
- retroperitoneal organs have both an adventitia and a serosa
sphenic circulation
arteries that branch off the abdominal aorta to serve the digestive organs and hepatic portal circulation
Arterial supply
- branches of the celiac trunk supply the spleen, liver and stomach
- mesenteric arteries supply the large and small intestines
hepatic portal circulation
collects nutrient-rich venous blood draining from the digestive viscera and brings it to the liver
The GI tract’s own nervous system is called the
enteric nervous system
SLide 15
structure on slide 19
What is found in saliva
- mostly water and slightly acidic
- contains electrolytes, salivary amylase, mucin, lysozyme, urea, IgA antibodies, and defensins
functions of saliva
- cleanse the mouth
- dissolved food chemicals for taste
- moisten food, compact it into a bolus
- begin breakdown of starch with the enzyme salivary amylase
3 salivary glands
- parotid
- submandibular
- sublingual
parotid
anterior to the eat, external to the masseter; parotid duct to the oral vestibule
submandibular
medial to the body of the mandible; duct to the base of lingual frenulum
sublingual
anterior to the submandibular; opens to the floor of the mouth via 10-12 ducts
How many mature permanent teeth are there
32
deciduous teeth
- 20 baby teeth
- erupt between 6 and 24 months
incisors
chisel shaped for cutting
canines
fang-like for tearing, piercing
premolars (bicuspids)
broad crowns with rounded cusps, used to grind/crush
molars
broad crowns with rounded cusps, best for grinding
where does the esophagus pierce through the diaphragm
esophageal hiatus
gastroesophageal/cardiac sphincter
surrounds the orifice
- orifice is close when food is not being swallowed
- mucus cells on both sides of the sphincter helps protect the esophagus from acid reflux
heartburn
- burning, radiating, substernal - pain; mimics MI pain
cause: regurgitation of starch acid into the esophagus - symptoms: GERD
hiatal hernia
- structural abnormality caused by abnormal weakening of the gastroesophageal sphincter
- superior portion of the stomach protrudes above the diaphragm
deglutination
swallowing
2 phases of deglutination
- buccal phase
- pharyngeal esophageal phase
buccal phase
voluntary contraction of the tongue
pharyngeal-esophageal phase
involuntary phase driven by the vagus nerve; controlled in the swallowing centers of the medulla and lower pons; respiration is momentarily inhibited, and all undesired routes are blocked
