3 (23) The Digestive System Flashcards
(122 cards)
What is digestion?
the process of breaking down larger food molecules into smaller food molecules
What is absorption?
the passage of the smaller molecules into blood and lymph
What is the alimentary canal? What structures are accessory organs?
- (GI tract) tube that runs from mouth to anus; digests food and absorbs fragments (mouth, pharynx, esophagus, stomach, small intestine, large intestine)
- accessory organs: teeth, tongue, salivary glands, liver, gallbladder
What is the splanchnic circulation?
all blood flow originating from the celiac, superior mesenteric, and inferior mesenteric arteries, which is widely distributed to all abdominal viscera
- receives about 25% of cardiac output when at rest
What is the “tube within a tube” model?
- one for food to enter the body (mouth), one for wastes to leave the body (anus)
- the tube-within-a-tube plan allows specialization of parts along the tube, such as a stomach, intestine, etc.
What are the four structural layers of the alimentary canal?
mucosa
submucosa
muscularis
serosa
The mucosa can be further divided into what three parts?
1 - EPITHELIUM => strat. squam. epithelium, simp. col. epithelium, and enteroendocrine glands
2 - LAMINA PROPRIA => areolar CT; blood, lymph vessels and nodules
3 - MUSCULARIS MUCOSAE => two layers of smooth muscle
In which of these parts would we find MALT?
lamina propria
How does the epithelium of the mucosa change throughout the alimentary canal?
mouth, esophagus, anal canal => strat. squam. epithelium
stomach and intestines => simp. col. epithelium
What are the three functions of the mucosa?
1 - SECRETION => mucus, digestive enzymes/hormones
2 - ABSORPTION => nutrients from digestion
3 - PROTECTION => from infectious diseases
Where would you find the submucosal plexus? The myenteric plexus?
SUBMUCOSAL PLEXUS => found in submucosa; autonomic nerve supply to muscularis mucosae, blood vessels, and secretory cells
MYENTERIC PLEXUS => found in muscularis mucosae;
How does the type of muscle found in the muscularis layer change along the alimentary canal?
mouth, pharynx, superior esophagus, external anal sphincter => voluntary (skeletal) muscle
the rest of GI tract => smooth muscle
In general, how do parasympathetic fibers and sympathetic fibers affect the alimentary canal?
PARASYMPATHETIC => stimulate digestive activities
SYMPATHETIC => inhibit digestive activities
What is another name for the serosa? What is its function?
serous membrane = visceral peritoneum
- lubricates
Where does adventitia replace the serosa?
esophagus
What is mastication?
chewing
What is the oral cavity?
buccal cavity; mouth
(cheeks, lips, tongue, hard/soft palates)
lies between teeth and gums
What is the vestibule?
the area between the teeth, lips and cheeks
What is the labial frenulum? The lingual frenulum?
LABIAL => the soft tissue that attaches the lip to the anterior surface of the maxillary gingiva
LINGUAL => a fold of mucous membrane connecting the ventral tongue to the floor of the mouth
What is ankyloglossia?
tongue-tie => an unusually short, thick or tight band of tissue (lingual frenulum) tethers the bottom of the tongue’s tip to the floor of the mouth
What type of muscle is found in the tongue? Where does this muscle attach?
- skeletal muscle
- attaches at lingual frenulum at the floor of the mouth
What covers the surface of the tongue?
papillae cover the surface of the tongue: filiform, fungiform, circumvallate, foliate (foliate does not have taste buds)
What kind of epithelium lines the oral cavity? Why is this helpful?
- non-keratinized stratified squamous epithelium
- helpful bc it is stratified squamous, it is protective to the tissue behind it and regenerates quickly
Where would you find the lingual tonsils? The palatine tonsils? The pharyngeal tonsils (adenoids)?
LINGUAL => near back of tongue, underneath it
PALATINE => found near roof of mouth near soft palate
PHARYNGEAL => near opening of auditory tube and near base of nasal cavity