Digestive System (quiz 3) Flashcards
What are the 2 ways to get out of the GI tract?
absorption or excretion
The digestive system consists of the digestive tract- oral cavity, esophagus, stomach, small and large intestines, and the anus- and its associated glands/structures are….
salivary glands, liver, and pancreas
The inner layer of the entire digestive tract forms an important protective barrier between the content of the tract’s _________ and fluids of the body
lumen
The GI tract is a hollow tube with a lumen of variable diameter and a wall made up of 4 main layers. What are they?
-mucosa
-submucosa
-muscularis
-serosa
The oral cavity is lined with which tissue?
stratified squamous epithelium
may be keratinized, partially keratinized, or nonkeratinized depending on the location
In the oral cavity, the keratinized cell layers resists damage from abrasion and are best developed in the…
masticatory mucosa on the gingiva (gum) and hard palate
In the oral cavity, the nonkeratinized squamous epithelium predominates in the lining mucosa over the….
soft palate, cheeks, the floor of the mouth, and the pharynx
In the oral cavity, the lining mucosa overlies a thick submucosa containing _________________ which secrete continuously to keep the mucosal surface wet and diffuse lymphoid tissue
salivary glands
The tongue is a mass of ____________ muscle covered by mucosa, which manipulates ingested material during mastication and swallowing. The muscle fibers are oriented in all directions, allowing a high level of mobility.
striated
What does glossus mean?
mechanically breakdown food (tongue and hard palate do this)
Taste buds are structures within the stratified epithelium on the tongue’s surface. A taste bud has 50-100 cells, about half of which are elongated ____________ cells/neurons
gustatory
What are papillae?
projections on the surface of the tongue that holds clusters of epithelial cells w/ neurons
the clusters are called taste buds which contain gustatory cells/neurons (the gustatory cells are receptors for neurons)
There are ______ permanent teeth, arranged in 2 bilaterally symmetric arches in the maxillary and mandibular bones
32 (these are secondary dentition)
Each tooth has a _________ exposed above the gingiva, a constricted __________ at the gum, and one or more ___________ that fit firmly into bony sockets in the jaws called dental alveoli
crown, neck, roots
The crown of a tooth is covered by a very hard acellular __________
enamel
The roots of a tooth are coated by a bone-like tissue called ____________
cementum
The enamel and cementum of the tooth meet where?
at the neck of the tooth
(enamel covers the crown, cementum covers the roots)
The bulk of a tooth is composed of calcified material called dentin which surrounds an internal….
pulp cavity (arteries and veins are here)
Dental pulp is highly vascular and consists largely of _____________________ CT
loose mesenchymal
(these are stem cells that help replace odontocytes)
Food mixed with saliva and is mechanically chewed up is called what?
bolus
The esophagus is a muscular tube that transports material from where to where?
from pharynx to the stomach
The esophageal mucosa has what type of tissue?
nonkeratinized stratified squamous epithelium
In the esophagus, the submucosa contains small mucus-secreting glands called the _____________ glands which lubricate and protect the mucosa
esophageal
The upper 1/3 of the esophagus has a muscularis layer that is exclusively skeletal muscle. Why?
voluntary control for swallowing and vomiting
What tissue is found at the middle portion of the esophagus?
combination of skeletal and smooth muscle fibers
What tissue is found at the lower 1/3 of the esophagus, muscularis layer?
exclusively smooth muscle
The distal 1-2cm of the esophagus is covered by serosa, the rest is enclosed by the loose CT of the……
adventitia
What does the mucosa consist of?
-an epithelial lining
-an underlying lamina propria of loose CT rich in blood vessels
-lymphatics, lymphocytes, smooth muscle cells, small glands
-thin layer of smooth muscle called the muscularis mucosae separating the mucosa from the submucosa and allowing local movements of the mucosa
What is another name for the mucosa?
mucous membrane
The submucosa contains denser CT with larger blood and lymph vessels than the mucosa. The submucosal layer also contains a _______________ plexus of autonomic nerves, glands, and significant lymphoid tissue
Meissner
The thick muscularis or muscularis externa, is composed of smooth muscle cells organized as _____ sublayers. The internal sublayer (closer to the lumen) has a fiber orientation that is generally circular, and the external sublayer is longitudinal. The CT between the muscle sublayers contains blood and lymph vessels, and the _____________________ nerve plexus. Contractions of the muscularis, which mix and propel the luminal contents forwards, are generated and coordinated by the myenteric plexus
2+, myenteric (Auerbach)
The serosa is a thin sheet of loose CT that is rich in blood vessels, lymphatics, and adipose tissue. It is covered with a simple squamous covering epithelium or _______________.
mesothelium
What layer is this?
It is the outermost layer of the digestive tract located within the abdominal cavity
serosa
The serosa of the small and large intestines is continuous with portions of the ____________, which is a large fold of adipose CT covered on both sides by mesothelium that suspends the intestines
mesentery
What tissue is found in the esophagus compared to the stomach?
esophagus = stratified squamous
stomach = simple columnar
The stomach is a greatly dilated segment of the digestive tract. It is made up of 4 major regions. What are they?
-cardia
-fundus
-body
-pylorus
What part of the stomach is this?
narrow transitional zone between the esophagus and the stomach
cardia
What part of the stomach is this?
funnel-shaped region that opens into the small intestine
pylorus
What 2 regions of the stomach are primarily involved with mucus production and are histologically similar?
cardia and pylorus
What 2 regions of the stomach are identical in microscopic structure and are the sites of gastric glands releasing acidic gastric juice?
fundus and body
The mucosa and the submucosa of the empty stomach have large, longitudinally directed folds called _________, which flatten when the stomach fills with food
rugae (not seen when stomach is full)
At the esophagogastric junction, stratified squamous epithelium lining the esophagus is abruptly replaced by….
simple columnar epithelium
The mucosa of the stomach wall contains invaginations called gastric pits that lead into ____________. These structures are lined by simple columnar epithelium containing 5 functional cell types
gastric glands
What is chyme?
once bolus but has been converted to liquid form in the stomach
What cells are found within the fundus and body regions of the stomach (gastric pit > gastric gland)?
-mucus cells
-parietal cells
-chief cells
-endocrine cells
Where are the mucus cells found?
at the top of the gastric pits (within the fundus and body regions of the stomach)
What do mucus cells do?
release mucus through exocytosis and line the stomach
the mucus protects the stomach from its own acid
What do parietal cells do?
secrete HCI (low pH will unfold protein and denture it in the stomach)
What do chief cells do?
release pepsinogens (hits HCI and then becomes pepsin to breakdown proteins within the stomach
What do endocrine cells do?
release hormones/chemical messengers into the stomach
The muscularis has 3 layers within the stomach. What are they?
-outer longitudinal layer
-middle circular layer
-innermost oblique layer
(these layers are used for rhythmic contractions to mix ingested food (bolus) and chyme with mucus, HCI, and digestive enzymes)
What is the small intestine designed for?
absorption and get in as many nutrients as possible
The small intestine is where nutrients (products of digestion) are absorbed by cells of the…..
epithelial lining
What are the segments of the small intestines?
-duodenum
-jejunum
-ileum
these 3 segments are similar in histological features
The lining of the small intestine has permanent circular or semilunar folds called __________________, consisting of mucosa and submucosa. Covering the entire mucosa are short villi that project into the lumen. The villi are covered by a simple columnar epithelium with microvilli
pilcae circulares (pleated to increase SA)
What organs empty its contents into the small intestine?
liver, gallbladder, and pancreas
The pancreas releases how many enzymes into the small intestine? For what?
4 enzymes to breakdown carbs, lipids, proteins, and nucleic acids
What does the gallbladder release into the small intestine?
bile (detergent to emulsify fats)
What is the largest internal/visceral organ?
liver
How many lobes does the liver have?
2 major lobes (L and R) and 2 smaller inferior lobes
Which organ is the major interface between the digestive system and the blood?
liver
(nutrients absorbed in the small intestine are processed in the liver before distribution throughout the body)
What are the key cells of the liver and the most functionally diverse cells of the body?
hepatocytes (large cuboidal or polyhedral epithelial cells, with large, round central nuclei and eosinophilic cytoplasm rich in mitochondria)
The liver parenchyma is organized as thousands of small lobules in which hepatocytes form hundreds of irregular plates arranged radially around a small central vein. Peripherally, each lobule has 6 portal areas each of which contains 3 structures that form the….
portal triad
