Lecture Quiz 1 Flashcards
What makes up the ailmentary canal?
mouth pharynx esophagus stomach small intestine large intestine
What are the accessory digestive organs?
teeth tongue gallbladder salivary glands liver pancreas
Define ingestion
taking food into the digestive tract
Define propulsion
swallowing
peristalsis
What is peristalsis?
waves of contraction and relaxation in the muscles in organ walls
What is mechanical digestion??
chewing, mixing, and churning food
What is chemical digestion?
catabolic breakdown of food
What is absorption?
movement of nutrients from the GI tract to blood or lymph
What is defecation?
elimination of indigestible solid wastes
What do mechano- and chemoreceptors respond to in the GI tract?
stretch, osmolarity, pH
presence of substrate, end products of digestion
What do the receptors of the GI tract do?
activate or inhibit digestive glands
mix lumen contents and move them along
What are the intrinsic controls of the GI tract?
nerve plexuses near the GI tract initiate short reflexes
short reflexes are medicated by local enteric plexuses
What are the extrinsic controls of the GI tract?
long reflexes arising within or outside GI tract
CNS centers and extrinsic autonomic nerves
What is GI tract ultimately controlled by?
reflex
sympathetic nervous system
Vagus nerve
What is the peritoneum?
serous membrane of the abdominal cavity
has external visceral layer and internal parietal layer
What does the peritoneal cavity do?
lubricates digestive organs and allows them to slide across one another
What is the mesentery?
double layer of the peritoneum
What does the mesentery do?
provides vascular and nerve supplies to the viscera
hold digestive organs in place and store fat
Look up which organs are retroperitoneal and peritoneal
**
What arteries make up the splanchnic circulation?
hepatic
splenic
left gastric
inferior and superior mesenteric
What does the hepatic portal circulation do?
collects nutrient-rich venous blood from the digestive viscera
delivers this blood to the liver for metabolic processing and storage
What is the mucosa?
moist epithelial layer that lines the lumen of the alimentary canal
consists of three layers: lining epithelium, lamina propria, muscularis mucosae
Describe the epithelial lining of the mucosa
simple columnar epithelium and mucus-secreting goblet cells
What does mucus secretion do?
protect digestive organs from digesting themselves
ease food along the tract
What do stomach and small intestine mucosa contain?
enzyme-secreting cells
hormone-secreting cells
these organs are both digestive and endocrine organs
Describe the lamina propria of the mucosa
loose areolar and reticular connective tissue
nourishes the epithelium and absorbs the nutrients
contains lymph nodes - important in defense against bacteria
Describe the muscularis mucosae of the mucosa
smooth muscle cells that produce local movements of mucosa
scant layer
What is the submucosa?
dense connective tissue containing elastic fibers, blood, and lymphatic vessels, lymph nodes, and nerves
What is the muscularis externa?
responsible for segmentation and peristalsis
inner circular and longitudinal layer of smooth muscle
What is the serosa?
protective visceral peritoneum
replaced by fibrous adventitia in the esophagus
retroperitoneal organs have both an adventitia and serosa
What does the submucosal nerve plexus do?
regulates glands and smooth muscle in the mucosa
What does the myenteric nerve plexus do?
major nerve supply that controls GI tract mobility
What controls segmentation and peristalsis?
autonomic NS, local reflex arc, and myenteric nerve plexus
largely automatic
Describe the mouth
lined with stratified squamous epithelium
withstands abrasion
gums, hard palate, dorsum of tongue slightly keratinized
What are the muscles of the lips and cheeks?
orbicularis oris and buccinators