Exam Five - Digestive System One Flashcards
T or F: digestion is one of the organ systems
true
what structures make up the oral cavity
- mouth
- pharynx
what structures make up the GI tract?
- esophagus
- stomach
- small intestine
- large intestine
the GI tract is divided by ________
sphincters
where are the two exceptions of autonomic control in the GI tract?
anal sphincter
upper esophagus
T or F: the digestive lumen is external to the body
true!
what are some accessory glandular organs of the digestive tract
salivary glands
pancreas
liver
the stomach produces _____-
chyme
products of digestion are absorbed ___________- and ___________
across epithelium into interstitial fluid
from interstitial fluid to blood/lymph
digestive system is home to ______
microbiome
describe the digestive system path from mouth to anus
chewing & salivary glands in mouth, esophagus (bolus), lower esophageal sphincter, stomach (chyme), pyloric sphincter, duodenum, jejunum, ileum, colon, rectum, anus (exits as feces)
how does the liver help with digestion
produce enzymes to help with digestion
how does the pancreas help with digestion
- endocrine and exocrine function
- releases bicarbonate buffer to neutralize acid escaped by stomach
most of the GI tract is controlled by _______ muscle
smooth
what are some modifications in the GI system that are used in increase surface area?
- rugae (in stomach)
- plicae (in small intestine)
- villi
- gastric glands, crypts, and submucosal glands
What are the layers of the digestive tract from the lumen outwards?
lumen
mucosa
submucosa
muscularis externa
serosa
whats important to know about the mucosal layer
1 - epithelium
2 - lamina propria
3 - muscularis mucosa (move villi)
where are peyer’s patches
mucosal layer with lamina propria
associated with GALT (immune function)
what should you know about the submucosal layer
contained submucosa plexus of the enteric nervous system
what should you know about the muscularis externa layer
contains myenteric plexus of the enteric nervous system
(stomach has 3 layers of muscle, intestines only 2)
what should you know about the serosa layer
outer covering of the digestive tract, helps keep intestines in place
what are the four basic processes of the digestive system
1 - digestion
2 - absorption
3 - secretion
4 - motility
what are the 3 challenges for the digestive system
1 - avoiding autodigestion
2 - mass balance
3 - defense
secretion
movement of material from cells into lumen or ECF
digestion
chemical/mechanical breakdown of food into absorbable units
absorption
movement of material from GI lumen to ECF
motility
movement of material through the GI tract resulting from muscle contraction
T or F: we secrete a lot of fluid
false, we keep most of it
mucins are produced by:
mucous cells, serous cells, and goblet cells
________ receptor regulates fluid secretion
Guanylate cyclase-C (GC-C)
- bacteria overactivate receptor and cause diarrhea
- agonist to treat constipation
peristalsis
moving food through the tract
segmentation
mechanically mixing food to break it into uniformly small particles
T or F: segmentation is the same thing as persitalsis
lol false
tonic contractions last:
minutes or hours (long time)
phasic contractions last:
seconds
where do slow-wave potentials (peristalsis) originate from
interstitial cells of Cajal
contractions occur in 3 patters:
1 - migrating motor complex
2 - peristalsis
3 - segmentation
GI motility can have ____ contractions connected by ________
graded
gap junctions
enteric nervous system can act ________-
independently
________ nervous system controls motility, secretion and growth of the digestive system
enteric
what are some enteric NS features that are shared with CNS?
1 - intrinsic neurons
2 - NT and neuromodulators
3 - glial support cells
4 - diffusion barrier
5 - integrating center
short reflexes integrate in the _____-
ENS
long reflexes integrate in the _______
CNS
cephalic reflexes originate_____
outside the digestive system
what hormones are in the gastrin family? Other category?
gastrin and cholecystokinin (CCK)
(other = motilin)
what hormones are in the secretin family
secretin
vasoactive intestinal peptide (VIP)
GIP
GLP-1
gastrin
comes from G cell in stomach
- stimulates gastric acid secretion and mucosal growth
Secretin
(in intestines)
- stimulates HCO3 secretion from pancreas
- inhibits gastric emptying and acid secretion
CCK
(in intestines)
signal that food is coming also promotes satiety
Motilin
(in intestines)
stimulates migrating motor complex when we haven’t eaten for a while
GIP
(intestines)
- stimulates insulin release from pancreas beta cells (feedforward mechanism)
- inhibits gastric emptying and acid secretion
GLP-1
(in intestines)
- stimulates insulin release
- inhibits glucagon and gastric function
- big satiety promoter
What initiates cephalic phase?
anticipation of or presence of food in oral cavity activates neurons in the medulla
what are the 4 functions of salivary secretions
1 - soften and lubricate food
2 - digestion of starch (amalase)
3 - taste
4 - defense
mechanical digestion begins with ________-
chewing (mastication)
saliva is an ____________ function and under ________- control
exocrine
autonomic
what are the 3 pairs of salivary glands
parotid
sublingual
submandibular
what happens to the epiglottis when you swallow?
it closes and temporarily halts breathing
