GI 1 Flashcards
primary functions
move nutrients, water, and electrolytes from external environment into body’s internal environment
___% of health care costs are related to GI system.
10
Digestion begins in the mouth with ___________ and the addition of _______.
mastication, saliva
What are the 3 salivary glands
- parotid
- sublingual
- submandibular
Functions of salivary glands
- moisten and lubricate food
- amylase partially digests polysaccharide
- dissolve some food molecules (taste)
- lysozyme kills bacteria
Does any digestion occur in the esophagus?
NOOOO
top 1/3 of the esophageal wall is…
skeletal muscle
bottom 2/3 of the esophageal wall is…
smooth muscle
How does food move through the esophagus?
via peristaltic waves
chyme
food mixed with acid and enzymes YUM
rugae
surface folding in the stomach to increase surface area
majority of digestion takes place in the…
small intestine
3 parts of small intestine
- duodenum (first 25 cm)
- jejunum
- ileum
- (j+i make up the rest, 260cm)
______ and _________ release exocrine secretions into the __________.
liver, pancrease, duodenum
the large intestine is also known as the….
colon
How long is the large intestine?
~150cm
4 parts of the large intestine
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
____ of watery chyme pass into the large intestine each day.
1.5L
Water and electrolytes are removed in the large intestine to create…
semisolid feces
defecation reflex
when faces enter the rectum
what are the GI layers
- mucosa
- submucosa
- muscularis externa
- serosa
Neurons of the enteric nervous system are collected into two types of ganglia:
submucosal (in submucosa) and myenteric (in muscular externa)
In the stomach, surface area is increased by…
gastric glands –> rugae
In the intestine, surface area is enhanced by….
villi and crypts
3 parts of mucosa
- epithelium
- lamina propria
- muscularis mucosae
columnar epithelium
absorbs nutrients
enteroendocrine cells
secrete hormones
Epithelium junctions in stomach and colon are ____, but _____ in the small intestine.
tight, leaky
lamina propria
-subepithelial tissue containing nerve fibres, small blood vessels and lymph vessels
muscularis mucosae
-thin layer of smooth muscle that can alter the surface area available for absorption
submucosa
middle distensible layer containing larger vessels, the submucosal plexus; one of major nerve networks in enteric nervous system
muscular externa
two layers of smooth muscle (circular and longitudinal) and myenteric plexus
serosa
outer covering of connective tissue that is a continuation of peritoneal membrane
4 digestive function and processes
- digestion
- secretion
- absorption
- motility
digestion
chemical and mechanical breakdown of food into absorbable units
secretion
movement of material from cells into lumen or ECF, or from ECF to lumen
absorption
movement of material from GI lumen to ECF
motility
movement of material through the GI tract as a result of muscle contraction
challenges of the digestive system
- avoiding autodigestion
- defense
