Chapter 22 Flashcards
digestive system
organ system responsible for digestion and the processing of food, extracting nutrients, and eliminating residue
five stages of digestion
ingestion, digestion, absorption, compaction, defecation
ingestion
selective process of food intake
digestion
breakdown of food into a form that is useable by the body
absorption
uptake of nutrients from food by absorption into the epithelial cells of the digestive tract, then into blood and lymph
compaction
absorbing water and consolidating indigestible residue to form feces
defecation
elimination of feces
mechanical digestion
physical breakdown of food into smaller particles through chewing and churning
chemical digestion
hydrolysis reactions that break down macromolecules into monomers by digestive enzymes
chemical digestion is required in absorption of all nutrients except for
vitamins, amino acids, minerals, cholesterol, and water`
alimentary canal
muscular tube from the mouth to anus
alimentary canal is also called
the digestive or gastrointestinal tract
organs in the alimentary canal
mouths, pharynx, esophagus, stomach, small intestines, large intestines
accessory organs of the digestive tract
teeth, tongue, salivary glands, liver, gallbladder, pancreas
walls of the alimentary canal
mucosa, submucosa, muscularis externa, serosa or adventitia
layers of the mucosa
epithelium, lamina propia, mucosae
submucosa
thin layer of loose connective tissue that allows passage of blood vessels
the submucosa contains what
submucosal nerve plexus
muscularis externa
two muscular layers responsible for movement of stuff through the alimentary canal
arrangement of the layers of the muscularis externa
inner circular layer and outer longitudinal layer
serosa are found
in alimentary canal organs within the abdominal cavity
the serosa is composed of
areolar connective tissue and a simple squamous outer layer
the serosa attaches to
the mesentery of the periosteum
Adventa is found
in the alimentary canal outside of the abdominal cavity
the adventitia is composed of
fibrous connective tissue
peritoneum
lining of the abdominal cavity
the peritoneum is composed of
connective tissue lined with simple squamous epithelium
the peritoneum contains
vessels and nerves to supply the abdomen
layers of the peritoneum
parietal and visceral
parietal peritoneum
outer layer lining the abdominal wall
visceral peritoneum
inner layer lining the abdominal organs
mesentary
visceral peritoneum lining the alimentary canal that attaches to the serosa
enteric nervous system
regulates motility, secretion, and blood flow from the esophagus through the intestines
is the enteric nervous system dependent or independent
independent of the CNS but influenced by the ANS
submucosal plexus controls
secretion from mucosa glands and movement of mucularis mucosae
where is the submucosal plexus located
submucosa
myenteric plexus controls
contractions of muscularis externa and contains parasympathetic ganglia
where is the myenteric plexus located
between layers of muscularis externa
myenteric reflexes are known as
short reflexes
myenteric reflexes
stretch or chemically stimulate myenteric plexus to trigger peristalsis
vasovagal reflexes are known as
long reflexes
vasovagal reflexes
parasympathetic stimulation of the digestive tract to target myenteric nerve plexus and other organs
stomach acid secretes
HCl
stomach acid secretion process
histamine made by enterochromaffin cells in the stomach help stimulate HCl secretion
G-cells function
make gastrin when the stomach is distended by food to stimulate HCl production
oral cavity is also called
buccal cavity or mouth
functions of the oral cavity
ingestion, taste, mechanical digestion, chemical digestion
mechanical digestion of the oral cavity
chewing
chemical digestion of the oral cavity
saliva
bolus
chewed, saliva-mixed food that is swallowed
epithelium of the oral cavity
stratified squamous
epithelium of the hard palate and gums
keratinized stratified squamous
functions of saliva
moisten mouth, prevent cavities, dissolve food molecules to stimulate taste buds, begin chemical digestion
cavities are caused by
acid made by bacteria
how does saliva prevent cavities
saliva lysosomes kill bacteria that produce acid, IgA antibodies inhibit bacterial growth, saliva buffers acid and remineralizes enamel
salivary gland
secrete saliva
parotid is located
pair of glands inferior and anterior to ears
what saliva gland makes the most saliva
parotid gland
submandibular gland is located
inferior to mandibular angular
location of sublingual glands
inferior to the tongue
saliva chemical digestion enzymes
salivary amylase, lingual lipase
salivary amylase digests
starch
lingual lipase digests
fats
what activates lingual lipase
stomach acid
how much saliva is produced per day
1-1.5 Liters
salivation is regulated by
the salivatory nuclei
where is the salivatory nuclei located
in the oblongata and pons
what stimulates the salivation
odor, sight of food, thought of food, flavor,chewing
the salivatory nuclei sends signals through
the facial and glossopharyngeal nerves
parasympathetic signals from the salivatory nuclei stimulates
secretion
sympathetic signals from the salivatory nuclei stimulates
less secretion, more nucleus
pharynx
muscular funnel connecting the oral cavity to esophagus
the pharynx is part of what to body systems
respiratory and digestive
esophagus anatomy
muscular tube connecting the pharynx to the stomach
peristalsis
an involuntary wave of muscle contractions pushing food that is the final phase of swallowing
functions of the stomach
food storage and gastric digestion
how much food can the stomach store
1-4 liters
gastric digestion
mechanical churning and chemical digestion of proteins and fats to produce chyme
chyme
semi-digested food that goes to the small intestine
most digestion and absorption occurs
in the small intestines
layers of the muscularis externa
inner oblique, middle circular, outer longitudinal
the muscularis externa is made of
smooth muscle
the stomach is made of what type of epithelium
simple columnar epithelium covered with mucous to protect from stomach acid
gastric pits
depressions in gastric mucosa
most numerous cell type in the stomach
chief cells that secrete gastric enzymes
gastric enzymes
gastric lipase and pepsinogen
gastric lipase
breaks down fats
pepsinogen
a zymogen activated by HCl that forms pepsin
zymogen
inactive enzyme activated by the removal of an amino acid
pepsin
enzyme that chemically digests protein
gastric juice
mix of water, HCl, pepsinogen, gastric lipase, and intrinsic factor
how much gastric juice is produced per day
2-3 Liters
HCl is secreted by
parietal cells
functions of HCl in the stomach
breaks up bolus, activate digestive enzyme, disease resistance
how does HCl break up bolus
how is bolus broken up liquefication into chyme and protein denaturing
what enzymes are activated by HCl
activation of lingual ligase and turning pepsinogen to pepsin
how does HCl in the stomach contribute to disease resistance
destroys ingested pathogens
intrinsic factor
glycoprotein secreted by parietal cells
why is intrinsic factor needed
to absorb vitamin B12
what is vitamin B12 needed for
hemoglobin synthesis in the body
the only indispensable function of the stomach
using intrinsic factor to absorb vitamin B12
segments of the small intestine
duodenum, jejunum, ileum
segments of the small intestine from proximal to distal
duodenum, jejunum, ileum
main function of small intestine
most chemical digestion and absorption occurs here
duodenum receives what material
chyme from the stomach, bile from the liver/gallbladder, and digestive enzymes from the pancreas
bile
yellow/green fluid containing bile salts, cholesterol, bile rubin
bile salts
steroids that emulsify fats
bile is synthesized from
cholestrol
emulsification
aid in fat digestion and absorbtion
liver
produces and secretes bile
gallblader
stores and concentrates bile
pancreas anatomy
spongey gland that is inferior and posterior to the great curvature of the stomach
is the pancreas an endocrine or exocrine gland
both, but mostly exocrine
endocrine function of the pancreas
insulin, glucagon, somatostatin, and hormone release
exocrine function of the pancreas
secrete pancreatic juice
how much pancreatic juice is secreted per day
12-1500 mL per day
pancreatic juice
mix of water, enzymes, bicarbonate, electrolytes, zymogens
where is the pancreatic juices secreted to
into pancreatic duct
purpose of bicarbonate
buffers stomach HCl
zymogens
inactive enzymes
zymogens from the pancreas
trypsinogen, Pro carboxypeptidase
trypsinogen
converted to trypsin in order to digest proteins
what does trypsin do after being activated
converts more trypsinogen to trypsin
procarboxypepdatidase
digests proteins as carboxypeptidase
procarboxypepatidase is activated by
trypsin
enzymes of the pancreas
pancreatic amylase, pancreatic lipase, ribo/deoxyribonuclease
pancreatic amylase digests
starches
pancreatic lipase digests
fats
ribo/deoxy ribonuclease digests
nucleic acids
function of duodenum
receive stomach contents, pancreatic juices, bile, neutralizes stomach acids, fat emulsification, chemical digestion
jejunum function
major site of chemical digestion
most vascularized part of the small intestine
jejunum
ileum
prominent lymphatic nodules resist pathogens
plicae circularis
circular folds of mucosa and submucosa that promote the spiral flow of chyme
villi
semi-microscopic projections of mucosa that causes the inner-surface of the small intestine to appear fuzzy
what does each villi in the small intestine have?
capillaries and lacteal
lacteal
lymphatic capillary for fat absorbtion
microvilli
small cellular projections attached to enterocytes
enterocytes
simple columnar epithelial cells lining the lumen
brush border
microvilli of the small intestine form a border on each absorptive cell
brush border enzymes are found in
microvilli plasma membrane
contact digestion
chyme must contact the brush border for digestion to be completed
carbs and amino acids are absorbed into enterocytes via
transport proteins
carbs and amino acids diffuse out of enterocytes into
capillaries
micelle
droplets of bile acids and fatty acids absorbed into enterocytes
fatty acids are transported in
chylomians
chylomians
droplets of triglycerides surrounded by phospholipids
lipids in the small intestine are absorbed into
lacteals
function of large intestines
absorption of water and salts
how much reside is received by the large intestine from the small intestine each day
500 mL
how much residue is reduced to through absorbtion
150 mL
how long does it take to convert residue to feces
36-48 hours
defecation
elimination of feces
defection exits through
rectum and anal canal
vermiform appendix
contains lymphocytes and bacteria, attached to the large intestine
epithelium of the mucosa of the large intestine
simple columnar
anal canal epithelium
non-keratinzed stratified squamous
intestinal crypts
glands extending into the lamina propia
intestinal crypts contain
goblet cells that produce mucus
taenia coli
three thickened strips of concentrated longitudinal fibers in the muscularis externa
haustra
pouches along the large intestine that residue moves through
distension of haustrum causes
contraction
internal anal sphincter
involuntary smooth muscle that relaxes to release feces
mass movement are also known as
bowel movement
mass movement
strong contractions of the large intestine 1-3 times a day
mass movements are triggered by
gastrocolic and duodenoscopic reflexes
gastrocolic reflex
filling of the stomach
duodenocolic reflex
filling of the duodendum
rectum
distal portion of the large intestine
anal columns and sinuses secrete
lubricating mucus
stimulation of large intestine
stretch of rectum for defecation
intrinsic defecation reflexes
stimulation of the myenteric nerve plexus to contract the rectum m and relax the internal sphincter
is the intrinsic defecation reflex strong or weak
weak
parasympathetic defecation reflex
spinal cord signals intensify peristalsis and relaxation of anal sphincter
is voluntary stimulation required for defecation
yes
how many microbes are in the gut
over 800
function of the gut microbiome
digest material that enzymes cannot, and help synthesize vitamins B and K
flatus
intestinal gas
what is flatus made of
swallowed air and bacterial gas
flatus odor is caused by
hydrogen sulfide, indole, skatole