Digestive System Flashcards
Identify the alimentary canal organs of the digestive system and there function
- digest foods and absorbs fragments
mouth, pharynx, esophagus, stomach, small intestines, large intestines
identify the 4 accessory organs of the gi system
teeth
tongue
gallbladder
digestive glands ( salivary, liver, pancreas)
What are the 6 main process of digestion
1) ingestion: taking in food
2) propulsion: moving food through the system
3) Mechanical breakdown: chewing, stomach
4) Digestion: stomach and small intestines
5) Absorption: small intestine to lymph vessels
6) Defecation: releasing indigestible food
What type of epithelium lines the lumen and what is its function
surrounded by mucosa secretes mucus, some enzymes and hormones innermost layer non-keratinized squamous globet cells secrete mucus
What type of tissue lines the submucosa
connective tissue
What type of epithelium line the muscularis and what is its function
two layers of smooth muscles
inner layer has circular arrangement
outer layer has longitudinal arrangement
contraction of the 2 layers lead to peristalsis
mouth,pharynx,esophagus and anus all have skeletal muscle
What type of connective tissue is found in the serosa
loose connective tissue that anchors the organ in place
Define peristalsis
contraction of the inner and outer layer of the muscularis that result in the propulsion of food and waste through the tract
Define the enteric controls of the digestive system.What part of the gi tract is it located?What does it assist in?
autonomic control by ~200-600 million neurons
within the submucosal and muscularis layers in small and large intestines
can work independently of CNS control
help with gut motility, blood flow and secretion
Define the extrinsic control
autonomic input
parasympathetic ( increase activity by vagus nerve) and sympathetic ( decrease)
Define buccal cavity
oral cavity
surrounded by lips,cheeks,palate, tongue
define oral orifice
opening of the buccal cavity
Define labial frenulum
fold that attaches lips to gums inside
What type of epithelium is the mouth lined with
non-keratinized squamous epithelium
Describe the characteristics of the hard palate
part of maxillae
creates friction with tongue
Define the characteristics of the soft palate
skeletal muscle
closes nasopharynx during swallowing
uvula: extends down from it
List the 3 functions of the tongue
1) reposition food during chewing
2) helps with swallowing, speech and taste
3) anchored to floor of mouth by lingual frenulum
What is the tongue papillae and what are the 4 parts
surface of tongue
filiform, fungiform, vallate, foliate
define filiform
creates friction on tongue
define fungiform
contain taste buds
define vallate
v-shaped, in back of tonge, contain taste buds
define foliate
side of tongue
contains taste buds for children and infants
What are the 5 functions of salivary
1) cleanses mouth
2) dissolves food chemicals for taste
3) moisten food
4) amylase
5) lipase
What is the function of amylase in the mouth
to break down carbs
Whta is the function of lipase in the mouth
to break down fatty acids
What is saliva made of?
98% water
electrolytes( sodium, potassium, chloride)
enzymes( amylase, mucin ,lysozyme and IgA antibodies)
metabolic waste ( urea and uric acid)
What are the 3 main salivary glands
submandibular glands, sublingual glands, parotid
Define submandibular glands
in the floor of the mouth
secrete saliva through submandibular ducts
Define sublingual glands
below the tongue
secrete saliva through lesser sublingual ducts
define parotid glands
in between the skin and masseter muscle, near the ears
secrete saliva into the mouth through the parotid duct
Compare deciduous teeth to permanent teeth
deciduous teeth: baby teeth comes in 6-24 months, roots are reabsorbed when teeth fall out
permanent teeth: by age 21; 32 teeth, third “ wisdom” molar comes in age 17-25
What are the 4 types of teeth
incisors, canines, premolars, molars
define incisors teeth
used for cutting
define canines teeth
used for piercing/ tearing meat; fanglike
define premolar teeth
grind/crush veggies
define molar teeth
best grinders for veggies
What is the crown of a tooth and what is it covered by
part above the gums
covered by enamel
What is the root of a tooth
connects tooth to jawbone
What id the cement of the tooth
calcified connective tissue
cover the roots
Define periodontal ligament
anchors tooth in bony socket
DEFINE DENTIN IN TOOTH STRUCURE
BONELIKE MATERIAL UNDER ENAMEL
Define pulp cavity in tooth structure
full of connective tissue,blood vessels and nerves
Define root canal in tooth structure
place where pulp cavity joins root
Define apical foramen in tooth structure
entry for blood vessels, nerves, etc
Define the esophagus and the 2 sphincters that are part of it
flat muscular tubes from laryngopharyx to stomach ( 10 in in length)
two sphincters are upper esophageal spincters and gastroesphageal sphincter
Define upper esophageal sphincter
muscles at the top of the sphincter that closes off laryngopharynx to esophagus
define gastroesophageal sphincter
closes off esophagus from stomach
What are the 3 phases of swallowing/ deglutition
1) voluntary
2) pharyngeal
3) esophageal
Define the voluntary phase of deglutition
chewing is complete
tongue will move upward and push back the food
esophageal sphincter is closed
bolus leaves mouth and initiates next step
define pharyngeal step of deglutition
upper esophageal spincter relaxes to allow food to enter
uvula and soft palate rise and closes off the nasopharynx
laryngeal muscles contract to prevent food from entering
Define the esophageal phase in deglutition
food enters esophagus
peristaltic motion pushes the food toward the stomach
esophageal glands secrete mucus to lubricate the bolus as it moves down
Define the cardia in reference to stomach anatomy
entrance to the stomach from the esophagus
Define fundus in terms of stomach anatomy
dome-shaped beneath diaphragm
Define body in terms of stomach anatomy
midportion
Define pyloric part in terms of stomach anatomy
connects stomach to small intestines
Define the pyloric sphincter in terms of stomach anatomy
valve that opens and closes between stomach and small intestines
Define lesser curvature ( medial/concave) in terms of stomach anatomy
lesser omentum attached between lesser curvature and liver
define greater curvature ( lateral/convex) in terms of stomach anatomy
has greater omentum attached
Define the greater omentum
made of peritoneal fold
hangs from stomach, down anteriorly over intestines and folds back to attach to transverse colon
has adipose tissue
Define the rugae in terms of stomach anatomy
ridges in the stomach creating high surface area and it allows for distension when food enters
What does th e mucosa layer of the stomach contain
contains gastric pits ( glands)
there are 4 types: parietal cells, chief cells, mucous cell, enteroendocrine cell
Define the mucous cells of the mucosa layer of the stomach
secretes mucin ( muscus production)
Define the parietal cells of the mucosa layer in the stomach tissue
secrete HCL and intrinsic factor ( to absorb vitamin b12)
define the parietal cells in the stomach mucosa layer
secrete HCL and intrinsic factor
to absorb vitamin b12
Define chief cells in the stomach tissue of the mucosa layer
secrete pepsin (digest proteins)precursor and lipase ( digest lipids)
Define enteroendocrine cell in the stomach tissue of the muscosa layer
secrete gastrin
How is the stomach muscosal layer is maintained
mucus rich in bicarbonate which prevent damage to underlying tissues
What are the three phases of gastric secretion
cephalic
gasric
intestinal
Define chyme
delivered to small intestine
Describe the hormonal inputs for stimulating gastric juice secretion
gastric secretion
causes parietal cells to secrete hydrochloric acid
pepsinogen secretion
promotes stomach contractions
Describe the neutral input for stimulating gastric juice secretion
acetylcholine (Ach) stimulate gastric juice secretion
What are three factors of massive HCL release
Ach+ gastrin+ histamines
What percentage of acid secretion occurs in the cephalic phase of food digestion
30% of acid secretion occurs even before food enters the stomach
What 3 stimulatory events occur to start the cephalic phase
1) vagus nerve secretes ACh and that activated the parietal cells to release HCL
2) sight and thought of food
3) smell and taste of food
What are 2 inhibitory events of the cephalic phase of food digestion
1) loss of appetite ( low pH)
2) depression, illness, menopause
What percentage of gastric acid secretions are secreted in the Gastric phase
50-60%
What 4 things stimulate the release of gastric juices in the gastric phase
1) hormones ( gastrin, ACh, histamine)
2) stomach bloating with food entering the stomach
3) increase pH due to the food
4) food chemicals( caffeine and proteins)
When does the intestinal phase of food digestion start
when stomach chyme first enters the small intestine
Describe digestion during the intestinal phase
when small intestines bloat and fill with acidic, fatty or salty chyme
then gastric secretion slows down ( inhibit vagus nerve, activate sympathetic)
liver ,pancreas, gallbladder support stimulated ( further lowers secretion of gastric secretion)
Describe how the stomach is empty from chyme
chyme dumps in 3 mL amounts into small intestines
usually in 4 hrs
with larger meals it would be faster then 4 hrs
fluids travel fast out of system
Describe how the stomach is empty after vomiting
Vomiting occurs due to extreme stretching, irritants, or hormonal activation, Ach activation
vomiting raises the pH of the blood
Alcohol ,bacterial toxins, certain drugs, spicy foods, motion sickness, pregnancy
How long and how many sphincters does the small intestines contain
9-15 ft
2 sphincters
Define the pyloric sphincter
in the small intestines
ileocecal valve
What are the 3 parts of the small intestines and approximate length
Duodenum: 10-15 in
jejunum: 8 ft
lieum: 9-12 ft long
Define circular folds
deep folds that slows the movement of chyme
located in small intestines
Deine villi in the small intestines
1 mm extension of mucosa
lacteals embedded within the core of the villi
intestinal crypts in between the villi
Define microvilli
miniature filaments on the villi
What type of enzymes those the small intestines contain
ones to break down carbs and proteins
Define the Brunner Gland’s in the duodenum of the small intestines
produce alkaline mucosal secretion that has bicarbonate
helps neutralize acidic gastric chyme
What type of epithelium tisssue is found in the duodenum of the small intestine
Simple columnar epithelium
that has paneth cells ( maintains the intestinal barrier and defense ( defensins)
What is the job of the duodenum
emulsifies fat into micelle to absorb into the blood
How are the jejunum and ileum similar to the duodenum
similar to the microanatomy of the duodenum of the duodenum but no paneth cells
Define the jejunum of the small intestine
9 ft long
high surface area
where most of biomolecule absorption occurs
Define the ilieum of the small intestines
over 9 ft long
contains peyer’s patches
What is the mesentary
independent organ
formed from the folds of the peritoneum
attaches the small intestines to posterior abdominal wall
What is the function of the mesentary
to store fat, blood vessel and lymph vessels
How does Chrohn’s disease affect the mesentery
it is thicken and and homeostasis is reduced
How many lobes does the liver have
2
left and right
What are 4 reasons the liver is important
1) detoxifying drugs, toxins, etc
2) makes proteins
3) produce bile
4) store glycogen
What are the two forms of blood supply to the liver
1) Hepatic Artery ( enters liver frpm abnormal aorta)
2) Hepatic Portal Vein( collects blood from GI tract, pancreas, spleen)
What is the name of liver cells
hepatocytes
Describe how the liver is structured
made of liver lobules
hexagonal shape
each corner has 3 vessels: 1 artery, 1 vein, and a bile ducts
What do liver macrophages aid in
help clear debris
What are the 5 composition of bile
alkaline solution that has
1) bile salts
2) bile pigments
3) cholesterol
4) triglycerides
5) phospholipids
Define bile salts
made of cholesterol to recycle in liver
Define bile pigment
bilirubin
made from the breakdown of RBCs
What is the function of the gallbladder
muscular sac that is behind the liver
stores bile not needed for digestion and concentrates it
How do gallstones form
too much cholesterol or not enough bile salt
crystalized cholesterol
prevent flow of bile out of the gallbladder
What is the job of the pancreas
to produce and secrete enzymes
enzymes include: protease, amylase, lipase, and nucleases
What 2 hormones are produced in pancreas
glucagon: allows glucose uptake in cells
insulin: stimulate liver, muscle, adipose to absorb glucose from blood stream
What does the pancreas secrete to neutralize chyme when entering small intestines
sodium bicarbonate
What is the purpose of the central pancreatic duct
merges with bile duct ( from liver)and feed it into the duodenum
Define the acini cells of the pancrea and its purpose
exocrine portion
produces digestive enzyme
What is the first part of the large intestines called
cecum
What are the 4 regions of the large intestines
ascending
transverse
descending
sigmoid
How many valves those the rectum have and what is the purpose
3
prevents defecation while passing gas
What are the 2 anal sphincters
internal anal sphincter
external anal sphincter
What is the purpose of the internal anal sphincter
involuntary
smooth muscle
What is the purpose of the external anal sphincter
voluntary
skeletal muscle
What is the 3 function of the large intestines
1) water reabsorption
2) process remaining indigestible components of feces
3) where gut microbes ( bacteria, fungi, and protozoans) are colonized
What part of the gi has skeletal muscle
mouth,pharynx,esophagus and anus
What is the purpose of the gut flora
supplementing the immune system
processing or producting vitamins and nutrients that diets or small intestines absorption cant help with
