Digestive System Flashcards
Functions of the digestive system include..
- ingesting food
- transporting food
- breaking food into smaller absorbable components
- secretion of waste products
The digestive system includes what two parts?
alimentary canal
accessory organs
From mouth to anus, the tubular alimentary canal (or digestive tract) exhibits _______ and _________ muscles to keep food moving in one direction
circular and longitudinal
The coordinated, rhythmic contractions of the gastrointestinal tract is called…
peristalsis
Food is broken down…
mechanically and chemically (with enzymes)
Mastication
chewing
What are the primary muscles of mastication?
temporalis
masseter
pterygoids
Where does the temporalis muscle originate?
lateral skull
Where does the temporalis muscle insert?
coronoid process of mandible
Function of the temporalis
elevates mandible
Where does the masseter muscle originate?
zygomatic arch
Where does the masseter insert?
lateral surface of mandible and angle
Function of the masseter
elevates mandible
Where do the medial and lateral pterygoids originate?
lateral pterygoid plate of pterygoid process
Where does the lateral pterygoid insert?
disc of temporomandibular joint
Where does the medial pterygoid insert?
angle of mandible
Function of the pterygoid muscles
move mandible side-to-side for grinding
The muscles of mastication are innervated by…
the mandibular division of the trigeminal nerve (V3)
The oral cavity is the space…
inside the dental arches
The space between the dental arches and lips/cheeks is called the…
vestibule
What forms the roof of the oral cavity?
hard and soft palate
The hard palate is formed by…
maxillary and palatine bones
The soft palate is…
fibromuscular
Function of the uvula
seals off nasopharynx during swallowing
Which muscles help move food to the pharynx with swallowing and form a “bed” for the palatine tonsil?
palatoglossus and palatopharyngeous
Superior Labial Frenulum
mucosal fold connected to upper lip
Inferior Labial Frenulum
mucosal fold connected to lower lip
Lingual Frenulum
mucosal fold connected to inferior surface of tongue
The tongue is convered by mucous membranes with specialized features called…
papillae
Which part of the tongue has lingual tonsil?
posterior 1/3
General sensation from the anterior 2/3 of the tongue is carried by which nerve?
mandibular division of the trigeminal nerve (V3)
Taste from the anterior 2/3 of tongue is carried by which nerve?
facial nerve (CN VII)
General sensation and taste from the posterior 1/3 of the tongue is carried by…
the glossopharyngeal nerve (CN IX)
The muscles of the tongue are innervated by…
hypoglossal nerve (CN XII)
Saliva assists with…
initial activities of digestion
What is the volume of daily secreted saliva estimated to be?
1-1.5 L
What percentage of saliva is water?
99.5%
What enzyme in saliva begins to break down carbohydrates?
Amylase
Saliva also contains…
antibodies and antibacterial substances
Parotid Glands
- largest of the salivary glands
- near angle of mandible
Function of parotid glands
transport saliva to oral cavity by parotid duct
- produces 25-30% of saliva
Where do the parotid glands get their parasympathetic innervation?
from glossopharyngeal nerve (CN IX)
Submandibular Glands
located in upper neck, under body of mandible
Function of submandibular glands
transport saliva to oral cavity by submandibular duct
- produces 60-70% of saliva
Where do the submandibular glands get their parasympathetic innervation?
from facial nerve (CN VII)
Sublingual Glands
- located under the tongue in floor of oral cavity
- has multiple sublingual ducts under tongue
- produces 3-5% of saliva
Where do the sublingual glands get their parasympathetic innervation?
from facial nerve (CN VII)
Salivary glands have cells that produce…
mucus and serous fluid
Esophagus location
descends along posterior thorax
Function of Esophagus
transports food from pharynx to stomach
Does the esophagus absorb nutrients?
no
The esophagus passes through the diaphragm at the…
esophageal hiatus
Mucosa in the esophagus is composed of…
thick, nonkeratinized stratified squamous epithelium
The submucosa of the esophagus has what kind of fibers to allow for distension during swallowing?
elastic fibers
The muscular layer of the esophagus has what components?
circular (inner) and longitudinal (outer)
Which part of the esophagus has voluntary skeletal muscle?
upper part
What part of the esophagus has involuntary smooth muscle?
lower part
The esophageal sphincter between the esophagus and stomach prevents…
movement of food from stomach into esophagus (if this happens, it is called reflux)
Cardia
entryway into stomach from esophagus
Fundus
dome of the stomach
Body (of the stomach)
large, middle region of stomach
Pylorus
funnel-shaped end of stomach with pyloric sphincter to control food leaving stomach
Lesser curvature (of the stomach)
small concavity of right side
Greater curvature (of the stomach)
large convexity of left side
Gastric Folds (rugae)
internal folds of stomach allowing for expansion
The stomach is lined with…
simple columnar epithelium with surface mucous cells that secrete alkaline fluid
Gastric pits receive secretions from…
gastric glands
Chief cells of gastric glands
secrete pepsinogen (which break down protein) and gastric lipases
Parietal cells of gastric glands
secrete intrinsic factor (binds vitamin B12) and hydrochloric acid
Mucous neck cells of gastric glands
secrete acid fluid containing mucin
Enteroendocrine cells of gastric glands
secrete gastrin into bloodstream to stimulate gastric secretions and muscle contractions
The small intestine is approximately how many feet long?
20 feet
Where are 90% of nutrients (and water) absorbed?
small intestine
The small intestine consists of the…
duodenum, jejunum, and ileum
Duodenum
- first part of small intestine
- about 10 inches long
- C-shaped and cradles the head of the pancreas
The duodenum receives…
secretions (bile) from the liver and gallbladder, as well as digestive enzymes from the pancreas
Jejunum
- second part of the small intestine
- about 7.5 feet long
The jejunum is the main region of the small intestine for…
chemical digestion and nutrient absorption
Ileum
- 3rd and last part of the small intestine
- about 10 feet long
The distal end of the ileum terminates at the ileocecal valve, which controls…
movement of materials into large intestine
In terms of histology, the small intestine has…
mucosa, muscular layer, and serosa (adventitia)
In the small intestine, mucosa is thrown into…
circular folds
Finger-like villi in the small intestine…
increase surface area for absorption and secretion
The endothelium in the small intestine consists of…
simple columnar epithelia (with microvilli) and goblet cells
The simple columnar epithelia cells, or enterocytes, of the small intestine do what?
absorb nutrients and water
What is in the center of each villus in the small intestine?
capillary network and lacteal (lymphatic vessel)
Intestinal glands contain…
unicellular gland cells and enteroendocrine cells
Enteroendocrine cells secrete…
hormones, some of which slow down movement of food out of the sotmach
Submucosal (Brunner) glands produce…
an alkaline mucus to protect the duodenum from acidic chyme
The muscular layer of the small intestine consists of…
inner layer of circular muscle and outer layer of longitudinal muscle
Large Intestine
- commonly referred to as large bowel
- approximately 5 feet long
Main function of large intestine
absorb water and ions from remaining digested material
The large intestine consists of the…
cecum, ascending oclon, transverse colon descending colon, and sigmoid colon
Cecum
- first part of the large intestine
- pouch-like structure extending inferiorly from ileocecal valve
What structure is attached to the cecum?
the appendix, which is a finger-like structure lined with lymphatic nodules
Ascending Colon
- second part of large intestine
- ascends from cecum to the area of the liver
- travels along right side of abdomen
- transitions into the transverse colon at the right colic (hepatic) flexure
Transverse Colon
- third part of large intestine
- originates at the right colic flexure and courses to the left, just inferior to the stomach
- as it approaches the spleen, it makes a turn inferiorly at the left colic (splenic) flexure to become the descending colon
Descending Colon
- fourth part of the large intestine
- descends along the left side of the abdomen from the left colic flexure to the ileum, where it transitions into te sigmoid colon
Sigmoid Colon
- S-shaped part of the large intestine
- it courses over the iliac fossa on the left and descends into the pelvis and transitions into the rectum (the rectum then terminates at the anus)
Teniae Coli
3 external longitudinal bands of smooth muscle visible throughout the length of the large intestine
Function of teniae coli
help to shorten the large intestine during peristalsis
The teniae coli muscles are shorter than the length of the large intestine, which causes the large intestine to form pouches called…
haustra
Anus
- terminal part of the large intestine
- has internal and external sphincter
Internal Sphincter of Anus
made of smooth muscle, under the control of the autonomic nervous system
External Sphincter of Anus
skeletal muscle, under the control of the somatic motor system
The mucosa of the large intestine is lined with…
simple columnar epithelium and goblet cells
The simple columnar cells of the large intestine absorb…
water and nutrients
Goblet cells of the large intestine secrete…
mucous to lubricate the undigested material
Does the mucosa of the large intestine have villi?
no
The submucosa of the large intestine containes…
many lymphatic nodules
The large intestine’s muscular layer has..
inner circular layer and outer longitudinal layer (in the form of taniae coli)
When the rectum is storing feces, the wall is ________ while the internal anal sphincter is _________; this is under the control of sympathetics
relaxed ; contracted
When stool builds up in the rectum, _______ _________ send signals up to the defecation reflex center of the brain
stretch receptors
The reflex center in the brain activates parasympathetics, which causes….
the internal anal sphincter to relax and the wall of the rectum to contract (DEFECATION REFLEX)
To override the defecation reflex, the __________ ______ __________ must contract to hold feces until it is convenient to defecate.
external anal sphincter
Polyps
outgrowths of the colon mucosa into the lumen
- can give rise to cancer
Hiatal hernia
part of the stomach protrudes through the diaphragm into the thorax
Diverticulosis
out-pocketing of the intestinal wall (usually the large intestine)
Peptic Ulcer
erosion of the lining of the stomach or duodenum
The liver is located in which quadrant?
upper right quadrant of the abdomen
The superior surface of the liver is fused to what?
the diaphragm
The liver consists of how many lobes?
4
What are the two major lobes of the liver?
right and left
What are the two minor lobes of the liver?
caudate and quadrate
What is the name of the connective tissue structure located between the right and left lobe that attaches the liver to the anterior abdominal wall?
falciform ligaments
At the inferior aspect of the falciform ligament, there is a dense cord of tissue called the…
round ligament of the liver
During fetal development, what was the round ligament?
a functional blood vessel (umbilical vein) that carried oxygenated blood from the placenta to the heart
The liver has many functions. What is an important one?
removes harmful substances from the substances being absorbed by the gastrointestinal tract (in hepatic portal vein)
The cells of the liver (hepatocytes) form…
wheel-like hepatic lobules - branches of the hepatic portal vein pass from the periphery to the center of the lobules, past the cells which detoxify the blood
Another function of the liver is to produce ______ to break down fats in the digestive tract
bile
Bile is transported to the duodenum by the…
bile duct
What does the gall bladder do?
stores bile produced by the liver until needed by the digestive tract
Why is the liver considered to be an exocrine gland?
it uses a duct to transport its secretions
Liver secretes bile into the…
hepatic duct
The gall bladder secretes bile into the…
cystic duct
The hepatic duct and cystic ducts join to form the…
common bile duct
The pancreatic duct joins the common bile duct to empty into the…
duodenum
Why is the pancreas considered a mixed gland?
it has both exocrine and endocrine functions
What does the exocrine part of the pancreas consist of and do?
consists of acinar cells which synthesize and secrete pancreatic juice to help with digestion
What does pancreatic juice consist of?
mucin and digestive enzymes (transported by the pancreatic duct, which joins with the common bile duct)
What does the endocrine part of the pancreas consist of and do?
consists of islet cells which produce insulin
The serous membrane that lines the abdominal cavity is called the…
peritoneum
- as the abdominal organs grow into the abdominal cavity, they acquire a covering of this peritoneum
When peritoneum is found on the surface of an abdominal organ, it is called…
visceral peritoneum
Where peritoneum is found on the inner wall of the abdominal cavity, it is called…
parietal peritoneum
When the peritoneum sandwiches the neurovascular supply of “intraperitoneal” organs, it is called…
mesentery
- certain parts of the digestive tract (small intestine, transverse colon, sigmoid colon) grow into the abdominal cavity such that the peritoneum behind them “collapses” on the nerves and blood vessels traveling to them