APHY102 - Marieb - Chapter 23 Flashcards

Large intestine
Terms Definitions
Name the six major alimentary canal organs in order.
mouth, pharynx, esophagus, stomach, small intestine, large intestine
Name the six major accessory digestive organs.
teeth, tongue, gallblader, liver, salivary glands and pancreas.
What's another name for the alimentary canal?
GI tract (gastrointestinal tract)
What's another name for the GI (Gastrointestinal) Tract?
Alimentary canal
What are the six essential activities of digestion?
1) ingestion
2) propulsion (swallowing and peristalsis)
3) mechanical digestion (chewing, segmentation)
4) chemical digestion
5) absorption
6) elimination/defecation
What word describes the phenomenon of alternate contraction and relaxation of the intestine resulting in distal propulsion of food?
peristalsis
What word describes nonadjacent segments of the intestine contracting and relaxing, moving food back and forth and resulting in further mixing of food?
segmentation
Match the arteries to the organs:
1) hepatic artery
2) splenic artery
3) left gastric artery
4) right gastric artery
5) superior mesenteric artery
6) inferior mesenteric artery
1) liver
2) spleen
3) stomach (superior portion)
4) stomach (inferior portion)
5) small intestine and large intestine (up until the last third of transverse colon)
6) large intestine (from the end of the transverse colon til the rectum)
What system moves nutrient-rich venous blood from the digestive viscera to the liver, where it can be processed?
Hepatic portal system
What two major nerve plexuses constitute the enteric nervous system?
1) submucosal nerve plexus
2) myenteric nerve plexus
which nerve plexus is responsible for motility of the GI tract?
myenteric nerve plexus (Auerbach's plexus)
which nerve plexus regulates glands and smooth muscle in the alimentary canal?
submucosal nerve plexus (Meissner's plexus)
Which muscle is the primary mover of the lips?
orbicularis oris
What muscle group is responsible for the movement of the cheeks?
Buccinators
What structure fastens the tongue to the floor of the mouth and prohibits excessive posterior movement?
lingual frenulum
What's another word for "gums?"
gingivae
what do you call your upper lip?
superior labia
your lower lip is your ____.
inferior labia
which salivary gland has two big ducts that pump a lot of saliva out right beneath the tongue?
submandibular salivary gland
What organ is responsible for mixing food with saliva and forming a bolus, as well as positioning food during chewing and forming sounds in speech?
tongue
what are the four types of papillae present on the tongue?
1) filliform papillae
2) fungiform papillae
3) circumvillate papillae
4) foliate papillae
which papillae on the tongue provide friction?
filliform papillae -- and they DON'T contain taste buds
which papillae are scattered widely over the tongue, giving it a reddish hue? Hint -- they DO contain taste buds.
fungiform papillae
which papillae are located only at the posterior portion of the tongue and only number about a dozen?
circumvallate papillae -- oh, and they also contain taste buds
what tastebud-containing papillae reside on the lateral aspects of the tongue?
foliate papillae
what is the major function of the soft palate?
to close off the nasopharynx during chewing.
What four things does saliva do?
1) cleanses mouth (lysozyme)
2) assists in bolus formation
3) moistens and dissolves food chemicals
4) breaks down starches
the intrinsic salivary glands scattered throughout the mucosa are called the ____ _____.
buccal glands
which salivary glands do the most work?
extrinsic salivary glands (parotid, submandibular, sublingual)
what two secretory cells in the salivary glands release saliva?
serous and mucous cells
what do serous cells in salivary glands produce?
a watery secretion containing lysozyme (disinfectant) and sailvary amylase (dissolves starch). Also includes ions and a wee bit of mucin.
what do mucous cells in salivary glands produce?
mucus, dummy.
is saliva acidic?
Yep! Slightly.
secretion of saliva is under _________ control.
parasympathetic control
stemming the flow of mucus can be an action taken by the ______ division, which can result in drymouth.
sympathetic
food and drink activate chemoreceptors within the oral cavity, stimulating the swallowing center in the ____.
pons
what two nerves innervate the salivary glands?
glossopharyngeal nerve, facial nerve
what are primary teeth?
primary teeth are your baby teeth -- also called deciduous (think of leaves falling off) or milk teeth (think of babies). They erupt form 6-24 months of age.
what are secondary teeth?
permanent, adult teeth.
how many adult teeth should there be?
32
primary teeth are replaced by secondary teeth generally by age ___.
13
which teeth erupt first?
incisors (choppers in the front) at about 6 months.
which teeth erupt second?
molars/premolars, at about 10 months
which teeth are the last to erupt?
canine (eyetooth)
what are the four types of teeth?
1) incisor
2) canine
3) bicuspid/premolar
4) molar
what are the three main parts of any tooth?
1) crown
2) neck
3) root
which part of the tooth is the exposed section above the gingiva?
crown
which part of the tooth is embedded in the jawbone?
root
which part of the tooth is simply the part where the crown and root join?
neck
what acellular, brittle material composed of calcium salts and hydroxyapatite crystals is the hardest substance in the body?
tooth enamel
what are the two main building blocks of tooth enamel?
hydroxyapatite crystals, calcium salts
what is cementum?
calcified connective tissue that covers the root and anchors the root to the periodontal ligament
calcified connective tissue that covers the root and anchors it to the periodontal ligament is called _____.
cementum
what connects the tooth to the alveolus in the jaw?
periodontal ligament
what does the periodontal ligament do?
anchors teeth to the alveolus in the jaw
specifically, what kind of synarthroses are the periodontal ligaments?
gomphoses
what bonelike material lies deep to the enamel and forms most of the tooth?
dentin
what is the big cavity in the tooth that contains pulp?
pulp cavity
what is pulp made up of?
connective tissue, blood vessels, nerves inside the tooth.
what is the root canal?
the segment of the pulp cavity that extends into the root.
what is the apical foramen?
the proximal opening to the root canal.
What's another word for your throat (the part that passes both food and air)?
pharynx
what's the scientific name for swallowing?
deglutition
what's deglutition?
a fancy pants way of saying swallowing
deglutition involves how many muscle groups?
22
what structures/organs are involved in swallowing?
tongue, soft palate, pharynx, esophagus
what's the muscular tube that transports food (in the form of a bolus) from the laryngopharynx to the stomach via peristalsis?
esophagus
what's the esophagus?
a muscular tube that transports food (in the form of a bolus) from the laryngopharynx to the stomach via peristalsis.
what are the four main types of gastric glands found in the stomach?
1) mucous neck cells (secrete acid mucus)
2) chief cells (produce pepsinogen)
3) parietal cells (produce HCl and intrinsic factor)
4) enteroendocrine cells (secrete gastrin, histamine, endorphins, serotonin, cholecystokinin (CCK), and somatostatin)
what do mucous neck cells do?
secrete acid mucus
what do chief cells do?
produce pepsinogen, which degrades to pepsin. It's also called propepsin
what does pepsin do?
it breaks down proteins
what do parietal cells in the stomach do?
secrete HCl and intrinsic factor
what important vitamin does intrinsic factor help us digest and absorb?
B12
what do enteroendocrine cells do?
secrete gastrin, histamine, endorphins, serotonin, cholecystokinin (CCK), and somatostatin
what are the four major tasks of the stomach?
1) to hold ingested food
2) to physically and chemically degrade food and deliver chyme to the small intestine
3) to enzymatically digest proteins using pepsinogen, pepsin, and rennin
4) assist in absorption of vitamin B12 (using intrinsic factor)
what two types of control mechanisms regulate the release of gastric juice?
neural and hormonal
secretory events of the stomach involve three phases. what are they?
1) cephalic (head. starts when you think "food.")
2) gastric - 3 or 4 hours long, provides most of gastric juices. distension, peptides, and low acidity are the big triggers
3) instestinal - happens once chyme hits the intestine
stomach pressure remains constant until roughly how much food is digested?
1 liter
what two factors result in a constant stomach pressure?
1) reflex-mediated relaxation
2) plasticity
what three reflex-mediated events occur in the stomach?
1) adaptive relaxation (stomach relaxes when food hits esophagus)
2) receptive relaxation (stomach dilates in response to gastric filling)
3) plasticity (intrinsic ability of smooth muscle to exhibit stress-relaxation response)
How frequently do peristaltic waves occur in the stomach?
every 20 seconds or so (about 3 per minute)
where do the most vigorous segmentation and peristalsis occur in the stomach?
towards the pyloris
Once chyme is created in the stomach, what happens to it?
it either slowly leaks into duodenum or gets forced back into stomach for further mixing.
What two reflexes regulate gastric emptying?
The neural ENTEROGASTRIC reflex,
and the hormonal ENTEROGASTRONE reflex
The enterograstric (neural) and enterogastrone (hormonal) reflexes do what, exactly?
They inhibit gastric secretion and duodenal filling.
What moves more quickly through the duodenum: carbohydrate-rich chyme or lipid-rich chyme?
carbohydrate-rich chyme
What three structural modifications increase surface area of the small intestine?
1) Plicae circulares (circular folds of mucosa and submucosa)
2) Villi - fingerlike extensions of mucosa
3) Microvilli - tiny projections of mucosal cells' plasma membranes
What is the "brush border?"
It's the border formed by the absorptive microvilli of the small intestine's epithelial cells
what do "brush border enzymes" do?
they digest both carbohydrates and proteins in the small intestine.
What type of epithelium constitutes the small intestine wall?
Simple columnar epithelium
What type of cell junction is characteristic of cells in the small intestine?
Tight junction
What type of cells are present in the small intestine that sense the conditions luminal environment and secrete hormones such as cholecytokinin and secretin into the blood?
Enteroendocrine cells
What do enteroendocrine cells in the small intestine do?
They sense the conditions of the luminal environment and secrete hormones such as cholecytokinin and secretin into the blood.
What special structure is present in the submucosa of the small intestine (especially the ileum) that is large, ovular, and composed of lymphoid tissue?
Peyer's Patch
What are the three main functions of the small intestine?
1) Neutralization
2) Chemical digestion
3) Absorption
What three enzyme in the small intestine digest carbohydrates?
Which two digest proteins?
Which ones get lipids?
Carbs - sucrase, lactase, maltase
Proteins - peptidases, proteases
Lipids - Lipases
What gets absorbed by the small intestine?
Water, electrolytes, and dietary organic molecules
What's the largest gland in the body?
The liver
Name some of the important metabolic functions of the liver?
1) production of plasma proteins
2) production of cholesterol and lipoproteins
3) conversion of glucose to glycogen and glycogen storage
4) regulation of blood levels of amino acids
5) processing of hemoglobin for use of its iron (the liver stores iron)
6) conversion of ammonia (poison!) to urea
7) clearing out drugs and poisons
8) regulating blood clotting
9) bile production
what does bile do?
Bile carries away waste and breaks down fats in the small intestine during digestion.
What does bile contain?
bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolytes
What do the cholesterol derivatives called bile salts do?
1) emulsify fat
2) facilitate fat and cholesterol absorption
3) Help solubilize cholesterol
4) Stimulate liver to produce bile
What is the chief bile pigment?
bilirubin -- a waste product of heme
When do cholesterol gallstones develop?
When bile contains too much cholesterol and not enough bile salts. Also, certain proteins that inhibit or promote cholesterol crystallization play a role
What happens when bile contains too much cholesterol and not enough bile salts, and proteins are present that promote cholesterol crystallization?
Cholesterol gallstones develop.
What color is the gallblader?
The gallbladder is green.
What are the three major functions of the gallbladder?
1) Storage of bile
2) Concentration of bile by absorbing water and ions
3) Releasing bile via the cystic duct which merges into the bile duct
What happens when acidic, fatty chyme enters the duodenum?
1) The duodenum secretes cholecystokinin and secretin into the bloodstream
2) Secretin, along with bile salts in the bloodstream, signal the liver to produce bile more rapidly
3) Vagal stimulation and the cholecystokinin cause gallbladder to contract, secreting bile into the duodenum
What two exocrine secretions are produced by the pancreas? What do they do?
1) Acinar cells secrete pancreatic juice -- break down all sorts of food
2) Bicarbonate -- neutralizes stomach acid in duodenum
What are the endocrine cells of the pancreas called?
Islets of Langerhans
What do the islets of langerhans do?
The Islets of Langerhans produce insulin, glucagon, and somatostatin.
What two types of bacteria live in the large intestine?
1) Those that survived the small intestine and enter the cecum.
2) Those entering via the anus
What four things do colon bacteria do?
1) Colonize the colon
2) Ferment indigestible carbohydrates
3) Release irritating acids and gases (flatus)
4) Synthesize B complex vitamins and vitamin K
What is the major purpose of the colon?
Propelling feces toward the anus.
What makes the colon different from the rest of the digestive organs?
It doesn't really digest anything (besides enteric bacteria), and it's actually not necessary for human life (though it sure helps).
Distension of the rectal walls caused by feces does what two things?
It stimulates contraction of the rectal walls and relaxes the internal anal sphincter.
What's a "mass movement?"
A mass movement is basically a giant peristaltic contraction that strips an area of the colon of its contents.
What provents feces from being passed with gas?
Three valves of the rectum stop it.
Where does the word feces come from?
The latin 'faex,' meaning dregs.
What is feces composed of?
water, undigested food residues, digestive secretions, bacteria
The reddish-brown color of feces comes from what?
The reddish brown hue comes from bacterial action on bilirubin, which creates stercobilin.
What is responsible for the odor of feces?
Bacterial action produces smelly stuff like:
Indoles
Skatoles
Mercaptans
All of these are rich in sulfur. Bacteria also produce hydrogen sulfide.
Define "hydrolysis."
A chemical reaction that uses water to break down a compound.
What enzymes digest carbohydrates throughout the digestive system?
Salivary amylase, pancreatic amylase, brush border enzymes
Where does protein digestion begin?
In the stomach.
What is the pH level of the stomach?
1.5-2.5
What enzymes in the small intestine digest proteins?
Pancreatic enzymes trypsin, chymotrypsin, carboxypeptidase.

Brush border enzymes aminopeptidases, carboxypeptidases, dipeptidases
How are lipids absorbed?
They combine with proteins and extrude chylomicrons, then enter lacteals and enter circulation via lymph.
How are glycerol and short chain fatty acids absorbed?
They enter capillary blood in the villi and travel via the hepatic portal vein using bile salts and pancreatic lipase.
How are nucleic acids digested?
Membrane-bound enzymes in epithelial cells of the ileum break the nucleotides into their constituent components and absorb them. Pancreatic ribonuclease and deoxyribonuclease breaks them down and they travel to the liver via the hepatic portal vein.
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