a&p 2 ch 23

what vitamins does the small intestine absorb?

- fat soluble vitamins (A,D,E,K) are carried by micelles; diffuse into absorptive cells - water soluble vitamins ( C and B) are absorbed by diffusion or by passive or active transporters - vitamin B12 binds with intrinsic factor and is absorbed by endocytosis

list the pancreatic enxymes

- proteases (for proteins) - amylase (for starch) - lipases (for fats) - nucleases (for nucleic acids)

what stimulates pancreatic secretion?

-CCK induces secretion by acinar cells of enzyme rich pancreatic juice -secretin causes secretion by duct cells of HCO3- rich pancreatic juice -vagus nerve weakly stimulates during cephalic and gastric phases

what are the three factors that create the mucosal barrier of the stomach?

-a thick coating of bicarbonate rich mucus -the epithelial cells of the mucosa are joined together by tight junctions (prevents gastric juice from leaking out) -damaged epithelial mucosal cells are shed and quickly replaced by stem cells

how can the duodenum prevent overfilling

-by controlling how much chyme enters -duodenal receptors respond to stretch and chemical signals -enterogastric reflex and enterogastron inhibit gastric secretion and duodenal filling

functions of saliva

-cleanses the mouth -dissolves food chemicals so they can be tasted -moistens food and helps compact it into a bolus -contains the enzyme amylase that begins the digestion of starchy foods

how does valsalva maneuver help in defaction?

-closing of glottis, contraction of diaphragm and abdominal wall muscles cause increased intrabdominal pressure -levator ani muscle contracts, causing anal canal to be lifted superiorly and allowing feces to leave body

what four main factors in duodenum cause inhibition of gastric secretions?

-distension of duodenum due to entry of chyme -presence of acidic chyme -presence of fatty chyme -presence of hypertonic chyme -inhibitory effects protect the intestine from being overwhelmed by too much chyme or acidity

what are the differences in the tunica layers in the esophagus?

-esophageal mucosa contains stratified squamous epithelium -esophageal glands in submucosa secrete mucus to aid in bolus movements -has adventitia instead of serosa

what is vomiting (emesis) causes by?

-extreme stretching -intestinal irritants (bacterial toxins, excessive alcohol, spicy food, certain drugs)

metabolic function of gut bacteria

-fermentation: gut bacteria ferment some indigestible carbohydrates and the mucin in gut mucus -vitamin sysnthesis: B complex vitamins and some of the vitamin K the liver needs in order to produce several clotting proteins are synthesized by gut bacteria

what are the three common monosaccharides in our diet? disaccharides? polysaccharides?

-glucose, fructose, galactose -sucrose, lactose, maltose -glycogen, starch

what is hepatitis and what is it caused by?

-inflammation of the liver -caused by: toxic effects of alcohol, drugs, and wild mushrooms

give characteristics of the mucosa layer

-innermost layer -3 sublayers: a lining epithelium, a lamina propria, and a muscularis mucosae

what is the purpose of the gastroesophageal/ cardiac sphincter

-keeps orifice closed when food is not being swallowed -mucus cells on both sides of sphincter help protect esophagus from acid reflux

proteins are broken into:

-large polypeptides -small polypeptides and peptides -amino acid monomers

what are the 4 basic layers or tunics that all digestive organs of the alimentary canal have?

-mucosa -submucosa -muscularis externa -serosa

periodontitis

-neglected gingivitis escalate to bacterial disease

how do parasympathetic and sympathetic stimuli affect digestion?

-parasympathetic system enhances digestive process -sympathetic system inhibits digestion

what is peritonitis caused by?

-piercing abdominal wound, perforating ulcer, or ruptured appendix

what happens during gingivitis?

-plaque calcifies to form calculus

what stimulates cholecystokinin release? secretin release?

-porteins and fats in chyme -acidic chyme

how can a disease like periodonotis increase heart disease and stroke>

-promotes plaque fomration 0

what are the symptoms of irritable bowel syndrome?

-recurring abdominal pain, stool changes, bloating, nausea, depression -stress management is important in treatment

functions of the mucosa

-secrete mucus, digestive enzymes, and hormones -absorb the end products of digesting into the blood -protect against infectious disease

what chemical messengers do enteroendocrine cells secrete?

-serotonin and histamine -somatostatin and gastrin

what are some of the events included during the defaction reflex?

-sigmoid colon and rectum contract -the internal anal sphincter relaxes

what stimulates the gastric phase?

-stomach distentsion activates stretch receptors and initiates both short and long reflexes -chemical stimuli is provided by partially digested proteins, caffeine, and rising pH, they activate gastric secreting G cells gastrin also stimulates the production of HCl during this phase

functions of the gallbladder

-stores bile that is not immediately needed for digestion and concentrates it by absorbing some of its water and ions

what is the epithelium layer of mucosa made of?

-stratified squamous in rhe mouth, esophagus, and anus -simple columnar epithelium

what are some of the mechanical and chemical stimuli that provoke digestion?

-stretching of the organ by food in the lumen, changes in osmolarity, changes in pH, and the presence of substrates and end products of digestion

what are the two ways potentially harmful bacteria in our large intestine are kept in check?

-the beneficial bacteria outcompete and actively suppress harmful bacteria -our immune system prevents bacteria from entering the body through gut epithelium

Name one organ of the alimentary canal found in the thorax. Name three organs located in the abdominal cavity.

-the esophagus is found the in the thorax -three alimentary canal organs found in the abdominal cavity includes the stomach, small intestine, and large intestine

what two mechanisms cause the ileocecal valve to open?

-the gastroileal reflex, a long neural reflex triggered by stomach activity, increases the force of segmentation in the ileum and relaxes the ileocecal valve -gastrin, a hormone released by the stomach, increases the motility of the ileum and relaxes the ileocecal valve

how does the wall of the large intestine differ from the wall of the small intestine?

-there are no circular folds, villi, or brush border because most food is absorbed before reaching the large intestine -its mucosa is thicker, its abundant crypts are deeper, and the crypts contain tremendous numbers of goblet cells. mucus produced by goblet cells eases the passage of feces and protects the intestinal wall from irritation by acids and gases released by resident bacteria

what are the two main groups of digestive organs?

-those of the alimentary canal -accessory digestive organs

what are the most likely causes of heart burn?

-when a person has eaten or drunk to excess -extreme obesity -pregnancy -running

Mechanism of HCl secretion by parietal cells

1. H+ and HCO3- are generated from the dissociation of carbonic acid produced from co2 and h2o by carbonic anhydrase 2. H+, K+ ATPase pumps H+ into the lumen and K+ into the cell. K+ returns to the lumen through membrane channels 3. HCO3- leaves the cell in exchange for interstitial fluid cl- (alkaline tide) 4. Cl- diffuses through membrane channels into the lumen

the enterohepatic circulation

1. bile salts are secreted into the duodenum 2. as bile salts travel through the small intestine, they allow lipid digestion and absorption to occur 3. 95% of bile salts are reabsorbed by the ileum 4. reabsorbed bile salts travel via the hepatic portal vein back to the liver, where they are recycled

deglutition phases

1. buccal phase: -the upper esophageal sphincter closes -the tongue presses agaisnt the hard palate, forcing the food bolus into the oropharynx 2. pharyngeal-esophageal phase begins: -the tongue blocks the mourth -the soft palate and its uvula rise, closing off the nasopharynx -the larynx rises so that the epiglottis blocks the trachea -the upper esophageal sphincter relaxes; food enters the esophagus 3. pharyngeal- esophageal phase -the constrictor muscles of the pharynx contract forcing food into the esophagus -the upper esophageal sphincter contracts after food enters -peristalsis moves food through the esophagus to the stomach -the gastroesophageal sphincter surrounding the cardial orifice open -after food enters the stomach, the sphincter closes, preventing regurgitation

what are the 3 key concepts that govern regulation of digestive activity?

1. digestive activity is provoked by a range of mechanical and chemical stimuli 2. effectors of digestive activity are smooth muscle and glands 3. neurons (intrinsic and extrinsic) and hormones control digestive activity

emulsification, digestion, and absorption of fats

1. emulsification. bile salts in the duodenum break large fat globules into smaller fat droplets, increasing the surface area available to lipase enzymes 2. digestion. pancreatic lipases hydrolyze triglycerides yielding monoglycerdies and free fatty acids 3. micelle formation. free fatty acids and monoglycerides assemble with bile salts, forming micelles. micelles ferry their contents to enterocytes 4. diffusion. fatty acids and monoglycerides diffuse from micelles into enteryocytes 5. chylomicron formation. fatty acids and monoglycerides are recombined and packaged with other fatty substances and proteins to form chylomicrons 6. chylomicron transport. chylomicrons transport. chylomicrons are extruded from enterocytes by exocytosis, enter lacteals, and are carried away from the intestine in lymph

defaction reflex steps

1. feces move into and distend the rectum, stimulating stretch receptors there. the receptors transmit signals along afferent fibers to spinal cord neurons 2. a spinal reflex is initiated in which parasympathetic motor fibers stimulate contraction of the rectum and sigmoid colon, and relaxation of the internal anal sphincter 3.if it is convenient to defecate voluntary motor neurons are inhibited, allowing the extrernal anal sphincter to relax so feces may pass

carbohydrates digestion and absorption in the small intestine

1. pancreatic amylase breaks down starch and glycogen into oligosaccharides and disaccharides 2. brush border enzymes break oligosaccharides and disaccharides into monosaccharides 3. monosaccharides are contrasported across the apical membrane of the enterocyte. this activae transport uses the Na+ concentration gradient established by the Na+, K+ ATPase in the basolateral membrane 4.monosaccharides exit across the basolateral membrane by facilitated diffusion and enter the capillary via intracellular clefts

protein digestion and absorption in the small intestine

1. pancreatic proteases break down proteins and protein fragments into smaller pieces and amino acids 2. brush border enzymes break protein fragments into amino acids 3. amino acids are cotransported across the apical membrane of the enteryocyte. this activae transport uses the Na+ concentration gradient established by the Na+, K+ ATPase in the basolateral membrane 4. amino acids exit across the basolateral membrane via facilitated diffusion and enter the capillary via intracellular clefts

peristaltic waves in the stomach

1. propulsion. peristaltic waves move from the pylorus toward the pylorus 2. grinding: the most vigorous peristalsis and mixing action occur close to the pylorus. the pyloric end of the stomach acts as a pump that delivers small amounts of chyme into the duodenum 3. retropulsion: the peristaltic wave closes the pyloric valve, forcing most of the content of the pylorus backward into the stomach

how many baby teeth do we have? permanent teeth?

20 baby teeth and 32 permanent teeth

Besides preparing food for swallowing, the tongue has another role. What is it?

: The tongue is important for taste and for speech, particularly for uttering consonants.

What common advantage do circular folds, villi, and microvilli provide to the digestive process?

All of these modifications increase the surface area of the small intestine.

Name three antimicrobial substances found in saliva.

Antimicrobial substances found in saliva include lysozyme, defensins, and IgA antibodies.

What are brush border enzymes?

Brush border enzymes are enzymes associated with the microvilli of the enterocytes of the small intestine mucosa.

What stimulates CCK release and what are its effects on the digestive process?

CCK is secreted in response to the entry into the duodenum of chyme rich in protein and fat. It causes the pancreatic acini to secrete digestive enzymes, stimulates the gallbladder to contract, and relaxes the hepatopancreatic sphincter.

Name the layer and sublayer of the alimentary canal wall that houses the capillaries into which nutrients are absorbed

Capillaries that receive absorbed nutrients are in the lamina propria of the mucosa of the small intestine.

Distension of the stomach and duodenal walls have different effects on stomach secretory activity. What are these effects?

Distension of stomach walls enhances stomach secretory activity. Distension of the walls of the small intestine reduces stomach secretory activity (to give the small intestine time to carry out its digestive and absorptive activities).

How are the respiratory passages blocked during swallowing?

During swallowing the larynx rises and the epiglottis covers its lumen so that foodstuffs are diverted into the esophagus posteriorly.

composition of saliva

Electrolytes (Na+, K+, Cl−, PO43−, and HCO3−) The digestive enzymes salivary amylase and lingual lipase (lingual lipase makes only a minor contribution to overall fat digestion) The proteins mucin, lysozyme, and IgA Metabolic wastes (urea and uric acid)

In what ways are gut bacteria important to our nutrition?

Enteric bacteria synthesize B vitamins and some of the vitamin K the liver needs to synthesize clotting proteins.

What is the makeup of the fluid in the pancreatic duct? In the cystic duct? In the bile duct?

Fluid in the pancreatic duct is bicarbonate-rich, enzyme-rich pancreatic juice. Fluid in the cystic and bile ducts is bile.

Jerry has been given a drug that inhibits parasympathetic stimulation of his digestive tract. Should he "eat hearty" or temporarily refrain from eating, and why?

He should temporarily refrain from eating because the parasympathetic nervous system stimulates digestive activities.

what hormonal controls control gastric secretion?

Hormonal control of gastric secretion is largely the province of gastrin. It stimulates secretion of HCl by the stomach, and of hormones (mostly gastrin antagonists) by the small intestine.

what defenses does saliva contain?

IgA, lysozyme (inhibits bacterial growth), and defensins

_____- diffuses in response to osmotic gradients; lost if water absorption is poor

K+

Suppose you had a patient that was unable to make bile salts. What digestive processes would be affected and what might be some of the consequences?

Lack of bile salts would dramatically decrease both digestion and absorption of fats and fat-soluble vitamins. Without bile salts, you would expect the patient to have fatty stools. The patient might exhibit signs of weight loss and malnutrition. (In children this would be seen as lack of growth and failure to thrive.) The patient may also exhibit signs of deficiency of fat-soluble vitamins (see Table 24.2).

What is the MMC and why is it important?

MMC is the migrating motor complex, a pattern of peristalsis seen in the small intestine that moves the last remnants of a meal plus bacteria and other debris into the large intestine. MMC is important to prevent the overgrowth of bacteria in the small intestine.

____ absorption is coupled with active absorption of glucose and amino acids

Na+

What is the functional difference between pancreatic acini and islets?

Pancreatic acini produce the exocrine products of the pancreas (digestive enzymes and bicarbonate-rich juice). The islets produce pancreatic hormones, most importantly insulin and glucagon.

Describe the process by which solids are broken apart into smaller pieces in the stomach.

Peristaltic contractions become more and more powerful as they approach the pylorus. Only a small squirt of liquid chyme is allowed through the pyloric sphincter before this sphincter closes as part of the peristaltic wave. Once the pyloric sphincter is closed, solids in the stomach are propelled back into the stomach (a movement called retropulsion) while being pummeled and ground together.

When sensors in the GI tract are stimulated, they trigger reflexes. What types of digestive activity may be put into motion via those reflexes?

Reflexes associated with the GI tract promote muscle contraction and secretion of digestive juices or hormones.

After a meal, what is the small intestine's most common motility pattern? Why?

Segmentation is the most common motility pattern after a meal. Segmentation mixes chyme with digestive enzymes and exposes the products of this digestion to the absorptive epithelium where brush border enzymes complete digestion and where absorption occurs.

Two substances secreted by cells of the gastric glands are needed to produce the active protein-digesting enzyme pepsin. What are these substances and which cells secrete them?

The chief cells produce pepsinogen, which is the inactive enzyme pepsin, and the parietal cells secrete HCl needed to activate pepsinogen.

What is the importance of the enterohepatic circulation?

The enterohepatic circulation is an important recycling mechanism for retaining bile salts needed for fat absorption.

How is the muscularis externa of the esophagus unique in the body?

The esophageal muscularis externa undergoes a transformation along its length from skeletal muscle superiorly to smooth muscle near the stomach.

What is the functional significance of the epithelial change seen at the esophagus-stomach junction?

The esophagus is merely a chute for food passage and is subjected to a good deal of abrasion, which a stratified squamous epithelium can withstand. The stomach mucosa is a secretory mucosa served well by a simple columnar epithelium.

What name is given to the venous portion of the splanchnic circulation?

The hepatic portal circulation is the venous portion of the splanchnic circulation.

The two types of smooth muscle are unitary and multi unit (see Chapter 9). Which type would you expect to find in the muscularis externa, and what characteristics make it well suited for this location?

The muscularis externa is unitary smooth muscle. Characteristics of unitary smooth muscle that make it well suited for this location are that it is electrically coupled by gap junctions and so contracts as a unit, is arranged in longitudinal and circular sheets, and exhibits rhythmic spontaneous action potentials.

Which structure forms the roof of the mouth?

The palate forms the roof of the mouth. The hard palate supported by bone is anterior to the soft palate (no bony support).

To which two organ systems does the pharynx belong?

The pharynx is part of the digestive and respiratory systems.

How does the presence of food in the small intestine inhibit gastric secretion and motility?

The presence of food in the duodenum inhibits gastric activity by triggering the enterogastric reflex and the secretion of enterogastrones (hormones).

The term "gut brain" does not really mean there is a brain in the digestive system. What does it refer to?

The term "gut brain" refers to the enteric nervous system, the web of neurons closely associated with the digestive organs.

Name the three phases of gastric secretion.

The three phases of gastric secretion are the cephalic, gastric, and intestinal phases.

how does the location of the visceral peritoneum differ from that of the partieal peritoneum?

The visceral peritoneum is the outermost layer of the digestive organ; the parietal peritoneum is the serous membrane covering the wall of the abdominal cavity.

In order to be absorbed, nutrients must pass through two plasma membranes. Name these membranes.

To be absorbed, nutrients pass through the apical and then the basolateral membranes of enterocytes.

what is a mesentery and what is its functions?

a double layer of peritoneum; layers are fused back to back -extends from body wall to digestive organs -provides routes for blood vessels, lymphatics, and nerves -holds organs in place -stores fat

what is the condition xerostomia characterized by?

a dry mouth due to abnormal salivary gland function

what inhibits gastric secretion?

a high pH -occurs in-between meals

what do mucous neck cells secrete?

a thin acidic mucus -the function is unknown

what is the large intestine's major digestive function?

absorb the remaining water from indigestible food residues, store the residues temporarily, and then eliminate them from the body as semisolid feces

5. _________________ is the passage of digested end products from the lumen of the GI tract through the mucosal cells by active or passive transport into the blood or lymph

absorption

what does pancreatic juice consist of?

acini: cluster of secretory cells that produce zymogen granules contaning proenzymes ducts: secrete to duodenum via main pancreatic duct; smaller duct cells produce water and bicarbonate

What is the result of stimulation of stretch receptors in the rectal walls?

activation of stretch receptors in the rectal walls initiates the defecation reflex

peristalsis

adjacent segments of the alimentary canal organs alternately contract and relax -food is moved distally along the tract -primarily propulsive; some mixing may occur

In the esophagus, the serosa is replaced by an _____________

adventitia

what are the 5 major types of cells found in the mucosal epithelium of villi and crypts

anterocytes, goblet cells, enteroendorcrine cells, paneth cells, stem cells

material enter cells through the _______ membrane and exit through the __________ membrane

apical; basolateral

what is the submucosa layer of the mucosa made of?

areolar connective tissue

what is the cephalic (reflex) phase triggered by?

aroma, taste, sight, thought of food

splanchnic circulation

arteries that serve digestive organs -hepatic, splenic, gastric, inferior/ superior mesenteric -the hepatic portal acts as the vein

where does the esophagus pierce the diaphragm?

at the esophageal hiatus

what causes a dental caries/ cavity

bacterial action that demineralizes enamel and underlying dentin. -starts as dental plaque

what does bile do?

bile is a fat emulsifier that breaks fats into tiny particles to make them more readily digestible

what the most powerful stimulation for bile secretion?

bile salts returning from enterohepatic circulation

what are the sources of enzymes for digestion?

bile, digestive enzymes, and bicarbonate ions brush border enzymes

_________ a rounded mass of food prepared by the mouth for swallowing

bolus

____________________ enzymes perform the final digestion of food into the simple components that can be absorbed by intestinal cells

brush border

what breaks down nucleotides even further?

brush border enzymes

what are the 2 major processes of deglutition (swallowing)?

bucal phase and pharyngeal-esophageal phase

the _________ phase occurs in the mouth and is voluntary. it ends when a food bolus or a "bit of saliva" leaves the mouth and stimulates tactile receptors in the posterior pharynx, initiating the next phase

buccal

heartburn

burning radiating substernal pain that occurs when stomach acid regurgitates into the esophagus

How is pepsinogen activated to pepsin?

by HCl and pepsin

what moves quickly through the duodenum?

carbohydrate rich chyme

where does the esophagus join the stomach

cardiac orifice

digestion is a __________ process

catabolic

what subdivision does the large intestine have?

cecum, appendix, colon, rectum, anal canal

what is a common malabsorption disease?

celiac disease -gluten causes immune cell damage to intestinal villi and brush border

what are the 3 phases of gastric secretion?

cephalic (reflex) phase, gastric phase, intestinal phase

list a few mechanical processes

chewing, mixing food with saliva by the tongue, churning food in stomach, and segmentation

what is cirrhosis

chronic disease of the liver, characterized by an overgrowth of connective tissue

______________________, an anaerobic bacterium, is the most common cause of antibiotic associated diarrhea

clostridium difficile

how is the mucosa layer of the stomach different?

consists of simple columnar entirely composed of mucous cells -secretes two-layer coat of alkaline mucous (surface layer traps bicarbonate rich fluid layer that is beneath it -also contains gastric glands that produces gastric juice

________________ can occur when food remains in colon for extended periods of time and too much water is absorbed -stool becomes hard and difficult to pass -may result from insufficient fiber or fluid in the diet

constipation

what does the hepatopancreatic sphincter do? and when does it relax

controls entry of bile and pancreatic juice into duodenum CCK causes it to relax

what is the pyloric sphincters function

controls food entry into the duodenum

6. _______________ eliminates indigestible substances from the body via the anus in the form of feces

defaction

____________ colon: travels down left side of abdominal cavity

descending

The most important brush border enzymes are ________________ and ____________________, which act on oligosaccharides composed of more than three simple sugars, and maltase, sucrase, and lactase, which hydrolyze maltose, sucrose, and lactose respectively into their constituent monosaccharides.

dextrinase; glucoamylase

_______________, watery stools, results when large intestine does not have sufficient time to absorb remaining water

diarrhea

4. ______________ involves a series of steps in which enzymes secreted into the lumen of the alimentary canal breakdown complex food molecules to their chemical building blocks

digestion

_______________ is a catabolic process that breaks down large food molecules to monomers

digestion

function of the alimentary canal

digests food (breaks it down into smaller fragments) and absorbs the digested fragments through its lining into the blood

most digestive organs are intraperitoneal and are suspended from the body wall by a ________________

dorsal mesentery

the sympathetic nervous system causes a ____ mouth

dry

what glands does the submucosa of the small intestine have?

duedenal glands that secrete alkaline mucus neutralize acidic chyme

what are the three subdivisions of the small intestine?

duodenum, jejunum, and ileum

Which tooth substance is harder than bone? Which tooth region includes nervous tissue and blood vessels?

enamel is harder than bone. Pulp consists of nervous tissue and blood vessels.

what is the hardest substance in the body and where can it be found?

enamel; over the teeth

the GI tract has its own ________ nervous system

enteric

_____________ reflex: the duodenum inhibits acid secretion in the stomach by short reflexes through the enteric nervous system and by long reflexes involving sympathetic and vagus nerves

enterogastric

what are two ways inhibition of the intestinal phase is achieved?

enterogastric reflex and enterogastrones

Feedback via the______________________ and ______________________ to the stomach pylorus carefully controls food movement into the small intestine to prevent the duodenum from being overwhelmed

enterogastric reflex; enterogastrones

what hormones regulate the secretion of bile and pancreatic juice into the small intestine?

enterogastrones and cholecystokinin (cck)

___________________: the enterogastrone hormones are released by a scattering of enteroendocrine cells in the duodenal mucosal epithelium. the two most important enterogastrones are __________ and ______________________

enterogastrones; secretin; cholecystokinin

___________________________: fat-filled pouches of visceral peritpneum

epiploic appendages

ionic iron is stored in mucosal cells with _________and when needed transported in the blood by _______________

ferritin and transferrin

the conical _____________________ roughen the tongue surface, helping us lick semisolid foods and providing friction for manipulating foods. These papillae, the smallest and most numerous type, align in parallel rows on the tongue dorsum. They contain keratin, which stiffens them and gives the tongue its whitish appearance.

filiform papillae

Pleatlike ______________ are located on the lateral aspects of the posterior tongue.

foliate papillae

what stimulates the major glands to produce saliva?

food entering the mouth

what is the purpose of the hard palate?

forms a rigid surface against which the tongue forces food during chewing

paneth cells in the mucosa of the small intestine

fortify small intestine's defenses -secrete defensins and lysozymes

The mushroom-shaped ________________________ are scattered widely over the tongue surface. Each has a vascular core that gives it a reddish hue.

fungiform papillae

what causes the secretion of bile from the gallbladder

gallbladder contraction caused by CCK or vagus nerve

anything that breaches the gel-like mucosal barrier causes inflammation of the stomach wall, a condition called ____________

gastritis

what is the function of the submucosa layer of the mucosa?

has abundant elastic fibers that help the stomach regain its normal shape after storing a large meal

enterocytes in the mucosa of the small intestine

has villi which absorb nutrients and electrolytes the crypts produce intestinal juicy, watery mixture of mucus that acts as carrier fluid for chyme

_________________: pocketlike sacs caused by tone of teniae coil

haustra

___________________: most contractions of colon, where haustra sequentially contract in response to distension

haustral contractions

what are most ulcers caused by?

helocobactoer pylori

heartburn is also common in those with a _______________, a structural abnormality in which the superior part of the stomach protrudes slightly above the diaphragm

hiatal hernia

what parietal cells secrete?

hydrochloric acid and intrinsic factor

the enzymatic breakdown of any food molecules is ________________ because it involves adding a water molecule to each molecular bond to be broken

hydrolysis

chyme entering duodenum is usually ________________; therefore, chyme delivery has to be slow to prevent osmotic loss of water from blood

hypertonic

what is the major stimulus for the production of intestinal juice

hypertonic or acidic chyme

what is the point called where the small intestine and large intestine joint togeter?

ileocecal valve

ACTIVATION OF PANCREATIC PROTEASES

in powerpoint

appendicitis

inflammation of the appendix that results from a blockage that traps infectious bacteria in its lumen

1. ______________ is taking food into the digestive tract (eating)

ingestion

what are the 4 digestive processes the mouth helps with?

ingestion, mechanical breakdown, propulsion

what are the 6 essential activities seen in digestion?

ingestion, propulsion, mechanical breakdown, digestion, absorption, defacation

what does the endocrine part of the pancreas secrete?

insulin and glucagon by pancreatic islets

what are the two sphincters of the anus

internal anal sphincter (smooth muscle) and external anal sphincter (skeletal muscle)

_____________________: organs that are located within the peritoneum

intraperitoneal organs

what is the purpose of the peritoneal cavity?

it contains serous fluid that allows the mobile digestive organs to glide easily across one another and along the body wall

how is the muscularis externa different in the stomach?

it has an extra layer called the oblique layer -the smooth muscle of the stomach allows it to churn, mix, move chyme, and pummel it, which increases the physical breakdown and rams it into the small intestine

how is the small intestine mucosa layer different?

it has intestinal crypts

what does gastrin do?

it is a hormone secreted by the stomach; regulates gastric juice secretion by stimulating HCL production

what is the significance of intrinsic factor?

it is the glycoprotein required for vitamin B12 absorption in the small intestine

what is the condition ankyloglossia

it is when children are born with a short lingual frenulum

why does radiation and chemotherapy cause nausea, vomiting, and diarrhea?

it targets rapidly dividing cells, even those in the GI tract

what is the function of the lamina propria of the mucosa layer?

its capillaries nourish the epithelium and absorb digested nutrients -also contains lymphoid follicles that help defend against microorganisms (apart of MALT)

people with _______________ intolerance have deficient amounts of lactase and cannot consume lactose

lactose

Fill in the blank: Amylase is to starch as ___ is to fats.

lipase

what molecule can be passively absorbed through the membrane

lipids

one in blood, chylomicrons are broken into free fatty acids and glycerol by ____________________ so they can be used by cells

lipoprotein lipase

___________ reflexes involve CNS integration centers and extrinsic autonomic nerves (extrinsic controls)

long

what neural controls control gastric secretion?

long (vagus nerve) and short reflexes (enteric) -acetylcholine is released stimulating the output of gastric juice -vagus nerve stimulation increases secretion -sympathetic stimulation decreases secretion

what is the lamina propria of the mucosa layer made of?

loose areolar connective tissue

__________________, or impaired nutrient absorption, has. many and varied causes. it can result from anything that interferes with the delivery of bile or pancreatic juice to the small intestine.

malabsorption

Name and briefly describe the types of motility that occur in the large intestine.

mass movements and hasutral contractions occur in the large intestine. mass movements are long, slow, powerful contractions that move over large areas of the colon three or four times day, forcing the contents toward the rectum. haustral contractions are a special type of segmentation.

what does the gastrocolic reflex result in?

mass movements: slow, powerful peristaltic waves that are activated a couple times during the day

As food enters the mouth, its mechanical breakdown begins with ________________, or chewing

mastication

3. _________________ increases the surface area of ingested food, physically preparing it for digestion by enzymes

mechanical breakdown

during peristalsis between meals each wave starts distal to the previous wave. what is this referred to us?

migrating motor complex

as _____________ blood levels rise, peristaltic waves are initiated

motilin

is the large intestine essential for life?

no, if the colon is removed the terminal ileum can be brought out through abdominal wall

segmenation

nonadjacent segments of the alimentary canal organs contract and relax -food is moved forward, then backward -primarily mixes food and breaks it down mechanically; some propulsion may occur

accessory digestive organs -list the organs it includes

organs that contribute to the digestive process but are not part of the alimentary canal includes the tongue, teeth, gallbladder, salivary glands, pancreas, liver

what is the significance of hydrochloric acid?

pH 1.5-3.5 -denatures proteins -activates pepsin -breaks down plant cells -kills many bacteria

Of the following organs, which is/are retroperitoneal? Stomach, pancreas, liver.

pancreas

______________________ breaks down starch or glycogen that escaped salivary mylase into oligosaccharides and disaccharides

pancreatic amylase

what does the exocrine part of the pancreas secrete?

pancreatic juice

______________________ in pancreatic juice hydrolyze the nucleic acids to their nucleotide monomers

pancreatic nucleases

what increases the motility of the small intestine

parasympathetic nervous system

digestion begins in stomach when pepsinogen is converted to _________

pepsin

what can gastritis promote?

peptic ulcers called gastric ulcers that cause erosion in the stomach wall

_________________, the major means of propulsion, involves alternating waves of contraction and relaxation of muscles in the organ walls. its main effect is to squeeze food along the tract

peristalsis

________________ is inflammation of the peritoneum.

peritonitis

the ________________ phase is involuntary and is controlled by the swallowing center in the brain stem. (vagus nerve)

pharyngeal-esophageal phase

bile salts function:

play a crucial role in digestion and absorption of fats

what is the livers digestive function?

producing bile for export to the duodenum

2. _______________ moves food through the alimentary canal, includes swallowing and peristalsis

propulsion

what digestive processes take place in the stomach?

propulsion, mechanical breakdown, digestion, and absorption -carries out breakdown of food -serves as holding area for food -delivers chyme to small intestine -denatures proteins by HCl -pepsin carries out enzymatic digestion of proteins

what is secreted in infants that breaks down milk?

rennin

__________________: located outside, or posterior to, the peritoneum -includes most of pancreas, duodenum, and parts of the large intestine

retroperitoneal

some digestive organs are _________________ because they have lost their mesentery during development

retroperitoneal

what is the function of the soft palate

rises reflexively to close off the nasopharynx when we swallow (keeps us from breathing and swallowing at the same time)

___________________, present in saliva, splits starch into oligosaccharides, smaller fragments of two to eight linked glucose molecules

salivary amylase

When we ingest food, chemoreceptors and mechanoreceptors in the mouth send signals to the _________________ in the brain stem

salivatory nuclei

goblet cells in the mucosa of the small intestine

secrete mucus

what is the one stomach function essential to life?

secretion of intrinsic factor for vitamin b 12 absorption -B12 is needed for red blood cells to mature -lack of intrinsic factor causes pernicious anemia

_________________ mixes food with digestive juices and makes absorption more efficient by repeatedly moving different parts of the food mass over the intestinal wall

segmentation

whats the difference between what serous cells produce and mucous cells?

serous cells produce watery secretion, enzymes, ions, bit of much mucous cells produce mucus

parotid and submandibular glands contain mostly _______cells, but sublingual gland consists mostly of _________ cells

serous; mucous

___________ reflexes are mediated entirely by enteric nervous system plexuses in response to stimuli within the GI tract. control of the pattern of segmentation and peristalsis is largely autonomic (intrinsic controls)

short

_______________ colon: the s shaped portion that travels through the pelvis

sigmoid

______________ is the major organ of digestion and absorption

small intestine

what is the purpose of the musclaris mucosae?

smooth muscle that produces local movements of mucosa enhancing digestion and absorption

what important feature does the muscularis externa form?

sphincters that act as valves to control food passage from one organ to the next to prevent backflow

what does bilirubin break down to in the small intestine that gives feces its brown color

stercobilin

does protein inhibit or stimulate gastrin secretion?

stimulate

what do rectal valves do?

stop feces from being passed a long w gad

what is the gallbladders digestive function?

storage of bile

what are the 2 intrinsic nerve plexuses and what do they do?

submucosal nerve plexus (regulates glands and smooth muslce in mucosa) and myenteric nerve plexus (controls GI tract motility)

what is the pancreas digestive function?

supply the enzymes needed to digest chyme, as well as bicarbonate to neutralize stomach acid

digestive system

system that processes food into absorbable units and eliminates indigestible wastes

stomach definition

temporary reservoir in the gastrointestinal tract where chemical breakdown of proteins begins and food is converted into chyme

what unique 3 features does the large intestine have?

teniae coli, haustra, epipolic appendages

___________________: three bands of longitudinal smooth muscle in muscularis

tenisae coll

what part of MALT is attached to the cecum

the appendix

what does the termincal sulcus divide

the body (portion of the tongue that resides in oral cavity) and root (posterior third residing in oropharynx) of the tongue

what is the first part of the large intestine?

the cecum

alimentary canal -list the organs it includes

the continuous hollow tube extending from the mouth to the anus includes the oral cavity, pharynx, esophagus, stomach, and small/large intestines

where does the gallbaldder secrete bile into?

the cystic duct to the bile duct

where do the bile ducts and pancreatic duct fuse together in the duedenum?

the hepatopancreatic ampulla

what do chief cells produce?

the inactive form of pepsin called pepsinogen

what do the intrinsic muscles of the tongue do vs the extrinsic

the intrinsic muscles change the shape of the tongue while the extrinsic muscles alter the tongues position

what happens to people who eat lactose when they are lactose intolerant

the lactose will remain undigested and create an osmotic gradient in the intestine that prevents water from being absorbed causing diarrhea

what secures the tongue to the floor of the mouth and limits its posterior movements?

the lingual frenulum

what is the serous membrane lining the interior of the abdominal cavity and covering the surfaces of abdominal organs called?

the peritoneum

what is the gastrocolic reflex initiated by

the presence of food in the stomach

which digestive system activity moves nutrients from the outside to the inside of the body?

the process of absorption moves nutrients into the body

what is alkaline tide

the resulting increase of HCO3- in blood leaving the stomach

what is the usual site of ingestion?

the usual site of ingestion is the mouth

what is the serosa layer made of?

the visceral peritoneum -formed from areolar connective tissue covered with mesothelium

where are peyers patches more common at the distal end of the small intestine?

there are bigger numbers of bacteria there that must be prevented from entering into the blood stream

why is it important to keep your baby teeth healthy as well?

they act as place holders for permanent teeth

why are microvilli important to the small intestine?

they create a brush border that has a lot of enzymes which complete the digestion of carbohydrates and proteins in the small intestine

what is the function of the circular folds of the small intestine

to force chyme to spiral through the lumen, slowing its movement and allowing time for full nutrient absorption

during peritonitis why is it important that the peritoneal coverings stick together?

to localize the infection, providing time for macrophages to prevent inflammation from spreading

what is the function of the muscularis externa layer?

to produce segmentation and peristalsis

what is the main function of the endothelium layer of the mucosa

to produce slippery mucus that keeps the organs from being digested by enzymes

what are gallstone caused by? and what are its effects

too much cholesterol or too few bile salts -can obstruct flow of bile from gallbladder -obstructive jaundice: blockage can cause bile salts and pigments to build up in blood, returning jaundiced yellow skin

Eight to twelve large ________________ are located in a V-shaped row at the back of the tongue. They resemble the fungiform papillae but have an additional surrounding furrow.

vallate papillae

some intraperitoneal digestive organs are also suspended from the body wall by _________________

ventral mesentaries

the ______________ peritoneum covers the external surfaces of most digestive organs and is continuous with the ___________ peritoneum that lines the body wall

visceral; peritoneum

what regulates the absorption of Ca 2+

vitamin D and parathyroid hormone

what vitamins does the large intestine absorb?

vitamine K and B

what causes the defaction reflex?

when mass forces push feces into the rectum and the rectal wall expands

what stimulates the intestinal phase

when partially digested food enters the small intestine it causes the release of intestinal gastrin

what causes diverticula

when the diet lacks fiber and the volume of residues in the colon is small, the colon narrow and its contraction become more powerful, increasing the pressure on its walls