A&P2: Gastro Flashcards
Define Metabolism?
Use of nutrients gained from food to build, maintain and provide energy
Interactive set of chemical pathways to make life possible
After food is digested, molecules are placed into which part of the circulatory system?
Portal vascular system
Define assimilation
When nutrient molecules enter cells and undergo chemical changes
How is thermal heat released into the body and for what purpose?
Frequent, small bursts
Homeostatic body temps
What has to happen to chemical energy before it can be used?
Transferred into ATP
What is the difference between Micro and Macro nutrients and their ability to be absorbed?
Micro- absorbed in original form
Macro- need to be catabolized into smaller forms
What is the largest size a protein can be and still be absorbed?
AAs
Dipeptide
Tripeptides
All can be absorbed as is
What length/form do carbohydrates need to be in order to be absorbed?
Monosaccharide
Glucose, fructose, galactose
What form/length do lipids need to be in order to be absorbed?
Fatty acids
Monoglycerides
What are examples of Micronutrients?
Vitamins
Minerals
Needed in SMALL quantities
How many essential micronutrients are there?
28
What is the major source of biological energy used by organisms?
Carbs
Carbohydrates come in what 3 forms?
Mono
Di
Poly
Digestion of carbohydrates requires what type of enzymes?
Amylases
What is the absorbable form of carbohydrates?
Monosaccharides
Glucose
Fructose
Galactose
What are the nonabsorbable forms of disaccharides?
Sucrose- glucose + fructose
Lactose- Glucose + galactose
Maltose
Which disaccharide is a byproduct of starch digestion?
Maltose
What are the polysaccharide forms that are unable to be absorbed as is?
Starches
Glycogen
Cellulose
What combines to make starches?
Amylose + amylopectin
Where is glycogen placed for storage?
Liver
Muscles
Glial cells of brain
What is the chemical name for fiber?
Cellulose
Carbs can be classified within the diet under what two categories?
Simple- mono and disaccharides
Complex- polysaccharides
What is the most common form of lipid found in the diet and in the body?
Triglycerides (TAGs)
Define TAGs
High energy nutrient synthesized and stored in adipocytes and hepatocytes
TAGs are required in the body for absorption of ____?
Fat soluble vitamins
What provides constituent molecules for cellular membranes?
TAGs
What are the simple lipids?
Fatty acids: Sat/unsat/triacyglycerols
What compounds can join triacyglycerols to make compound lipids?
Phopholipds- FA+phosphorus+N
Glycolipids- FA+carbs+N
Lipoproteins
Where are functions of compound lipids?
Cell membrane
Nerve sheath
Helps w/ cellular recognition
Where are glycolipids found?
Cell membrane
Facilitate cell recognition
What are the types of Lipoproteins?
Chylomicrons
VLDL
LDL
HDL
Define Derived Lipid
Simple+compound lipid
What are examples of derived lipids?
Steroids- especially cholesterol
Terpenes
Fat soluble vitamins
Ketone bodies
Where are derived lipids synthesized?
Liver
Almost all cells including endothelial
What are the functions of Derived Lipids?
Plasma membranes
Vit D synthesis precursor
Androgen/sex hormone synth
In order to be absorbed at a cellular level, what has to happen to triglycerides first?
Hydrolyzed into FA/Monoglycerides by lipase enzymes
How are lipids transported?
Chylomicrons VLDL LDL HDL FFAs
During _____ state, blood can have so many chylomicrons that it can appear what color?
Absorbed
Turbid, yellow
During what state are chylomicrons going to be low or nonexistent?
Post-absorptive
What state are lipoproteins going to be most active?
Post-absorptive
Where are lipoproteins made?
What are they made from?
Liver
Lipids and proteins
What combine to make free fatty acids?
FA + albumin
During starvation state, what will free FA levels be?
Increased due to fat-catabolism
What is the largest/lowest density lipoprotein?
What is the smallest/heaviest density lipoprotein?
Largest- Chylomicron VLDL IDL (intermediate) LDL Smallest- HDL
Where are chylomicrons synthesized?
What is used to make them?
Enterocytes of small intestines
Fat and cholesterol from small intestine
How are chylomicrons transported so they can enter circulation?
Enter lacteals (lymphatic capillaries) -> thoracic duct -> circulation
Where are VLDLs synthesized?
What is used to make them?
Liver
Fats and cholesterol from portal circulation
How are LDLs made?
VLDLs are stripped of triglycerides, leftovers are remodeled into LDLs
What is the function of HDLs?
Reverse cholesterol transport, returns excess cholesterol to liver for recycling
Where are HDLs made?
Liver
Small Intestine
LIpogenesis/anabolism includes the formation of what lipids?
Triglycerides
Phospholipids
Cholesterol
Prostaglandins
What word means protein hydrolysis?
Proteases- pepsin, trypsin
20 total aa, of these there are _ essential, _ conditionally essential and _non-essential
9 essential
7 conditional- illness/inc stress
4 nonessential
Every cell synthesizes its own _____ proteins
Structural
Digestive system is closely associated with what other system? Why?
Cardiovascular
Due to vessels involved in digestive process
How does the Cardiovascular System impact the digestive system?
Supply organ with O2
Processes nutrients
How does the Endocrine System impact the digestive system?
Hormone regulate digestive system actions
How does the Integumentary System impact the digestive system?
Protects digestive organs
Vit D absorption
How does the Lymphatic System impact the digestive system?
MALT defense against pathogens
Lacteals absorb lipids
How does the Nervous System impact the digestive system?
Sensory/motor neurons regulate secretions and GI tract contractions
How does the Respiratory System impact the digestive system?
Provides O2
Removes CO2
How does the Urinary System impact the digestive system?
Kidneys make calcitriol to aid w/ Ca+ absorption
How long is the GI tract in humans?
16-23 alive
23-29 dead
What are the accessory digestive organs?
Teeth Tongue Salivary Glands Liver Gallbladder Pancreas
What are the 6 processes of the digestive system?
Ingestion Secretion Mixing/propulsion Digestion Absorption Defecation
Define motility
Mix and movement of material along tract
What are examples of substances that can be absorbed w/out chemical digestions?
Vitamins
Ions
Essential FA
Water
What are the 4 layers of the GI tract?
Outer to Inner Serosa/Adventitia Muscularis Submucosa Mucosa
Adventitia layer of the GI tract starts and ends where?
Esophagus through proximal duodenum
What are the layers of the GI tract’s muscularis layer?
2-3 layers of smooth muscle
What structures are found in the GI tract’s submucosa layer?
CT
Glands
Vessels
Nerves
What are the layers of the GI tract’s mucosa layer?
Epithelium
Lamina propria
Muscularis mucosa
The serosa layer of the GI tract is AKA ?
Visceral periotneum
What parts of the GI tract’s muscularis layer is skeletal and smooth muscle?
Skeletal- mouth, pharynx, upper esophagus, external anal sphincter
Smooth- everywhere else
Where is the Myenteric Plexus located?
What is it AKA ?
Between circular and longitudinal muscle layers
Plexus of Auerbach
Where is the Submucosal Plexus located?
What is it AKA?
Submucosa layer of GI tract
Plexus of Meissner
What layer of the GI tract has the nerves and vessels?
Submucosa layer
The inner, mucosa layer of the GI tract is composed of that 3 layers?
Muscularis mucosae
Lamina Propria
Epithelium
What layer of the GI tract five the small intestine and stomach the folded appearance?
Mucosa, muscularis mucosae layer
Muscular movement within what layer of the GI tract ensured the absorption cells are fully exposed to the GI tract contents?
Mucosa muscularis mucosae
What layer of the GI tract contains the MALT defenses?
Lamina propria
Where is MALT tissue present in the GI tract?
Tonsils
Small intestine
Appendix
Large intestine
What layer of the GI tract is thicker and provides the tract protection from scraping/damage of passing contents?
Mucosa layer
What are the functions of the exocrine and enteroendocrine cells in the mucosa layer?
Exo- mucus/fluid/enzyme secretion
Entero- secrete hormones
What part of the NS innervates the GI tract?
Regulated by intrinsic (enteric NS) and extrinsic (ANS)
What is considered the “brain” of the guy?
Enteric NS
Where does the enteric NS exist in the GI tract?
Mouth to anus
The enteric NS is broken up into what two parts within the GI tract?
Both branches are composed of what structures?
Myenteric Plexus (Auerbach)- muscularis Submucosal Plexus (Meissner)- submucosa
Neurons, interneurons, sensory neurons
What is the function of the Myenteric plexus?
What is the function of the Submucosal plexus?
M= motor impulses to longitudinal/circular muscles of muscularis layer, GI tract motility (frequency/strength) S= secretory cells of mucosal epithelium
What structure connects the myenteric and submucosal plexuses?
Inerneurons
Sensory neurons supply which layer of the GI tract?
Some sensory neurons also act as what other function?
Mucosal epithelium
Chemo/baroreceptors
What is the Sympathetic NS and vagus nerve impact on the cardiovascular and GI system?
NS= Secretes NorEpi activating adrenergic receptors, stims cardiac activity; inhibits GI activity Vagus= secrete ACh activating cholinergic receptors, inihib cardiac and stim GI tract
What CN regulates the enteric NS?
CN10- supplies parasympathetic nerves to most of GI tract
Stimulation of the parasympathetic nerves that innervate the GI tract causes what result?
Increased GI secretions and motility by increasing enteric NS activity
How does the sympathetic nerves supplying the GI tract arise and connect?
From thoracic and lumbar regions of spinal cord
Stimulation of the sympathetic nerves in the GI tract causes what result?
Decreased GI secretion/motility by inhibiting enteric NS
What is the largest serous membrane in the body?
Peritoneum
What is the peritoneum divided into?
Parietal- wall of abdominopelvic cavity
Visceral- covers some of the organs
What is the space in between the two peritoneum layers called?
Peritoneal cavity, contains lubricating fluids
Organs in the retroperitoneal space are covered by the peritoneum on what surface?
What organs does this include?
Anterior Kidneys Ascending/Descending Colon Duodenum Pancreas
What are the 5 folds of the peritoneum?
Greater omentum Falciform ligament Lesser omentum Mesentery Mesocolon
What is the largest peritoneal fold?
What organs does it cover?
Where does it travel to/through?
Greater omentum
Transverse colon and small intestine
Attaches stomach and duodenum, anterior to small intestine, folds, extends to attachment on transverse colon
What part/fold of the peritoneum is a contributor to the term “beer belly”?
Greater Omentum
What part of the GI tract contains many lymph nodes that have macrophages and antibody producing cells to combat GI tract infections?
Greater omentum
The greater omentum is AKA what ligament?
Gastrocolic
What is the falciform ligaments function?
Attaches liver to ventral surface of abdominal wall
What does the free border of the falciform ligament contain?
Ligamentum teres (round ligament), remnant of umbilical vein
Where does the lesser omentum arise from?
What does is cover/hold?
Anterior fold of serosa of stomach/distal duadenum and connect to liver
What pathway for vessels entering the liver pass through which part of the peritoneum?
What vascular structures does this sight contain?
Lesser omentum Portal vein Common hepatic artery Common bile duct Lymph nodes
What part of the peritoneum has a fan-shaped fold?
What organs does this part hold?
Mesentery
Jejunum and ileum to posterior wall
What two folds of the peritoneum add to abdominal growth during weight gain?
Mesentery
Greater omentum
Where does the mesentery fold start and end?
Posterior peritoneal wall (same as mesocolon), wraps around small intestine, returns to origin
What is the function of the mesocolon?
Two-part fold that holds transverse and sigmoid colon to posterior wall
What two folds holds the small intestines in place?
Mesocolon
Mesentery
What are the two frenula in the mouth?
Labial- mandible and maxillary
Lingual
What two structures form the hard palate in the mouth?
Palatine and maxillae
What is the soft palate in between?
Oropharynx
Nasopharynx
What is the function of the uvula?
Rises w/ soft palate to close off nasopharynx
What are the two muscular folds that run laterally along the uvula?
Palatoglossal arch- anterior, to base of tongue
Pataopharyngeal- posterior, side of pharynx
What are the different pairs of tonsils?
Palatine- between arches, most commonly infected/removed
Lingual- singular, base of tongue
Pharyngeal- aka adenoids, superior nasopharynx, commonly removed w/ palatine
What are the major glands that secrete most of the saliva?
Parotids
Submandibular
Sublingual
Where are Parotid glands located and what duct do they secrete through?
Inf/Ant to ears between skin and masseter muscle
Secrete via Parotid Duct (Stenson’s Duct) to opposite second maxillary molar
What salivary gland pierces the buccinator muscle?
Parotid gland
Where are Submandibular glands located and what duct do they secrete through?
Floor of mouth, medial and inferior to mandible body
Submandibular glands open on side of lingual frenulum via Whartons Ducts
Where are Sublingual glands located and what duct do they secrete through?
Beneath tongue superior to submandibular glands
Lesser sublingual ducts open to floor of mouth lateral to opening of submandibular ducts
Chemically, saliva is __% water and _% solutes
What solutes are found here?
99.5 water .5 solutes
Na K Cl HCO3 HPO4
IgA, lysozyme and salivary amylase
What type of saliva do the salivary glands secrete?
Parotid- water
Submandibular- serous and mucous
Sublingual- thicker fluid w/ small amount of salivary amylase
Water in saliva serves what 3 purposes?
Medium for dissolving
Taste
Digestive reactions to begin
Salivary amylase begins the digestion process of what part of food?
What activated salivary amylase to start this process?
Carbs
Cl-
What two substances help buffer acidity in the mouth?
Bicarb and Phosphate
Makes saliva slightly acidic at 6.35-6.85
What are the chemical waste products that are secreted/excreted into saliva?
Urea
Uric acid
Salivation reflex is controlled by what NS?
Signals to promote are sent along what CNs?
ANS
Parasympathetic keeps continuous secretion
CN7 and 9
Define xerostomia
Dry mouth due to stimulation of Symp NS during stress
What divides the tongue in half?
Median septum
How is the tongue attached to the skull?
Hyoid bone
Styloid process of temporal bone
Mandible
What are Von Ebners glands and where are they located?
Lingual glands in lamina propria of the tongue that secrete serous fluid with lingual lipase (acts on triglycerides)
What surfaces of the tongue contain papillae?
Dorsal and lateral surfaces
What are the 4 types of papillae?
Vallate (circumvallate)- inverted V in posterior tongue
Fungiform- mushroom shaped
Foliate- lateral margins, degenerate in childhood
Filiform- entire surface of tongue, no taste, tactile only
What are two enzymes that contribute to chemical digestion by secretion in the mouth?
Salivary amylase- carbs
Lingual lipase- lipids
Where is salivary amylase de/activated?
Where is lingual lipase activated?
SA- Cl in mouth activate, stomach acid deactivates
LL- activated by stomach acid
What is the first anatomical area a bolus passes after chewing?
Pharynx
Oropharynx then laryngopharynx
Where does the pharynx start and end?
Internal nares to posterior esophagus/anterior larynx
What are the 3 parts of the pharynx?
Nasopharynx- only respiration
Oropharynx- digestion and respiration
Hypo/laryngopharynx- digestion and respiration
Where does the esophagus begin and end?
Start- inferior end of hypo-laryngopharynx
End- superior stomach
What are the layers of the esophagus?
Adventitia Muscularis Submucosa Mucosa- muscularis mucosae lamina propria nonkeratinized
What are the two sphincters of the esophagus?
Upper- skeletal muscle regulating movement from hypopharynx to esophagus
Lower- smooth muscle regulating movement from esophagus to stomach
What are 2 functions the esophagus does and does not do?
Does- secrete mucus and transport food
Not- produce enzymes, absorb
What are the three phases of deglutition?
Voluntary
Pharyngeal
Esophageal
What occurs during the Voluntary Stage of swallowing?
Starts when bolus is force to back of oral cavity
Up/backward movement of tongue moves bolus to oropharynx
What occurs during the Pharyngeal Stage of swallowing?
Bolus passes into oropharynx and laryngopharynx and into esophagus
Bolus triggers receptors to send signals to deglutition center in medulla oblongata and lower pons
Signals cause soft palate/uvula to close nasopharynx and epiglottis to cover trachea
Once bolus is through laryngopharynx esophageal sphincter relaxes
What events occur during the Esophageal Phase of swallowing?
Begins once bolus is in esophagus
Peristalsis takes over and allows lower sphincter to relax
Why is the stomach the most distensible part of the GI tract?
Mucosa lies in rugae
What are the 4 regions of the stomach?
Cardia
Fundus
Body
Pyloric
What are the three parts of the pyloric part of the stomach?
Pyloric antrum- connects to stomach body
Pyloric canal- leads to pylorus
Pylorus- connects to duodenum via sphincter
What are the 4 layers of the stomach?
Serosa
Muscularis- 3 layers of smooth
Submucosa
Mucosa- gastric and exocrine glands, enteroendocrine cell
What are the two parts of the stomach serosa?
Greater curvature continues as greater omentum
Lesser curvature continues as lesser omentum
What layer of the stomach has Mysenteric and Submucosal plexuses?
Muscularis- Auerbach/myenteric plexus
Submucosa- Meissner/submucosal plexus
What part of the stomach are gastric glands located?
Mucosa layer of mucosal layer (inner layer)
Gastric glands contain what three types of exocrine glands?
Mucous neck cells
Chief cells
Parietal cells
(All within the mucosa layer of the mucosal layer)
Gastric glands also contain what enteroendocrine cells?
G-cell and Enterchromaffin-like cells- secrete hormone into bloodstream
What activates lingual lipase?
HCl
What does intrinsic factor do within the digestive system?
Aid w/ absorption of B12/cyanobalamin
What are the enteroendocrine cells within the digestive system?
G-Cells- secrete gastrin to bloodstream
Enterochromaffin-like cells- secrete histamine
Where are G Cells located?
Pyloric antrum
What does release of Gastrin into the bloodstream stimulate?
HCl production (with histamine)
Gastric motility
Chief cells to produce pepsin
What activates parietal cells to produce HCl?
Histamine
What is the function of the mixing waves?
Peristaltic waves that aid with macerating food
At this point, chyme
Define Gastric emptying
3mL of chyme ejected to small intestine w/ each mixing wave
What is the only proteolytic (protein digesting) enzyme in stomach?
Pepsin
Where is Pepsin made?
What kind of environment is it most effective in?
Prepared as pepsinogen in Chief Cells
HCl/pepsin activates pepsinogen in lumen
Most efficient in acidic environment
What prevents pepsin from digesting proteins found in the stomach’s epithelial cells?
Alkaline mucous layer
When is Gastric Lipase released?
What does it digest?
Very small quantities, usually during pancreatic insufficiency
Triglycerides
Where does the majority of the digestion of lipids occur?
Small intestine from pancreatic juies
What can be absorbed in the stomach?
Water Ions Short chained FA Some drugs ETOH
What molecules spend the least and most time in the stomach?
Carbs- least
Protein- longer
Fat- longest
Where is the pancreas located?
Retroperitoneal, behind great curvature
What are the two functions of the pancreas?
Exocrine- Acini, clusters of glandular cells producing enzymes/fluids
Endocrine- Pancreatic islets, hormones
What is the primary duct in the pancreas?
What other duct does it merge with?
What duct does this merger form?
What sphincter controls the merger duct?
Duct of Wirsung
Merges w/ Common Bile Duct
Hepatopancreatic ampulla (Ampulla of Vater)
Controlled by Sphincter of Oddi
What is the accessory duct of the pancreas?
Duct of Santorini
Branches off of pancreatic duct, drains to duodenum proximally to ampulla of vater
What is the sequence of ducts from the liver?
Hepatic ducts-> common hepatic duct
Common hepatic + cystic duct= common bile duct
Common bile + pancreatic duct= hepatopancreatic ampulla
Hepatopancreatic ampulla drains into duodenum @ major juodenal papilla
Accessory pancreatic duct empties pancreatic secretion into duodenum @ minor duodenal papilla
What causes pancreatic juices to be slightly alkaline?
Sodium Bicarbonate
pH 7.1-8.2
What stops the action of pepsin leaving the stomach?
Sodium Bicarbonate
What enzymes and their digestive functions are in pancreatic juice?
Trypsin- protein
Chymotrypsin- protein
Carboxypeptidase- protein
Elastase- protein
Pancreatic amylase- carbs
Pancreatic lipase- principle triglyceride
Phospholipase- phospholipid
Cholesterol esterase- cholesterol
_____ digesting enzymes are produced in zymogenic form
Protein digesting Trypsinogen Chymotrypsinogen Procarboxypeptidase Prolastase
Liver is located in which abdominal quadrants?
R hypochondriac
Part of epigastric region
What part of the peritoneum covers the liver?
Visceral
What ligament divides the liver into lobes?
Falciform ligament
Liver receives blood from what two sources?
Hepatic artery Portal vein (majority 75%)
What are the components of the Biliary Tree?
Bile ducts in liver Common hepatic duct Gallbladder and cystic duct Common bile duct Pancreatic ducts
What are the functions of the biliary tree?
Make/store/secrete bile and pancreatic enzymes
Rids body of waste products
Aids small intestine w/ digestion
What is the major functional unit of the liver?
Hepatic lobule
What and where are Portal Triads?
Corners of hepatic lobules
Consists of bile duct, portal vein and hepatic artery
What type of cell makes up 80% of the liver’s mass?
Why are their abundance so important?
Hepatocytes
Form layer that separates sinusoidal blood from canalicular bile
Hepatocytes are the location of synthesis of what things?
Transport proteins (albumin, fibrinogen) Lipoproteins FAs Triglycerides Cholesterol Bile
Location and function of hepatic sinusoids
Permeable capillaries between hepatocytes
Receive oxygenated blood from hepatic artery and nutrient deoxygenated blood from portal vein
What is the location and function of Stellate Reticuloendothelial cells?
Kupffer cells
Phagocytes w/in liver sinusoids that destroy R/WBCs, bacteria and debris
What are the functions of the liver?
Carbohydrate/lipid metabolism Protein synthesis Drug/hormone processing Bilirubin excretion Storage of glycogen/ADEKs Phagocytosis Bile synthesis
What liver function occurs when plasma glucose is low? When it’s high?
Low= glycogenolysis High= glycogenesis
What type of lipid synthesis occurs in the liver?
Triglycerides
Lipoproteins
Cholesterol
What transport proteins are synthesized in the liver?
Haptoglubin IGF binding Sex-hormone binding Thyroxin binding Transferrin Vi-D binding
Which hormones does the liver alter/deactivate?
Thyroid/steroid like T3/T4, estrogen, aldosterone
Where is a majority of the bilirubin in bile metabolized and eliminated?
Metabolized in small intestine
Eliminated w/ feces
What minerals does the liver store?
Fe
Cu
Bile synthesis in the liver is the combination of what 3 things?
Bile salts
Bile pigments
Cholesterol
Amount, color and pH of normal bile?
600-1000mL/day
Yellow/brown/olive green
7.6-8.6
What is the importance of bile?
Fat digestion and absorption
Means for excretion of waste products from blood
What can the gallbladder walls reabsorb?
Water
Ions
Spleen acts as a large reservoir of what WBC?
Macrophage
Hematopoiesis of the spleen includes?
Mono/lymphocyte development and activation
Fetal RBC development
Adult RBC development during extreme anemia
What cells does the spleen remove from circulation?
Old RBCs
Imperfect platelets
Breaks apart Hgb molecule to save iron and globin
Where does the small intestine begin and end?
Start- after pyloric sphincter
End- ileocecal sphincter
What are the 3 regions of the small intestine?
Duodenum- shortest
Jejunum
Ileum- longest
What valve merges the small and large intestine?
Ileocecal Sphincter
What is the Ligament of Treitz and what is it’s function?
AKA Suspensory Ligament of Duodenum
Suspensory muscle
Begins at diaphragm, connects to duodenojejunal flexure and suspends it upward
Landmark of importance, anatomical difference between Upper and Lower GI
All of the small intestine is covered by the serosa (visceral peritoneum) except for where?
Proximal portion
Muscularis layer of the small intestine contains which plexus?
Myenteric (Auerbach)
Submucosa layer of the small intestines contain which plexus and glands?
Submucosal (Meissner)
Brunner’s glands- alkaline mucus secretors
What and where are Crypts of Lieberkuhn?
AKA for intestinal glands
Deep crevices in mucosal lining of small intestine
What are the miscellaneous cells within the mucosa layer of the Small Intestine?
Absorptive- enterocytes, absorb nutrients from chyme
Goblet- secrete mucus
Paneth- secrete lysozomes capable of phagocytosis
What are the enteroendocrine cells of the small intestine?
S cells
CCK cells
K cells
What do the S cells in the small intestine do?
Secrete secretin
Stims pancreatic juice/inhibs gastric juice
What do CCK cells do in the small intestine?
Secrete cholecystokinin
Helps satiety
Stims pancreatic juice flow Relaxes sphincter of Oddi
Stims gallbladder contraction
What do K cells in the small intestine do?
Secrete glucose dependent insulinotropic polypeptide
AKA gastric inhib polypeptide
Dec gastric emptying rate
Define Plicae Circulares and where are they located
Circular folds in the small intestine
Permanent ridges beginning near proximal duodenum, ending midpoint of ileum
Increases SA and causes chyme to spiral
What are the special features of the small intestine?
Plicae circulares
Villi
Microvilli
What structures within the small intestine give the walls of the lumen a velvet appearance?
Villi
What makes the brush border of the small intestine?
Microvilli- projections of apical membrane of absorptive cells
What special features of the small intestine also produces digestive enzymes?
What are these enzymes called?
Microvilli
Brush-border enzymes
What are the brush border enzymes and what do they digest?
Carbs- a-dextrinase maltase sucrase lactase
Peptidases-
aminopeptidase
dipeptidase
Lipase-
phospholipase b1
How are carbs digested in the small intestine?
Pancreatic amylase
Once split into monosaccharides they are absorbable
Pancreatic amylase can not digest what carbohydrate which causes a large bulking of feces?
Cellulose
Which pancreatic juices perform protein digestion in the small intestine?
When is protein digestion considered complete?
Trypsin Chymotrypsin Carboxypeptidase Elastase Ends w/ small/single chained AAs
What pancreatic juices complete lipid digestion in the small intestine?
Lipase- begins in stomach
Pancreatic lipase- continues in small intestine
What are the overall functions of the large intestine?
Complete absorption
Produce Vit K and biotin
Form feces
Excrete solid wastes
What are the 4 regions of the large intestine?
Extending from ileum to anus: Cecum Colon (Ascend/transverse/descend/sigmoid) Rectum Anal canal
How is the large intestine held to the posterior abdominal wall?
Mesocolon fold
What is the sphincter between the small and large intestine?
Ileocecal
Where does the cecum of the large intestine begin?
Inferior to ileocecal valce
Where is the vermiform appendix attached to on the large intestine?
Cecum
What are the 4 portions of the colon?
Ascending- R side to border of liver, turns at hepatic flexure
Transverse- turns inferior at splenic flexure
Descending- L side to iliac crest
Sigmoid- projects medially, ends at rectum
What parts of the colon are peritoneal and retroperitoneal?
Retro: ascending, descending
Peri: transverse, peritoneal
Rectum is at what vertebral level?
3rd sacral vertebrae
Mucus membranes of the anal canal are arranged into folds called?
What do the formations contain?
Longitudinal folds called columns
Contain arteries and veins
What are the two sphincters of the anal canal?
Internal: smooth/involuntary
External: skeletal/voluntary
Define Pectinate (dentate) Line
Inferior portion of anal column
Above the line= upper 2/3, only sensitive to stretch
Below the line= lower 1/3, sensitive to pain, temp and touch
What does the serosa layer of the large intestine contain?
Omental appendices
What are the thickened bands on the large intestine called?
What layer do they occupy?
Teniae coli
Muscularis
What is the function of teniae coli?
Contract to form haustra= puckered/pouched appearance
What is the difference between the external and internal layer of the large intestines muscularis layer?
External= longitudinal smooth muscle Internal= circular smooth muscle
How is digestion accomplished in the small intestine?
What is secreted here?
Symbiotic bacteria
Mucus
What gases are produced in the large intestine?
H, CO2, methane= gas
Indole, skatole, H2S= odor
How does feces accomplish it’s normal brown color?
Bacteria breakdown of bilirubin to stercobilin
Chemically speaking, what does feces contain?
Water
Epithelial cells
Bacteria/decomposition
Unabsorbed/indigestible material
What are the two types of movement that occur in the GI tract?
Peristalsis- wavelike ripple triggered by bolus stretch
Segmentation- mixing, forward/backward movement, aids w/ mechanical digestion
How is gastric emptying regulated?
Hormonal
NS- enterogastric reflex
What causes GDIP to be released?
Fats/nutrients in duodenum
Inhibits gastric muscle, decreases peristalsis and slows gastric emptying
What stimulates/triggers the enterogastric reflex?
Chem/baroreceptors in duodenum
Inhibits gastric peristalsis, slows gastric emptying
What are the different types of motility that occur within the GI tract?
Gastric motility
Intestinal motility
Reflexes
What are the two types of intestinal motility?
Peristalsis
Segmentation
What are the motility reflexes?
Gastroileal
Enterogastric
Gastrocolic
Defecation
Define the Gastroileal Reflex
Secretory and motor activity of stomach signals distal ileum early in meal, accelerates movement through ileocecal sphincter
Define the Enterogastric Reflex
Small and large intestine distension inhibit stomach motility and secretion
Define the Gastrocolic Reflex
Excess stomach activity causes feces in colon to move forward
Define the Defecation Reflex
Distension of rectum trigger baroreceptors that signal colon and anal canal to contract
What are the pressures needed during the defecation triggering process?
18mmHg- conscious desire
55mmHg- internal sphincter relaxes, external sphincter held tight consciously
80mmHg- external sphincter may fail
“Normal” bowel movement frequency and influencing factors
Diet Health Stress
1-3/day
3-4/week