Ch. 23 The Digestive System

What are the characteristics of the Mucosa Lamina Propria?

2nd layer, layer of loose areolar connective tissue, directly below epithelium. Contains Vessels capillaries that deliver and collect nutrients. Contains immune cells.

(Foregut) What is the mechanical digestion of the stomach entail?

3 layers of smooth muscle in wall. Longitudinal, circular, and oblique. Causes churning and mixing, mixes food with gastric juices, produces chyme, a creamy paste that enters the small intestine.

(Head Gut) What is the composition of saliva?

99% water, Hypotonic and low electrolytes. Protective proteins, IGA and Lysozyme Digestive proteins: Mucin, protein that makes mucus, and lubricates. Alpha Amylase, breaks down carbohydrates, and lingual lipase breaks down fats.

What is bezoars?

A mass of indigestible material too big to pass through the pylorus. Can contain: Hair, Gum, Seeds, Plant fiber, and medications. Common in cud chewing animals, also found in humans.

(Digestive Process) What is Absorption?

After Mechanical, and chemical digestion absorption happens. Intake of nutrients, through the mucosal epithelium. Intestinal lumen goes through blood or lymph vessels to digest food molecule, vitamins, minerals and water.

What are the two classes of digestive organs in the Digestive system?

Alimentary Canal: The Gastrointestinal tract (GI Tract) Single, continous muscular tube that food passes through, lumen is contnious with outside space. Site of digestion and absorption. Accessory Organs: Connected to the alimentary canal, assist in digestive process.

(Head Gut) What is the oral cavity?

Anterior opening of the oral orifice, only site of ingestion. It is continuous posteriorly with oropharynx.

What are the Restroperitoneal Organs?

Attach directly to the abdominal wall, lost mesentery. Organs: Duodenum of Small intestine, liver, pancreas, ascending colon, descending colon.

(Hindgut Large Intestine) What are the characteristics of Vermiform appendix?

Attached to cecum, houses immune cells. Can fill with bacteria, that causes inflammation and swelling, cuts off blood supply (ischemia). Tissue dies and appendix bursts. Spraying abdominal cavity with bacteria.

What is The Vermiform of the large intestine?

Attaches to the cecum. Houses immune cells. Can fill with bacteria, to cause inflammation and swelling. Cuts off the blood supply, causing ischemia. Tissue dies and appendix bursts, spraying the abdominal cavity with bacteria.

What are the characteristics of Helicobacter pylori?

Bacteria capable of living in stomach - Burrow into mucus layer • Break it down - Neutralize HCl using ammonia produced by the enzyme urease (NH2)2CO +H2O CO2 + 2 NH3 - Ammonium is toxic to cells • NH3 + H+ NH4+ - H. pylori secrete other toxic substances as well

Where is Bilirubin found?

Bilirubin is a pigament found in bile. Left over pigment after iron is recycled from hemoglobin. Liver collects billirubin. Secretes bilirubin in bile. Metabolized by bacteria in small intestine. Into Stercobilin: Turns poop brown Into Urobilinogen: Reabsorbed and than excreted by the kidneys, turns urine yellow.

What is the functions of low pH in the stomach?

Breaks down organic material in plant cell walls, protein digestion begins in the stomach and activates pepsinogen. Kills ingested microorganisms, helps with iron absorption

(Hindgut Large Intestine) What are the characteristics of the Colon?

Bulk of the large intestine, accending, transverse, descending and sigmoid. Flexures are bends in the colon.

What are the two types of COX?

COX1: makes signals that promote mucus production and promote blood cloting. COX2: makes signals that cause pain, causes inflammation.

What are the regions of the large intestine?

Cecum Vermiform of the large intestine. Colon Rectum Anal Canal

(Hindgut Large Intestine) What are the 5 regions of the Large intestine?

Cecum, Vermiform appendix, Colon, Rectum and Anal canal.

(Midgut) What do Circular folds do?

Circular folds increase surface area. AKA Pliccae circulares. Large deep folds of the mucosa and submucosa. Each circular fold contain many villi.

(Hindgut Large Intestine) What are the functions of the large intestine?

Concencentrates indigestible material , absorbs water and electrolytes. Contains a large amount of normal microbiota, to digest remaining material, produce vitamins, and to release gas. Stores indigestible material until defecation, takes 12 hours to move waste through large intestine. Not necessary for life most of the nutrients have already been absorbed.

(hindgut) What are the functions of the large intestine?

Concentrates indigestible material; absorbs water and electrolytes. Contains a large amount of normal microbiota; to digest remaining material, produce vitamins, and release gas. Stores indigestible material until defecation. Takes 12 hours to move waste through the large intestine Not necessary for life, most of the nutrients have already been absorbed.

(Head Gut) What is the characteristics of Enamel?

Covers the entire crown, hardest substances in body, Cannot be replaced by the body, cells die after tooth erupts.

(Head Gut) What are the characteristics of Cementum?

Covers the entire root, calcified connective tissue, binds to periodantal ligaments, forming gomophosis.

What are Gallsontes?

Crystallized bile salts, can block ducts. Prevent release of bile because bilirubin accumulates and causes jaundice and feces to turn greay with white fatty streaks.

What do COX2 inhibitors do?

Cyclooxygenase (COX) is an enzyme that makes lipid signals, called eicosanoids they are made from arachidonic acid. There are two closely related versions of COX, isomers and COX1 and COX2

(Midgut) What is the structure of the pancreas?

Deep to greater curvature of stomach. Tadpole shaped. Head is nestled in curvature of duodemum. Tail touches spleen and pancreatic duct connects pancreas to duodenum.

What is the location and structure of the gallbladder?

Deep to right lobe of the liver. Thin green muscular sac (size of a kiwi). Connected to duodenum via bile duct, sphincter regulates opening of bile duct.

(Head Gut) What is in the Head Gut?

Digestive organs in the head. Oral cavity: Mouth Pharynx: Throat Accessory organs: Teeth and salivary glands.

(Head Gut) What is the functions of Saliva?

Dissolves food: Allows for tasting, Cleans mouth by innate immunity, Lubricates for swallowing, and begins chemical digestion, contains enzymes.

What is the Peritoneum?

Double layer serous membrane lining abdominal cavity. Contains two; Parietal Layer: Lines body wall Visceral Peritoneum: Lines Organs

(Head Gut) What is Xerostomia?

Dry mouth. Causes: Extreme activation of the SNS causing vasoconstriction that inhibits blood flow, so no liquid to make saliva from, and dehydration. Effects, increased cavities, difficulty talking and swallowing, slows food digestion causing Halitosis; bacteria grows on undissolved food.

(Midgut) How does food get moved through the small intestine?

During nutrient absorption, mostly segmentation, faster in the duodenum and ileum, it mixes chyme with digestive juices. After digestion: Peristalsis predominates as migrating motor complex (MMC) initiated in the duodenum every 90-120 mins. Pushes material toward the large intestine takes 2 hours to get to the ilium.

(Digestive Process) What is Defecation?

Eliminates indigestible substances, Feces.

Name two differences between enamel and dentin?

Enamel cannot be replaced by the body, it is the hardest substance in the body. Dentin can be made, and it is not as hard as enamel.

(Midgut) how does the small intestine do absorption of nutrients?

Enterocytes of brush boarder cells absorb nutrients. Cells containing microvilli lining the small intestine. Can only absorb the smallest nutrients the building blocks: Amino Acids, Monosaccharides, Fatty Acids, and nucleic acids. Nutrients enter apical side and leave basolateral side.

What are gastric ulcers?

Erosions of the stomach wall caused by loss of protective mucus, Gastric juices eat away at stomach wall Two factors that contribute to stomach ulcers: Helicobacter pylori & COX inhibitors

(Head Gut) What are the two types of salivary glands that produce saliva?

Extrinsic Salivary glands: Outside oral cavity, empty into oral cavity, produce most saliva main pairs. Buccal (Inrinsic) Salivary glands: Inside oral cavity mucosa, small.

True or False? The external nare is the only site of injestion?

False

(Midgut) How are Fats and Cholesterol processed?

Fats and Cholesterol have a lower density than proteins, as fat is used density increases because only proteins remain. VLDL: Very low density, full of fat. LDL: Low Density contain fat HDL: High Density mostly protein, good cholesterol.

(Midgut) How does Absorption of fats happen?

Fatty acids and cholesterol are packaged into chylomicrons, lipid and protein spheres after being passed from microvilli. Transferred to the lacteals for transport to blood. Special lymph vessels that carry fats.

Which Papillae do not function in taste?

Filiform

(Head Gut) What are the four different types of papillae?

Filiform Papillae: Appearance and location, is the smallest and most abundant, cover most of the anterior surface anterior surface, conical. Function: Roughen surface of tongue, contain (keratin; white), lick semisolids. Fungiform Papillae: Appearance and Location, Round like a mushroom, larger than filiform, and scattered throughout the anterior surface. Function: House of the taste buds. Vallate Papillae: Appearance and location, larges, V-shaped line of at back of tongue. "wall' between body and root of tongue. Function: Also house the taste buds. Foliate Papillae: Appearance and Location, ridges on lateral aspect of posterior tongue. Function: House taste buds, only used during infancy and early child hood.

(Head Gut) What is the characteristics of Dentin?

Forms the bulk of the tooth. Bone-Like material. Not as hard as enamel. New dentin can be made. Surrounds pulp cavity, contains soft tissue, with blood vessels and nerves .

What are the functions of Saliva? For each function name a substance present in saliva to accomplish that function.

Function of Saliva: Antimicrobial by Lysozyme, IGA, H2O(washing). , Dissolve for taste and chemical digestion by H20. Lubrication by Mucin and H20. and Chemical Digestion:Amylase and lingual lipase.

(Midgut) What are the functions of the small intestine?

Functions: All chemical digestion is completed, nutrients are absorbed and waste is pushed into large intestine. Divided into 3 sections: Duodenum, Jejunum, and Ileum

What is the Structure of the alimentary canal walls?

Has four layers, Mucosa, Submucosa, Muscularis Externa, and Serosa.

How are parietal cells regulated?

Histamine and acetylcholine increase the activity of parietal cells. H2 blockers antagonize histamine receptor, decrease acid production by pepsid and zantac. Proton pump inhibitors slow H+ release, like prilosec and prevacid

(Head Gut) What is the anatomy and function of the Lips?

Inferior boarder of the nose. Superior boarder of chin, red portion is translucent, no sweat or sebaceous glands. Contains the Superior and Inferior, anchors the lips to the gums. Lip Function: Manipulation of food, formation of suction.

What is the Location of the Liver?

Inferior to diapragm, occupies most of right hypochondriac and epigastric abdominal regions. Ducts connect the liver to the duodeneum. Common hepatic duct leads to bile duct.

(Midgut) How does the digestion work in the small intestine?

It primarily takes place in the duodenum, uses the enzymes from the pancreas (Lipase, amylase and proteases) liver and epithelial cells of small intestine, they brush the boarder cells. Brush boarder enzymes: Eneteropeptidase: Activates pancreatic proteases. Lactase, Maltase and trehalase for carbohydrate digestion.

(Hindgut Large Intestine) What is Haustra?

Large pouches along length of large intestine, formed by tone of teniae coli how poop gets its shape

(hindgut) What is the Haustra?

Large pouches along length of large intestine, formed by tone of teniae coli.

What are the characteristics of the anal canal in the large intestine?

Last segment in the large intestine. Anus; is the opening to the outside. Guarded by two anal sphincters: Internal with smooth muscle and Involuntary. External with skeletal muscle and are voluntary.

(Hindgut Large Intestine) what are the characteristics of the anal canal?

Last segment of the large intestine, contains the Anus: Opening to the outside, guarded by two anal sphincters: Internal: Smooth muscle and Involuntary External: Skeletal and Volunatry

What is Mesentery?

Layer of peritoneum attaching some organs to abdominal wall. Functions are to route the vessels and nerves, hold organs in place and stores fast.

What are the characteristics of the Mucosa epithelium?

Layer of simple columnar epithelium, contains goblet cells, unicellular exocrine glands that secrete mucus.

(Head Gut) What are the characteristics of the Lips and Cheeks?

Lines the oral cavity. Oral Cavity Proper: Space between teeth. Vestibule: Space between teeth and cheeks.

(Head Gut) What is the location and function of the Extrinsic Salivary gland, the paratoid gland?

Location: Anterior to the ear, superficial to masseter, and is the largest. Function: Produce water saliva, empties into vestibule near 2nd molar, swells when we have the mumps.

(Head Gut) What is the location and function of the extrinsic salivary gland, Sublingual gland?

Location: Anterior to the submandibular gland, smallest of the three. Function: Produces mostly sticky mucus. Empties via 10-12 ducts in floor of mouth.

(Head Gut) What is the location and function of the extrinsic salivary gland, the submandibular gland?

Location: Lies along body of mandible. Function: Produces watery saliva and mucus. Empties at base of the lingual frenulum.

(Forgut) What is the structure of the stomach?

Location: The upper right quadrant. Function: Distensible site of food storage, contain Rugae which is large folds in the stomach that allow it to stretch. 50 to 4000 mL. Mechanical Digestion: Makes Chyme Chemical Digestion: Begins protein digestion.

What are stem cells?

Location: Where gastric pit meets the gastric gland. Function: to Replace damaged epithelial cells, HCl and Pepsin. Surface of stomach is replaced every 3-6 days, cells in the gastric gland last longer.

(Foregut) What is the structure of the esophagus?

Long muscular tube, 1/3 Skeletal muscle, 1/3 Skeletal and smooth muscle, and 1/3 smooth muscle. Esophageal Sphincters, upper and lower, keeos stomach acid out of pharynx and keeps air out of stomach. Esophageal Hiatus: Gap in diaphragm where esophagus enters abdominal cavity.

(Hindgut Large Intestine) What is Teniae coli?

Longitudinal layer of muscularis reduced to three bands of smooth muscle.

(Hormonal control of the digestive process) What is Gastrin?

Made by Enteroendocrince calls in the pyloric region of the stomach, AKA G cells. Released in response to PROTEIN IN PYLORIC REGION Effect: Stimulates acid release, and stimulates gastric emptying.

(Hormonal control of the digestive process) What is Cholecystokinin (CCK)?

Made by I cells in the duodenum, released in response to proteins and fats in the small intestine. The effect is that the pancreas to secrete, the gallbladder to contract, and slows the stomach from emptying.

(Hormonal control of the digestive process) What is Motilin?

Made by M cells in the duodenal mucosa. Released in response to FASTING, the effect is it stimulates migrating mobility complex (MMCs) in proximal duodenum.

What are the characteristics of the Colon in the large intestine?

Makes up the bulk of the large intestine, made of the ascending colon, transverse, descending, sigmoid and the flexures are bends in the colon.

(Head Gut) What are the functions of the teeth?

Mechanical Digestion: Cut and tear apart big objects, sharp incisors and canines. Grinding and Smashing by flat pre-molars and molars. Mastication= Chewing, begins voluntarily, continues refluxively.

What are the following processes in order and the purpose of each?

Mechanical Digestion: Physical forces break food apart, prepares for chemical digestion, contains mastication and segmentation. Chemical Digestion: Uses Chemicals to breakdown (hydrolyze) macromolecules into subunits. Propulsion: Peristalsis Waves of coordinated smooth muscle contractions, propel food towards the anus. Absorption: Intake of nutrients throug the mucosal epithelium. Defecation: To eliminate indigestible substances, feces.

(Midgut) What are Microvilli?

Microvilli increases the surface area, they are projections of plasma membrane, microscopic villi that form the brush boarder.

What are the organs of the alimentary canal?

Mouth, Pharynx, Esophagus, stomach, small intestine, and large intestine. Entire canal is 30 ft. long

(Digestive Process) What is Propulsion?

Movement through the GI tract. Peristalsis: Waves of coordinated smooth muscle contractions. Propel food through the anus.

Which layer is closest to the alimentary lumen?

Mucosa

What lines the rest of the stomach surface?

Mucus cells line the rest of the stomach surface, they secrete mucus outer viscous mucus traps particles, inner alkaline mucus protects against stomach acid.

What is the Cecum?

Nestled in the right iliac fossa Below the ileocecal valve, its the entrance to the large intestine.

(Hindgut Large Intestine) What are the characteristics of the Cecum?

Nestled in the right iliac fossa, below the ileocecal valve, the entrance into the large intestine.

What are NSAIDs?

Nonsteroidal anti-inflammatory drugs, NSAIDs block COX 1 and COX 2 (nonspecific) like aspirin, Acetaminophen and Ibuprofen. Cause side effects as a result of COX1 inhibition, causes stomach ulcers.

(Foregut) What is Gastroesophageal reflux disease (GERD)?

Open lower esophageal sphincter allows reflux of acidic stomach contents. Causes inflammation of the esophagus. Extreme reflux causes Barrett's Disease. Hardening of the esophagus, cancer and bad breath.

Imagine you just ate a hamburger. Beginning with the oral cavity describe how your body digests this delicious snack?

Oral cavity: Injestion, Mechanical

What is the composition of the pancreatic Juice?

Pancreatic juice is hypotonic, comprosed of waater, electrolytes and digestive enzymes. Major electrolytes, bicarbonate made by using carbonic andydrase, alkaline (pH 8) and neutralizes HC.

(Midgut) What is Bariatric Surgery?

Performed to loose weight. Stomach is bypassed, so you must eat smaller meals. Duodenum is bypassed, less chemical digestion=less absorption. There are several types, varys in how much of GI tract is bypassed.

(Digestive Process) What is Mechanical Digestion?

Physical forces break food apart. Prepares food for chemical digestion. Chewing=Mastication Segmentation= Alternating contractions of nonadjacent segments, moves food forward and backward, and mixes food with digestive juices. Happens primarily in the stomach

(hindgut) What are epiploic appendages?

Pockets of fat hanging from surface, and the function is unknown.

(Hindgut Large Intestine) What are Epiploic appendages?

Pockets of fat hanging from the surface. FUNCTION UNKNOWN.

What are parietal cells?

Produce HCl, using carbonic anhydrase, mitochondria make the Co2, HCO3 goes into the blood in the Cl- shift, H+ is pumped into the stomach and the Cl- follows the H+. Has a large surface area, contain microvili, improves HCl secreation.

What are the digestive enzymes in pancreatic juice?

Protein chemical digestion: Proteases; Trypson, Carboxypeptidase and Chymotrypsin. Carbohydrate chemical digestion by Amaylase. Nucleic Acid, chemical digestion by nucleases. Fat and Chemical digestion uses lipases and phospholipases

(Hindgut Large Intestine) What are the characteristics of the Rectum?

Rectal Valves: Folds in mucosa, separates feces from flatulence. Can palpate abdominal organs through anterior rectal wall, rectal exam can feel prostate on males.

What are the characteristics of the Rectum in the large intestine?

Rectal valves, are folds in the mucosa, it separates feces from flatulence. Can palpate abdominal organs through anterior rectal wall (rectal exam)

(Foregut) What are Schatzki's rings?

Rings of fibrous connective tissue surrounding esophagus, prevents stretching when food bolus passes through. Bolus gets stuck. Inherited in families, most east small bites or food is regurgitated.

What accessory organs assist in digestion?

Salivary glands, teeth, tongue, gallbladder, liver, pancreas. Either they line the alimentary canal or are connected to it by a duct.

What are enterondocrine cells?

Secrete chemical signals to regulate digestion, paracrine signals such as histamine, and endocrine cells such as gastrin that regulates stomach secreations and motility.

What are chief cells?

Secrete pepsinogen, an inactive pepsin (enzyme) Activated to pepsin by low pH. Pepsin contain protease an enzyme that digests proteins. Functions only at low pH unusual for enzymes.

(Foregut) What is a sliding hiatal hernia?

Stomach is forced into the thoracic cavity, Common in late pregnancy. Lower esophageal sphincter raises above the diagram, so it cannot close well. Increases frequency of the reflux.

What are gastric glands?

Stomach mucosa is lined with gastric pits, invaginations of mucosa. Pits turn into gastric glands and secrete gastric juices. Specialized epithelial cells in gastric gland mucosa, contain cheif cells, parietal cells, enteroendocrine cells and stem cells.

What is the function of the gallbladder?

Stores and concentrates bile. Bile is 10X more concentrated than bile from the liver. Contracts to release bile when needed.

(Midgut) How does absorption happen in the small intestine?

Structure of small intestine wall is modified to increase surface area, to increase absorption. Ileum is the site of most absorption.

( Digestive Process)What is ingestion?

Taking in food into the digestive tract, via mouth.

What are second generation of COX2 inhibitors?

Target only COX2, like celebrex, Vioxx and Bextra. Fewer gastointestinal side effects, however increased risk of MI

What is the Muscularis Externa?

The 3rd layer of the alimentary wall. Layers of smooth muscle, inner circular layer and outer longitudinal layer. Responsible for big gut movements, Intrinsic myenteric nerve plexus, between circular and longitudinal layers.

(Foregut)What is the Structure and function of the stomach?

The Fundus: is the superior part of the stomach Cardia: is where food enters Pylorus: is where food exits through an opening regulated by pyloric sphincter.

What Accessory organs are connected to the duodenum? How does each one aid in digestion?

The Pancreas: The pancreas produces pancreatic juices, that neutralize HCl in the stomach and contain enzymes for chemical digestion of large food molecules. The liver: Produces bile, bile salts emulsify fats into small droplets. The Gallbladder: stores and concentrates bile, 10X more concentrated than bile from the liver.

What is the Mucosa?

The inner most layer of the alimentary canal. A mucous membrane with sublayers, contains Epithelium, Lamina propria, and muscularis mucosae. The functions are secretion: Mucus, enzymes, and hormones. Absorption of nutrients, protection from pathogens.

What does the liver do?

The liver produces bile, a yellow-Green alkaline solution. Contains pigments, bile salts, and phosphlipids. Biel salts emulsify fate breaks fats into smaller droplets, increases the surface area so more access for lipase. Unused salts are recycles and reabsorbed in ileum.

(hindgut) What is Teniae coli?

The longitudinal layer of muscularis reduced to three bands of smooth muscle, in the large intestine.

What is the Submucosa?

The middle layer of the alimentary wall. Moderately dense connective tissue. Contains blood, nerves, and lymphatic vessels. Stretch, contains elastic fibers. Regulates glands and muscularis mucosae. Intrinsic submucosal nerve plexus.

What is the Omentums?

The names given to specific areas of mesentery. Lesser Omentum: Extends from lesser curvature of stomach to liver. Greater omentum: Extends from greater curvature of stomach to small intestine

What is the Serosa?

The outer layer of the alimentary canal, AKA the visceral peritoneum. Protects and connects. Two layers: Inner; areolar connective tissue. Outer; simple squamous "Mesothelium".

What is the juice that the pancreas produces?

The pancreas produces pancreatic juice, it neutralizes from HCl from stomach. Contains enzymes for chemical digestion of large molecules like proteins, lipids, carbs and lipids, carbs and nucleic acids.

How are peristalsis and segmentation different?

The purpose of peristalsis is to move the food, and the purpose of segmentation is to break down the food

How are the four classes of papillae similar and how are the different?

They are all located on the tongue, Fungiform, Vallate, and Foliate papillae house the taste buds.

What are the Intraperitoneal Organs?

They are suspended from the abdominal wall by mesentery. Examples are: The stomach, 2 parts of small intestine the Jejunum and Ileum, the transverse colon, and sigmoid colon.

(Head Gut) What is the structure of teeth?

Three main parts of a tooth: Crown; exposed part of the tooth. Neck: Constriction connecting crown and root. Root: Portion embedded in jaw.

What is the function of the digestive system?

To break down food into molecules and to build fuel cells. Take in food, break down into small molecules, absorb the food molecules and expel undigested waste

(Head Gut) What is the Anatomy and Function of the tongue?

Tongue anatomy: Lines the floor of oral cavity, fills oral cavity in closed mouth. Anchored by lingual frenulum. Covered in papillae, bumpy projections on the tongue. Tongue functions: licking, tasting, and food bolus formation.

(Head Gut) What is bolus formation and deglutition?

Tongue mixes food with saliva and forms a bolus. Deglutition=swallowing phases Bucal Phase: Voluntary, tongue forces food though isthmus of the fauces. Pharyngeal-Esophageal phase: Involuntary, peristalsis pushes food toward the stomach.

(nervous control of the digestive system) What is defecation reflex?

Triggered by feces in the rectum. Effect is contraction of sigmoidal colon and rectum. Opening of internal anal sphincter, and closing of exterior anal sphincter until we voluntarily open it.

(nervous control of the digestive system) What is sampling reflex?

Triggered by flatulence and feces in the rectum. The effect is internal anal sphincter relaxes, and allows for passage of gas but not feces. Occurs 4x per hour in healthy adults, increased frequency after eating prior to defecation.

(nervous control of the digestive system) What is ileal break?

Triggered by high nutrient content in the ileum. The effect is it slows contractions in the stomach, duodenum, jejunm and ileum. Triggers feelings of satiety in the CNS.

(nervous control of the digestive system) What is Gastrocolic reflex?

Triggered by nutrients in the stomach and small intestine. The effect is increased large intestine mobility and signal travels via the vagus nerve.

T or F? The lumen of the alimentary canal is contnous with outside enviroment?

True

(Digestive Process) What is Chemical Digestion?

Uses chemicals to break down macromolecules, to break down into small molecules. Nonspecific Chemicals: Attacks all kinds of organic food molecules, example is stomach acid. Specific Chemicals: Attach a specific type of organic molecule. Example: Enzymes. Starch molecule will break down sugar molecules into small bonds. Called Hydrolysis.

Which of the following chlomicrons contains the most lipid and cholesterol?

VLDL

What are the characteristics of the Mucosa Muscularis mucosae?

Very thin layer of smooth muscle external to lamina propria, responsible for small local movements.

(Midgut) What do Villi do?

Villi increase the surface area of the small intestine as well. Small folds of mucosa, mm high, gives the small intestine velvety appearance. Contains capillary beds and lacteals at their core, every cell lining the villi contains microvilli in their plasma membrane.

(Foregut) What is Peristalsis in the stomach?

Waves of peristalsis push food toward the pylorus, 3 times per minute controlled by interstitial cells of cajal (pacemaker cells) Grinding occurs near pylorus, pyloric muscle is thicker, for stronger contractions more mixing with gastric juices makes more chyme. Retropulsion: most chyme smashes into wall, pushed back into the stomach for further grinding. Smallest particles squirt into duodenum through partially open pyloric valve

(Head Gut) Control of saliva production?

We make 1L of saliva a day, parasympathetic nervous system activates parotid glands. Factors that increase saliva production: Sensory input, chemoreceptors in mouth, and mechanoreceptors in mouth, to sense pressure.