Digestive system

Describe the anabolic and catabolic processes of protein metabolism (e.g., deamination, transamination) and how these processes interact with carbohydrate metabolism

When amino acids are degraded, the first thing that happens to them is deamination: we remove the amine group of the amino acid and amine group will enter the urea cycle. So from the amine group, we are creating urea. The remaining components will be burnt to provide ATP: cellular respiration. The urea is released in the blood and transported to the kidney for excretion. But the amino acids don't have to be degraded or burnt, they can form protein. The liver produces a lot of plasma protein: albumin, fibrinogen, clotting factors

Define mastication.

(chewing) breaks food into smaller pieces to be swallowed , requires little thought.

Hepatitis A

(infectious hepatitis) is caused by hepatitis A virus and is spread by fecal contamination. It does not cause lasting liver damage -vaccine

Identify and describe the gastric glands, including their cells (e.g., parietal cells, chief cells)

1. Surface mucous cells: thick alkaline mucus to protect lining (mucosal barrier) 2. Mucous neck cells: thin acidic mucous (function ?) 3. Parietal cells: secrete HCl (function: acid activates pepsin to breaks down food and bacteria) and intrinsic factor (essential for Vit. B12 absorption) 4. Chief cells: secrete pepsinogen activated by HCl to form pepsin to break down proteins; and lipase for fat breakdown 5. Enteroendocrine cells: secrete several paracrines and hormones (includes G cell)

Describe the general functions of the stomach.

1.activates the enzymes pepsin and lingual lipase 2.breaks up connective tissues and plant cell walls, turning a bolus into a liquid called chyme 3.converts ingested ferric ions to ferrous ions 4.contributes to innate immunity by destroying most ingested pathogens The rug are ridges produced by folding of the wall of the stomach, allow for expansion of the stomach after the consumption of foods and liquids

identify and describe the structure and functions of the pancreas

5" long (12 cm) by 1" thick (2-3 cm) Head close to curve in C-shaped duodenum Flattened, spongy, retroperitoneal gland pressed between the body wall and greater curvature of stomach. Functions: Endocrine (regulation of glucose metabolism): pancreatic islet cells release hormones (insulin, glucagon, and somatostatin) into blood Exocrine (digestion): acinar cells produce digestive enzymes (pancreatic juice) and pancreatic duct cells produce bicarbonate ions; these are released into duodenum via pancreatic ducts

Identify and describe the major histological components of the pancreas (pancreatic acini and pancreatic islets [islets of Langerhans]) and discuss their major functions

Acini - dark clusters - 99% of gland - produce pancreatic juice • Islets of Langerhans - 1% of gland - pale staining cells - produce hormones

Describe the general functions of the large intestine, rectum, and anal canal

Anal canal: above anal canal, rectal valves allow gases to pass without feces, ridges called anal column separated by anal sinuses: anal glands release mucus under pressure of feces passing to help poop. internal sphincter-smooth muscle involuntary control, external sphincter- skeletal muscle and voluntary control

Trace the path of bile and pancreatic juice through the biliary apparatus

Bile passes from bile ducts to the right and left hepatic ducts which unite to form the common hepatic duct Common hepatic duct joins the cystic duct to form the common bile duct which enters the hepatopancreatic ampulla

Identify the locations of chemical digestion of macromolecules (e.g., carbohydrates, proteins, lipids). Define zymogen and describe its importance in chemical digestion.

Carbohydrates: Mouth: salivary amylase, duodenum: pancreatic amylase, brush border enzymes: maltase, sucrase, and lactase act on disaccharides- produce monosaccharides--fructose, glucose & galactose- lactose intolerance (no lactase enzyme; bacteria ferment sugar)--gas & diarrhe Proteins: stomach: HCl denatures or unfolds proteins, pepsin cuts proteins into peptides Pancreas: digestive enzymes: split peptide bonds between different amino acids Brush border enzymes (aminopeptidase or dipeptidase): enzymes break peptide bonds that attach terminal amino acids to carboxyl ends of peptides (carboxypeptidases), enzymes break peptide bonds that attach terminal amino acids to amino ends of peptides (aminopeptidases) Depeptidasu: enzymes split dipeptides to amino acids

Homeostatic imbalances of the Digestive System: Aging

Changes that occur - decreased secretory mechanisms - decreased motility - loss of strength & tone of muscular tissue - changes in neurosensory feedback - diminished response to pain & internal stimuli • Symptoms - sores, loss of taste, periodontal disease, difficulty swallowing, hernia, gastritis, ulcers, malabsorption, jaundice, cirrhosis, pancreatitis, hemorrhoids and constipation • Cancer of the colon or rectum is common

identify and describe the different regions of the pharynx with respect to the passage of air and/or food.

Funnel-shaped tube extending from internal nares (choanae) to the esophagus (posteriorly) and larynx (anteriorly). Connects the oral cavity to the esophagus and the nasal cavity to the larynx . Has a deep layer of longitudinally oriented skeletal muscle and superficial layer of circular skeletal muscle. The circular muscle which is divided into superior, middle, and inferior pharyngeal constrictors, force food downward during swallowing

Describe metabolic pathways that produce or store glucose (e.g., glycogenesis, glycogenolysis, gluconeogenesis).

Glucose will be stored and released (depending on blood levels, insulin, and glucogon) in hepatocytes as glycogen. Fructose and galactose will be transformed into glucose so they can be stored in glycogen. All monosaccharides in the hepatocytes will be converted into glucose. The formation of glycogen from glucose is called glycogenesis. The breaking down of glycogen to release glucose is called glycogenolysis. The conversion of those monosaccharides into glucose is called gluconeogenesis. You can also convert glycerol and amino acids into glucose.

Identify and describe the boundaries of the oral cavity

Hard, soft palate, and uvula: roof of mouth, tongue: floor of mouth, cheeks: side of mouth, Lip (labia) and cheeks: contain buccinator muscle that keeps food between UPPER and LOWER teeth. Vestibule: area between cheeks and teeth Fauces: separates the oral cavity from oropharynx, they are 2 pillars of paired skeletal muscle folds covered by mucous membrane Palatoglossal muscle: extends from the palate to tongue. Forms the first arch, posterior limit of the mouth, anterior pillar Palatopharyngeal muscle: extends from palate to pharyngeal wall, forms the second arch, and it is the posterior pillar

dentify and describe the histological components of the classic hepatic lobule

Hexagon shaped liver cells called hepatocytes, they are about 2mm long by 1mm in diameter. Irrigated by sinusoids: very leaky blood capillaries and is made up of kupffer cells that phagocytize microbes. The blood come from hepatic portal vein: deoxygenated, nutrient rich from small intestine to liver to be detoxified and empty into portal venues. The other source is oxygen rich blood delivered by the hepatic artery and empty into portal arteriole. The blood will mix in the sinusoids to provide oxygen and nutrients to hepatocytes . Bile canaliculi collect bile and empty into bile duct. Portal triad: bile duct and portal venue and arteriole. Sinusoids will empty into central vein, then empty into interlobular veins, then hepatic vein, then return it to right atrium.

Identify gastric folds (rugae) and discuss their functional significance

Increase surface area and Allow expansion of stomach as it fills

Describe the location of the gallbladder relative to other body structures

It's head (fundus) usually projects slightly beyond the inferior margin of the liver. Its neck(cervix) leads into the cystic duct, which leads in turn to the bile duct. It adheres to the liver's inferior surface.

Identify and describe the gross anatomy of the large intestine, rectum and anal canal, including their location relative to other body structures

Large intestine: measure about 1.5 m long and 6.5 cm in diameter. It consists of four regions: the cecum, colon, rectum, and anal canal. Rectum: about 15cm long, has three infoldings called transverse rectal folds (rectal valves) Anal canal: final 3cm or the large intestine, passes through the elevator ani muscles of the pelvic floor and terminates at anus. Mucosa forms longitudinal riches called the anal columns with depressions between them called anal sinuses

dentify and describe the biliary apparatus components (i.e., left and right hepatic ducts, common hepatic duct, cystic duct, common bile duct, main pancreatic duct, hepatopancreatic ampulla [ampulla of Vater], hepatopancreatic sphincter [sphincter of Oddi], major duodenal papilla).

Left and right hepatic duct: between the lobules, they converge on the inferior side to form the common hepatic duct. A short distance farther on, this is joined by the cystic duct coming from the gallbladder. Their union forms the bile duct, which descend through the lesser momentum towards the duodenum.The bile duct joins the duct of the pancreas and forms an expanded chamber called the hepatopancreatic ampulla. The ampulla terminates at a fold of tissue called the hepatopancreatic duodenal papilla. The muscular hepatopancreatic sphincter regulates the passage of bile and pancreatic juice into the duodenum

Describe the functions of the liver.

Liver functions: carbohydrate, lipid, and protein metabolism; removal of drugs and hormones from the blood; excretion of bilirubin; synthesis of bile salts; storage of vitamins and minerals; phagocytosis; and activation of vitamin D.

Describe the location of the pancreas relative to other body structures

Main duct for pancreatic juices joins common bile duct from liver Sphincter of Oddi (hepatopancreatic sphincter) on major duodenal papilla

Describe the anatomic specializations of the esophageal tunics (e.g., composition of the mucosa and muscularis [muscularis externa]) compared to the tunics of the rest of the GI tract

Mucosa:non keratinized stratified squamous epithelium Submucosa: contains esophageal glands that secrete lubricating mucus into the lumen Muscularis: composed of skeletal muscle in the upper one-third of the esophagus, a mixture of skeletal and smooth muscle in the middle one third, and smooth muscle in the lower third.

Explain how volume, chemical composition, and osmolarity of chyme affect motility in the stomach and in the duodenum

Only about 3 mL of chyme is squirted into the duodenum at a time; this small amount allows duodenum to: neutralize the stomach acid and digest nutrients little by little. The duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes

Describe the compositions, locations, and functions of the inferior esophageal (cardiac, lower esophageal) sphincter and the pyloric sphincter.

Pyloric sphincter: regulates the passage of chyme into the duodenum, made of thick ring of smooth muscle Esophageal sphincter: upper Under contraction except during swallowing and Prevents reflux of stomach contents

Describe the defecation reflex and how it is affected by somatic and autonomic innervation

Reflex aided by a few muscle, the diaphragm, and the abdominal muscles via the valsalva maneuver. Starts with gastrocolic reflex: move feces into the rectum. Once in the rectum, it will stretch receptors: detect stretch and send signal to spinal cord, and the spinal cord will send signals to effectors, those effectors are cells of the internal sphincter to relax and the wall of the rectum to contract and push feces out. The brain can control internal sphincter so that it is voluntary.

Describe the general functions of the esophagus

Secrete mucus and transport food to the stomach

Identify and describe the structure and functions of the gallbladder

Structure: pear shaped sac on the underside of the liver, 10cm long, made of simple columnar epithelium (with microvilli), it is lined by highly folded mucosa with simple columnar epithelium, and no submucosa. It is made up of three layers of smooth muscle cells, serosa or visceral peritoneum Function: store bile between meals and concentrate it (reabsorption of water

Describe the structure and function of the salivary glands

Structure:Parotid-below the ear lying over the master, submandibular gland-under lower edge of mandible, and the sublingual: deep to the tongue in floor of mouth, All empty into the oral cavity and is controlled by the parasympathetic nervous system Function:secretes saliva

Describe the location of the liver relative to other body structures.

The gallbladder adheres to a depression on the inferior surface of the liver between the right and quadrate lobes. The posterior aspect of the liver has a deep sulcus that accommodates the inferior vena cava. The superior surface has a bare area where it is attached to the diaphragm

List and identify the organs that compose the gastrointestinal (GI) tract

The stomach and intestines constitute the gastrointestinal tract

Relate the anatomic specializations of the esophagus to the organ's functions

The submucosa containing the esophageal glands, secrete lubricating mucus into the lumen. When the esophagus is empty, the mucosa and submucosa are deeply folded into longitudinal ridges, giving the lumen a starlike shape

Describe lactose intolerance

To digest lactose, we need enzymes called lactase that usually ceases after weaning. When a person with lactose intolerance consumes milk, lactose passes undigested into the large intestine, increases the osmolarity of the intestinal contents, and causes colonic water retention and diarrhea.

Describe the major functions of the biliary apparatus

To drain waste products from the liver into the duodenum. To help in digestion with the controlled release of bile

identify and describe the structures (e.g., taste buds, papillae) and the functions of the tongue

Tongue: has eight different muscles allowing it to be flexible, to manipulate food, and modify sound for speech. Structure: The surface is covered with non-keratinized stratified squamous epithelium and exhibits bumps and projections called lingual papillae, the site of most taste buds. The anterior 2/3 of the tongue is called the body and occupies the oral cavity, the posterior 1/3 is the root and it occupies the oropharynx. Attached to hyoid, mandible, hard palate, and styloid process. Papillae: bumps, taste buds are protected by being on the sides of papillae

Describe the anabolic and catabolic processes of fat metabolism (e.g., lipolysis, lipogenesis) and cholesterol synthesis.

We have triglycerides and fatty acids, the fatty acids come from the blood flow, nutrients extracted absorbed in the small intestine, and these fatty acids can be stored in the liver under the form of triglyceride: lipogenesis. These triglycerides can be broken down to release fatty acids into the circulation-lipolysis. The fatty acids can be oxidized- beta oxidation: gives acetyl CoA- can be changed into water soluble molecules and these can be released into blood directly, transported to other cells, and oxidized in cellular respiration to produce ATP. The other route is to use acetyl CoA to form cholesterol, can be used as is and be transported in blood by lipoproteins. Cholesterol can give bile salts, how bile is produced, bile salts are not release in blood circulation but in bile canaliculi.

Anorexia nervosa

a is a chronic disorder characterized by self-induced weight loss, body-image and other perceptual disturbances, and physiologic changes that result from nutritional depletion. The disorder is found predominantly in young, single females and may be inherited. Individuals may become emaciated and may ultimately die of starvation or one of its complications. Treatment consists of psychotherapy and dietary regulation.

large intestine

absorb water, electrolytes and vitamins B and K

Hard (bony) palate

anterior portion supported by the palatine processes of the maxillae and by the smaller palatine bones. Has transverse ridges called palatine rug that aid the tongue in holding and manipulating food

Periodontal diseases

are characterized by inflammation and degeneration of the gingivae (gums), alveolar bone, periodontal ligament, and cementum.

Peptic ulcers-in stomach

are crater-like lesions that develop in the mucous membrane of the GI tract in areas exposed to gastric juice. The most common complication of peptic ulcers is bleeding, which can lead to anemia if blood loss is serious. The three well-defined causes of peptic ulcer disease (PUD) are the bacterium Helicobacter pylori; nonsteroidal anti-inflammatory drugs, such as aspirin; and hypersecretion of HCl

Diverticula

are saclike outpouchings of the wall of the colon in places where the muscularis has become weak -The development of diverticula is called diverticulosis -Inflammation within the diverticula, known as diverticulitis, may cause pain, nausea, vomiting, and either constipation or an increased frequency of defecation. High fiber diets help relieve the symptoms.

mouth

bite, mechanical digestion (chewing), swallowing

small intestine

chemical and mechanical digestion, and also water absorption

stomach

chemical and mechanical digestion; absorption of water and alcohol

Prevention for A and E

clean water, good hygiene,

Uvula

conical median projection, helps retain food in the mouth until one is ready to swallow

chemical digestion

consists of the breakdown of macromolecules through hydrolysis -take place in small intestine

Mesecolon

continuous to mesentery, suspends transverse colon to the post. Wall of abdominal cavity

rectum and anus

defecation

Retroperitoneal organs

esophagus, rectum, duodenum, descending and ascending colon

Lesser Omentum

extends from the lesser curvature of stomach to the liver

Describe hiatal (diaphragmatic) hernia and gastroesophageal reflex disease (GERD)

f lower sphincter fails to open- dissension of esophagus feels like chest pain or heart attack. If lower esophageal sphincter fails to close- stomach acid enter esophagus and cause heartburn (GERD), for a weak sphincter- don't eat a large meal and lay down in front of TV, smoking and alcohol make the sphincter relax worsening the situation. -avoid coffee, chocolate, tomatoes, fatty foods, onion and mint -take Tagamet HB or Pepcid AC 60 mins before eating -neutralize existing stomach acids with tums

Serous fluid

forms a translucent, membranous curtain suspending and anchoring the viscera

submucosa function and structure

function: Contains blood vessels and lymphatics, a nerve plexus, and in some places glands secrete lubricating mucus into the lumen. Malt prevent ingested microbes to cross the alimentary tract wall structure: Thick layer of loose connective tissue/ dense irregular connective tissue. Rich in elastic fibers

mucosa function and structure

function: Inner epithelium: simple columnar in most of digestive tract, stratified squamous in oral, esophagi., and lower anal. Secrete and absorb. Muscularis Mucosae: tenses to create grooves and ridges to enhance surface are. Mucosa exhibits an abundance of lymphocytes and lymphatic nodules, MALT structure: Inner epithelium, loose connective tissue)lamina propria), thin layer of smooth muscle called muscularis mucosae

muscularis externa function and structure

function: to mix and propel food (peristalsis) structure: inner circular and other circular longitudinal

serosa function and structure

function:Secrete serous fluid for lubrication, help anchor binary structures (only if organs are peritoneal) structure:thin areolar connective tissue

peristalsis

involuntary muscle contractions that are wave-like, they move the food down towards the stomach.

Hepatitis

is an inflammation of the liver and can be caused by viruses, drugs, chemicals, including alcohol or autoimmune response

Hepatitis B

is caused by hepatitis B virus and is spread primarily by sexual contact and contaminated syringes and transfusion equipment. It can produce cirrhosis and possibly liver cancer -vaccine

Hepatitis D

is caused by hepatitis D virus. It is transmitted like hepatitis B and, in fact, a person must be co-infected with hepatitis B before contracting hepatitis D. It results in severe liver damage and has a high fatality rate -vaccine

Hepatitis E

is caused by hepatitis E virus and is spread like hepatitis A. It is responsible for a very high mortality rate in pregnant women

Hepatitis C

is caused by the hepatitis C virus. It is clinically similar to hepatitis B and is often spread by blood transfusions. It can cause cirrhosis and possibly liver cancer

Dental caries, or tooth decay

is started by acid-producing bacteria that reside in dental plaque, act on sugars, and demineralize tooth enamel and dentin with acid.

Greater momentum

large apron like structure, hangs down from greater curvature of the stomach

mechanical digestion

more physical, including actions like chewing, churning, and segmentation -small intestine, mouth, stomach

functional segments of GI tract (alimentary canal)

mouth/pharynx, esophagus, stomach, small intestine, large intestine, colon -these break down the foods into more simple forms, monomers, so that they can be transported via blood stream

parietal

outer layer of the peritoneum, it lines the abdomino-pelvic cavity

Describe the anatomic specializations of the small intestine tunics (e.g., circular folds [plicae circulares], villi, microvilli) compared to the tunics of the rest of the GI tract

plicae circulares (circular folds) - permanent ½ inch tall folds that contain part of submucosal layer - not found in lower ileum - can not stretch out like rugae in stomach villi - 1 millimeter tall - core is lamina propria of mucosal layer - contains vascular capillaries and lacteals (lymphatic capillaries) microvilli - cell surface feature known as brush border Circular folds- largest of these elaborations, are transverse to spiral ridges up to 1cm high. These involve only the mucosa and submucosa Epithelium: Simple columnar - Absorptive cells (enterocytes) w/ tight junctions and goblet cells (mucus) - Pits with intestinal crypts: enteroendocrine cells (hormones), tuft cells (defense, parasite), Paneth cells (antimicrobial peptides), etc... Submucosa: Areolar CT - contains aggregated lymph tissue called Peyer's patches - duodenal glands in duodenum only

Soft palate

posterior to hard palate, spongy texture and is composed mainly of skeletal muscle and granular tissue, but no bone

Epiglottis

prevents food from entering the the respiratory system

prevention for B, C, D

screening blood prior to transfusion, abstaining from the use of injection drugs, safe needle and sharps practices in healthcare settings, and safe sex practices

Peritoneal cavity

space between the parietal and visceral layers

Intraperitoneal organs

stomach, liver, and other parts of the small and large intestine

Visceral

suspends certain abdominal viscera from the body wall, covering their outer surfaces, and holding them in place, forms serosa. Also called the mesentery

The accessory structures

teeth, tongue, salivary glands, liver, gallbladder, pancreas -these facilitate digestion of food

Mesentery

translucent sheet that suspends the intestines and other abdominal viscera from the posterior wall. Provides passage for the blood vessels and nerves that supply the digestive tract, and contain many lymph nodes and lymphatic vessels.

pharynx and esophagus

transport

Intraperitoneal

when an organ is enclosed by mesentery (serosa) on all sides

Retroperitoneal

when an organ lies against the posterior body wall and is covered by peritoneal cavity

adventitia function and structure

-If organs are retroperitoneal, it helps anchor binary structures -Fibrous connective tissue

Describe mumps

-Myxovirus that stacks the parotid gland. Symptoms: inflammation and enlargement of the parotid fever, pain, headache & sore throat (especially swelling sour foods) Swelling on one or both sides Complications may include meningitis, pancreatitis, inflammation of the heart, permanent deafness, and testicular inflammation which uncommonly results in infertility. • Vaccine available since 1967 (MMR)

Describe the general functions of the small intestine

-Receives bile and pancreatic secretions, Primary site for digestion, Primary site for absorption of nutrient

Trace the pathway of ingested substances through the gastrointestinal (GI) tract

1.Begins in the mouth where the teeth break food into smaller particles during mastication. Salivary glands begin chemical digestion and keep food moist 2.the food is swallowed and the soft palate blocks the upper pharynx to prevent food from entering nasal cavity. Voluntary muscles including the tongue push the food particles through the pharynx and over the epiglottis and then into the esophagus. 3.Peristalsis causes the bolus to move down the esophagus and into the stomach. 4.stomach cells secrete HCl, pepsinogen, and various regulatory hormones that chemically digest the bolus, the bolus is now turned into chyme. 5.chyme exits stomach through the pyloric sphincter and enters the small intestine. 6.Bile from the liver and digestive enzymes from the pancreases empty into the duodenum to aid in digestion. 7.Absorbed nutrients pass from the lumen of the small intestine into blood and lymph. 8.Chyme not absorbed by the small intestine goes through the cecum, ascending, transverse, descending, and sigmoid colon. 9. Water and salts are absorbed and chyme is converted into feces, the rectum stores feces until nervous simulation initiate defecation reflexes.

Identify and describe the gross anatomy of the stomach, including its location relative to other body structures

A J-shaped enlargement of the GI tract from. The bottom of the esophagus to the pyloric sphincter. It is divided into four regions: cardia-small area within about 3cm of the cardinal orifice, fundus- dome superior to the esophageal attachment, body(corpus)- greatest part distal to the cardinal orifice, and the pylorus-slightly narrower pouch at the inferior end. It has two margins called the greater (the long way around, about 40cm, along the inferior later surface) and lesser curvature( the shorter distance from the esophagus to the duodenum, about 10cm along the superomedial margin facing the liver). Contains ruga

identify the specific segments and related flexures of the large intestine

Colon: it is part of the large intestine between the ileocecal junction and rectym. It is divided into the ascending:begins at the ileocecal valve and passes up the right side of the abdominal cavity and makes a 90 degree turn, transverse:passes horizontally across the upper abdominal cavity and turns 90 degrees downward , descending:passes down the left side of the abdominal cavity, and sigmoid colon. Cecum: blind pouch in the lower right abdominal quadrant inferior to the ileocecal valve. Appendix: blind tube 2 to 7 cm long

Describe the composition and functions of saliva

Composition:mucus, electrolytes, lysozyme: inhibit bacterial growth, fight pathogens, they are antimicrobial peptides. Antibody IgA:present in secretions of the body(saliva, tears, milk) prevent antibodies from entering body. Salivary amylase: digest complex sugars, Lingual lipase: digest fats Function: mosisten and cleans mouth, inhibit bacterial growth, dissolves tastants, digest starch and fats, lubricates making swallowing easier

ist the structures involved in deglutition and explain the process of deglutition, including the changes in position of the glottis and larynx that prevent aspiration

Deglutition: after mastication, the bolus is swallowed. It involves over 22 muscles in the mouth, pharynx, and esophagus. It is coordinated by the swallowing center, a pair of nuclei in the medulla oblongata.It uses the trigeminal(5), facial(7) glossopharyngeal(9), and hypoglossal nerves(12). Voluntary phase---tongue pushes food to back of oral cavity • Involuntary phase----pharyngeal stage - breathing stops & airways are closed - soft palate & uvula are lifted to close off nasopharynx - vocal cords close - epiglottis is bent over airway as larynx is lifted • Involuntary phase----esophageal stage - Peristalsis moves food by pressure gradients: circular fibers behind bolus and longitudinal fibers in front of bolus shorten the distance of travel - Travel time is 4-8 seconds for solids and 1 sec for liquids - Lower sphincter relaxes as food approaches

Identify and describe the function of the following small intestine structures: duodenal glands (Brunner glands), intestinal glands (crypts of Lieberkuhn), and Peyer patches (lymphoid [lymphatic] nodules)

Duodenal Glands(brunner glands)- coiled, tubular mucous gland, produces alkaline secretion that neutralizes acidity of chyme form stomach Intestinal glands (crypts of lieberkuhn)- contains enterocytes, goblet cells, panted cells, stem cells, and enteroendocrine cells. Enterocytes absorb water and products of digestion Goblet cells produce mucin Paneth cells produce lysozyme (a digestive enzyme) Stem cells produce replacement lining cells Enteroendocrine cells produce peptide hormones Peter patches (lymphoid nodules)- aggregates of lymphatic nodules surround by diffuse lymphatic tissue, function is to initiate immune response to antigens within the small intestine

Identify the specific segments of the small intestine (i.e., duodenum, jejunum, ileum), including their relative length

Duodenum: C-shaped and is about 25 cm long and has a width of 12 fingers. Begins at pyloric valve, receives ingested material (chyme) from stomach, enhances gastric secretion, absorbs nutrients, bile and pancreatic juices enter second part, digests carbs, protein, and lipids. Jejunum:is the first 40% of the small intestine. It is about 1 to 1.7 meters long and begins in the upper left quadrant of the abdomen. Chemical digestion and nutrient absorption Ileum: forms the last 60% of the small intestine and is about 1.6-2.7 meters.Wall is thinner, less muscular, less vascular and has a paler pink color compared to jejunum

Mesentery proper

It attaches your intestines to the wall of your abdomen and holds them in place.

identify and describe the gross anatomy of the small intestine, including its location relative to other body structures.

Most important organ for digestion. Extends from the pyloric sphincter to the ileocecal sphincter Three divisions: duodenum-starts in pyloric sphincter, jejunum-most of absorption, and ileum-ends at ileocecal valve

Describe the anatomic specializations of the stomach tunics compared to the tunics of the rest of the GI tract.

Mucosa: layer of simple columnar granular epithelial cells called mucous surface cells Epithelial cells extend down into the lamina propria forming gastric pits and gastric or pyloric glands:consist of three types of exocrine glands: mucous neck cells (secrete mucus), chief cells (secrete pepsinogen and gastric lipase), and parietal cells (secrete HCl).Gastric glands also contain enteroendocrine cells which are hormone producing cells = G cells secrete the hormone gastrin into the bloodstream. Submucosa is flat and smooth, but they form conspicuous longitudinal wrinkles with the mucosa called gastric rugae. Lamina propria is entirely occupied by tubular glands Muscularis: three layers: outer longitudinal, middle circular, and inner oblique layers

Describe the specializations of the large intestine tunics (e.g., composition of the muscularis [muscularis externa]) compared to the tunics of the rest of the GI tract

Mucosa: simple columnar ET except anal canal; but thick with crypts. Goblet cells produce mucus that eases passage of feces Anal columns are long folds in anal canal with stratified squamous epithelium Two sphincters control release of feces

Compare and contrast the following: peristalsis, mixing waves, segmentation, and mass movement.

Peristalsis: produced by waves of contraction of the muscularis externa, propels the chem onward through the intestinal tract, happens in esophagus and stomach Segmentation: coordinated contraction of the muscle that pushes the food back and forth to break it and mix with digestive juices. Chyme will remain for 3 to 5 hours in stomach. Mixing waves: every 15 to 25 secs, mixes bolus with 2 quarts/day of gastric juice to turn it into chyme (a thin liquid). Mass movements: stronger contractions that occur one to three times a day. They last 15 mins and move residue several cm at a time. They occur in transverse to sigmoid colon often within an hour after breakfast.

Identify and describe the gross anatomy of the esophagus, including its location relative to other body structures

Straight muscular tube 25 to 30 cm long, begins at a level between vertebra C6 and the cricoid cartilage, inferior to the larynx and posterior to the trachea and heart. Goes through diaphragm at hiatus( gap in the diaphragm). Has a mucosa (contains a stratified squamous epithelium), submucosa )areolar connective tissue and lumen, muscular external (longitudinal layer and circular layer), and a adventitia (fibrous connective tissue)

Describe the structure and function of teeth.

Structure:Crown-sticks out of the gingiva, covered in enamel, the gum, and the root anchored in bone tissue via periodontal ligaments, neck separates crown from the root. Four major tissues: Enamel- hardest substance in body, calcium phosphate minerals, hydroxyapatite, and carbonate, Dentin: beneath enamel, composed of calcified connective tissue, Cementum: covers root of tooth, close in composition to bone and periodontal ligaments are attached to it to maintain the tooth anchored inside jawbone tissue, and Pulp cavity Function: called the dentition. They serve to masticate the food, breaking it into smaller pieces. We have primary and secondary teeth. 2 central and lateral incisors, 2 canine, 2 first and second premolars, and 2 first, second, and third molars.

Identify and describe the structure of the liver, including the individual lobes, ligaments (e.g., coronary ligament, falciform ligament, round ligament [ligamentum teres]), and the porta hepatis

The liver is divided into four lobes: right, left, (quadrate, and caudate) both on right The falser forum ligament: divides right from left Round ligament( ligament teres): remnant of the umbilical vein, carries blood from the umbilical cord to the liver of a fetus Porta hepatis: point of entry for the hepatic moral vein and proper hepatic artery and a point of exit for the bile passage