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Anatomy and Physiology abdominal distention

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					                                 Anatomy and Physiology 2402
                                         Chapter 23

The digestive system takes in food, breaks it down into molecules, absorbs those that can be into
the blood, then rids the body of the indigestible remains.
                                                                    The GI tract is technically
                                              Overview              outside the body because
                                                                    it is open at both ends.
Two Main Groups:
       1. Alimentary canal (Gastrointestinal tract) – long muscular tube consists of the
          mouth, pharynx, esophagus, small intestine, large intestine, and anus.
       2. Accessory organs: teeth, tongue gall bladder, salivary glands, liver, and pancreas

                                         Digestive Process         The GI tract is 9m (30 ft) long in
                                                                   a cadaver. It is shorter in a living
Six Essential Activities:                                          person due to muscle tone
       1. Ingestion: taking in food via the mouth


       2. Propulsion: moving food through the alimentary canal
              Swallowing: initially voluntary
              Peristalsis: waves of muscular contractions (involuntary)
                      a. Moves food through entire GI tract (even upside down)
                      b. Mixes food in stomach

       3. Mechanical digestion: chewing, mixing food with saliva, churning in stomach
          and segmentation (rhythmic local constrictions of intestine – mixes food with enzymes and
          moves different parts of food next to intestinal wall.

       4. Chemical digestion: food is broken down into molecules by enzymes secreted
          from the lumen of the GI tract. This begins in the mouth and ends in the small intestine

       5. Absorption: passage of digested products through mucosal cells into blood or
          lymph (occurs mostly in small intestine)

       6. Defecation: eliminates indigestible parts of food

Propulsion:
  Peristalsis: Smooth muscles alternately relax and contract moving food distally

Food Mixing:
  Segmentation: nonadjacent segments of the intestine alternately contract and relax moving the
  food forward and then backward. This results in food mixing rather than food propulsion
                                              Basic Functional Concepts

       Two facts that apply to the regulatory Mechanism of digestion:

       1. Digestive activity is produced by a range of mechanical and chemical stimuli
           a. Sensors (mechanoreceptors and chemoreceptors) in lumen wall
                  1. Stretch
                  2. Osmolarity
                  3. pH of contents
           b. Sensors function
                  1. Activate or inhibit glands (that secrete enzymes into lumen or hormones into blood.
                  2. Mix lumen contents and move it along GI tract

             2. Controls of digestive activity are both intrinsic and extrinsic
                    a. Hormones (local producing cells)
                    b. Nerve plexuses (in house – in GI wall along entire length
                            1. Short refliexes – mediated by local nerve plexuses (Gut – brain) in
Which of these are             response to stimuli.
extrinsic and which         2. Long reflexes – mediated by CNS and extrinsic autonomic centers in
are intrinsic?                 response to stimuli (inside or outside GI tract)

                                                 Digestive System Organs

           Peritoneum:
           Visceral peritoneum                       Covers surface of most digestive organs and lines
           Parietal peritoneum         2401          the cavity wall. Fluid fills the space between
           Peritoneal cavity                         membrane layers.

                   Purpose: lubricates organs – reduces friction as organs slide past each other.

           Mesentery: Double layer of peritoneum – sheet of two serous membranes fused back to back and
           extends from digestive organs to the cavity wall.

                   Purpose: a. Routes for blood vessels, lymphatics and nerves
                            b. Hold organs in place
                            c. Stores fat

                   Names: a. ventral mesenteries
                          b. dorsal mesenteries
                          c. omenta

     Retroperitoneal organs: have lost their mesenteries and lie posterior to the peritoneum. Includes most
     of the pancreas, parts of large intestine and small intestine which adhere to the dorsal cavity wall.

     Intraperitoneal organs: retain their mesenteries and remain inside the peritoneum
     Includes the stomach
                                     Peritonitis: inflammation of the peritoneum * (Read in text)
                                                       Blood Supply

         Splanchnic circulation (“liver, stomach, spleen, mesentery”) arteries branching off aorta to
                 1. Digestive organs
                 2. Hepatic portal circulation                                 Serve spleen        Discussed in
                                                Hepatic artery                 Liver               Circulation
                                                Splenic artery                 Stomach             chapters.
Abdominal artery          Celiac trunk                                         mesenteric
                                                Left gastric branches


           Hepatic portal circulation collects nutrient rich venous blood and carries it to the liver
           Nutrients are processed or stored before released back to the blood for general use.

                                                         Histology
           Mucosa: (mucous membranes) – innermost tunic (tunic = layer)
                Functions: 1. secretion of mucous, digestive enzymes and hormones
                           2. absorption of digested food
                           3. Protection against disease

                  Mucosa has 3 layers
                        1. Lining epithelium – contains goblet cells in stomach and small intestine
                           Contains enzyme and hormone secreting cells
                        2. Lamina propria – MALT (mucosa associated lymphatic tissue)
                           Helps to defend against pathogens
                        3. Muscularis mucosae – very thin layer, local contractions
                           make twitches to throw off food and folds to increase surface area.

           Submucosa: (external to mucosa)
                Dense CT: 1. Contains vast amounts of blood vessels, lymphatics, lymphoid
                               follicles nerve fibers.
                            2. Made of elastic CT especially in stomach (for recoil

           Muscularis externa: Function: segmentation and peristalsis
                               Structure: Inner circular layer and outer longitudinal layer

           Serosa: Visceral peritoneum – mesothelium (epithelial layer) and underlying areaolar CT
                  In the esophagus, the serosa is replaced by an adventitia: a fibrous CT that binds
                  esophagus to surrounding tissues.

                                         Enteric Nervous System of the Alimentary Canal

         Enteric neurons: “in house” nerve supply. Comprise most of two major intrinsic nerve plexuses
            1. Submucosal nerve plexus: (in submucosa) regulates the activity of glands and smooth
               muscle of mucosa
            2. Myenteric nerve plexus: (between layers of muscularis externa) controls GI mobility
 This system is largely automatic, but is linked to the
       1. parasympathetic branch of CNS – increases activity of digestive system
       2. sympathetic branch of CNS – decreases activity of digestive system

                   Part 2: Functional Anatomy of the Digestive System
                   Mouth, Pharynx and Esophagus                            Be able to define in words for
                                                                           lecture:
Mouth:
Ingestion                                                                  Mouth
Chewing                                                                    Oral cavity
Saliva is mixed with food (contains enzymes to begin digestion)            Oral orifice
Swallowing                                                                 Oropharynx
                                                                           Lips
How does the mouth, which is teeming with disease causing microbes,        Cheeks
remain so remarkably healthy? ______________________________                Vestibule oral cavity proper
                                                                           Red margin
Lips and Cheeks: Keep food between the teeth                               Labial frenulum
Lips extend from inferior boundary of nose to superior boundary of chin Palate
Red margin, the pink part is only a part of the lips.                      Hard palate
                                                                           Soft palate
Tongue:                                                                    Raphe
                                                                            Uvula
∆ Ankyloglossia – child is born with extremely short lingual frenulum. Palatoglossal arches
Generally referred to as “tongue-tied”. Frenulum is usually surgically     Palatopharyngeal arches
cut.                                                                       Fauces
                                                                           Tongue
Filiform papillae: give the tongue its roughness and provide friction for manipulating food.
                                                                           Intrinsic muscles
     Most numerous                                                         Extrinsic muscles
     Aligned in parallel rows                                              Lingual frenulum
     Stiffened by keratin (gives them their whitish color)                 Filiform papillae
                                                                           Fungiform papillae
Fungiform papillae mushroom shaped                                         Circumvallate papillae
     House taste buds                                                      Sulcus terminalis
                                                                           Lingual tonsils
Circumvallate papillae form a V-shaped row at posterior of tongue
     House taste buds

Salivary Glands produce saliva
       1. cleanse mouth
       2. dissolves food chemicals so they can be tasted
       3. moistens food and aids in contracting it into a bolus
       4. contains enzymes beginning digestion of starchy foods

Intrinsic salivary glands (buccal glands) scattered throughout
oral cavity mucosa
Extrinsic salivary glands lie outside the mouth
   Parotid gland: lies below and in front the ears
   Parotid duct: carries saliva to oral cavity
Submandibular gland: Lies under the mandible
Sublingual gland: Lies under the tongue

∆ Mumps inflammation of the parotid gland, caused by myxovirus – mode of transmission is saliva
Two types of cells in salivary glands:
1. Serous cells produce watery secretion containing enzymes, ions and a tiny bit of mucin
2. Mucous cells produce mucus.

Composition of Saliva: 99% water
                       Slightly acidic (6.75 – 7.0)
                       Electrolytes: Na+, K+ Cl- PO4- and HCO3-
                      Proteins: amylase, mucin, lysozyme and IgA, metabolic wastes
                      A cyanide compound

Function of these ingredients
   Amylase: chemical digestion of starchy food
   Mucin: thickens saliva
   Lysozyme: bacteriostatic enzyme – inhibits bacterial growth and prevent tooth decay
   IgA: produces antibodies
   Defensins (produced by injured cells) antibiotic and acts as a cytokine to call immune cells
   Cyanide compound kills bacteria
                                                                          Know the names of the
                                            Teeth
                                                                          following teeth and their
Primary dentitions (deciduous or baby or milk teeth) = 20
                                                                          function in chewing:
Permanent teeth = 32
     2I, 1C, 2PM, 3M                                                      Incisors
                          X 2 = 32 teeth
     2I, 1C, 2PM, 3M                                                      Canines (cuspids)
                                                                          Premolars (bicuspids)
                                          Tooth Structure
                                                                          Molars
Crown: exposed enamel covered part of the tooth
Gingiva: gum, seals tightly around the exposed part of tooth
Enamel: hardest substance in the body. Cells that produce enamel degenerate when the tooth erupts ,
so any decayed or cracked areas of enamel will not heal
Root: portion of tooth embedded in jawbone                       How does enamel, dentin and
    Canines, incisors and premolars: one root                    cementum, which are all calcified
    First upper premolars and first two lower molars: two roots  and resemble bone actually
    First two upper molars have 3 roots                          different from bone?
    Third molar: often a single fused root
Neck: connects crown and root
Cementum: Outer surface of root is covered by a calcified CT which attaches the tooth to the
            periodontal ligament
Periodontal ligament: anchors tooth in the bony alveolus of the jaw
Dentin: bonelike material, underlies the enamel and forms the bulk of a tooth
Pulp cavity: central portion; contains pulp
Pulp composed of a number of soft tissue structures CT, blood vessels, nerve fibers)
Root canal: Where pulp cavity extends into the root
Apical foramen: at proximal end of each root canal; provides route for blood vessels , nerves… to
          enter the pulp cavity.
Odontoblast: cell type that secretes and maintains the dentin; lines pulp cavity. Dentin is formed
          throughout life. New dentin can be secreted rapidly to compensate for tooth damage or
          decay.
                                      ∆Tooth and Gum Disease
∆ Halitosis
∆ Impacted tooth
∆ Root canal therapy
∆Dental caries: cavities; result from gradual demineralization of enamel and underlying dentin by
 bacterial action
∆Dental plaque: film of sugar, bacteria … adheres to teeth. Bacterial metabolism produces acids,
 which dissolves calcium of teeth. Once calcium is weakened, rest of tooth is digested by enzymes
 released from bacteria.
∆Calculus tartar: calcified plaque which disrupts the seals between the gingivae and teeth putting
 gums at risk for infection
∆Gingivitis: gums become red and swollen and may bleed. Tartar build up allows bacteria to enter at
 gum-line and cause infection. Will heal if tartar is removed
∆Periodontal disease: periodontitis; bacteria invades the bone around the teeth forming pockets of
 infection. Immune system attacks intruders and body tissues carving deep pockets around teeth and
 dissolving bone away
              Periodontal disease affects 95% of all adults over 35
              and accounts for 80-90% of tooth loss in adults.
                     1. Can it be treated? How?
                     2. List two reasons why periodontal disease could
                        put a person at risk of heart disease?

                                            The Pharynx

Oropharynx and Laryngopharynx: posterior to mouth; muscles propel food to esophagus

                                           The Esophagus

Esophagus: carries food to stomach; collapses when not involved in food propulsion
Cardiac orifice: entry to stomach
Cardiac (gastroesophageal) sphincter: muscle that, like valve, opens to let food in, but closes so that
    it does not back up into the esophagus.
 ∆Heartburn                                ∆Esophageal cancer            ∆Hiatal hernia
 ∆Gastroesophageal reflux disease          ∆Esophageal ulcers            ∆Esophagitis
 The submucosa contains mucus-secreting esophageal glands. As bolus moves through the esophagus,
 it compresses these glands, causing them to secret mucus that “greases” the esophageal walls and aids
 food passage.

                 Digestive Process Occurring in the Mouth, Pharynx, and Esophagus

 1. Mastication: chewing
     Mixes food with saliva, digestion of starchy foods begin. No absorption except for nitroglycerine

 Swallowing:
   Buccal phase: voluntary
   Pharyngeal-esophageal phase: involuntary

                                             Stomach
 Stomach: a temporary storage tank
    Breakdown of proteins
    Food is converted to chyme – a creamy paste
                                                                   Parts of Stomach: Be able to
     Rugae: longitudinal folds                                     describe these parts in words.
     Cardiac region: surrounds the cardiac orifice
     Fundus: dome shaped part beneath the diaphragm
     Body: midportion of stomach
     Pyloric region: funnel shaped part below the body
     Pyloric antrum: wider more superior part of pyloric region
     Pyloric canal: Where pyloric antrum narrows
     Pylorus: where pyloric canal ends and where duodenum begins
     Pyloric sphincter: circular muscle that controls the emptying of stomach contents into duodenum
     Greater curvature: the convex lateral surface of stomach
     Lesser curvature: the concave medial surface of stomach
     Mesenteries: help tether the stomach to other organs
            Lesser omentum: runs from liver to lesser curvature to visceral peritoneum
            Greater omentum: drapes inferiorly from greater curvature to cover small intestine and
                   other digestive organs.
                   Filled with fatty deposits and many lymph nodes
                   Immune cells and macrophages in these nodes police peritoneal cavity and
                   intraperitoneal organs.

                                           Microscopic Anatomy

Endothelial lining composed entirely of goblet cells produces a double layer of alkaline mucus, that
traps a layer of bicarbonate rich liquid beneath, which protects living layers from stomach acid.
Endothelial lining contains millions of gastric pits which contain gastric glands that produce gastric
juice.
        Gastric glands:
                   Mucous neck cells: secrete an acidic mucus (function unknown)
                   Parietal cells: middle region of glands, secrete hydrochloric acid and intrinsic factor
                           Acidic conditions activates pepsin, helps digest protein, and destroys many
                           microorgansisms.
Stomach juices             Intrinsic factor is required for B12 absorption
are 100,000        Chief cells: produce pepsinogen (inactive form of protein digestive enzyme pepsin)
times more         Enteroendocrine cells: produce gastrin, histamine, endorphins, serotinin, cholecystokinin
acidic than                and somatostatin which diffuse into blood.
blood! How is              Gastrin: regulates stomach secretion and mobility
the stomach
protected?
                    1. Thick coating of bicarbonate rich mucus
                    2. Epithelial cells joined by tight junctions
                    3. Glandular cells in gastric pits are impermeable to HCl
                    4. Damaged epithelial cells are replaced by undifferentiated stem cells that reside in gastric
                       pits. Lining of stomach is replaced every 3 – 6 days!



           ∆ Gastric ulcers                        How is the bacterium H. pylori involved in the
                                                   process of ulcer formation in the stomach?
           ∆ Gastritis
           ∆ Heliobacter pylori
           ∆ Pernicious anemia
           Hormone          Function

            Gastrin         In stomach stimulates production of HCl
                            Increases gastric gland activity
          Histamine         Stimulates parietal cells to secrete HCl
          Endorphins        Feeling of saiety
          Serotonin:        In response to food - stimulates stomach muscles to contract
         Somatostatin       Growth hormone inhibitory hormone
        Cholecystikinin     1. Stimulates pancreas to release enzyme rich pancreatic juice
           (CCK):           2. Stimulate gall bladder to release bile
                            3. Relaxes Sphincter of Oddi to allow bile and pancreatic juice enter duodenum
                            4. Reduces contractile force of stomach muscles and rate of emptying.

                                       Digestive Process Occurring in the Stomach

           Already mentioned:
                  HCl: ____________________________________________________________
                  Pepsin: __________________________________________________________
                  Rennin: _________________________________________________________
                  Intrinsic factor: ___________________________________________________
                                       Regulation of Gastric Secretion

Gastric mucosa produces about 3L gastric juice per day
                                                                   The only function of the stomach that is
1. Cephallic phase                                                 essential to life is the production of intrinsic
2. Gastric phase                                                   factor. A person could live without many
                                                                   GI problems even after a total gastrectomy
3. Intestinal phase
                                                                   if given B12 injections
      a. excitatory
      b. inhibitory

Cephalic phase:
  Stimulates stomach activity: smell, sight of food, sound of cooking, thought of food
  Inhibits stomach activity: anything that causes loss of appetite, depression… bad news stinking smells
Gastric phase:
  Stimulates gastric activity: stretching of stomach, food chemicals, caffeine, rising pH, peptides
  Inhibits gastric activity: acidic or fatty chyme, distention or irritation of duodenum
Intestinal phase:
  Stimulates gastric activity: low pH, partially digested foods in duodenum
  Inhibits gastric activity: distention of duodenum, fatty or acidic or partially digested food

 It seems that the same things both stimulate and inhibit gastric activity. What happens is that gastric
activity is initially stimulated by the chyme (peptides and amino acids) that enters it, but is soon after,
when the duodenum is distended, and the acidity (and partially digested fats) is detected, gastric activity
is inhibited so that duodenum can neutralize and process chyme that enters it. The pyloric shpincter
closes tightly to prevent more chyme from leaving the stomach.

                           Regulation and Mechanisms of HCl Secretion
Notice that Gastrin, ACh and Histamine bind to parietal cells to initiate production of HCl

                                  Response of Stomach to filling
Stomach stretches (smooth muscle relaxes) until about 1L of food has been ingested, then pressure rises.

Stomach contractions promote * (~3/min)
    1. Emptying
    2. Mixing (important because _____)

Pyloric valve opens only a small amount when stomach is relaxed and about 30 mL enters pyloric
region. Only liquids and small particles can get through this small opening. When muscles contract,
sphincter closes. It squirts only about 3mL of chyme into the small intestine at a time. The rest is
pushed back into the stomach.

                                     Regulation of Gastric Emptying
Emptying usually takes about 4 hours, but the larger the meal, the longer it takes.
Solids take longer to leave than liquids.
Proteins and fats take longer to leave the stomach.
Carbohydrates leave much more rapidly.                    1. List causes of vomiting
                                                          2. List consequences, such as: acidic to
  ∆ Vomiting (emesis) – to “launch lunch”                 esophagus, loss of fluids (dehydration), loss of
                                                          nutrients, electrolyte imbalance, pH imbalance
                                                          (stomach tries to replace lost acid)
                            The Small Intestine and Associated Structures

The small intestine is the major digestive organ. Almost all absorption occurs here.
Iliocecal valve: where small intestine joins large intestine
Duodenum: relatively immovable. Only about 10 inches long. Bile duct delivers bile here from liver.
              Main pancreatic duct delivers pancreatic juice
Jejunum: “empty” about 8 feet long.
Ileum:       “twisted” about 12 feet long
                                                Mesentery

1. Suspends jejunum and ileum from posterior abdominal wall
2. Nerves
3. Blood vessels

Nutrient rich blood from veins drain into hepatic portal vein, which goes to the liver

                         Microscopic Anatomy: Modifications for Absorption
Surface area:
1. Great length folded into a small space
2. Plicae circularis deep circular folds (~1cm deep) of mucosa and submucosa force chyme to spiral
  through, slowing its movement.
3. Villi “tufts of hair” (~1mm high). In the core of each villus is a capillary bed and a lacteal, which is
  a wide lymph capillary. Food are absorbed through intestinal cells into the capillary blood and lacteal.
4. Microvilli: tiny projections of the plasma membrane of the absorptive cells of the mucosa.

                                         Histology of the Wall
Simple columnar epithelium (absorptive cells)
    Goblet cells – secrete mucus
    Enteroendocrine cells – produce a variety of hormones
    Intraepithelial lypmphocytes (IELs) – immune response
    Intestinal crypts (crypts of Lieberkühn) – intestinal glands in deep pits; secrete intestinal juice
    Paneth cells – deep in pits, secrete lysozyme (antibacterial)
Submucosa contains
    1. Peyer’s patches: aggregations of lymphoid follicles*
    2. Duodenal (Brunner’s) glands: secrete mucus that is alkaline (bicarbonate rich) to neutralize
       acidic chyme entering from stomach.

                                    Gross Anatomy of the Liver (Lab) –
                  Location: right hypochondriac/ epigastric region, below diaphragm.
4 lobes: Right lobe, Left lobe, Caudate lobe, Quadrate lobe

Falciform ligament – separates right and left lobes
                             anchors liver to diaphragm and anterior abdominal wall
Round ligament (ligamentum teres) – fibrous remnant of umbilical vein
Dorsal mesentery and lesser omentum anchor liver to lesser curvature of stomach
Hepatic artery _______________________________________________________
Hepatic portal vein ________________________________________________________
Gall bladder – stores bile until needed
Common hepatic duct – bile leaves the liver through several ducts which fuse to form this one
Cystic duct – drains the gall bladder
Bile duct – fusing of common hepatic duct and cystic duct

                                 Microscopic Anatomy of the Liver
Liver is composed of sesame seed sized functional units called liver lobules. Lobules are composed of
plates of hepatocytes organized like bricks. Hepatocyte plates radiate outward from a central vein like a
book opened all the way around.

Kupffer cells: hepatic macrophages forming part of the sinusoid walls
    Function: _________________

                                      Function of Hepatocytes
     1. Makes bile
     2. Process blood borne nutrients
              ex: glucose to glycogen
              ex: use amino acids to make proteins
     3. Store fat soluble vitamins
     4. Detoxification
               ex: converting ammonia to urea
               ex: converting hydrogen peroxide to oxygen and water

     Function of Bile: Emulsify fats so they may be absorbed

                   Bile is Recycled (Chapter on blood – go back and review this process!)

     Enterohepatic circulation – recycling mechanism for bile
           1. Bile salts are reabsorbed into the blood by the ileum
                                                                                  The liver produces
           2. returned to the liver via the hepatic portal blood
                                                                             500 – 1000 mL of bile a day.
           3. re-secreted in newly formed bile

     Bile Pigments: Bilirubin: chief bile pigment
            Waste product of the heme of hemoglobin when old RBCs are destroyed.

     It is metabolized in the intestine by bacteria to among other things, urobilogen and excreted in
     feces – makes the brown color.*
                                                  Gall Bladder
     Cystic Duct: When the muscular wall contracts, bile is sent through here and then to the bile duct.

                                        Regulation of Bile Release
     CCK (cholecystokinin) - intestinal hormone released to blood is major stimulus for gall bladder
     contraction. CCK is stimulated by fatty chyme entering the duodenum
∆ Gall stones (biliary canaliculi)
∆ Obstructive Jaundice

                                                Pancreas
Pancreatic juice – exocrine product
        Contains enzymes that break down all categories of foodstuffs
        About 1200 – 1500 mL of pancreatic juice is released daily
Pancreatic duct
Acini (acinar cells) - secretory portions of the pancreas.
Exocrine products go through ducts to the duodenum
Zygomen granules - contain digestive enzymes manufactured in the rough ER of acinar cells.
The pancreas makes and releases many digestive enzymes. How does the pancreas keep from
digesting itself? (2)
Pancreatic juice is alkaline so it adjusts the pH of chyme to what is optimum for enzyme function.
Pancreatic Islets (Islets of Langerans) – produce insulin and glucagon.

                               Regulation of Pancreatic Secretion


   HCl stimulates                                     stimulates release of bicarbonate
   release of secretin                                rich pancreatic juice


Entry of proteins & fats to duodenum                   stimulates release of enzyme
stimulates release of CCK                              rich pancreatic juice.

Amount of HCl should = amount of bicarbonate in pancreatic juice. So, the pH of blood after
absorbing food does not change.

Digestive Process Occurring in the Small Intestine

       Proteins and carbohydrates are only partially degraded and lipids have not degraded at all
       in the stomach. So, the greatest part of digestion occurs here.
       Food moves through in 3-6 hours (peristalsis)

Parts of the Large Intestine: Know parts and function.

       Tenia coli: horizontal muscle layer. Three bands that make the large intestine pucker
       Haustra: the pockets caused by the puckering of the intestine.
       Epicolic appendages: small fat filled pouches of visceral peritoneium hanging from the
       surface.
       Cecum: sac-like blind pouch (beginning of large intestine)
       Vermiform appendix: contains lymphoid tissue, part of MALT, twisted structure allows
       enteric bacteria to accumulate and multiply (appendicitis)
       Ascending colon
       Transverse colon
       Descending colon
       Sigmoid colon
       Rectum
       Anus
       Hepatic flexure (Right colic flexure)
       Splenic flexure (Left colic flexure)
       Mesocolon: Mesentery sheets - anchors all but the transverse & sigmoid colon to the
       posterior abdominal wall
       Internal anal sphincter: involuntary
       External anal sphincter: voluntary

Define these functions:

       Haustral contractions
       Mass movements
       Gastrocolic reflex
       Valsalva’s maneuver

Homeostatic Imbalances:

∆ Hemorrhoids
∆ Diarrhea
∆ Constipation
∆ Diverticula
∆ Diverticulosis
∆ Diverticulitis
Hormones:

Hormone                   Source                Site of Action          Function
Salivary amylase
Pancreatic amylase
Lactase
Maltase
Sucrase
Pepsin
Tripsin
Chymotripsin
Bile
Pancreatic lipase
Nucleosidases
Phosphatases

				
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Description: Anatomy and Physiology abdominal distention