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Male/Stomach Cancer/feeding tube/removed gallbladder (Upstream Causes…
Male/Stomach Cancer/feeding tube/removed gallbladder
Upstream Causes
feeding tube used to bypass oral cavity, esophagus, & duodenum
All organs but large intestines are being bypassed
Cannot receive carbs, fats, proteins or nucleic acids
Downstream Effects
Bile cannot be stored because of no gallbladder, cannot emulsify fats
The food he can intake will be limited to what can be digested and absorbed by the large intestine; limiting to food residues for vitamin K & B, absorbing mainly water and electrolytes
Background Information
Alimentary Canal
Mouth (oral cavity)
Ingests
; begins
mechanical breakdown
by chewing; initiates
propulsion
by swallowing; starts
digestion
of polysaccharides
Palate: forms roof of mouth
soft palate: closes off nasopharynx during swallowing with help of uvula
hard palate: formed by palatine bones and palatine processes of maxillae
Pharynx
food passes from mouth into Oropharynx and then into laryngopgharynx
stratified squamous epithelium lining with mucus-producing glands
Esophagus
flat muscular tube that runs from the laryngopharynx to stomach
Gastroesophageal (cardiac) sphincter
surrounds cardial orifice and keeps orifice closed when food is not being swallowed
Esophageal mucosa contains stratified squamous epithelium
changes to simple columnar at the stomach
Stomach
Temporary storage tank that starts chemical breakdown of protein digestion; converts bolus to Chyme
Major Regions
Cardial region: surrounds cardial orifice
Fundus: dome-shaped region beneath diaphragm
Body: the midportion
Pyloric region: terminates in pylorus; continuous with duodenum through pyloric valve.
Greater curvature: convex lateral surface of stomach
Lesser curvature: concave medial surface of stomach
Microscopic Anatomy
Mucosa layer consist of simple columnar epithelium entirely composed of mucous cells
dotted with gastric pits; lead into gastric glands
Gastric gland cells
Enteroendocrine cells: secrete chemical messengers
Chief cells: secrete pepsinogen
Parietal cells secrete: 1. Hydrochloric acid (HC1) 2. Intrinsic factor
Mucosal barrier: protects stomach from harsh conditions
Small Intestine
Ileocecal valve: point at which it joins large intestine
Subdivisions
Duodenum: mostly retroperitoneal; curves around head of pancreas
Jejunum: attached posteriorly by mesentery
Ileum: attached posteriorly by mesentery; joins large intestine at ileocecal valve
Microscopic anatomy
Circular folds
permanent folds that force chyme to slowly spiral through lumen, allowing more nutrient absorption
Villi
Fingerlike projections of mucosa with a core that contains dense capillary bed and lymphatic capillary called a lacteal for absorption
Microvilli
Brush border that contains membrane-bound enzymes called brush border enzyme, used for final digestion of proteins, carbohydrates, and nucleic acids
Large Intestine
Unique features
Teniae coli: three bands of longitudinal smooth muscle in musclularis
Haustra: pocketlike sacs caused by tone of teniae coli
Subdivisions
Cecum: first part of large intestine
Appendix: contains masses of lymphoid tissue; part of MALT of immune system
Colon: several regions, most are retroperitoneal (except transverse and sigmoid)
Ascending, transverse, and descending colon: travels up right side, across, and down left side of abdominal cavity
Sigmoid Colon: S-shaped portion that travels through pelvis
Anal canal: last segment that opens to the body exterior at anus
external anal sphincter: skeletal muscle
Internal sphincter: smooth muscle
Anus
Histology
all digestive organs have the same 4 basic tunics
Muscularis
smooth muscle layer responsible for segmentation and peristalsis
sphincters: thickened circular areas that act as valves
Submucosa:
contains blood and lymphatic vessels; consist of areolar connective tissue
Serosa
outermost layer, made up of the visceral peritoneum
replaced by adventitia in esophagus
Mucosa: innermost layer that lines the lumen
Accessory Digestive Organs
Digestive glands: produce secretions that help breakdown food
Salivary glands
amylase: enzyme that breaks down starch; found in saliva
Minor (intrinsic)
scattered throughout oral cavity; to keep mouth moist
Major (extrinsic)
Parotid: anterior to ear and external to masseter muscle
Submandibular: medial to body of mandible
Sublingual: anterior to submandibular gland under tongue
Serous cells: produce water secretion, enzymes, ions, bit of mucin
Mucous cells: produce mucus which lubricates oral cavity and hydrates foodstuffs
Liver
Pancreas
Teeth
lie in sockets in gum-covered margins of mandible and maxilla
Primary dentition consists of 20 deciduous teeth, or baby teeth
Permanent teeth consists of 32
Shape Classification
Incisors: chisel shaped for cutting
Canines: fang-like teeth that tear or pierce
Premolars (bicuspid): broad crowns with rounded cusps used to grind or crush
Molars: broad crowns, rounded cusps: best grinders
Structure
Root: portion embedded in jawbone
Cement: calcified connective tissue that covers root
Crown: esposed part above gum
Covered by enamel, the hardest substance in the body
Periodontal ligament: forms a fibrous joint called gomphosis
Dentin: bone-like material under enamel
Pulp cavity: surrounded by dentin; contains blood vessels and nerves
Root Canal: extension of pulp cavity into root
Tongue
composed of interlacing bundles of skeletal muscle
forms bolus: mixture of food and saliva
Filiform papillae
gives tongue roughness for friction; do not contain taste buds
Gallbladder
Store and concentrate bile by absorbing water and ions
honeycomb folds that allow it to expand as it fills
muscular contractions release bile via cystic duct, flows into bile duct
Liver
Microscopic anatomy
Liver lobules: hexagonal structural and functional units
Portal triad in each corner of lobule contains:
branch of hepatic artery, supplies oxygen
branch of hepatic portal vein, brings nutrient-rich blood from intestine
Bile duct: receives bile from bile canaliculi
Liver sinusoids: leaky capillaries located between hepatic plates
Stellate macrophages: remove debris and old RBCs
Bile: yellow-green, alkaline solution
Bile salts: cholesterol derivatives, function in fat emulsification and absorption
Bilirubin: pigment formed from heme
cholesterol, triglycerides, phospholipids, and electrolytes
Pancreas
Endocrine function: secretion of insulin and glucagon by pancreatic cells
Composition of pancreatic juice
Watery, alkaline solution to neutralize acidic chyme coming from stomach
Electrolytes; digestive enzymes
Amylase: for carbohydrates
Lipases: for lipids
Protease: for proteins; trypsin
Nucleases: for nucleic acids
Exocrine function: secrete pancreatic juice via duct
Acini: clusters of secretory cells that produce zymogen granules containing proenzymes
Organization of Digestive System
Peritoneum: serous membrane of abdominal cavity
Viscal peritoneum: membrane on external surface of most digestive organs
Parietal peritoneum: membrane that lines body wall
Peritoneal cavity: potential space between the two peritoneums; contains slippery fluid
Mesentery: double layer of peritoneum; layers are fused back to back
Lesser omentum: runs from liver to lesser curvature of the stomach
Falciform ligament: suspends liver from diaphragm and anterior abdominal wall
Mesentery proper: suspends most of small intestine from posterior abdominal wall
Mesocolon: secures parts of large intestine to the posterior abdominal wall
Greater omentum: drapes inferiorly from the greater curvature of the stomach
Intraperitoneal organs: located within the peritoneum
Retroperitoneal organs: located outside (posterior to) the peritoneum