Digestive and Gastrointestinal Function PDF

Digestive and Gastrointestinal Function Prepared by: Dr. Sheryl Nakpil-Guevara  Assessment of Digestive and Gastrointestinal Function Bleeding, perforation, obstruction, inflammation, and cancer GI tract is susceptible to many or...

Digestive and Gastrointestinal Function Prepared by: Dr. Sheryl Nakpil-Guevara  Assessment of Digestive and Gastrointestinal Function Bleeding, perforation, obstruction, inflammation, and cancer GI tract is susceptible to many organic diseases Extrinsic factors (stress and anxiety, fatigue and sudden changes in diet)  Anatomic and Physiologic Overview A long, folded tube from the mouth to the anus Includes mouth, esophagus, stomach, small intestine, cecum, colon (large intestine), rectum, and anal canal Move food through the tract by peristalsis for digestion and absorption Esophagus fibromuscular tube, approximately 25cm in length, that transports food from the pharynx to the stomach originates at the inferior border of the cricoid cartilage (C6) and extends to the cardiac orifice of the stomach (T11) Passes through diaphragm at an opening called diaphragmatic hiatus Esophagus Barrett’s Oesophagus Metaplasia of lower esophageal squamous epithelium to gastric columnar epithelium. Cause: Chronic acid exposure from a malfunctioning lower esophageal sphincter. Effect: Acid irritates the esophageal epithelium, leading to a metaplastic change. Common Symptom: Long- term burning sensation of indigestion. Detection: Via endoscopy of the esophagus. Monitoring: Patients are monitored for any cancerous changes. Esophageal Carcinoma Around 2% of malignancies in the UK are esophageal carcinomas. The clinical features of this carcinoma are: Dysphagia – difficulty swallowing. It becomes progressively worse over time as the tumour increases in size, restricting the passage of food. Weight loss There are two major types of esophageal carcinomas: squamous cell carcinoma and adenocarcinoma. Squamous cell carcinoma – the most common Adenocarcinoma – only occurs in the inferior third of the oesophagus and is associated with Barrett’s oesophagus  Esophageal Varices Abnormally dilated sub-mucosal veins in Fig 1.3 - Endoscopic view of oesophageal varices this anastomosis. Cause: Typically caused by increased pressure in the portal system (portal hypertension). Portal Hypertension: Often results from chronic liver disease (e.g., cirrhosis) or portal vein obstruction. Risk: Varices are prone to bleeding; patients often present with haematemesis (vomiting blood). High-Risk Group: Alcoholics are particularly at risk of developing oesophageal varices. The esophagus begins at the level of the cricoid cartilage. Which vertebral level is this? C3 C4 C5 C6 Stomach intraperitoneal digestive organ located between the esophagus and the duodenum Divisions of the Stomach Cardia – surrounds the superior opening of the stomach at the T11 level. Fundus – the rounded, often gas filled portion superior to and left of the cardia. Body – the large central portion inferior to the fundus. Pylorus – This area connects the stomach to the duodenum. It is divided into the pyloric antrum, pyloric canal and pyloric sphincter. The pyloric sphincter demarcates the transpyloric plane at the level of L1. Stomach Greater curvature – forms the long, convex, lateral border of the stomach. Lesser curvature – forms the shorter, concave, medial surface of the stomach. o The lesser curvature gives attachment to the hepatogastric ligament and is supplied by the left gastric artery and right gastric branch of the hepatic artery. Stomach The pyloric sphincter is situated between the pylorus and the duodenum. Controls the exit of chyme from the stomach. An anatomical sphincter with smooth muscle that constricts to regulate stomach content discharge. Stomach Peritoneum: A double-layered membrane within the abdominal cavity. Function: Supports most abdominal viscera and assists with attachment to the abdominal wall. Omenta: Greater and Lesser Omenta: Structures consisting of peritoneum folded over itself (four membrane layers in total). Attachment: Both omenta attach to the stomach and serve as important anatomical landmarks. Gastro-Esophageal Reflux Disease (GERD) digestive disorder affecting the lower esophageal sphincter. It refers to the movement of gastric acid and food into the esophagus. GERD is a common condition, affecting 5-7% of the population. Symptoms include dyspepsia, dysphagia, and an unpleasant sour taste in the mouth. There are three main causes of reflux disease: Dysfunction of the lower esophageal sphincter Delayed gastric emptying Hiatal hernia (see below) Treatment involves lifestyle changes, medication such as a PPI to reduce stomach acid, and as a last resort, surgery. Hiatal Hernia occurs when a part of the stomach protrudes into the chest through the esophageal hiatus in the diaphragm The esophagus opens into the ___________ of the stomach. Pylorus Cardia Fundus Body  Small intestine A 6.5m long organ in the gastrointestinal tract, aiding in digestion and absorption. Location: Extends from the stomach's pylorus to the ileocaecal valve, meeting the large intestine. Divisions: Comprises three parts: duodenum, jejunum, and ileum. Small intestine The Duodenum Most Proximal forming a 'C' shape around the pancreas. Small intestine Small intestine Small intestine  Duodenal Ulcers Erosion of the mucosa in the duodenum, also known as a peptic ulcer when referring to stomach ulcers. Common Location: Most likely to occur in the superior portion of the duodenum. Causes: Helicobacter pylori infection and chronic NSAID therapy. Symptoms and Treatment: Painful but treatable medically. Complications: Complete perforation through the bowel wall, a surgical emergency requiring immediate repair. Peritonitis: Inflammation causing damage to surrounding organs (liver, pancreas, gall bladder). Gastroduodenal Artery Erosion: Leading to haemorrhage and potential hypovolaemic shock. Jejunum and Ileum  Cecum : Most proximal part of the large intestine, located in the right iliac fossa of the abdomen. Location: Lies inferiorly to the ileocecal junction. Palpation: Can be palpated if enlarged due to feces, inflammation, or malignancy. Name Origin: Derived from the Latin word 'caecus', meaning 'blind', referring to its inferior blind-end  Appendix a narrow blind-ended tube that is attached to the posteromedial end of the cecum (large intestine). It contains a large amount of lymphoid tissue but is not thought to have any vital functions in the human body  Appendicitis Inflammation of the appendix, causing acute severe abdominal pain. Tenderness: Most tender at McBurney's point, located one third from the right anterior superior iliac spine to the umbilicus. Cause: Young Individuals: Increase in lymphoid tissue size, occluding the lumen. Adults (30+ years): More likely due to a faecolith blockage. Pain Progression: Starts in the umbilical region, then localizes to the right lower quadrant as inflammation increases. Complications: If untreated, the appendix can necrotize and rupture, leading to peritonitis (inflammation of the peritoneum).  Colon Colon (Large Intestine): Distal part of the gastrointestinal tract. Function: Receives digested food from the small intestine; absorbs water and electrolytes to form feces. Length: Averages 150 cm. Sections: Divided into four parts – ascending, transverse, descending, and sigmoid. Forms an arch around the small intestine.  Ascending Colon The colon begins as the ascending colon, a retroperitoneal structure which ascends superiorly from the cecum. When it meets the right lobe of the liver, it turns 90 degrees to move horizontally. This turn is known as the right colic flexure (or hepatic flexure), and marks the start of the transverse colon  Transverse Colon extends from the right colic flexure to the spleen left colic flexure (or splenic flexure) phrenicocolic ligament transverse mesocolon  Descending Colon Inferiorly towards the pelvis  Sigmoid Colon 40cm long sigmoid colon is located in the left lower quadrant “S” shape sigmoid mesocolon  Rectum most distal segment of the large intestine, and has an important role as a temporary store of faeces. iT begins at the level of the S3 (as a continuation of the sigmoid colon). It is macroscopically distinct from the colon, with an absence of taenia coli, haustra, and omental appendices.  characteristic features The large intestine has a number of characteristic features, which allows it to be distinguished from the small intestine: Attached to the surface of the large intestine are omental appendices – small pouches of peritoneum, filled with fat. Running longitudinally along the surface of the large bowel are three strips of muscle, known as the teniae coli. They are called the mesocolic, free and omental coli. The teniae coli contract to shorten the wall of the bowel, producing sacculations known as haustra. The large intestine has a much wider diameter compared to the small intestine. Digital Rectal Examination  anal canal final segment of the gastrointestinal tract. It has an important role in defecation and maintaining faecal continence. Except during defecation, the anal canal is collapsed by the internal and external anal sphincters to prevent the passage of faecal material. Anal Sphincters The anal canal is surrounded by internal and external anal sphincters, which play a crucial role in the maintenance of faecal continence: Internal anal sphincter – surrounds the upper 2/3 of the anal canal. It is formed from a thickening of the involuntary circular smooth muscle in the bowel wall. External anal sphincter – voluntary muscle that surrounds the lower 2/3 of the anal canal (and so overlaps with the internal sphincter). It blends superiorly with the puborectalis muscle of the pelvic floor.  Haemorrhoids vascular cushions found within the anal canal of healthy individuals, which help with the maintenance faecal continence They can cause bleeding and itchiness, and depending on the severity, can be managed conservatively or surgically.  Abdominal pain Abdominal pain can be broadly classified into three: a. Somatic - can arise from the skin, fascia, muscles, and parietal peritoneum - can be severe and precisely localized - When the origin is on one side of the midline, the pain is also lateralized b. Visceral - arises in abdominal organs, visceral peritoneum, and the mesenteries - stretching of a viscus or mesentery, distention of a hollow viscus, impaired blood supply (ischemia) to a viscus, and chemical damage - dull and poorly localized (colic) c. Referred - feeling of pain at a location other than the site of origin of the stimulus but in an area supplied by the same or adjacent segments of the spinal cord - both of the places are supplied by the same nerves  Function of the Digestive System Digestion Absorptoin Elimination  Function of the Digestive System Reflex Salivation: Eating, sight, smell, or taste of food can trigger salivation. Daily Saliva Production: Approximately 1.5 liters of saliva secreted daily. Salivary Glands: Parotid, submaxillary, and sublingual glands contribute to secretion. Ptyalin (Salivary Amylase): Enzyme that begins starch digestion. Water and Mucus: Components that lubricate food, facilitating chewing and swallowing. Gastric Function Gastric Function Gastric Function Ghrelin hormone produced in the stomach, small intestine, pancreas, and brain "hunger hormone“ Regulates appetite and energy balance stimulates the release of growth hormone promotes fat storage Promotes intake of calories and reduce energy expenditure Leptin signals satiety and inhibiting hunger  Gastric Function Peristalsis propels food to pylorus then to body of stomach due to pyloric sphincter (mechanical) 30 minutes to several hours in stomach (depends on volume, osmotic pressure, and chemical composition) Chyme partially digested food mixed with gastric secretions Hormones and regulators control secretions and motility  Small Intestine Function Duodenum: continues the digestive process Secretions: from pancreas, liver, gallbladder, and intestinal glands Digestive Enzymes: amylase, lipase, and bile Pancreatic Secretions: Alkaline due to high bicarbonate concentration, neutralizing stomach acid Enzymes: trypsin (protein digestion), amylase (starch digestion), lipase (fat digestion)  Small Intestine Function Drainage: Secretions enter the pancreatic duct, then the common bile duct at the ampulla of Vater Bile: Secreted by the liver, stored in the gallbladder, fat digestion Sphincter of Oddi: controls bile flow to duodenum Approximately 1 L/day of pancreatic juice, 0.5 L/day of bile, and 3 L/day of intestinal gland secretions  Small Intestine Function 2 TYPES OF CONTRACTIONS Segmentation contractions Intestinal peristalsis Chyme stays in the small intestine for 3 to 6 hours, (nutrient breakdown and absorption)  Small Intestine Function Villi Small, fingerlike projections lining the entire intestine Function: Produce digestive enzymes and absorb nutrients (main) vitamins and minerals are absorbed unchanged absorption begins in the jejunum via active transport and diffusion Nutrient Absorption Locations: Jejunum: fats, proteins, carbohydrates, sodium, and chloride Ileum: vitamin B12 and bile salts Throughout Small Intestine: magnesium, phosphate, and potassium  Colonic Function Peristalsis pushes residue from terminal ileum to cecum 4 hrs postprandial through ileocecal valve Gut Microbes assist in breaking down waste material 2 types of secretions Bicarbonate neutralizes bacterial end products Mucus protects the colonic mucosa and helps fecal mass adherence slow, weak peristalsis allows efficient reabsorption of water and electrolytes (main fxn) intermittent strong waves propel contents Transit Time: Waste materials reach and distend the rectum in about 12 hours some waste remains for up to 3 days  Waste Products of Digestion Feces consist of undigested food, inorganic materials, water, and bacteria (75% fluid and 25% solid) Brown color due to breakdown of bile by bacteria (STERCOBILIN) odor from chemicals like methane, hydrogen sulfide, and ammonia Gases (150 mL in the GI tract); absorbed into the portal circulation or expelled as flatus  Gut Microbiome Assists in waste breakdown, vitamin synthesis, and immune function Colonization: Begins shortly after birth; established by age 2 Factors Influencing Composition: o Genetics (Bacteroides) o Diet (Lactobacillus, Bifidobacterium, Bacteroides) o Hygiene o Infections (Helicobacter pylori, Salmonella) o Vaccinations o Aging (Bacteroides: Decline ) o Chronic disease (IBD, Crohn’s disease ) o Medications (Clostridium difficile, enterococcus) “pseudomembranous colitis”  Gut Microbiome Protects against pathogens, produces anti-inflammatory metabolites, destroys toxins, prevents pathogen colonization, provokes immune responses Intestinal epithelium: First defense against pathogens; contains innate immune cells (macrophages, dendritic cells, granulocytes, mast cells) and plays a role in T-cell responses Peyer's Patches: Gut-associated lymph tissue involved in antigen processing and immune defense  Health History Pain o Referred abdominal pain o Meals, rest, activity, defecation patterns  Dyspepsia: Upper abdominal discomfort, commonly known as indigestion. Symptoms: Pain, discomfort, fullness, bloating, early satiety, belching, heartburn, and regurgitation. Related to GERD: Dyspepsia frequently presents with heartburn in GERD, which increases with age. Trigger Foods: Fatty Foods: Cause the most discomfort, remaining in the stomach longer. Other Foods: Salads, coarse vegetables, and highly seasoned foods may cause significant GI distress. Distinction: Health care providers may distinguish between gastroesophageal reflux (GER) and GERD, with GERD being more serious and longer-lasting.  Intestinal Gas: Belching: Expulsion of gas from the stomach through the mouth. Flatulence: Expulsion of gas from the rectum. Gas Passage: Gases in the small intestine usually pass into the colon and are released as flatus. Symptoms: Bloating Distention Feeling “full of gas” Excessive Flatulence Related Conditions: Food Intolerance Gallbladder Disease Mallory-Weiss Tear Change in Bowel Habits and Stool Characteristics Past Health, Family, and Social History toothbrushing and flossing routine dental visits history of sore throat or bloody sputum Past and current medication Current nutritional status use of tobacco and alcohol appetite or eating patterns unexplained weight gain or loss psychosocial, spiritual, or cultural factors  Physical Assessment Oral Cavity Inspection and Palpation Tongue Depression: Use a tongue blade to depress the tongue. Press firmly beyond the midpoint to avoid a gagging response. Patient Instructions: Tip the head back. Open the mouth wide. Take a deep breath and say “ah.” Visualization: This flattens the posterior tongue. Allows a full view of the tonsils, uvula, and posterior pharynx. Inspection Criteria: Color Symmetry Evidence of Exudate Ulceration Enlargement Normal Findings: Uvula and soft palate rise symmetrically with a deep inspiration upon saying “ah”. Indicates an intact vagus nerve (10th cranial nerve). Abdominal Inspection, Auscultation, Percussion, and Palpation IAPP PILONIDAL DISEASE  PILONIDAL DISEASE Pilonidal disease is a chronic skin condition that occurs in the crease of the buttocks near the tailbone. Here’s a quick overview: Description: A pilonidal sinus or cyst forms due to hair and skin debris getting trapped in the skin. It can lead to infection and abscesses. Symptoms: Pain or discomfort in the affected area Swelling and redness Fluid drainage (pus) and foul odor Fever in severe cases  Risk Factors: Obesity, family history, and a sedentary lifestyle More common in men aged 15–35 Management and Treatment: Hygiene: Regular cleaning and hair removal to prevent recurrence. Medical Procedures: Incision and drainage for abscesses; more extensive surgery for recurrent cases. Preventive Care: Laser hair removal or shaving the area. Stool Tests Breath Tests Abdominal Ultrasonography Nursing Interventions