Digestive System ANAPHY-DIGESTIVE SYSTEM 1 PDF

ENTERIC NERVOUS SYSTEM DIGESTIVE SYSTEM Consists of nerve plexuses within wall of INTRODUCTION digestive tract Consists of: Capable of controlling: o Digestive tract (Ali...

ENTERIC NERVOUS SYSTEM DIGESTIVE SYSTEM Consists of nerve plexuses within wall of INTRODUCTION digestive tract Consists of: Capable of controlling: o Digestive tract (Alimentary tract/canal) o Complex peristaltic o Accessory organs → Glands o Mixing movements Gastrointestinal tract → stomach and o Blood flow to the digestive tract intestines o ▪ Oral cavity PERITONEUM ▪ Pharynx Mesenteries – a connective tissue sheet ▪ Esophagus that hold the organs of the abdominal ▪ Stomach cavity in place ▪ Small intestine a. Lesser omentum – connects the lesser ▪ Large intestine curvature of the stomach to the liver and ▪ Anus diaphragm b. Greater omentum – connects the greater FUNCTIONS OF THE DIGESTIVE SYSTEM curvature of the stomach to the transverse Ingestion – consumption of solid and liquid colon and posterior to the body wall food c. Omental bursa – a cavity or pocket created in the looping back to the Mastication – chewing; mechanical digestion; transverse colon of the greater omentum Propulsion o Swallowing o Peristalsis ORAL CAVITY o Mass Movement “Mouth” o Mixing Divided into 2 regions: o Secretion Vestibule Digestion – chemical digestion; breakdown of Oral cavity proper large organic molecules into smaller ones 1. Lips Absorption – movement of the molecules out Labia of the digestive tract and into the blood or Muscular structures formed mostly by lymphatic system orbicularis oris muscle Elimination – removal of undigested material 2. Palate Separates the oral and nasal cavities HISTOLOGY OF THE DIGESTIVE TRACT Prevents food from passing into nasal cavity during chewing and swallowing 1. MUCOSA/MUCOUS MEMBRANE Hard Palate Innermost tunic Soft Palate Consists of 3 layers 3. Tongue o Inner mucous epithelium Large, muscular organ that occupies most o Lamina propria (Loose CT) of the oral cavity o Muscularis mucosae (Thin outer Frenulum – a thin fold of tissue that layer of smooth muscle) attaches the mouth to the floor anteriorly 2. SUBCOSA Papillae – contains taste buds; Thick connective tissue layer responsible for the sense of taste Contains nerves, blood vessels, lymphatic 4. Teeth vessels and small glands 32 adult teeth (permanent or secondary Meissner plexus → submucosal plexus; teeth) network of nerve cells 20 primary teeth or deciduous 5. Salivary Glands 3. MUSCULARIS Scattered throughout the oral cavity SEROSA/ADVENTITIA Produce saliva, a mixture of serous and mucous fluids 3 pairs o Parotid gland – largest salivary gland o Submandibular gland o Sublingual gland – smallest  Mumps – inflammation of the parotid 2. Mucous neck cells – produce mucus gland caused by a viral infection 3. Parietal cell – produce HCl and intrinsic factor 4. Endocrine cells – produce regulatory chemicals 5. Chief cells – produce pepsinogen (a SWALLOWING precursor of the protein-digesting enzyme pepsin) PHARYNX / THROAT Oropharynx and Laryngopharynx → Regulation of Stomach transmit food 2-3L of Gastric juice are produced each day ESOPHAGUS Movements of the Stomach Muscular tube connecting the pharynx with Stomach Filing the stomach Mixing of Stomach content Esophageal sphincter – upper and lower Stomach emptying ends of the esophagus; regulates the movement of food into and out of the esophagus (lower is also called cardiac sphincter) SMALL INTESTINE Major site of digestion and absorption SWALLOWING PHASE About 6m long Deglutition Modification that increases the surface of the 3 Phases: small intestine a. Voluntary – bolus (mass of food) formed in o Circular folds the mouth o Villi – fingerlike projection of the mucosa b. Pharyngeal – pharynx elevates to receive o Microvilli – cytoplasmic extension the bolus from the mouth c. Esophageal – moving food from the Consists of 3 parts: pharynx to the stomach through peristaltic o Duodenum - 25cm movement o Jejunum - 2.5m o Ileum - 3.5m STOMACH - Ileocecal junction – site where the Storage and mixing ileum connects to the large intestine Gastric juice Secretions of the Small Intestine o Mucus o HCl Mucosa of the small intestine produces o Digestive enzymes secretions that contain primarily mucus, a. Gastroesophageal opening – opening from electrolytes, and water the esophagus into the stomach Intestinal secretions lubricate and protect b. Esophageal sphincter – regulates the the intestinal wall from the acidic chyme entrance of food and the action of digestive enzymes c. Cardiac region – opening in the stomach region Movement in the Small Intestine d. Fundus – most superior part of the stomach Mixing and propulsion of chyme are the e. Body – largest part of the stomach primary mechanical functions of the small f. Pyloric opening – opening into the small intestine intestine Aid of segmental and peristaltic g. Pyloric sphincter – regulates the exit in the contractions accomplished by the smooth stomach muscle in the wall of the small intestine h. Rugae – large folds in the stomach; allows and propagated for short distances stretching Usually takes 3-5 hours for chyme to move from the pyloric region to the ileocecal junction. CELLS OF THE GASTRIC GLANDS 1. Surface mucous cells – lining the gastric pit LARGE INTESTINE and produce mucus Consists of: o Cecum – proximal end of the large intestine; Nutrient interconversion joins with the small intestine at the ileocecal Detoxification junctions Phagocytosis o Appendix – a tube attached to the cecum Synthesis o Colon → Chyme is converted to feces ▪ Ascending colon ▪ Transverse colon GALLBLADDER ▪ Descending colon ▪ Sigmoid colon Saclike structure Located at the inferior surface of the liver RECTUM AND ANAL CANAL Stores bile up to 40-70mL RECTUM A straight muscular tube that begins at the PANCREAS terminal of the sigmoid colon and ends at Endocrine part consists of pancreas islets / the anal canal islets or Langerhans Exocrine part is an acinar gland ANAL CANAL o Acini – produce digestive enzyme Anus – external digestive tract opening Exocrine secretions of the pancreas → Internal anal sphincter – at the superior Pancreatic juice end o Aqueous component and an enzymatic External ana sphincter – at the inferior component end o Delivered to the small intestine through the pancreatic ducts → functions in digestion NOTE! 18-24 hours are required for material to pass through the large intestine DISEASES OF THE DIGESTIVE SYSTEM 1. VOMITING Contraction of the diaphragm and abdominal muscles LIVER Relaxation of the esophageal sphincters to force fully expel gastric contents Processes nutrients, detoxify, and produce Vomiting reflex is initiated by irritation of bile the stomach or small intestine Largest internal organ Located at the right upper quadrant of the 2. PEPTIC ULCER abdomen Lesions in the lining of the stomach or Consists of: duodenum o 2 Major lobes: Due to bacterial infection → Helicobacter ▪ Right lobe pylori ▪ Left lobe o 2 Minor lobes: 3. HEPATITIS ▪ Caudate lobe – smaller lobes Inflammation of liver ▪ Quadrate lobe Causes hepatocyte death Falciform ligament – a connective tissue that Replacement by scar tissue separate the right and left lobe If not treated → Loss of liver function → Hepatic ducts – transport bile out of the liver death Common hepatic duct – forms when the right and left hepatic duct unites 4. HEPATITIS A Common bile duct – forms when the Infectious hepatitis common hepatic duct and cystic duct (in the Transmitted by poor sanitation practices gallbladder) unites Duodenal papilla – a sphincter that regulates the opening into the duodenum 5. HEPATITIS B Serum hepatitis LIVER FUNCTIONS Transmitted through blood and other body Bile production fluids Storage Sexual contact or contaminated needle  Caused by a protozoan → Giardia 6. HEPATITIS C lamblia Blood borne virus Chronic disease leading to cirrhosis 14. DIARRHEA Possibly cancer of the liver Large secretion of water and ions by the intestinal mucosa → irritation, 7. CIRRHOSIS inflammation or infection Damage and death of hepatocytes Moves feces out of the large intestine more Loss of normal liver function rapidly Interferes blood flow through the liver Speeds recovery Most common cause → Alcoholism 15. DYSENTERY 8. GALLSTONES Severe form of diarrhea Due to excess cholesterol in the bile With blood or mucus in the feces Block the release of bile and pancreatic Caused by → Bacteria, Protozoa or enzymes Amoeba Interferes digestion 9. CONSTIPATION EFFECTS OF AGING ON THE DIGESTIVE Slow movement of feces through the large SYSTEM intestine Connective tissue layer → thin Feces → dry and hard Blood supply decreases Increased fluid absorption Reduced motility in Digestive tract Decrease secretion → mucus, pancreatic 10. FOOD POISONING enzymes, bile Caused by ingesting bacteria or toxins Bacteria: o Staphylococcus aureus o Salmonella o Escherichia coli Symptoms → Nausea, abdominal pain, vomiting and diarrhea Severe cases → Death 11. TYPHOID FEVER Caused by a virulent strain → Salmonella typhi Can cross the intestinal wall and invade other tissues Symptoms → Severe fever, headache, and diarrhea Usually transmitted through poor sanitation 12. CHOLERA Caused by bacterium → Vibrio cholerae Contaminated water Bacteria produce a toxin that stimulated the secretion of chloride, bicarbonate and water in to the large intestine → severe diarrhea Loses 12-20L of fluid per day Shock, Circulatory collapse and Death 13. GIARDIASIS