GIT SYSTEM DR AMAL ALBTOOSH ALRAWASHDEH GIT Definition

GIT SYSTEM DR AMAL ALBTOOSH AL-RAWASHDEH

GIT: Definition and function • Alimentary Canal, or Gastro. Intestinal Tract (GIT), or the digestive system • It is a collection of organs, the GI tract and the accessory organs. • Aliment: food; nourishment. • Gastro: relating to the stomach. • Responsible for the food intake, digestion, absorption of nutrients, and elimination of the solid waste. 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 2

Gastrointestinal Tract 01/03/2020 Accessory organs DR AMAL ALBTOOSH AL-RAWASHDEH 3

Oral Cavity v. Mouth : Extends from the lips to the oropharyngeal isthmus • is divided into § Vestibule: Slit like space between the cheeks and the gums § The mouth cavity [Oral cavity proper ]: It is the cavity within the alveolar margins of the maxillae and the mandible v. The oropharyngeal isthmus: • Is the junction of mouth and pharynx. • Is bounded: • Above by the soft palate and the palatoglossal folds • Below by the dorsum of the tongue 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 4

Epiglottis v. The epiglottis is a cartilaginous flap that covers the laryngeal inlet upon swallowing. v Dysfunction of the epiglottis results in dangerous dysphagia [ ]ﻋﺴﺮ ﺍﻟﺒﻠﻊ and could cause aspiration pneumonia [ ﺍﻻﻟﺘﻬﺎﺏ ﺍﻟﺮﺋﻮﻱ ]ﺍﻟﺘﻨﻔﺴﻲ. 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 5

Pharynx v. The pharynx is a muscular tube that connects the nasal cavities to the larynx and oesophagus. v It is common to both The gastrointestinal and respirator y tracts. v. It begins at the base of the skull and ends inferiorly to the CRICOID CARTILAGE (C 6). It is comprised of three parts (from superior to inferior). ; • NASOPHARYNX • OROPHARYNX • LARYNGOPHARYNX 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 6

OESOPHAGUS • The oesophagus is a muscular tube (25 cm ). • It originates at the inferior border of the cricoids cartilage, C 6, extending to the cardiac orifice of the stomach, T 11. • It then enters the abdomen by piercing the diaphragm, through the oesophageal hiatus (HIATUS means: a hole in the diaphragm) at the T 10 level. • The abdominal part of oesophagus is approximately 2 cm long – it terminates by joining the cardiac orifice of the stomach at level of T 11. 01/03/2020 Functions include: 1. Secrete mucus 2. Moves food from the throat to the stomach using muscle movement called peristalsis ﺍﻧﻘﺒﺎﺿﺎﺕ • If acid from the stomach gets in here that’s heartburn. DR AMAL ALBTOOSH AL-RAWASHDEH 7

Terminology v Embryologically: The Primitive gut tube develops during week 3 -4. The tube is divided into 3 distinct sections; foregut, midgut and hindgut. v. The foregut gives rise to the oesophagus, stomach, liver, gallbladder, pancreas and portion of the duodenum. v. Midgut = from ½ way along the duodenum, jejunum, ileum, caecum, appendix, ascending colon to 2/3 rds of the way across the transverse colon v. Hindgut = rest of transverse colon, descending colon, sigmoid colon, rectum and anal canal 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 8

Quadrants • Median plane • Trans-umbilical plane (IV disc between L 3 and L 4) • Right and left upper and lower quadrants 01/03/2020 RU LU RL LL DR AMAL ALBTOOSH AL-RAWASHDEH 9

Regions • R &L hypochondrium • Epigastric • R &L lumbar • Umbilical • R&L inguinal [iliac] sub-costal • Suprapubic (hypogastric) Planes and lines are: Transverse[horizontal] ØSub-costal ØTrans-tubercular Vertical mid-clavicular 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 10

Stomach • J-shaped muscular bag that stores the food, breaks it down into tiny pieces. • Mixes food with Digestive Juices that contain enzymes to break down Proteins and Lipids • Acid (HCl) in the stomach Kills Bacteria. • Food found in the stomach is called Chyme. 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 11

Stomach morphology and covering LO GO 01/03/2020 • Intra-peritoneal • Lesser omentum from lesser curvature • Greater omentum from greater curvature • Layers (outer to inner) = serosa, muscularis externa (outer longitudinal, middle circular, inner oblique), submucosa, mucosa DR AMAL ALBTOOSH AL-RAWASHDEH 12

Stomach morphology oesophagus fundus • Smooth muscular bag from external view • When empty inner surface highly folded = rugae lesser curvature body pyloric antrum greater curvature pyloric valve leading to the 1 st part of the duodenum 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 13

Duodenum 1 s a e cr n pa 2 4 3 01/03/2020 jejunum • C-shaped [25 cm] • Surrounds the head of pancreas • Dorsal mesentery on 1 st part, 2 -4 retro-peritoneal • 1 st part = duodenal cap • 2 nd part = descending entrance of bile and pancreatic ducts at ampulla of Vater • 3 rd part = transverse • 4 th part = ascending to jejunum DR AMAL ALBTOOSH AL-RAWASHDEH 14

Small Intestine v‘Small’ intestine – actually 6 -7 m long v. Jejunum begins at the duodeno-jejunal junction v. Ileum from jejunum to ileocaecal junction v. Attached to mesentery – fan shaped fold of peritoneum that encloses the gut tube v. Allows ingress/egress of vessels, lymph and nerves. 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 15

01/03/2020 Feature Jejunum Ileum appearance upper, red lower, pale wall thicker, more plicae circularis thinner, less plicae bore wider narrower mesenteric vessels 1 or 2 arcades, long branches to wall numerous short branches from 3 or 4 arcades adipose tissue most near root of mesentery all through mesentery lymphoid tissue small amount numerous Peyer’s patches DR AMAL ALBTOOSH AL-RAWASHDEH 16

Features of the large intestine • Colon, large bowel • Absorb water and electrolytes, also store undigested material until expelled from the body • Haustra = sacculations of the wall (small intestine looks smooth) haustra • Appendices epiploicae = fatty tags (none on small intestine) • Teniae coli = longitudinal muscle collected into 3 bands (small intestine smooth muscle continuous layer) teniae coli appendices epiploicae 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 17

Large Intestine • Functions • Bacterial digestion • Ferment carbohydrates Absorbs more water – Concentrate wastes – 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 18

LARGE INTESTINE DESCENDING COLON • 25 cm long from L colic flexure to pelvic brim where it becomes the sigmoid colon • Retro-peritoneal CAECUM • Caecum covered in peritoneum – in R iliac fossa • Opening of ileum has 2 folds = ileocaecal valve (circular muscle of wall of ileum more effective sphincter) SIGMOID COLON • 25 -38 cm long from descending colon in front of L external iliac artery to 3 rd sacral vertebra where it becomes the rectum • Attached to posterior pelvic wall by pelvic mesocolon ASCENDING COLON • 13 cm long from caecum to transverse colon • Retro-peritoneal TRANSVERSE COLON • 38 cm long from right colic to left colic flexures • Hangs from the transverse mesocolon RECTUM • 13 cm long from 3 rd sacral vertebra to 2 cm in front of tip of coccyx where pierces pelvic diaphragm to become anal canal • Left colic flexure also has phrenicocolic ligament from diaphragm 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 19

Vermiform appendix • Anything from 2 -20 cm in length • Immune and bacterial store? • Small mesoappendix mesentery • Tip often retro-caecal • Right iliac region • 1/3 rd along line from anterior superior iliac spine to umbilicus • Pain to umbilicus (T 10) Mc. Burney’s point 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 20

Gut Arterial supply Lymph Pain Foregut coeliac axis pre-aortic at T 12 epigastric Midgut Hindgut 01/03/2020 superior mesenteric pre-aortic at L 1 umbilical inferior mesenteric pre-aortic at L 3 supra-pubic DR AMAL ALBTOOSH AL-RAWASHDEH 21

Areas of dual supply • Duodenum – proximal is foregut (coeliac axis), distal is midgut (superior mesenteric) • Transverse colon – proximal 2/3 rds is midgut (superior mesenteric), distal 1/3 rd is hindgut (inferior mesenteric) • Rectum – upper part is hindgut (inferior mesenteric + portal system), lower part is pelvic (internal iliac and systemic) 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 22

Accessory Organs The Glands • Not part of the path of food, but play a critical role. • Include: Liver, gall bladder, and pancreas • Some authors add salivary glands 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 23

Salivary glands • Major salivary glands: Ø parotid glands Ø submandibular glands Ø sublingual • Minor salivary glands: in lips, cheeks and palate 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 24

Liver • Directly affects digestion by producing bile • Bile helps digest fat • filters out toxins and waste including drugs and alcohol and poisons. anterior surface right lobe left lobe falciform ligamentum teres gall bladder 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 25

Liver morphology posterior surface caudate lobe IVC bare area left lobe right lobe porta hepatis quadrate lobe 01/03/2020 gall bladder DR AMAL ALBTOOSH AL-RAWASHDEH 26

Gall Bladder • Stores bile from the liver, releases it into the small intestine. • Fatty diets can cause gallstones 01/03/2020 DR AMAL ALBTOOSH AL-RAWASHDEH 27

Pancreas v. Endocrine and exocrine gland v head lies in concavity of duodenum, uncinate process behind superior mesenteric vessels v neck narrow area from head to body anterior to origin of superior mesenteric artery vbody across laterally and superiorly vtail passes in lieno-renal ligament and into contact with hilus of spleen 01/03/2020 • Produces digestive enzymes to digest fats, carbohydrates and proteins • Regulates blood sugar by producing insulin DR AMAL ALBTOOSH AL-RAWASHDEH 28

Spleen • • 01/03/2020 Largest single mass of lymphoid tissue in the body Lies inferior to ribs 9 -11 in the left hypochondrium (posterior to stomach) Gastro-splenic ligament carrying short gastric and gastro-epiploic vessels Lienorenal ligament to left kidney carrying splenic vessels and tail of pancreas DR AMAL ALBTOOSH AL-RAWASHDEH 29

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