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消化系統二

Digestive Systems • Upper left quadrant of abdomen • It continues the mechanical and chemical digestion of the bolus • The bolus eventually is processed into a pastelike soup called chyme • Possesses three layers of muscle to aid in the mechanical processing of ingested materials • Secretion of pepsin begins protein digestion – Functions under acidic conditions • Food remains in stomach approximately 4 hours 授課教師:洪君琳 醫學綜合大樓 (後棟) 8樓解剖學科 分機: 3267


Stomach • Upper left quadrant of abdomen • It continues the mechanical and chemical digestion of the bolus • The bolus eventually is processed into a pastelike soup called chyme 食糜 • Possesses three layers of muscle to aid in the mechanical processing of ingested materials • Secretion of pepsin begins protein digestion – Functions under acidic conditions • Food remains in stomach approximately 4 hours


• The inferior border of the stomach is the greater curvature and the superior border is the inferior curvature. • The internal surface of the stomach is thrown into folds called 賁門切跡 gastric folds (rugae). • Regions of the stomach 賁門區 – Cardiac region – Fundus 胃底 – Body 胃體 – Pyloric region 幽門區 胃角切跡

The Stomach

幽門狹窄


Cardia

Fundus

Esophagus Serosa

Muscularis externa Longitudinal layer Circular layer Oblique layer 小彎

Body Lumen

Lesser curvature

Rugae of mucosa 皺襞 Greater curvature 大彎

The Stomach Duodenum (a)

幽門管 Pyloric Pyloric canal antrum 幽門竇 Pyloric sphincter (valve) at pylorus 在幽門的幽門括約肌


• Are erosions of the mucosa of a region of the alimentary canal • Gastric ulcers 幽門區 – Occur in pyloric region of the stomach • Duodenal ulcers – Occur in duodenum of the small intestine • Caused by Helicobacter pylori 幽門螺旋菌 消化性潰瘍 • H. pylori Peptic Ulcers – Acid-resistant – Binds to gastric epithelium • Induces oversecretion of acid and inflammation Bacteria

Mucosa layer of stomach (a) A gastric ulcer lesion

(b) H. Pylori bacteria


Microscopic Anatomy of the Stomach • Epithelium is simple columnar epithelium 單層柱狀 胃小凹 • Mucosa dotted with gastric pits 胃腺 – Gastric glands—deep to gastric pits

Surface epithelium

Mucosa

Submucosa (contains submucosal plexus) Muscularis externa (contains myenteric plexus) Serosa

Lamina propria Muscularis mucosae Oblique layer Circular layer Longitudinal layer Stomach wall

(a) Layers of the stomach wall, longitudinal section


杯狀細胞 goblet cell Gastric pits

Microscopic Anatomy of the Stomach • Gastric glands of fundus and body – Mucous neck cells 頸黏液細胞 • Secrete a special mucus Gastric – Parietal (oxyntic) cells pit 壁(泌酸)細胞 • Secrete hydrochloric acid and 胃內在因子 gastric intrinsic factor 主(酶原)細胞 Gastric – Chief (zymogenic) cells 胃蛋白酶原 gland • Secrete pepsinogen – Pepsinogen is activated to pepsin when it encounters acid in the gastric glands 腸內分泌細胞

― Enteroendocrine cell G cell; gastrin

Surface epithelium (mucous cells)

Mucous neck cells Parietal cell

Chief cell

Enteroendocrine cell

(b) Enlarged view of gastric pits and gastric glands


The Small Intestine—Gross Anatomy • Longest portion of the alimentary canal • Site of most enzymatic digestion and absorption (12 hr) • 6 meters long in an unembalmed cadaver but much shorter in a living individual due to muscle tone • Three subdivisions – Duodenum (25 cm) 十二指腸 – Jejunum (2.5 m) 空腸 – Ileum (3.6 m) 迴腸


Duodenum Superior part 上方部

• C-shaped • Upper right quadrant

Suspensory muscle (ligament of Treita) Duodenojejunal flexure 十二指腸空腸曲 descending part 下降部

inferior part ascending part 上升部 下方部


• Receives digestive enzymes and bile 總膽管 • Main pancreatic duct and common bile duct enter duodenum 主胰管 – Sphincters control entry of bile and pancreatic juices •The major duodenal papilla is the site where bile and pancreatic secretions enter the duodenum Bile duct and sphincter

Accessory pancreatic duct

The Duodenum Gallbladder

Major duodenal papilla 肝胰壺腹及括約肌 Hepatopancreatic ampulla and Duodenum sphincter

Pancreas

十二指腸大乳頭

Main pancreatic duct and sphincter


Jejunum • Middle portion of the small intestine • Primary region for chemical digestion and nutrient absorption

Ileum • Last segment of the small intestine • Distal end terminates at the ileocecal valve, a sphincter that controls the entry of materials into the large intestine


The Small Intestine—Microscopic Anatomy • Modifications for absorption – Circular folds (plicae circulares) 環狀皺襞 • Transverse ridges of mucosa and submucosa Muscle – Villi 絨毛 layers • Finger-like projections of the Circular folds mucosa 單層柱狀上皮 • Covered with simple Villi columnar epithelium – Microvilli 微絨毛 • Further increase surface area for absorption

Vein carrying blood to hepatic portal vessel

Lumen


Histology of the Intestinal Wall • Absorptive cells 吸收細胞(enterocyte腸細胞) – Uptake digested nutrients Absorptive 杯狀細胞 • Goblet cells cells 乳糜管 – Secrete mucus Lacteal that lubricates Goblet cell chyme 潤滑食糜 Blood • Enteroendocrine capillaries 腸內分泌細胞 cells Mucosa associated – Secrete hormones lymphoid tissue • Intestinal crypts 腸隱窩 Intestinal – Epithelial cells crypt Intestinal stem cell secrete intestinal Muscularis mucosae 腸液 juice Duodenal gland

Microvill (brush border)

Vilus

Enteroendocrine cells Venule Lymphatic vessel Submucosa


• • • •

Digested residue contains few nutrients 12-24hr 直徑: Large intestine (6.5 cm) vs. small intestine (2.5 cm) Small amount of digestion by bacteria Main functions The Large Intestine – Absorb water and electrolytes 大規模蠕動運動 • Mass peristaltic movements force feces toward the rectum • Subdivided into 闌尾 結腸 直腸 肛管 盲腸 – Cecum, vermiform appendix, colon, rectum, anal canal


• Special features of large intestine – Teniae coli 結腸帶X3 • Thickening of longitudinal muscularis – Haustra 結腸袋 • Puckering created by teniae coli – Epiploic appendages 腸脂垂 • Fat-filled pouches of visceral peritoneum • Cecum – Blind pouch – Beginning of large intestine 迴盲瓣 – Ileocecal valve represents junction between small intestine and large intestine • Vermiform appendix – Contains lymphoid tissue – Neutralizes pathogens


• Colon – Divided into distinct segments • Ascending: right colic flexure (hepatic flexure) • Transverse: transverse mesocolon, left colic flexure (splenic flexure) • Descending: Makes contact with iliac fossa • sigmoid colon: S, sigmoid mesentery


左結腸(脾曲)

Left colic (splenic) flexur Transverse mesocolon Epiploic appendages

右結腸(肝曲)

Right colic (hepatic) flexure 橫結腸

Transverse colon

降結腸

Haustrum

Descending colon

升結腸

Ascending colon IIeum 迴盲瓣

IIeocecal valve

Teniae coli

Cecum

Sigmoid colon

Vermiform appendix

乙狀結腸

Rectum Anal canal

External anal sphincter


• Rectum – Descends along the inferior half of the sacrum – Muscular tube that readily expands to store accumulated fecal material prior to defecation 直腸橫褶 – Three thick, transverse folds of the rectum, 直腸瓣 called rectal valves, ensure that fecal material is retained during the passage of gas – The rectum terminates at the anal canal • Anal canal 3cm – The last subdivision of the large intestine – Lined with stratified squamous epithelium


Hemorrhoidal veins

Anal Canal

Levator ani muscle

Anal canal 肛管

外肛門括約肌

External anal sphincter 內肛門括約肌

Internal anal sphincter 肛柱 Anal columns

肛瓣

Anal valves

梳狀腺

Pectinate line

肛竇(分泌黏液)

Anal sinuses Anus

• Passes through an opening in the levator ani muscles of the pelvic floor • Anal columns line the internal surface of the anal canal • Anal sinuses secrete mucin for lubrication during defecation • Internal and external anal sphincters open and close the anal canal during defecation


Microscopic Anatomy of Large Intestine • Villi are absent • Contains numerous goblet cells 隱窩 • Intestinal crypts—simple tubular glands • Lined with simple columnar epithelial tissue – Epithelium changes at anal canal • Becomes stratified squamous epithelium

Absorptive cells

Lamina propria Goblet cells Intestinal crypts

Muscularis mucosae


Accessory Digestive Organs Includes the following organs: • Liver; gall bladder; pancreas; biliary apparatus

Liver • Largest gland in the body • – Performs over 500 functions – Digestive function • Bile production

Comprised of four incompletely separated lobes: right lobe; left lobe; caudate lobe; quadrate lobe

Q L R

R

C

L


Liver

Diagragmatic surface 橫膈面

鐮狀韌帶 圓韌帶 (ligamentum teres)


Visceral Surface of the Liver “裂”內的靜脈韌帶 Ligamentum Venosum (in fissure) Caudate lobe of liver 尾葉 Left lobe of liver

內臟面

Bare area

Sulcus for inferior vena cava

肝門 Porta hepatis containing hepatic artery (left) and hepatic portal vein (right) Quadrate lobe of liver 方葉 Ligamentum teres

Hepatic vein (cut) Bile duct (cut) Right lobe of liver Gallbladder

(a)


• Embedded on the inferior surface of the liver • Functions to collect and concentrate bile • The cystic duct connects the gall bladder to the common bile duct

Gall Bladder


Pancreas • Has both endocrine and exocrine functions • Exocrine functions involve secreting digestive enzymes and bicarbonate, collectively called pancreatic juices, into the duodenum via the pancreatic duct into the duodenum

Bile duct and sphincter

Accessory pancreatic duct 副胰管

tail

Mucosa with folds Gallbladder

Major duodenal papilla

body head

Hepatopancreatic ampulla and sphincter Duodenum

Tail of pancreas Pancreas Jejunum

主胰管

Main pancreatic duct and sphincter Head of pancreas


• Cirrhosis of the liver -portal hyper tension ● Alcoholic liver disease (60% to 70%) ● Viral hepatitis (10%) ● Biliary diseases (5% to 10%) ● Genetic hemochromatosis (5%) ● Cryptogenic cirrhosis (10% to 15%)

Portosystemic anastomosis -esophagus (lef. Gastric v. – esophageal v. (azygos v.)) -Rectum (sup. Rectal v.-mid & inf rectal v. (內髂)) -paraumbilical (paraumbilical v.-subcutaeous v. of ant. Abdominal wall (外髂))


Caput medusae Colorectal cancer

anatomy(digestion)  

class notes of anatomy

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