消化系统

  • Gastrointestinal (GI) tract 消化道
    • long tube that extends from the mouth to the anus.
    • About 5-7 m in length
    • Organs of the GI tract
      • oral cavity 口腔
      • pharynx 咽部
      • esophagus 食管
      • stomach 胃
      • small intestine 小肠
      • large intestine 大肠
    • Upper Digestive Tract
      • mouth
      • pharynx
      • esophagus
      • stomach
      • duodenum 十二指肠
    • Lower Digestive Tract
      • jejunum 空肠
      • ileum 回肠
      • the large intestine 大肠
    • Layers of the GI Tract
        1. Mucosa (mucous membrane) 黏膜层
        • absorb and secrete mucus and digestive enzymes
        • a layer of tight epithelium上皮 in direct contact with the contents of the GI tract.
        • a layer of loose connective tissue called the lamina propria固有层. It houses capillaries.
        • a thin layer of smooth muscles黏膜肌层 that help to break down food
        1. Submucosa 黏膜下层
        • consists of dense connective tissue
        • It contains vessels and plexus
        1. Muscularis 肌层
        • Most muscularis consists of smooth muscle in two sheets
          • inner circular fiber (segmentation)
          • outer longitudinal fibers (peristalsis)
        1. Serosa 外膜
        • is visceral peritoneum 内脏腹膜
      • 图
  • Oral cavity
    • Lips
    • Cheek
    • Palate 腭
      • hard palate (maxillae + palatine bones, 2/3)
      • soft palate (1/3)
      • Uvula 腭垂
      • 图
      • 硬腭在前,软腭在后
      • palatoglossal arch 腭舌弓,palatopharyngeal arch 腭咽弓,palatine tonsils腭扁桃体 is between the arches
    • Teeth
    • Tongue
      • The surfaces of the tongue are covered with papillae 舌乳头
      • Taste buds are in the papillae
      • 病-Intubation during Anesthesia 麻醉时插管
        • General anesthesia results in a total relaxation of the muscles.
        • Relaxation of the tongue muscles cause the tongue to fall posteriorly, which may obstruct the airway
    • Salivary gland 唾液腺
      • 3种
        • Parotid glands 腮腺
          • near the ears
          • 20-30%
        • Submandibular glands 下颌下腺
          • below the mandible
          • 60-70%
        • Sublingual glands 舌下腺
          • below the tongue
      • 图
      • Secrete saliva to lubricate润滑 the food The food → bolus食团
      • Chemical digestion of carbohydrates
      • 1.5 L of saliva produced/day
      • 病-Mumps 流行性腮腺炎
        • Mumps virus typically attacks the parotid glands
        • Inflammation and enlargement of the parotid glands accompanied by fever, general malaise, and extreme pain in the throat
  • Pharynx
    • 3部分
      • nasopharynx 鼻咽
        • 有一个opening of auditory tubes
        • pharyngeal tonsil咽扁桃体/adenoid腺样体在这
      • oropharynx 口咽
        • palatine tonsil 腭扁桃体在这
      • laryngopharynx 喉咽
    • pharynx vs. larynx
      • pharynx 咽 is digestive system + respiratory system
      • larynx 喉 is respiratory system
    • 图
    • Epiglottis 会厌
      • The epiglottis seals off the larynx, and the bolus is passed into the esophagus
  • Esophagus
    • a muscular tube that lies posterior to the trachea
    • connect oral cavity to stomach
    • No metabolic changes occur
    • layers
      • 图
      • Muscularis 肌层有两层
        • inner circular fibers 内环行肌纤维
          • segmentation = squeezing
        • outer longitudinal fibers 外纵行肌纤维
          • peristalsis = pushing 蠕动
        • 一个挤一个往前推
    • Muscularis 肌层有2个sphincters括约肌
      • upper esophageal sphincter
        • skeletal muscle
        • regulates the movement of food from the pharynx into the esophagus
      • lower esophageal sphincter
        • smooth muscle
        • regulates the movement of food from the esophagus into the stomach
    • 3处narrowing狭窄
      • first
        • Upper esophageal sphincter
        • Pharyngoesophageal junction
      • second
        • Aortic arch and the left main bronchus cross the esophagus
        • 位置在食管与左主支气管交叉处
        • 主动脉弓和左主支气管压迫形成
      • third
        • Esophageal hiatus in the diaphragm
        • 食管穿过esophageal hiatus膈肌食管裂孔处
      • 图
    • 病-Reflux 胃食管反流
      • stomach contents reflux into the esophagus HCl from the stomach can irritate the esophagus
      • resulting in heartburn (a burning sensation)
  • Stomach
    • 结构
      • Cardia贲ben门
        • deep to the heart
        • adjacent to the esophagus
      • Fundus 胃底
        • dome-shaped area on the top of the stomach
        • where the gas accumulates
      • Body
        • central portion
      • Pylorus 幽门
        • connects to the duodenum via the pyloric sphincter 幽门括约肌
      • 图
    • pyloric sphincter
      • a ring like muscle
      • control the rate of chyme食糜 moving from the stomach into the duodenum
      • preventing reflux
    • 腹膜连接
      • Greater curvature 胃大弯
        • convex border
        • the greater omentum大网膜
        • 胃下面连着大网膜
        • peritoneum continues downward and drapes over the intestines
        • greater omentum attaches the stomach and transverse colon,4 layers,是”beer belly”啤酒肚的成因
      • Lesser curvature 胃小弯
        • concave border of the stomach
        • the lesser omentum小网膜
        • 胃上面连着小网膜
        • peritoneum extends upward to the liver
    • Mucosa黏膜层
      • Gastric rugae 胃皱襞
        • help the stomach to expand
      • Gastric glands 胃腺
        • secrete HCl
        • open into the narrow channels called gastric pits胃小凹
        • Secretions from gastric glands flow into gastric pit and then into the lumen
    • Three layers of smooth muscle
      • an outer longitudinal layer
      • a middle circular layer
      • an inner oblique layer 斜行肌
      • 图
    • 病
      • Helicobacter pylori 幽门螺旋杆菌
        • Pylori (Greek) = gatekeeper
        • Resistant to acid
      • Pyloric Stenosis 幽门狭窄
        • a narrowing of the pyloric sphincter in infants
        • food does not pass through
        • Symptom is projectile vomiting 喷射性呕吐
  • Small intestine
    • 3部分
      • The duodenum十二指肠 (25 cm)
      • The jejunum空肠 (1 m)
      • The ileum回肠 (2 m)
    • duodenum
      • about as long as the width of 12 fingers
      • C-shaped tube
      • starts at the pyloric sphincter of the stomach
      • largely retroperitoneal
      • submucosa黏膜下层 secretes bicarbonate碳酸氢盐 to neutralize gastric acid in the chyme
    • Circular folds 环状襞
      • permanent folds of the mucosa and submucosa
      • extend from the duodenum to the ileum
      • increase surface area for digestion and absorption
      • The epithelial layer of the mucosa consists of simple columnar epithelium
    • Jejunum 相比于 ileum , jejunum have
      • thicker wall
      • more circular folds
      • villi are taller and more numerous
      • more vascular
      • darker in color
      • stronger ability to absorb the nutrients
    • Mesentery 肠系膜
      • binds the jejunum and ileum to the posterior abdominal wall
      • two layers
      • 这个图中大网膜被提溜起来,小肠被横向的扒拉了
    • Functions of the Small Intestine
      • Segmentations mix chyme with the digestive juices
      • After most of a meal has been absorbed, segmentation stops and peristalsis蠕动 begins.
      • Peristalsis pushes chyme forward.
      • Completes digestion of carbs, proteins, and lipids
      • Absorbs about 90% of the nutrients and water
  • Large intestine
    • The large intestine is about 1.5 m long and 6.5 cm in diameter
    • Cecum 盲肠
      • A small pouch about 6 cm long
      • Ileum joins the cecum at ileocecal sphincter 回盲括约肌
      • 病-Intussusception 肠套叠
        • A part of the intestine folds into another section of intestines, resulting in obstruction. (Ileum folds into the cecum)
        • In children, the cause may be linked to excessive peristalsis
        • In adults, the cause may be linked to polyp息肉 or tumor肿瘤
    • Appendix 阑尾
      • Attached to the cecum
      • 病-Acute Appendicitis 急性阑尾炎
        • often caused by bacterial infection
        • Initially, diffuse pain is felt in the periumbilical region肚脐周围
        • the appendix becomes more inflamed and irritates the parietal peritoneum, the pain becomes well localized to the right lower quadrant
    • Colon结肠
      • 4段
        • ascending
        • transverse
        • descending
        • sigmoid
      • 图
      • Features of the cecum and colon
        • Teniae coli 结肠带
          • three bands of longitudinal muscle assist in peristalsis
          • 3条纵向的带子
        • Haustra 结肠袋
          • sacculations of the colon created by the contracting tenia coli
          • 像袋子的凸起
        • Omental appendices 肠脂垂
          • small fat accumulations
          • 黄色的脂肪
        • 图
    • Rectum直肠
      • The rectum is about 15 cm in length and lies anterior to the sacrum骶骨 and coccyx尾骨
      • 图
    • Anal canal 肛管
      • The terminal 2–3 cm of the large intestine is the anal canal.
      • The opening of the anal canal is called the anus.
      • The anus is surrounded by internal and external anal sphincters. 肛门内括约肌 肛门外括约肌
      • 外括约肌是skeletal muscle, voluntary
      • 病-hemorrhoids痔疮
        • The mucosa of the anal canal is in longitudinal folds.
        • The mucosa contains rectal venous plexus.直肠静脉丛
        • If the vessels get swollen and enlarged, the hemorrhoids form.
        • Internal hemorrhoids - hemorrhoids above the dentate line 内痔
        • External hemorrhoids - hemorrhoids below the dentate line 外痔
        • Dentate line 齿状线
  • Liver
    • The liver is inferior to the diaphragm
    • Ligaments around the liver
      • Ligaments towards diaphragm
        • Falciform ligament 镰状韧带
          • attaches the liver to the anterior abdominal wall and diaphragm
          • divides the liver into a large right lobe and a smaller left lobe
          • 把两叶肝分开的//绿色
        • Coronary ligament 冠状韧带
          • 连接肝与diaphragm
          • 在上面,像皇冠一样
        • R/L triangular ligaments 左/右三角韧带
          • 延续冠状韧带,连接后方的肝到diaphragm
      • Ligaments towards organs
        • Lesser omentum小网膜
          • Lesser omentum attaches to the stomach, duodenum and liver.
          • Hepatogastric ligament 肝胃韧带
            • extends from the liver to the lesser curvature of the Stomach
          • Hepatoduodenal ligament 肝十二指肠韧带
            • extends from the liver to the first part of the duodenum
          • 小网膜 = 肝胃韧带 + 肝十二指肠韧带
          • 这个图肝被提溜起来了,底下的小网膜分别连接胃与十二指肠
        • Hepatorenal ligament 肝肾韧带
          • 连着肾//橙色的
        • Round ligament of the liver 肝圆韧带
          • 由胎儿时期的脐静脉闭锁形成
          • 胎儿期脐静脉将母体含氧血从胎盘输送至胎儿肝脏，大部分血液经静脉导管（Ductus venosus）直接汇入下腔静脉，绕过肝窦
          • 前面连着肚脐眼
          • 被夹在镰状韧带中间
    • Porta hepatis肝门
      • Hepatic artery proper 肝固有动脉
      • Hepatic portal vein 肝门静脉
        • 这里有一个非常重要的路径//通常肠系膜下静脉先汇入脾静脉
        • Superior mesenteric and splenic veins unite to form the hepatic portal vein
        • Hepatic portal vein delivers the blood to the liver, 进入肝脏后代谢营养物质,解毒,免疫防御等, 然后在从肝静脉出去
        • 病-Portal hypertension 门脉高压
          • 门静脉血压升高到>12mmHg
          • Ascites 腹水
          • Bleeding 流血
          • Caput Medusae 海蛇头
          • Diminished liver function 肝功能下降
          • Enlarged spleen 脾脏肿大
      • Common bile duct 胆总管
        • common hepatic duct 肝总管 + cystic duct 胆囊管 汇入胆总管
      • Lymphatic vessels
      • Nerves
      • 图
    • Gallbladder 胆囊
      • in a depression of the posterior surface of the liver
      • Part of the gallbladder projects inferiorly beyond the inferior border of the liver
      • 图
      • bile生产后从left/right hepatic duct进入common hepatic duct,不吃饭时候经过cystic duct进入gallbladder存储,吃饭时候流出来进入common bile duct, 最后在hepatopancreatic ampulla处与pancreatic duct汇合, 从major duodenal papilla十二指肠大乳头处进入duodenum
      • 肝胰壶腹结构
    • Functions of the liver and gallbladder
      • Filter blood coming from the digestive tract
      • Detoxification (alcohol and excrete drugs)
      • Produce bile 800-1000 mL/day
      • Synthesize cholesterol 胆固醇
      • Storage site for glycogen (maintain a normal blood glucose level), certain vitamins and minerals (iron and copper) 糖原 ⇌ 葡萄糖
      • The gallbladder stores and concentrates浓缩 the bile.
      • Between meals, after most absorption has occurred, bile flows into the gallbladder for storage because the sphincter of the hepatopancreatic ampulla closes off the entrance to the duodenum
    • Bile 胆汁
      • 成分
        • water
        • Bile salts 胆汁盐
          • emulsification乳化
          • Bile salts breakdown large lipid globules into a suspension of small lipid globules (large surface area)
        • Cholesterol 胆固醇
        • Bilirubin 胆红素
      • 病-Gallstones 胆囊结石
        • Cholesterol stones 胆固醇结石
        • Bilirubin stones/Pigmented stones 胆色素结石
        • insufficient bile salts or excessive cholesterol
        • cholesterol may crystallize to form gallstones
        • obstruction to the flow of bile
  • Pancreas
    • The pancreas lies posterior to the greater curvature of the stomach
    • The pancreas consists of a head, a body, and a tail
    • Pancreatic juices are secreted into the pancreatic duct and accessory duct
    • The pancreatic duct joins the common bile duct and enters the duodenum
    • 图
    • 有两个口
    • Pancreas produces pancreatic juice (a clear, colorless liquid) 1200-1500 mL/day
    • The enzymes in pancreatic juice
      • pancreatic amylase – carbohydrates into oligosaccharides
      • Trypsin - proteins into peptides
      • pancreatic lipase – triglycerides into fatty acids + glycerol
    • 有exocrine与endocrine两个作用
    • 病- neonatal新生儿 (physiological) jaundice黄疸dan
      • Jaundice is a yellowish coloration of the whites of the eyes, skin, and mucous membranes due to a buildup of bilirubin
      • Because the liver of a newborn functions poorly for the first week or so, many babies experience a mild form of jaundice
      • Usually, it is treated by exposing the infant to blue light, which converts bilirubin into substances the kidneys can excret
  • 总结
    • The digestive system has 6 processes:
        1. Ingestion
        • taking food in (eating)
        1. Secretion
        • accessory digestive organs secrete water, acid, buffers, and enzymes into the lumen.
        1. Segmentation and Peristalsis
        1. Digestion
        1. Absorption
        1. Defecation/bowl movement
        • Feces/stool leave the body through the anus.
    • 图
    • 图