DIGESTIVE. CHAPTER 17 Lecture: Part 1 Part 2 BIO 212: ANATOMY & PHYSIOLOGY II

Transcription

1 BIO 212: ANATOMY & PHYSIOLOGY II CHAPTER 17 Lecture: DIGESTIVE Part 1 Part 2 Dr. Lawrence G. Altman Some illustrations are courtesy of McGraw-Hill.

2 SMALL INTESTINE DUODENUM > JEJUNUM > ILEUM 2

3 SMALL INTESTINE 3

4 SMALL INTESTINE 4 PLICAE CIRCULARES Now, can you see the face? J

5 SMALL INTESTINE 5 PLICAE CIRCULARES

6 SMALL INTESTINE 6 INTESTINAL VILLI SEM

7 SMALL INTESTINE DUODENUM (Small Intestine) 10 inches; 25 cm. Small Intestine: Duodenum > Jejunum > Ileum Typical Digestive Tract Layers. DISTINCTIONS: PLICAE CIRCULARES: Folds thrown up from SUBMUCOSA. INTESTINAL VILLI (V): Projections from Mucous Layer into Lumen. Each villus formed from a layer Of Simple Columnar Epithelium. Peyer's Patches: ileum Muscularis Externa LACTEALS within VILLI MM V PC Submucosa Serosa 7

8 SMALL INTESTINE 8

9 SMALL INTESTINE 9 The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. VILLUS VS. MICROVILLI

10 SMALL INTESTINE 10 MICROVILLI ( Brush border ): numerous projections of the PLASMA MEMBRANE of individual cells of the Simple columnar epithelium in mucosa. Result: increase of surface area. Note: plicae circulares and villi formed by GROUPS of cells Microvilli: mostly ABSORBTIVE enzymes in membranes; complete digestion of some proteins and sugars

11 SMALL INTESTINE 11 VILLI MICROVILLI NOT SHOWN ABSORPTIVE CELL LACTEAL BLOOD CAPILLARIES DUODENAL GLANDS GOBLET CELL INTESTINAL CRYPT SUBMUCOSA crypts of Lieberkuhn- Brunner's glands (alkaline) DUODENUM ONLY

12 LARGE INTESTINE 12 MAJOR FUNCTIONS: Mostly, absorption of water; no villi. Absorption of bacterial vitamins (K and some B). Storage of feces. Lubrication: Increased number of goblet cells. WHY? Increased mucus production compensates for water absorption in region. MUCOSA of the LARGE INTESTINE Absorptive cells Goblet cells

13 LARGE INTESTINE 13

14 LARGE INTESTINE 14

15 LARGE INTESTINE 15

16 LARGE INTESTINE 16 ILEOCECAL JUNCTION

17 LARGE INTESTINE 17

18 LARGE INTESTINE 18

19 PANCREAS 19 Tadpole shaped; Main duct > Duodenum HEAD encircled by C- shaped duodenum BODY by greater curvature of stomach TAIL by spleen. CYSTIC DUCT from GALL BLADDER HEPATIC DUCT COMMON BILE DUCT Duodenum MAIN PANCREATIC DUCT AMPULLA of VATER (Sphincter of Oddi controls) HEAD BODY TAIL

20 PANCREAS 20 COMMON BILE DUCT: from cystic (gall bladder) and hepatic (liver) ducts MAIN Duodenum DUCT BODY STOMACH Hormones secreted into blood. HEAD ACINAR DUCT CELLS CELLS EXOCRINE EXOCRINE ISLETS of Langerhans ENDOCRINE TAIL

21 PANCREAS 21

22 PANCREAS 22

23 PANCREAS GLANDULAR REGIONS 23 Pancreatic Juice from: EXOCRINE + ENDOCRINE REGIONS Exocrine Contain acini; synthesize digestive enzymes ACINI arranged in grape - like clusters connected to ducts. Duct epithelium synthesizes bicarbonate solution; alkaline- neutralizes chyme so enzymes may function at proper ph. Endocrine Islets of Langerhans (pancreatic islets) scattered ALPHA CELLS - - > GLUCAGON BETA CELLS - - > INSULIN DELTA CELLS - - > SOMATOSTATIN

24 PANCREAS REGULATION 24 HORMONES CHOLECYSTOKININ (CCK) from duodenum - - > increase in digestive (exocrine) secretions of pancreas SECRETIN from duodenum - - > increase of Bicarbonate (exocrine) production by the pancreas Incidentally, GASTRIN in stomach causes increase in acid production/movement in stomach (Atypical hormone).

25 PANCREAS ENZYMES (related to PROTEIN digestion) 25 Pancreas (Inactive form) Trypsinogen Enterokinase in SI Small Intestine (Active form) Trypsin Pancreas (Inactive form) Chymotrypsinogen Procarboxypeptidase Trypsin Small Intestine (Active form) Chymotrypsin Carboxypeptidase

26 PANCREAS PANCREATIC ENZYMES (related to STARCH & LIPID digestion) 26 Pancreatic amylase Pancreatic lipases (actual lipid digestion in small intestine) Bile salts from bile: emulsification of lipid; increases surface area for lipases

27 PANCREAS 27

28 GALL BLADDER and LIVER 28 GALL BLADDER Stores Liver - produced BILE for digestion. Emulsification of fats. Chief pigment of bile: BILIRUBIN LIVER (4 lobes: 2 major, 2 minor) Production of bile by liver = exocrine function of liver. Detoxification (i.e. alcohol) and glycogen storage Synthesis of blood proteins Phagocytosis (Kupffer macrophages) of old blood cells/some bacteria Blood supply (2 sources): normal arterial (nutrients/oxygen); SINUSOIDS hepatic portal (Digestion products for Detox/protection)

29 GALL BLADDER and LIVER 29 FRONT VIEW INFERIOR VIEW

30 GALL BLADDER and LIVER 30 INFERIOR VIEW

31 GALL BLADDER and LIVER 31 FROM YOUR TEXT:

32 DIGESTIVE TRACT REGULATION 32 Generally- PARASYMPATHETIC STIMULATION INCREASES GI activity (glandular secretion and autonomic movements) SYMPATHETIC STIMULATION INHIBITS GI activity (glandular secretion and autonomic movements) EXCESSIVE/prolonged STRESS- (Sympathetic stimulation) > GI dysfunctions.

33 DIGESTIVE TRACT REGULATION PHASES of GASTRIC SECRETION CEPHALIC PHASE In response to sight/smell of food: Parasympathetic impulses in the VAGUS nerves initiate secretion of gastric juices GASTRIC PHASE Distension of mucosa + protein breakdown stimulates release of GASTRIN in stomach INTESTINAL PHASE Release of INTESTINAL GASTRIN in Duodenum caused by CHYME entrance. Stomach stimulated then INHIBITED (Secretin, GIP) 33

34 FROM YOUR TEXT: 34

35 FROM YOUR TEXT: 35

36 FROM YOUR TEXT: 36

37 FROM YOUR TEXT: 37

38 FROM YOUR TEXT: 38 LAST SLIDE