ppt Part 2: 10 Slides Excluding Assignment And Photos C. Liver READ 1. High regeneration capacity 2. Gross Anatomy a. *4 lobes: Give location of and which side it is best seen i) *Right ii) *Left Sternum Bare area Nipple Falciform ligament Liver Left lobe of liver Right lobe of liver Round ligament (ligamentum teres) Gallbladder (a)

a. 4 Lobes … Caudate Lobe Round Ligament Quadrate Lobe Gallbladder

iii) *Caudate small, seen mainly postero-superiorly; next to Vena Cava B. Liver … iii) *Caudate small, seen mainly postero-superiorly; next to Vena Cava iv) *Quadrate small and mainly seen postero-inferiorly below Left Lobe and next to gallbladder (Memory Aid: “q” like “g”) b. Ligaments Falciform Ligament: separates Right & Left lobes anteriorly and suspends liver from diaphragm Round ligament (ligamentum teres) – remnant of umbilical Vein READ Liver Falciform ligament Right lobe of liver Left lobe of liver Round ligament (ligamentum teres) Gallbladder (a)

*Bile Duct (Previous Name: Common Bile Duct) *Common Hepatic Ducts *Cystic Duct *R & L Hepatic Right and left hepatic ducts of liver Cystic duct Common hepatic duct Bile duct Gallbladder (bile storage) Pancreas Jejunum

*Hepatic Vein  Inferior Vena Cava d. Blood Vessels give where they are coming from and where they are going to *Hepatic Artery *Hepatic Portal Vein *Hepatic Vein  Inferior Vena Cava Bare area Lesser omentum (in fissure) Caudate lobe of liver Left lobe of liver Sulcus for inferior vena cava Porta hepatis containing hepatic artery (left) and hepatic portal vein (right) Hepatic vein (cut) Bile duct (cut) Right lobe of liver Quadrate lobe of liver Gallbladder Ligamentum teres (b)

3. Microscopic Anatomy of Liver a. Liver lobules = hexagonal structural and functional units *Hepatocytes: liver cells with a lot of what organelle? Functions: (1) produce bile (900 ml per day) (2)Process nutrients from blood (glucose  glycogen) (3) Store fat soluble vitamins (4) Detoxification (amino acids  ammonia  urea) ii) Liver sinusoids = leaky capillaries between hepatic plates Carry nutrient rich/oxygen poor blood from Hepatic Portal V. and oxygenated blood from Hepatic A. Kupffer cells (hepatic macrophages) in sinusoid walls READ LOBULE Portal Triad Sinusoid Capillaries Plates of Hepatocytes Central Vein

3. Microscopic Anatomy of Liver … b. Small Blood Vessels and Ducts: Portal triad = Bile Duct, Hepatic Arteriole (branch of Hepatic A.), Hepatic Venule (branch of Portal V.) – The blood vessels branch into sinusoids and mix; then Blood flows toward central vein; -- Bile from Hepatocytes  Bile canaliculi  Bile Ducts ii) Central Vein drains filtered blood leaving hepatocytes and moves it to the Hepatic Veins READ Hepatic Vein Bile canaliculi Portal Triad Plates of Hepatocytes Central Vein

a) * Function: and is it an enzyme? 3. Bile a) * Function: and is it an enzyme? b) Bile Composition: Bile Salts (acids derived from cholesterol) Pigments: bilirubin– break down product of RBCs Cholesterol Phospholipids READ c) Bile Salts Recycled: reabsorbed in ileum then

d. *Health– Gallstones = e. Control bile production Secretin: released from intestinal cells when they are exposed to fats  stimulates Liver to increase production of bile Recycled bile salts: as increase and recycle back to liver = major stimuli to liver for increased bile production READ

D. The Gallbladder *= describe and give duct b) *Function: c) Control: Cholecytokinin (CCK) released from duodenum when stimulus of acidic fatty chyme enters duodenum Causes contraction to release bile READ Gallbladder No digestion if: Hepatopancreatic Sphincter closed—then the bile backs up into gallbladder & is stored

E. Pancreas *Parts: b) *Location: c) Exocrine function: Pancreatic Juice i) Acini = round cluster of secretory cells that secrete enzymes; enzymes need alkalinity ii) Duct cells secrete bicarbonate: neutralizes stomach acid to pH of 8 Pancreas READ Pancreatic Duct Small duct Acinar cells Tail Head of Pancreas

Pancreas Islets Acinar cells

Pancreatic Duct, branch Pancreas Acinar cells Pancreatic Duct, branch

(1 of many brush border enzymes) Exocrine Function … READ iii) Enzymes: Pancreas secretes enzymes for all 4 major Biochemical groups (food molecules) Amylase, Lipases, Nucleases Proteases = secreted inactive (activated in duodenum) d) Control: Secretin target Duct cells AND Cholecystokinin targets acinar cells Epithelial Cells of Duodenum with Membrane-bound enzymes (1 of many brush border enzymes) Amylase Lipases Proteases Nucleases

READ Pancreas Endocrine Function: hormones insulin & glucagon from cells in the Islets of Langerhans Acinar cells

F. Large Intestine 1. Parts a) *Parts = list 2. *Gross Anatomy Teniae coli – Reduction of the 3 bands of longitudinal smooth muscle in muscularis to a thin band READ Transverse colon Epiploic appendages Haustrum Descending colon Ascending colon IIeum Teniae coli IIeocecal valve Sigmoid colon Vermiform appendix Cecum Rectum Anal canal

*Epiploic appendages - fat-filled pouches of visceral peritoneum F. Large Intestine … 2. Gross Anatomy *Haustra = *Epiploic appendages - fat-filled pouches of visceral peritoneum a) *Veriform describe Appendix Transverse colon Epiploic appendages Haustrum Descending colon Ascending colon IIeum Teniae coli IIeocecal valve Sigmoid colon Vermiform appendix Cecum Rectum Anal canal

*Parts: List and describe location b. *Cecum describe c. Colon *Parts: List and describe location d. Rectum & Anal Canal 3 rectal valves stop feces from being passed with gas READ

*Sphincter name and give function d. Rectum and Anus … Rectum Rectal valve *Rectum describe *Anal Canal describe *Sphincter name and give function Hemorrhoidal veins Anal canal

3. Bacterial Flora Enter from small intestine or anus READ 3. Bacterial Flora Enter from small intestine or anus Ferment indigestible carbs Release irritating acids and gases Synthesize B complex vitamins and vitamin K

4. Microscopic Anatomy a) Mucosa *Tissue: Anal Canal has stratified squamous ET

Colon

5. Functions of the Large Intestine READ 5. Functions of the Large Intestine Vitamins, water, and electrolytes reclaimed Major function = propel feces to anus Slow segmentation by haustra gradually move contents distally

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arteriole, hepatic venule, and bile duct Review Questions The digestive function of the liver is to produce _______ which functions in the chemical digestion of _________. Liver _________ are the functional units of the liver which contain a central vein and peripheral portal __________ with what 3 components? bile lipids lobules triads arteriole, hepatic venule, and bile duct

Review Questions CCK ________ stimulates the release of pancreatic enzymes and __________ of the gall bladder while ________ stimulates the release of __________ - rich pancreatic secretion to neutralize acidic _________ from the stomach. Enzymes that break down __________ must be activated in the duodenum. contraction secretin bicarbonate chyme proteins

Review Questions Motilin _________ is released during the ‘fasting state’ by the __________ and initiates the ___________ motility complex that gradually moves residues to the _________ ____________. Conscious control of defecation is via relaxation of the ___________ anal sphincter. duodenum migrating large intestine external

Review Questions Amylase, lactase, and sucrase (among others) are enzymes that help break down ___________. Amino acids are absorbed from the lumen via __________ transport. Fats are first _________ by bile salts, then travel as ________ between microvilli, and are finally converted to _____________ in the absorptive cells before being carried away in the ________ as part of the lymph. carbohydrates active emulsified micelles chylomicrons lacteals

Bile and Pancreatic Juice Regulation 1 Chyme in duodenum = release of cholecystokinin (CCK) + secretin from duodenal enteroendocrine cells. Figure 23.28, step 1

CCK and secretin potentiate one another 1 Chyme enter- ing duodenum causes release of cholecystokinin (CCK) and secretin from duodenal enteroendocrine cells. 2 CCK (red dots) and secretin (yellow dots) enter the bloodstream. CCK and secretin potentiate one another CCK = secretion of enzyme-rich pancreatic juice. Secretin = secretion of HCO3–-rich 3 Figure 23.28, step 3

secretin = liver produces bile more rapidly. Chyme enter- 1 Chyme enter- ing duodenum causes release of cholecystokinin (CCK) and secretin from duodenal enteroendocrine cells. 4 Bile salts returning from ileum + secretin = liver produces bile more rapidly. 2 CCK (red dots) and secretin (yellow dots) enter the bloodstream. 3 CCK induces secretion of enzyme-rich pancreatic juice. Secretin causes HCO3–-rich Figure 23.28, step 4

gallbladder contracts + hepatopancreatic sphincter 1 Chyme enter- ing duodenum causes release of cholecystokinin (CCK) and secretin from duodenal enteroendocrine cells. 4 Bile salts and, to a lesser extent, secretin transported via bloodstream stimulate liver to produce bile more rapidly. 5 CCK also = gallbladder contracts + hepatopancreatic sphincter relaxes; bile enters duodenum. 2 CCK (red dots) and secretin (yellow dots) enter the bloodstream. 3 CCK induces secretion of enzyme-rich pancreatic juice. Secretin causes HCO3–-rich Figure 23.28, step 5

gastric phases, vagal nerve causes weak contractions of gallbladder. 1 Chyme enter- ing duodenum causes release of cholecystokinin (CCK) and secretin from duodenal enteroendocrine cells. 4 Bile salts and, to a lesser extent, secretin transported via bloodstream stimulate liver to produce bile more rapidly. 5 CCK (via bloodstream) causes gallbladder to contract and hepatopancreatic sphincter to relax; bile enters duodenum. 2 CCK (red dots) and secretin (yellow dots) enter the bloodstream. 3 CCK induces secretion of enzyme-rich pancreatic juice. Secretin causes HCO3–-rich 6 Cephalic and gastric phases, vagal nerve causes weak contractions of gallbladder. Figure 23.28, step 6

• Glucose/galactose absorbed via cotransport w/ Na+. Carbohydrate digestion Enzyme(s) and source Site of action Foodstuff Path of absorption • Glucose/galactose absorbed via cotransport w/ Na+. Starch and disaccharides Salivary amylase Mouth • Fructose passes via facilitated diffusion. Pancreatic amylase Small intestine Oligosaccharides and disaccharides • All monosaccharides leave epithelia via facilitated diffusion, enter capillary blood in villi, and transported to liver via hepatic portal vein. Brush border enzymes in small intestine (dextrinase, gluco- amylase, lactase, maltase, and sucrase) Small intestine Lactose Maltose Sucrose Galactose Glucose Fructose

peptidase) + brush border enzymes (carboxypeptidase, Lumen of intestine Amino acids of protein fragments Brush border enzymes Pancreatic proteases Apical membrane (microvilli) 1 Proteins digested to amino acids by pancreatic proteases (trypsin, chymotrypsin, carboxy- peptidase) + brush border enzymes (carboxypeptidase, aminopeptidase, dipeptidase). Na+ Absorptive epithelial cell Na+ 2 amino acids absorbed by active transport into absorptive cells. Amino acid carrier Active transport Passive transport 3 Amino acids leave villus by facilitated diffusion, enter capillary via intercellular clefts. Capillary Figure 23.33

• Amino acids are absorbed by cotransport with sodium ions. Protein Protein digestion Enzyme(s) and source Site of action Foodstuff Path of absorption • Amino acids are absorbed by cotransport with sodium ions. Protein Pepsin (stomach glands) in presence of HCl Stomach • Some dipeptides and tripeptides are absorbed via cotransport with H+ and hydrolyzed to amino acids within the cells. Large polypeptides Pancreatic enzymes (trypsin, chymotrypsin, carboxypeptidase) Small intestine + Small polypeptides, small peptides • Amino acids leave the epithelial cells by facilitated diffusion, enter the capillary blood in the villi, and are transported to the liver via the hepatic portal vein. Brush border enzymes (aminopeptidase, carboxypeptidase, and dipeptidase) Small intestine Amino acids (some dipeptides and tripeptides) Figure 23.32 (2 of 4)

• Fatty acids and monoglycerides enter the intestinal cells via Fat digestion Enzyme(s) and source Site of action Foodstuff Path of absorption Unemulsified fats • Fatty acids and monoglycerides enter the intestinal cells via diffusion. Emulsification by the detergent action of bile salts ducted in from the liver Small intestine • Fatty acids and monoglycerides are recombined to form triglycerides and then combined with other lipids and proteins within the cells, and the resulting chylomicrons are extruded by exocytosis. Pancreatic lipases Small intestine • The chylomicrons enter the lacteals of the villi and are transported to the systemic circulation via the lymph in the thoracic duct. Monoglycerides and fatty acids Glycerol and fatty acids • Some short-chain fatty acids are absorbed, move into the capillary blood in the villi by diffusion, and are transported to the liver via the hepatic portal vein. Figure 23.32 (3 of 4)

by active transport via membrane carriers. Nucleic acid digestion Enzyme(s) and source Site of action Foodstuff Path of absorption Nucleic acids • Enter intestinal cells by active transport via membrane carriers. Pancreatic ribo- nuclease and deoxyribonuclease Small intestine • Absorbed into villi capillaries, transported to liver via hepatic portal vein. Brush border enzymes (nucleosidases and phosphatases) Small intestine Pentose sugars, N-containing bases, phosphate ions Figure 23.32 (4 of 4)

Processing in Small Intestine E. Regulation of Bile & Pancreatic Secretion and Entry into the Sm. Intest. Regulation of Gastric Secretion-- REVIEW Stimulatory events Inhibitory events Sight and thought of food 1 Cerebral cortex Lack of stimulatory impulses to parasym- pathetic center Cerebral cortex Loss of appetite, depression 1 Cephalic phase Conditioned reflex Stimulation of taste and smell receptors 2 Hypothalamus and medulla oblongata Vagus nerve Stomach distension activates stretch receptors 1 Vagovagal reflexes Medulla Vagus nerve Gastrin secretion declines G cells Excessive acidity (pH <2) in stomach 1 Gastric phase Local reflexes Overrides parasym- pathetic controls Sympathetic nervous system activation Emotional upset 2 Food chemicals (especially peptides and caffeine) and rising pH activate chemoreceptors 2 G cells Gastrin release to blood Stomach secretory activity Entero- gastric reflex Local reflexes Distension of duodenum; presence of fatty, acidic, hypertonic chyme, and/or irritants in the duodenum 1 Presence of low pH, partially digested foods, fats, or hypertonic solution in duodenum when stomach begins to empty 1 Intestinal (enteric) gastrin release to blood Vagal nuclei in medulla Brief effect Intestinal phase Pyloric sphincter Release of intestinal hormones (secretin, cholecystokinin, vasoactive intestinal peptide) Distension; presence of fatty, acidic, partially digested food in the duodenum 2 Processing in Small Intestine Stimulate Inhibit Figure 23.17

F. Digestion in the Small Intestine 1. Overall Function: finish digestion/absorb nutrients & water 2. Hypertonic Chyme moved slowly into Duodenum from stomach via slow peristalsis (3ml) Chyme = acidic and hypertonic w/ partially digested carbohydrates/proteins & undigested fats Pancreatic juices neutralize chime & make it isotonic 3. Segmentation Mixes chime w/ bile & pancreatic secretions and moves chime slowly towards Ileum

E. Regulation of Bile & Pancreatic Secretion and Entry into the Small Intestine Continuation after intestinal phase of Stomach: 1. Cholecystokinin & Secretin released Stimulus = Chyme entering Duodenum CCK & Secretin potentiate (syngergistic)one another Hormones  Blood Hepatopancreatic Sphincter relaxes (CCK) 4. Pancreatic Juice secreted (CCK & Secretin) 5. Liver produces more bile (Secretin, Bile Salts) 6. Gallbladder contracts (CCK) Secretions enter Duodenum

8. Absorption across ample surface area (circular folds, villi, microvilli) Breakdown products of carbohydrate protein, fat, & nucleic acid digestion 9. Peristalsis: occurs after most nutrients have been absorbed; 10. Ileocecal Sphincter relaxes Next Meal, increased stomach activity  increased segmentation in Ileum Gastrin from stomach relaxes ileocecal sphincter remaining substances move into Lg. Intestine Sm. Intestine is emptied START ALL OVER AGAIN WITH CYCLE