Accessory Organs

1
Accessory Organs

• Pancreas, Liver and Gallbladder

2
Pancreas

• Secretes pancreatic juice into pancreatic duct
  then to the duodenum
• Function contains 4 classes of enzymes to break
  down substances.
• Location posterior to stomach left side

3
(No Transcript)
4
(No Transcript)
5
Pancreatic Juice

• Pancreatic amylase
• splits starch and glycogen into disaccharides
• Pancreatic lipase
• splits triglycerides into fatty acids and
  monoglycerides
• Proteinases (Trypsin, chymotrypsin,
  carboxypeptidase)
• Breaks up peptide bonds
• Nucleases
• split nucleic acid molecules

6
(No Transcript)
7
Pancreatic Juice

• Bicarbonate ions make pancreatic juice alkaline
  to neutralize acidic chyme

8
Pancreatic Secretion Regulation

• During cephalic and gastric digestive phases
  parasympathetic impulses stimulate pancreatic
  secretion.
• Secretin hormone
• causes release of pancreatic juice into duodenum
• stimulates a bicarbonate-rich fluid.
• Activated by the duodenum filling up with chyme

9
Figure 17.25
10
Pancreatitis

• Inflammation of pancreas
• Caused by activation of enzymes in the pancreas
  gland
• Trypsinogen------trypson

11
Liver

• Largest internal organ
• 2 lobed structure
• Large right and small left
• Each lobe is made up of Hepatic lobules function
  unit of the liver

Figure 17.28
12
Liver

• Lobes are divided into hepatic lobules
• hepatic cells around a central vein
• hepatic sinusoids lead to the hepatic portal vein
• Kupffer cells remove bacteria by phagocytosis
• bile canals lead to hepatic ducts which merge at
  the common bile duct

Figure 17.29
13
Liver Functions

• 1. Metabolism
• Carbohydrate metabolism
• stores glycogen, regulates blood glucose levels
• Lipid metabolism
• synthesizes lipoproteins, regulates lipid
  metabolism
• Protein metabolism
• deamination of amino acids, forming urea
• transamination of amino acids
• synthesis of plasma proteins
• (clotting proteins)

14
Liver Functions

• 2. Stores minerals and vitamins
• iron is stored as ferritin, Vit A, B 12 and
  glycogen
• 3. Detoxification of substances, including
  alcohol
• 4. Destruction of damaged red blood cells
• 5. Phagocytosis of foreign antigens
• Contain Kupffers cells
• Remove and destroy microbes, foreign matter and
  worm platelets and erythrocytes
• 6. Serves as a bile reservoir and Secretion of
  bile
• 7. Blood reservoir

15
Bile Composition

• Yellowish-green fluid secreted by hepatic cells
• Contains water (90), cholesterol, and
  electrolytes
• Contains bile salts
• Emulsify (break down) fats
• Makes cholesterol
• Contains bile pigments
• bilirubin, biliverdin
• breakdown products of hemoglobin

16
Figure 17.30
17
Jaundice

• Abnormal Skin pigmentation
• Excess bilirubin in the blood. (Bilirubin is
  produced by the normal breakdown of red blood
  cells. Normally bilirubin passes through the
  liver and is excreted as bile through the
  intestines)i
• Jaundice occurs when bilirubin builds up faster
  than the liver can break it down and pass it from
  the body.

18
Liver Diseases

• Cirrhosis
• Jaundice

19
Gallbladder

• Bile is produced by the liver and concentrated in
  the gall bladder.
• Stores bile between meals

Figure 17.32
20
Gallbladder

• Cholecystokinin CCK released in response to
  proteins and fats in the small intestine,
  stimulates gall bladder contraction.
• Bile leaves through the cystic duct to the common
  bile duct and is squirted into the duodenum of
  the small intestine.

21
(No Transcript)
22
Function of Bile Salts

• Bile salts enhance absorption of fatty acids and
  fat-soluble vitamins.
• Bile salts reduce surface tension and break fat
  into small droplets (emulsification).
• Emulsification increases surface area so lipases
  can more easily digest fats.
• The intestinal mucosa reabsorbs nearly all of the
  bile salts.

23
Blocked cystict duct
24
cholecystitis
25
Small Intestine

• Extends from the pyloric sphincter to the large
  intestine
• Three portions duodenum, jejunum, ileum
• Receives secretions from the pancreas and the
  liver
• Complete digestion of nutrients in chyme, absorbs
  products of digestion, transports residue to the
  large intestine

Figure 17.33
26
Figure 17.33
27
Small Intestine

• Double-layered folds of peritoneum
• mesentery supports intestinal nerves, blood and
  lymphatic vessels
• greater omentum drapes over the intestine
• Inner intestinal wall has many tiny projections,
  the intestinal villi. Each contains blood
  vessels, nerves and a lacteal
• Intestinal glands extend into the mucosa
• Circular folds of the mucosa, plicae circulares,
  increase surface area

28
Figure 17.35
29
Figure 17.36
30
Figure 17.37
31
Small Intestine Secretions

• Mucus is secreted by goblet cells and glands in
  the submucosa
• Intestinal mucosa have digestive enzymes on their
  luminal surfaces
• peptidases split peptides into amino acids
• sucrase, maltase, lactase split disaccharides
  into monosaccharides
• intestinal lipase splits fats into fatty acids
  and glycerol